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1
Tolley, Rebecca. "Seed Bank." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etsu-works/5660.
Abstract:
Book Summary:Issues: Understanding Controversy and Society brings important issues in today's world to students' attention, highlighting the complete historical background, contemporary status, and global view of each. It provides students authoritative context, diverse expert perspectives, and carefully selected primary and secondary sources for truly understanding the issues that currently affect much of our global society, and for developing informed positions on those engendering controversy.
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Tolley, Rebecca. "Seed Banks." Digital Commons @ East Tennessee State University, 2007. https://www.amzn.com/031333725X.
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Book Summary: The business of food and drink is for better and worse the business of our nation and our planet, and to most consumers how it works remains largely a mystery. This encyclopedia takes readers as consumers behind the scenes of the food and drink industries. The contributors come from a wide range of fields, and the scope of this encyclopedia is broad, covering from food companies and brands to the environment, health, science and technology, culture, finance, and more. The more than 150 essay entries also cover those issues that have been and continue to be of perennial importance. Historical context is emphasized and the focus is mainly on business in the United States. Most entries include Further Reading. The frontmatter includes an Alphabetical List of Entries and a Topical List of Entries to allow the reader to quickly find subjects of interest. Numerous cross-references in the entries and blind entries provide other search strategies. The person and subject index is another in-depth search tool.
3
Yehnjong, Petra Seka. "Paleozoic Seed Bank and Their Ecological Significance." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2316.
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Soil seed banks are a reservoir of viable seeds present in the soil in plant communities. They have been studied and characterized in various ways in different habitats. However, these studies are limited to modern seed banks. This study extends seed bank studies to the Paleozoic Era. It was hypothesized that size distribution and seed density in Paleozoic seed banks exhibit similar patterns as in modern seed banks. Seed sizes and seed density of fossil seed from Wise Virginia were estimated. Modern seed bank information was obtained from published data. Data were analyzed using one-way ANOVA and Kruskal-Wallis test. The Paleozoic size distribution was predominated by larger seeds and the estimated seed density of 19 200 seeds m-3 falls within the range of modern seed banks but at a higher end of modern seed bank densities. During the Paleozoic they were sufficient to insure regeneration of these economically important forests.
4
Kellerman, Millicent Johanna Susanna. "Seed bank dynamics of selected vegetation types in Maputaland, South Africa." Diss., Connect to this title online, 2004. http://upetd.up.ac.za/thesis/available/etd-02012005-090837.
5
Cooper, Cara A. "Melinis repens Seed Bank Longevity in Miami-Dade County." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/677.
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The main objective of this research was to determine the seed bank longevity of Melinis repens at two Southern Florida sites. Seeds were divided among different exposure levels (shade versus sun) and depths (surface versus buried) and tested for baseline viability using 2,3,5-Triphenyl-tetrazolium chloride. Statistical analysis determined that at the pine rockland site there was a significant interaction between time, exposure, and depth. The initial mean viability at this site declined from 49.71% to 11.26% and 13.06% for sun/buried seeds and sun/surface seeds, respectively, by month 8. The mean viability of shade/surface seeds and shade/buried seeds declined to 24.56% and 22.06% after 8 months. There were no significant effects in the Florida scrub. In order for land managers to completely remove this species from a site, treatment with herbicide will need to continue for a minimum of one year to effectively kill all viable seeds in the seed bank.
6
Martin, Anna. "Mathematical modeling of seed bank dynamics in population genetics." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-321191.
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We study the genealogical structure of samples from a population for which any givengeneration is made up of direct descendants from one randomly chosen previousgeneration. These occur in nature when there are seed banks or egg banks allowingan individual to leave offspring several generations in the future. Kaj et al. studied in2001 the case where any given generation is made up of descendants from severalprevious generations and showed how this temporal structure in the reproductionmechanism causes a decrease in the coalescence rate. In this project we will showthat having all samples pick their parents in one randomly chosen generation will leadto a coalescent process which is equivalent to a time shifted version of Kingman’scoalescent, time shifted with the age distribution of the seed bank.
7
Davis, Jessica. "Soil seed bank dynamics in Mediterranean urban vegetation fragments." Thesis, Davis, Jessica (2012) Soil seed bank dynamics in Mediterranean urban vegetation fragments. Masters by Coursework thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/12926/.
Abstract:
Conservation of biodiversity in urban vegetation fragments is of increasingly high importance with growing urbanisation globally, particularly so in the biodiversity hotspot of the Mediterranean southwest of Western Australia. Relationships between fragmentation (connectivity, fragment size, time since isolation) and urban disturbances (weed invasion, human disturbance, rubbish) relative to the soil seed bank of a representative sample of Perth’s urban woodland fragments (N=36) were examined. In total, 182 seedling types comprising 57 invasive, 105 native and 20 unknowns were identified. Approximately 65% of the 21,770 seedlings counted were native, 33% invasive and 2% unidentified. The average soil seed bank seedling density was 2,787 germinates per m2. Community analysis (ordination) showed that the soil seed bank composition correlated with fragment age. Subsequent quantitative analysis (linear regression) did not find evidence for species or functional trait groups being vulnerable to decline due to isolation or fragment age, indicating that species extinction is not evident within Perth’s urban fragments. More invasive annual herbs were found within older fragments and the soil seed banks of smaller fragments were found to have lower native species abundance compared to larger fragments. A positive relationship was found between the number of footpaths within a fragment and the abundance of annual invasive herbs within the soil seed bank. High weed cover in a fragment resulted in high weed presence within the soil seed bank. It was also found that high weed cover did not necessarily indicate low native species diversity or abundance within the soil seed bank, suggesting caution in using weed cover to classify sites as suitable/unsuitable for topsoil transfer in restoration activities. The soil seed bank of the study sites contained a diverse range of native species, indicating that topsoil from these areas may be useful in restoration of degraded sites.
8
Passos, Isabel Maria Melo Mendes. "Importance of seed bank for the management of invasive Acacia dealbata." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13375.
Abstract:
Mestrado em Ecologia AplicadaThe management of invasive plants is a hard task, which may be further hampered by the existence of extensive and long-lived seed banks. Acacia dealbata is an Australian tree considered one of the most aggressive invasive plant species in Portugal; the species is known to produce a persistent seed bank, but its extension and viability hasn’t been explored. In this work we aim to characterize the seed bank of A. dealbata, namely its extension, germinability and viability, in order to contribute to the management of the species, but also increase knowledge about its ecology. The extension of the seed bank was assessed by collecting soil samples in invaded stands and adjacent areas and counting the seeds. These were then germinated at 25ºC and some were exposed to an initial temperature of 60ºC, aiming to assess the effect of extreme soil temperature in dormancy breaking. Results showed that beneath canopy the seed bank averaged 4 608 seed/m2 (± 820), but maximum values can reach 62 747 seeds/m2. In areas adjacent to the invaded stands a mean value of 9 seeds/m2 (± 5) was found, with maximum values of 632 seeds/m2. Although only 8,6% of the seeds germinated without any stimulus, in total 89,7% of the seeds found showed to be viable after scarification, with 81% of the seeds remaining dormant in the soil. Of the seeds exposed to 60ºC almost 64% germinated without any physical stimulation, suggesting that extreme soil temperatures, reached in hot days, may break seed dormancy. Multivariate analysis showed that the probability of accumulating high numbers of seeds in soil decreases with higher stoniness and root density, and increases with higher A. dealbata density and with fewer fire events. Our results show that the soil seed bank of A. dealbata is numerous and viable, suggesting that risk of reinvasion after plant removal is very high. It was also shown that the species has the ability to disperse seed beyond invaded stands Although frequently disregarded, this study alerts for the need to include extensive and long-lived seed banks in the management of invasive plants, since these hidden legacies may quickly hamper control efforts. Alternatives to deal with such seed banks are discussed.
O controlo de plantas invasoras é uma tarefa árdua, dificultada pela existência de bancos de sementes extensos e com longa viabilidade. A espécie Acacia dealbata é uma árvore nativa da Austrália, considerada como uma das espécies invasoras mais agressivas em Portugal. Sabe-se que o seu banco de sementes permanece viável no solo por muitos anos, no entanto a sua extensão e a viabilidade das sementes não são ainda conhecidos. O presente trabalho tem como objetivo caracterizar esse banco de sementes, a sua extensão, viabilidade e germinabilidade, de forma a contribuir para a sua gestão e para o conhecimento geral sobre a ecologia da espécie. A extensão do banco de sementes foi avaliada através da recolha de amostras de solo em áreas invadidas e zonas adjacentes não invadidas, realizando-se depois a contagem das sementes. Depois de contabilizadas, as sementes foram postas a germinar a 25ºC, sendo que uma parte foi exposta a uma temperatura inicial de 60ºC, com o objetivo de perceber se temperaturas extremas no solo podem quebrar a dormência das sementes. Os resultados indicam que nas áreas invadidas o banco de sementes tem uma densidade média de 4 608 sementes/m2 (± 820), sendo que os valores máximos observados foram de 62 747 sementes/m2. Nas áreas adjacentes observaram-se em média 9 sementes/m2 (± 5), com um valor máximo de 632 sementes/m2. Apesar de apenas 8,6% das sementes terem germinado sem qualquer estímulo, 89,7% do banco de sementes germinou após a escarificação das sementes, indicando que 81% das sementes armazenadas no solo se encontram dormentes. Das sementes inicialmente expostas a 60ºC, cerca de 64% germinaram sem escarificação, sugerindo que a ocorrência de temperaturas anormalmente altas pode estimular a germinação. De acordo com a análise estatística efetuada a probabilidade o número de sementes acumuladas no solo diminui com o aumento de pedregosidade e com a densidade de raízes; por outro lado, o banco de sementes aumenta com densidade de A. dealbata e em áreas sujeitas a menos incêndios. Os resultados obtidos demonstram a elevada viabilidade e densidade do banco de sementes de A.dealbata, evidenciando o elevado risco de reinvasão de áreas onde se realizam ações de controlo da espécie. Este estudo alerta para a necessidade de incluir a gestão do banco de sementes nos planos de controlo de espécies invasoras,alertando para o facto de a espécie ser capaz de dispersar sementes atém das áreas invadidas. Estas características transformam o banco de sementes numa herança escondida, que pode dificultar as ações de controlo. São discutidos diferentes métodos possíveis para lidar com bancos de sementes.
9
Goodson, Joanne Marie. "Environmental controls on the colonisation and establishment of vegetation on river banks under varying grazing pressure." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289259.
10
Auffret, Alistair G., and Sara A. O. Cousins. "Past and present management influences the seed bank and seed rain in a rural landscape mosaic." Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-69879.
Abstract:
1. Seed bank and seed rain represent dispersal in time and space. They can be important sources of diversity in the rural landscape, where fragmented habitats are linked by their histories. 2. Seed bank, seed rain and above-ground vegetation were sampled in four habitat types (abandoned semi-natural grassland (ABA), grazed former arable field (FAF), mid-field islet (MFI) and grazed semi-natural grassland (SNG)) in a rural landscape in southern Sweden, to examine whether community patterns can be distinguished at large spatial scales and whether seed bank and seed rain are best explained by current, past or intended future vegetation communities. 3. We counted 54 357 seedlings of 188 species from 1190 seed bank and 797 seed rain samples. Seed bank, seed rain and above-ground vegetation communities differed according to habitat. Several species characteristic of managed grassland vegetation were present in the seed bank, seed rain and vegetation of the other habitats. 4. The seed banks of SNGs and the seed rain of the FAFs were generally better predicted by the surrounding above-ground vegetation than were the other habitat types. The seed rain of the grazed communities was most similar to the vegetation in the FAFs, while the seed banks of the abandoned grasslands most resembled the vegetation in SNGs. 5. Gap availability and seed input could be limiting the colonisation of target species in FAFs, while remnant populations in the seed bank and the presence of grassland specialists in the above-ground vegetation indicate that abandoned grasslands and mid-field islets could be valuable sources of future diversity in the landscape after restoration. 6. Synthesis and applications. SNG communities are able to form seed banks which survive land-use change, but their seed rain does not reflect their above-ground communities. It is important that grassland plants set seed. By connecting existing grasslands with restoration targets, increased disturbance in the target habitats would allow for colonisation via the seed bank or seed rain, while decreased grazing intensity would benefit seed production in the source grasslands. Otherwise, landscape-wide propagule availability might increase with a more varied timing and intensity of management.
11
Short, Nicolyn. "Implications of green manure amendments on soil seed bank dynamics." University of Western Australia. School of Earth and Geographical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0022.
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[Truncated abstract] Weeds are a major limitation to agricultural and horticultural production and the main method of control is the use of herbicides. In addition to the resulting chemical pollution of the environment, the wide spread and continues use of herbicides have resulted in many weeds developing resistance to commonly used herbicides. This study investigated the potential of using green manures as a cultural method of control of weed invasion in agricultural fields. To understand the general mechanisms involved in the suppression of seed germination in green manure amended soils, seeds of crop species with little or no dormancy requirements were used in certain studies. Lettuce (Lactuca sativa) and cress (Lepidium sativum) seeds were sown to a sandy soil amended with green manures of lupin (Lupinus angustifolius), Brassica juncea, or oats (Avena sativa) to determine if the amendments affected seed germination and/or decay. It was hypothesised that the addition of plant material would increase the microbial activity of the soil thereby increasing seed decay, under laboratory and greenhouse conditions. Initial experiments used lettuce, cress and lupin seeds. Lettuce and cress are commonly used as standard test species for seed viability studies. Subsequent experiments used seeds of annual ryegrass (Lolium rigidum), silver grass (Vulpia bromoides), wild radish (Raphanus raphanistrum) and wild oat (Avena fatua) as these weed species are commonly found throughout agricultural regions in Western Australia. Amending the soil with lupin or Brassica green manure was established as treatments capable of developing environments suppressive to seed germination. Lupin residues as green manure showed the strongest inhibition of seed germination and seed decay. The decay of certain seeds was enhanced with changes to soil microbial activity, dissolved organic carbon and carbon and nitrogen amounts in lupin amended soil. Seeds of weed species were decayed in lupin amended soil, but showed varied degree of decay. Annual ryegrass and silver grass were severely decayed and wild oat and wild radish were less decayed, in lupin amended soil.
12
Strydom, Matthys. "A perspective on the seed bank dynamics of Acacia saligna." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20389.
Abstract:
Thesis (MScConEcol)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Acacia saligna, or Port Jackson, is an Australian Acacia which has spread throughout the Western and Eastern Cape provinces of South Africa where it has become invasive and a prominent feature of the vegetation. In areas where A. saligna establishes it replaces natural vegetation, alters ecosystem processes and interferes with agricultural practices. Consequently large management efforts have been made to eradicate this invasive alien tree. However, its large and persistent soil stored seed bank, even in the presence of management and biological control agents, poses a serious obstacle to its successful removal. Furthermore the reproductive output and the size of the seed bank of A. saligna over its whole distribution as well as the variation of seed production and the seed bank with environmental conditions in time and space is poorly known. Understanding the seed bank dynamics of A. saligna in time and space is essential for reducing invasive success and achieving management objectives. This study has filled this knowledge gap through studying the seed production and seed bank of A. saligna over its invaded range in South Africa, including how environmental factors influence these factors in time and space. The seed rain of A. saligna was assessed at 10 sites across its distribution in South Africa. The seed rain of A. saligna at the sites was determined through the use of seed rain traps. Twenty five traps were placed out at every site during November 2010 (pre-dehiscence) which was collected again during April 2011 (postdehiscence). The seed bank of A. saligna was estimated through sampling at 25 sites across its distribution range in South Africa. The seed bank was sampled during April 2010 (postdehiscence), November 2010 (pre-dehiscence) and April 2011 (post-dehiscence) through taking 50 litter and soil samples at every site which gave a total sampling size of 3 750 for both the seed in the soil and litter over its distribution in South Africa. In addition the average tree diameter, tree density, average number of Uromycladium tepperianum induced galls per tree, the summer aridity index, De Martonne aridity index, winter concentration of precipitation, temperature of coldest month and the soil texture for every site was determined. The damage done by the seed feeding weevil, Melanterius compactus, was also estimated for the seed rain study sites. Water availability during the hot summer months was assessed as the most important factor governing seed production and seed bank size. Riparian and non-riparian water regimes were shown to be important in understanding the seed bank dynamics of A. saligna over its distribution range in the Cape Floristic Region. In non-riparian A. saligna populations the seed production and consequently the size of the seed bank and its rate of accumulation is limited by both water and temperature and in riparian A. saligna populations, only by temperature. Therefore, two environmental gradients influence the seed bank dynamics of Port Jackson in South Africa. In non-riparian A. saligna populations the number of seed produced and the accumulation of seed in the seed bank generally increases along the west coast of South Africa from Clanwilliam towards Cape Town and along the south coast from Cape Town towards Port Elizabeth. Seed banks are larger closer to the coast, when A. saligna populations of similar age are compared. In riparian A. saligna populations, the number of seed produced generally increases from Port Elizabeth towards Cape Town and from Cape Town towards Clanwilliam, again, with larger seed banks being accumulated closer to the coast, when populations of similar age are compared. This study provides managers with a useful tool for prioritising management efforts.
AFRIKAANSE OPSOMMING: Acacia saligna of Port Jackson is ‘n indringerplant in Suid-Afrika wat afkomstig is uit Suid-Wes Australië. Acacia saligna is ‘n onmisbare kenmerk van die plantegroei in die Wes en Oos-Kaap. Waar Port Jackson vestig, verplaas dit natuurlike plantegroei, verander dit ekosisteem prossesse en verhinder dit landbou praktyke. Gevolglik is groot bestuurspogings aangewend om hierdie indringer plant uit te roei. In die teenwoordigheid van bestuursprogramme en biologiese beheer bly A. saligna lewensvatbaar as ‘n gevolg van die plant se groot blywende grond saadreserwes. Verder is die saad produksie en saadbank grootte van A. saligna oor sy verspreiding bereike asook hoe dit met omgewingstoestande in tyd en ruimte interreageer en varieer grootendeels onbekend. ‘n Goeie en omvattende begrip van die saadbankdinamika is belangrik om die indringings vermoë van die plant te verlaag en om bestuursdoelwitte te bereik. Hierdie studie vul die bestaande gaping in die kennis aangaande die saadbank dinamika van A. saligna aan deur die saadproduksie en die saadreserves van die indringerplant oor sy verspreiding in Suid-Afrika te bestudeer, insluitend hoe omgewingstoestande die saadbankdinamika beïnvloed in tyd en ruimte. Die saadreën vir 10 A. saligna populasies was bepaal deur die gebruik van saadlokvalle. Vyf-entwintig lokvalle was uitgeplaas in elke bestudeerde Port Jackson perseel gedurende November 2010 (voor-saadval) wat weer gaan haal is gedurende April 2011 (na-saadval). Die saadbank van A. saligna was bepaal in 25 populasies van die boom gedurende April 2010 (na-saadval), November 2010 (voor-saadval) en April 2011 (na-saadval) deur die neem van 50 blaar- en grondmonsters by elke perseel wat ‘n totaal van 3 750 blaar- en grondmonster gee oor die hele verspreiding van A. saligna in Suid-Afrika. Verder is die gemiddelde boomdeursnee, boomdigtheid, gemiddelde Uromycladium tepperianum geinduseerde galle per boom, die somers droogtheids indeks, De Martonnes droogtheids indeks, die winter konsentrasie van presipitasie, die temperatuur van die koudste maand en die grond tekstuur van elke Port Jackson stand bepaal. Die skade wat die saad voedende kewer, Melanterius compactus, aanrig aan die sade van A. saligna is ook vir die persele waar die saadreën eksperiment uitgevoer is, bepaal. Die beskikbaarheid van water vir A. saligna in die droë somermaande is bepaal as die belangrikste faktor wat die grootte van die saadproduksie en saadbank beïnvloed. Oewer en nie-oewer water omgewings is bevind as noodsaaklik om die saadbank dinamika van A. saligna oor die indringerplant se verspreidingareas in die Kaap Floristiese Streek te verstaan. In nie-oewer A. saligna populasies word saadproduksie en gevolglik die grootte en tempo van akkumulasie van die saadbank deur beide water en temperatuur omstandighede beperk, terwyl in oewer A. saligna populasies word die indringerplant slegs deur temperatuur omstandighede beperk. Gevolglik blyk dit dat twee water beskikbaarheids gradiënte bestaan waarop die plant reageer wat dan uitgedruk word in die plant se saad produksie en gevolglik ook die plant se saadbank. In nie-oewer Port Jackson populasies neem die saadproduksie en die tempo waarteen die saadbank akkumuleer algemeen toe langs die weskus van Clanwilliam na Kaapstad en van Kaapstad na Port Elizabeth, met grootter saadproduksie en saadbank akkumulasie nader aan die kusgebiede, wanneer A. saligna populasies van dieselfde ouderdom vergelyk word. In oewer Port Jackson populasies neem die saadproduksie en die tempo waarteen die saadbank akkumuleer algemeen toe van Port Elizabeth na Kaapstad en van Kaapstad na Clanwilliam, met grootter saadproduksie en saadbank akkumulasie nader aan die kusgebiede, wanneer A. saligna populasies van dieselfde ouderdom vergelyk word. Hierdie studie verskaf bestuursplanne met ‘n nuttige raamwerk waarvolgens uitroeiing en beheer programme vir A. saligna beplan kan word.
13
Fowler, William. "Soil seed bank dynamics in transferred topsoil: Evaluating restoration potentials." Thesis, Fowler, William (2012) Soil seed bank dynamics in transferred topsoil: Evaluating restoration potentials. Honours thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/13389/.
Abstract:
Global change, increasing human population growth and urbanisation represent increasing pressures on biodiversity and ecosystem function. It is now widely recognised that conservation of existing natural fragments will not be sufficient to maintain extant biodiversity or meet conservation goals. Thus there is a major and rapidly expanding need for the practice of ecological restoration whereby degraded lands are managed to increase and maintain indigenous species.
A soil seed bank germination experiment was conducted over a period of 13 weeks. This aimed to evaluate restoration values of topsoil transfer, by investigating soil seed bank similarity to standing vegetation, and exploring mechanisms to improve restoration outcomes on the Swan Coastal Plain, Western Australia. This was experimentally designed to make comparisons between the soil seed bank pre and post-transfer, an aspect of topsoil transfer that has not been looked at previously. In addition sampling was conducted at two depths, with treated (smoke and heat) and non-treated trials. This study examined the similarity of the soil seed bank to standing vegetation, the effect of soil transfer, and the influence of soil spreading depth and fire related germination cues.
Seventy-three per cent of germinants were found in the top 5 cm of natural (pre-transfer), soil transfer leading to mixing (no depth effect) and a reduction in germinant densities (-2472.00 germinants m-2). Treatment with germination cues (heat and smoke in concert) increased germinant densities by 1537.80 germinants m-2, however no increase in transferred soils was observed. Native annuals dominated species composition of transferred soils, contributing 68% of observed richness, with woody species only accounting for 9% overall. The similarity of the soil seed bank to the standing vegetation ranged from 15% to 19%, the higher similarity found when treatment was used. Overall topsoil transfer is a useful tool for restoration; however it must be used in conjunction with other methods, such as planting and direct seeding, to return a representative set of species to a site
14
Holmes, P. M. "A comparative study of the seed bank dynamics of two congeneric alien invasive species." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/17724.
Abstract:
Includes bibliographies.The unique vegetation in the lowlands of the fynbos biome is threatened by alien Acacia encroachment. The seed bank dynamics of the two most widespread invaders in the region, Acacia saligma and A. cyclops, was studied to elucidate those factors contributing most to their invasive success. This information was then used to assist in developing optimal control methods. On the basis of information available prior to this study, it was predicted that both species would have large, persistent seed banks in the so.il, and that seed bank processes would provide the - key to invasive success: namely, high seed longevity and heat-stimulated germination. Seed banks were monitored for several years following clearing of the parent stand, using either sites sampled in an earlier study, or sites providing chronosequences of clearing dates. Concurrently, a demographic study of the species' seed banks, including processes from seed rain through to seedling emergence and survival, was done in dense Acacia stands and in fynbos vegetation. Acacia saligma seed banks conformed to predictions, being large and persistent owing to high percentage viability and water-impermeable dormancy. Seed banks accumulate rapidly under dense stands and are "disturbance-coupled" as they have potentially high longevity unless stimulated to germinate by fire. Although A. cyclops seed banks also may be large and long-lived, they display variable percentage viability and dormancy, with the majority of a seed cohort surviving less than a year. Acacia cyclops seed banks do not respond to heat treatment and appear to be "disturbance-uncoupled".
15
Rossiter, Stephen Cary. "Effects of the seed bank and interseeding in reconstructed tallgrass prairies." Thesis, The University of North Dakota, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1552216.
Abstract:
Disturbances such as fire and mowing temporarily increase available resources for plants, opening a window of opportunity for establishment. During the recovery of vegetation after disturbance in remnant prairies, seedling establishment is often negligible compared to vegetative regrowth. It is unclear if this is the case in reconstructions. I tested the contribution of seedlings to diversity after disturbance in two, 25-year-old, low diversity reconstructed prairies by removing seedlings, allowing seedlings, and adding seed in 1 m 2 plots. Disturbance frequency effects were tested by clipping each treatment zero, one, or multiple times. After two growing seasons, in the wetter field site, seedlings removed plots had the lowest species richness and highest evenness, plots with seedlings from the seed bank were intermediate, and plots with added seed had the highest richness and lowest evenness. In the drier site, only adding seed impacted richness (higher) and evenness (lower). In both sites, the seeds present in the seed bank were over 80% from non-native species. Seedling establishment was quantified along with light, water, and nitrate availability within each seeded plot. In the wetter site, resource levels did not predict seedling numbers, but seedlings were more numerous in more frequently clipped, lighter plots. In the drier site, seedlings were more numerous in less frequently clipped plots which received less light and may have remained moister. Seedling establishment from any source never affected community diversity suggesting that while some seeds establish, reconstructions are primarily maintained by vegetative reproduction. The inconsistent effect of clipping highlights the need for management to adapt to varying precipitation, however, given the non-native dominated seed banks, any management intended to increase seedling establishment could result in increased non-native cover.
16
Jones, Naomi Elizabeth. "Temporal and spatial variation of the vegetation seed bank and seed-rain in set-aside and adjacent habitats." Thesis, University of Aberdeen, 1995. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU068101.
Abstract:
In this study set-aside development was monitored (1989-1992) at Aldroughty Farm, Morayshire as part of an integrated project looking at plant and animal dynamics in set-aside, crop and semi-natural habitats. The vegetation, seed bank and seed rain were monitored in adjacent set-aside, semi natural and cropped areas. Initially set-aside vegetation consisted of annual arable species, but wind dispersed species and longer-lived perennials invaded rapidly. This process was more rapid on smaller plots and ingress of perennials occurred more quickly closer to the field margin. There was little invasion from adjacent semi-natural habitats and the field margin was the most important source of colonising species. Cropped areas were not significantly affected by adjacent set-aside. Seed banks were analysed using germination and extraction techniques which gave different estimates. Highest densities were found on set-aside land indicating the problems associated with returning set-aside to agricultural production. Changes in the seed bank were less apparent than in the vegetation, but within-year variation was great and carryover of seeds from October to March was low. The seed rain was monitored using gravel traps. Densities were highest on set-aside and lowest in the crop and wood. Individual species exhibited different phenologies in seed shedding, but peak deposition coincided with cutting. Dispersal from the set-aside into the crop was very low and dispersal distances were small. Vegetation and seed rain were similar in species composition in the set-aside areas. Although the seed rain was similar to seed bank samples taken immediately after seed shed, a large proportion of seeds did not enter the seed bank. Set-aside land did not develop into semi-natural habitat, however species diversity increased and the land provided a food source and an undisturbed habitat for animals. The real concern is the return of set-aside land to agricultural production, because of increased seed bank densities.
17
Welling, P. (Pirjo). "Regeneration by seeds and vegetation structure in alpine plant communities, subarctic Finland." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:951426861X.
Abstract:
Abstract
The aims were to examine the importance of regeneration by seeds, the
influence of plant traits and disturbances, and the role of seed-seedling
conflicts in regeneration and in the determination of vegetation structure.
The study was carried out at in a subarctic alpine area (Kilpisjärvi
69°01'N 20°50E', Finland).
Seed bank and seedling densities were high in many plant communities
(ranges 99 -1109 viable seeds/m2 and 0.2-227
seedlings/m2, respectively). Effective seedling
recruitment is reflected in vegetation as a high proportion of plants with
poor or no vegetative reproduction ability. This development may take place
in meadows and snowbeds where herbs (e.g. Gnaphalium
supinum, Sibbaldia procumbens,
Veronica alpina and Viola
biflora) are abundant. On the other hand, the low proportion of
these plants in heath vegetation reflects ineffective seedling
recruitment.
Floristic similarities between the consecutive phases in the
regeneration pathway may be low despite effective seedling recruitment.
Clonality, large and small seed sizes and appendaged diaspores limit the
movement of species from phase to phase.
Generally, disturbances facilitate effective regeneration by seeds.
Grazing promotes species with large seed banks and is therefore one reason
for high seed bank densities. Freezing and melting processes negate a
negative influence of altitude on seed bank densities in the phase of
seedlings. However, if disturbances are severe and continuous and the soil
is compact, unstable or dry, disturbances are not beneficial. The same is
true if there is a shift in the species composition of seedlings from gaps
to closed vegetation. This phenomenon occurred in a rich meadow.
Seed-seedling conflicts limit regeneration by seeds in low-herb
snowbeds and Ranunculus glacialis-Gymnomitrion
snowbeds. Vegetative reproduction and infrequent pulses of seedling
recruitment negate an influence of short-term seedling recruitment on the
spatial structure of vegetation. Extreme conditions, such as low
temperatures, instability of the soil and late snowmelt modify the
influence of factors that are important in more moderate conditions.
To conclude, all transitions limit regeneration by seeds. However,
favourable conditions (e.g. moist conditions in a meadow) partly eliminate
the obstacles against seedling emergence. Regeneration by seeds therefore
has a major impact on the dynamics and structure of vegetation. In heath
vegetation, where bare soils are dry and the moss cover is thick, large
seed banks and seed rains do not guarantee effective seedling recruitment.
The regeneration process is reduced in the early phases, and plants that reproduce primarily by seeds have a minor role in vegetation. The accumulation of seed banks is effective in these circumstances.
18
Silva, Carla Antónia Mendes. "Optimização dos testes de germinação para monitorização das colecções de plantas autóctones conservadas em bancos de sementes." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5364.
Abstract:
Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaWith the aim to contribute to the optimization of germination tests to monitor the seed collections of native plants conserved in seed banks, germination percentage, germination rate (T50) and lenght of the germination period (T10-90) were evaluated in 16 species studied on four temperatures 15°C, 20°C, 25ºC and 15º/25 ºC. The species were subject to pre-germination treatments to break dormancy: cold stratification (30 days) at 4°C in Scrophulariaceae and Umbelliferae, mechanical scarification in Malvaceae, and Fabaceae, and thermal scarification (115ºC, 10 min.) in Cistaceae. Seeds were incubated in a photoperiod of 8 hours light/16 hours dark. According to results, the species germinated better for the following pretreatements and temperatures: in Cistaceae (thermal scarification): Tuberaria lignosa at 20°C and Halimium lasianthum to 15º/25ºC; in the Fabaceae (mechanical scarification): Adenocarpus complicatus at 15°C and 20°C, Cytisus villosus at 15°C and Vicia sativa subsp.nigra at 20°C; in Malvaceae (mechanical scarification): Alcea rosea at 20°C, Lavatera arborea and Lavatera cretica at 15°C. Pretreatements did not promote the germination of species of the families Scrophulariaceae and Umbelliferae.
19
Schelling, Lisa R. "Soil seed banks in mixed oak forests in Southeastern Ohio." Ohio : Ohio University, 2006. http://www.ohiolink.edu/etd/view.cgi?ohiou1141850222.
20
Nicol, Jason. "Vegetation dynamics of the Menindee Lakes with reference to the seed bank." Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phn633.pdf.
21
Horaist, David W. "Estimating Seed Bank Responses to Changing Environmental Conditions in the Louisiana Coastal Zone." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10002484.
Abstract:
The coastal zone of Louisiana is changing due to multiple pressures associated with sea-level rise, subsidence, and the inability of sediment or organic accretion to keep pace. The expected increases in sea level and salinity may affect the distribution of the existing plant communities. In addition, these changes in the environment could lead to shifts in plant community composition. During the summer of 2014, I researched how changes in salinity and water levels may change the establishment of vegetation in Louisiana marshes. Randomly selected Coastwide Reference Monitoring System (CRMS) sites were used to collect vegetation data and soil samples. The collected soil samples from fresh, intermediate, brackish, and saline marsh sites were used in a seed bank study. The seed bank study evaluated the effects of different levels of salinity and flooding on seed germination and species richness. Seed germination was highest in soil samples collected from fresh and intermediate sites when these samples were exposed to low salinity (0.0 ppt) and non-flooded conditions. My study only found 43 seedlings in the 10 ppt treatment of 336 total seed germinations, and only 2 seedlings were found in the 20 ppt salinity treatment. Salinity was the dominant factor governing seed germinations and species richness. I also determined that the parent plants for the species found in my seed bank study were more likely to be found within the study site. However, the species data showed at least one species or genus was not present in either the historical or the field collected data. Therefore, the dispersal distance of some seeds from their parental seed provider could have been several hundred meters.
22
Prigmore, Deborah Susan. "Ground flora variation and management in Forestry Commission plantations at Thetford, East Anglia." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297049.
23
Maighel, Mahmood [Verfasser]. "Effect of Arbuscular mycorrhizal fungi and biochar on soil seed bank viability / Mahmood Maighel." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1117028453/34.
24
Pessoa, Carla Daniela de Sales. "Soil Seed Bank in a Caatinga area in Regeneration, Center for Desertification IrauÃuba, CearÃ." Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9200.
Abstract:
CoordenaÃÃo de AperfeiÃoamento de NÃvel SuperiorO presente trabalho tem como objetivo conhecer os atributos do banco de sementes no solo e verificar quais desses refletem melhor a regeneraÃÃo da caatinga em Ãreas de desertificaÃÃo. Para tanto, investigou-se o banco de sementes no final da estaÃÃo seca, em uma Ãrea de caatinga em processo de degradaÃÃo/desertificaÃÃo, no municÃpio de IrauÃuba, CearÃ. Foram analisados os atributos densidade, composiÃÃo, diversidade e riqueza de espÃcies e cinÃtica de germinaÃÃo. As coletas foram realizadas em trÃs Ãreas, nas fazendas Formigueiro, Cacimba Salgada I e Cacimba Salgada II. Em cada Ãrea foi amostrado o banco de sementes no solo na parcela experimental (pousio) e na parcela em uso contÃnuo (controle). Cada parcela de cada Ãrea foi subdividida em dezesseis parcelas de 10x10m, das quais foram sorteadas cinco para estudo do banco de sementes no solo. No centro de cada uma das cinco parcelas de 100m2 foi retirada amostra de solo de 0,25m2 de Ãrea. A densidade e a composiÃÃo do banco de sementes no solo foram analisadas atravÃs da tÃcnica de emergÃncia de plÃntulas em casa de vegetaÃÃo. O banco foi composto prioritariamente por terÃfitos. As densidades encontradas foram 592, 1804, 2080 sem/m2 para as parcelas experimentais 1, 2 e 3, respectivamente e 680, 1288 e 1408 sem/m2, para as parcelas controle 1, 2 e 3, respectivamente. No parÃmetro riqueza, foram encontrados iguais valores para as parcelas experimento e controle (8 e 2 para as Ãreas 1 e 2, respectivamente), a Ãrea 3 apresentou maior riqueza na parcela em pousio (15 e 10 para as parcelas controle e experimento, respectivamente). Os valores de equabilidade nas parcelas experimento foram de 0,751, 0,041 e 0,740 para as Ãreas 1, 2 e 3, respectivamente, e de 0,613, 0,054 e 0,603 para as Ãreas 1, 2 e 3 das parcelas controle. Em relaÃÃo à diversidade, os valores para as parcelas experimentais 1, 2 e 3 foram 1,562, 0,028, 2,004, respectivamente, e 1274, 0,038 e 1,388 para as parcelas controle, 1, 2 e 3, respectivamente, o que revela uma maior diversidade nas Ãreas em pousio, com exceÃÃo da Ãrea 2. Os aumentos da diversidade e da densidade demonstram a ocorrÃncia de regeneraÃÃo do componente herbÃceo nas Ãreas em pousio.
The objective of this study is to gather knowledge about the attributes of a seed bank at soil level and to verify which of these attributes reflect the best regeneration of the caatinga in areas of desertification. In order to do that, we investigated the seed bank at the end of the dry season in a area of caatinga suffering the process of degradation/desertification, at the municipality of IrauÃuba, CearÃ. We analysed the attributes of density, composition, diversity and richness of species as well as germination dynamics. The collections were realized in three areas, at Formigueiro, Cacimba Salgada I and Cacimba Salgada II farms. In each area, we sampled a seed bank at soil level in the experimental portion (fallow) and at the continuous use portion (control). Each portion of each area was divided in sixteen portions of 10 x 10 m, from which were drawn five portions for the study of the seed bank at soil level. In the center of each one of the five portions of 100 m2, a soil sample of 0,25 m2 was removed. The density and the composition of the seed bank at the soil level were analysed using the plantule outgrowth in greenhouse. The bank was composed primarily by therophytes. The densities found were 592, 1804, 2080 seeds/m2 for the experimental portions 1, 2 and 3, respectively, and 680, 1288 and 1408 seeds/m2 for the control portions 1, 2 and 3, respectively. Regarding the richness parameter, we found equal values for both the experimental and control portions (8 and 2 for areas 1 and 2, respectively); area 3 presented greater richness in the fallow portion (15 and 10 for the control and experimental portions, respectively). The equability values of the experimental portions were equal to 0,751, 0,041 and 0,740 for areas 1,2 and 3 respectively and of 0,613, 0,054 and 0,603 for areas 1,2 and 3 of the control portions. Regarding diversity, the values for the experimental portions 1, 2 and 3 were 1,562, 0,028 and 2,004, respectively, and 1274, 0,038 and 1,388 for the control portions 1,2 and 3, respectively, which reveals a major diversity for the areas of fallow, with exception of area 2. The raising diversity and density demonstrate the occurrence of regeneration of the herbaceous component in the fallow areas.
25
Maze, Kristal E. "Seed bank depletion effects on post-fire recruitment of two co-occurring Protea species." Thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/23937.
26
Searle, Allyson B. "Reproductive Success and Soil Seed Bank Characteristics of Astragalus ampullarioides and A. holmgreniorum (Fabaceae): Two Rare Endemics of Southwestern Utah." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/3044.
Abstract:
Astragalus ampullarioides and A. holmgreniorum are two rare endemics of southwestern Utah. Over two consecutive field seasons (2009-2010) we examined pre-emergent reproductive success, based on F/F and S/O ratios, from populations of both Astragalus ampullarioides and A. holmgreniorum, estimated the density of the soil seed bank of A. holmgreniorum as a measure of potential post-emergent reproductive success, and estimated seed persistence within the soil seed bank. Fruit/flower (F/F) ratios and seed/ovule (S/O) ratios varied significantly between populations and among years in both species, and showed low reproductive output in both taxa. In Astragalus ampullarioides F/F and S/O were 0.06±0.01 and 0.16±0.02, respectively (2009), and 0.14±0.01 and 0.41±0.02, respectively (2010). For Astragalus holmgreniorum F/F and S/O ratios were 0.11±0.01 and 0.38±0.02, respectively (2009), and 0.23±0.01 and 0.66±0.02, respectively (2010). Although Astragalus holmgreniorum exhibited a low soil seed bank density (4.3 seeds m-2), seed persistence data showed low a low percentage of seeds germinated during the first year in the soil seed bank. Seeds remaining in the seed bank maintained high percent viability. Soil seed persistence of Astragalus ampullarioides differed from A. holmgreniorum in that a high percentage of seeds germinated during the first year in the soil seed bank. A high percentage of viability in ungerminated seeds was also maintained in A. ampullarioides. Although these species differ in life histories and dependence on soil seed banks, an understanding of the strategies unique to each species will prove useful in management plans.
27
Coulombe, Anne-Marie. "Evaluation of the seed bank content as a predictor of weed infestations in crop fields." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21063.pdf.
28
Jarvis, Jessie C. "Function of seed-bank ecology in mid-Atlantic semi-annual and perennial Zostera marina beds." W&M ScholarWorks, 2009. https://scholarworks.wm.edu/etd/1539616708.
Abstract:
The effects of water quality and sediment composition on mid-Atlantic semi-annual and perennial Zostera marina reproductive success, seed-bank viability, and seed germination were elucidated using laboratory and in situ experiments, quantitative field observations, and ecological model simulations. The sediment seed-bank was found to play a large role in the recovery of perennial Z. marina beds in the Chesapeake Bay and in the yearly re-establishment of beds in North Carolina which were determined to have a semi-annual life history. However, the resiliency provided by sediment seed-bank for both semi-annual and perennial Z. marina beds was limited as seeds remained viable for less than one year. When comparing the two life forms, semi-annual Z. marina beds produced a greater proportion of flowering shoots and more seeds than nearby perennial beds. Seed germination was significantly affected by sediment type and burial depth with maximum germination of seeds occurring in sediments containing >3% organic content and buried at depths <3 cm. Model simulations indicate that York River Z. marina beds are currently at their maximum temperature threshold and that projected increases of >1??C in water temperature within the Chesapeake Bay may result in large scale declines. While the sediment seed-bank may provide a mechanism for recovery following one year of increased temperature stress, seed-banks are depleted following large scale germination events and may not provide resiliency to multiple consecutive years of stressful conditions. Further research into the interactive effects of sediment and water column conditions and seed physiology on seed viability are required to gain a more comprehensive understanding of seed-bank dynamics in Z. marina beds. Monitoring of semi-annual and perennial Z. marina beds in North Carolina indicated that multiple life history strategies may be found within one Z. marina bed. Shoots within the semiannual Z. marina bed germinated from seeds, a portion of seedlings flowered during their first year of growth, and all shoots completed their life cycle and died within one year of germination like a semi-annual plant; however, not all shoots flowered and shoots reproduced both sexually and asexually similar to a perennial plant. Since the individual plants found within the semiannual bed did not display the all of the defining characteristics of either perennial or annual Z. marina life histories, this population cannot be completely described by either life history strategy. Research into the development of a semi-annual life history strategy for Z. marina within this site and the possibility of this form occurring at other geographic regions requires additional research. Sexual reproduction is an important component of both semi-annual and perennial Z. marina populations that should be included in ecological studies and models. Although most perennial Z. marina beds rely on asexual reproduction as a primary form of bed maintenance, the ability to reproduce sexually is maintained and, as shown here, may play a large role in the recovery, maintenance, and expansion of these populations. For these reasons and due to the use of seeds in restoration of Z. marina beds within large systems such as the Chesapeake Bay, research into the dynamics of sexual reproduction within existing beds, a better understanding of seed physiology, and additional research into environmental effects (including the sediment) on seed germination and viability are essential.
29
Camara, Armando Tadeo Rodriguez da [UNESP]. "Armazenamento de sementes pré-germinadas de Inga vera Willd." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/99770.
Abstract:
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camara_atr_me_botfca.pdf: 536810 bytes, checksum: 57f5286522d61f84e18be56157805a7d (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Sementes recalcitrantes sempre apresentam dificuldades em seu armazenamento, tornandose um problema para produtores de mudas que muitas vezes não têm como realizar a semeadura logo após a colheita das sementes ou necessitam produzir mudas em diferentes épocas do ano, além de dificultar a conservação de germoplasma. As sementes de ingá, depois de colhidas, perdem sua viabilidade rapidamente, geralmente não ultrapassando 15 dias. As espécies de sementes recalcitrantes normalmente não utilizam bancos de sementes como estratégia de regeneração em condições naturais. Observações ecológicas têm mostrado que é mais comum sua regeneração natural ser por meio de bancos de plântulas. O objetivo do trabalho foi avaliar o armazenamento de sementes pré-germinadas de Inga vera Willd., provenientes de frutos em dois estádios diferentes de maturação, em três condições diferentes de umidade de substrato e em baixa temperatura. Os frutos de Inga vera Willd. colhidos foram separados em duas categorias, de acordo com sua coloração de casca, entre verdes e maduros. Após seu beneficiamento, as sementes foram prégerminadas e armazenadas em substrato sem adição de água (testemunha), com 30 e 60% de umidade sob baixa temperatura (10°C), por um ano. O armazenamento feito a 30 e 60% de umidade mostrou-se com melhor eficiência, tanto para plântulas provenientes de frutos verdes, como as de frutos maduros. Entre os dois tipos de frutos, observou-se que as plântulas obtidas de vagem verde, obtiveram melhor desempenho sob as condições de armazenamento, em relação àquelas obtidas de vagem madura. Podem ser armazenadas por até quatro meses, mantendo 50% de sobrevivência das plântulas do lote, quando o armazenamento é feito sob baixa temperatura (10 ± 5°C) e em substrato com 30 e 60% de umidade. Após um período de armazenamento...
Recalcitrant seeds always present difficulties for storage procedures, becoming a problem for seedling producers that often have no choice to sow them immediately after seed harvest or when they need to produce seedlings through different times by the year. Inga seeds, once harvested, lose quickly their viability, often not exceeding a period of 15 days. Species of recalcitrant seeds do not use seed banks as regeneration strategy into the natural environment. Ecological observations have shown that is common occur their natural regeneration through seedling banks. The objective of this work was to evaluate pregerminated seed storage of Inga vera Willd. from two fruit maturation stages, under different conditions of substrate humidity, and under low temperature. The collected fruits of I. vera 9were splited into two types, according to their color, between unripe and ripe. After the processing of those seeds, they were pre-germinated on substrate and stored in substrate with no water addition (control), 30, and 60% humidity under low temperature (10°C) for a year. The storage made under 30 and 60% humidity showed to be the best for both, seedlings from unripe and ripe fruits. Between two types of fruits, we observed that the seedlings from unripe fruits, presented better performance under storage conditions, when compared to those obtained from mature fruits. They can be stored for until four months, with 50% of seedling survivals when stored under low temperature (10 ± 5°C) and with 30 and 60% of substrate humidity. After a year of seedling storage it was possible to get until 10% of survival... (Complete abstract click electronic access below)
30
Santos, Sandy Lia dos. "Dinamica de clareiras : comportamento de especies pioneiras e fatores que afetam sua colonização." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315170.
Abstract:
Orientador: Ivany Ferraz Marques ValioTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A Mata Santa Genebra é um fragmento isolado de Floresta Atlântica. Por se encontrar muito próximo a áreas urbanas, seu ecossistema está sujeito ao resultado das ações humanas. Devido a constante formação de clareiras em seu interior a floresta torna-se de fundamental importância para o conhecimento da dinâmica destas clareiras, visando sua preservação. O objetivo deste trabalho foi registrar e analisar alguns fatores que pudessem limitar a presença das espécies pioneiras nas clareiras. Para tanto, dados climáticos como irradiância solar, razão V:VE, temperatura e umidade do solo e do ar e precipitação pluviométrica foram registrados durante as estações seca e chuvosa. Também foram registrados dados sobre o banco e a chuva de sementes, a germinação de sementes, o recrutamento de plântulas, o crescimento e a sobrevivência de espécies pioneiras plantadas nas clareiras da MSG. Três clareiras com áreas aproximadas de 82m², 186m² e 660m² foram estudadas. Os mesmos dados foram observados nas três clareiras. No total, 49 espécies de 23 famílias foram registradas. Destas, 21 espécies estiveram presente no estudo do recrutamento, 35 espécies no estudo sobre o banco de sementes e 36 espécies no estudo sobre a chuva de sementes. As famílias mais representativas nos três estudos foram Asteraceae (27%) e Poaceae (14%). Das 49 espécies identificadas, 49% foram nativas, 27% ruderais, 2% exóticas e 22% não foram classificadas. O hábito herbáceo predominou com 49%, seguido pelo arbóreo (20%), arbustivo (12%) e trepadeiras (6%). A dispersão de 43% das espécies foi por anemocoria, 24% por zoocoria, 12% por autocoria e 21% não foram classificadas. Há uma fase da regeneração das clareiras de florestas tropicais onde as lianas predominam e permanecem por vários anos formando um dossel baixo e bastante fechado. A escassez de árvores nas clareiras se deve provavelmente à proliferação rápida das lianas, que reduzem o crescimento de outras plantas e aumentam a mortalidade de árvores. O manejo das lianas nas clareiras necessita de atenção e cuidados, pois, apesar da presença destas reduzir drasticamente a diversidade de espécies vegetais nas clareiras, sua presença é fundamental para a sobrevivência e equilíbrio ecológico, das espécies de animais que habitam nesta mata. Neste estudo à exposição do solo foi feita através do recuo para as margens das clareiras, da massa vegetal das lianas. O plantio de espécies nativas acelera a recuperação das clareiras e exige poucos cuidados quando realizado na estação chuvosa
Abstract: The Mata Santa Genebra (22°49¿45¿S 47°06¿33¿W) is an isolated fragment of the Atlantic Forest. Due to the constant formation of gaps in the interior of the forest it becomes of fundamental importance the knowledge of the dynamics of these gaps for the preservation of the forest. The objectives of this paper were to record and analyze factors which could limit the presence of pioneer species in the gaps. Then, climatic data such as solar irradiance, red: far-red ratio, air and soil temperatures and humidity were recorded during the dry and rainy season, beside pluviometric precipitation. Data were also recorded on seed bank, seed rain, seed germination, recruitment, growth and survival of pioneer species planted in gaps of the Mata Santa Genebra. Three gaps were studied with areas approximately of 82m², 186m² and 660m². Some observed data were very closed in the three gaps. In the three gaps 49 species were identified from 23 families. From that, 21 species were present in the recruitment, 35 in the seed bank and 36 in the seed rain. The most representative families were Asteraceae (27%) and Poaceae (14%). From the 49 identified species 49% were native, 27% were weed, 2% were exotic and 22% unclassified. Herbs were predominant (49%), followed by trees (20%), shrubs (12%) and lianas (6%). The dispersion of 43% of species was by anemocory, 24% by zoocory and 12% by autocory and 21% unclassified. There is a stage of gap regeneration in Tropical Forest where lianas are predominant and remain for many years as a low dense canopy. The rarity of trees in these gaps is probably due to the fast proliferation of lianas that besides reducing growth of other plants increases mortality of trees. The management of lianas in the gaps needs to be made very cautiously. Although their presence causes drastic reduction in the species diversity in the gaps, their presence is of fundamental importance to survival and ecological equilibrium of animals which live in the forest. In this paper some intervention was done in the gaps, in relation to bare soil by moving aside herbs and lianas. Planting local native species accelerates the recovery of gaps and do not require much attention when done during rainy season
Doutorado
Doutor em Biologia Vegetal
31
Osei, Nana Akwasi. "Large wood in fluvial systems : quantity, structure and landforms, sediment retention, and riparian seed bank development." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8813.
Abstract:
This thesis investigates the characteristics and impacts of large wood accumulations within river reaches of different size and style. Four reaches were studied: (i) a wide, braided, headwater reach, characterised by dead wood (Tagliamento River, Italy); (ii) a lower gradient, wide, braided reach, characterised by resprouting wood (Tagliamento River, Italy); (iii) a low gradient, single thread reach with a natural supply of dead wood (Highland Water, UK), and (iv) a low gradient, single thread reach that has been restored by felling trees into the river (River Bure, UK). In each reach, quantities of wood, types of accumulation and their association with sediment retention, landform and propagule bank development were investigated, generating four main findings: 1. There were marked differences in the size and character of large wood accumulations among the four reaches. 2. Retention of fine sediment and organic matter by wood was observed on all four reaches, giving rise to notable spatial heterogeneity in surface sediments. 3. Sediment retention resulted in the development of different landforms among the four reaches. In the two multi-thread reaches, accretion of finer sediment around large wood led to island development. In the naturally-functioning single-thread reach, wood jams spanned the river channel, accumulating sediment and organic matter to produce unvegetated wood jams, and inducing other landforms, notably pools and bars. Such geomorphic heterogeneity was anticipated in the restored reach, but to date this has not significantly occurred. 4. Spatio-temporal variations were observed in propagule abundance and species richness within different wood-related mesohabitats. Higher abundance and species richness were associated with finer, more organic sediments retained within wood accumulations and related mesohabitats. In the restored reach such associations were not statistically significant, further indicating that responses to wood emplacement take longer than the 4 years since restoration. iv Overall, this research has strengthened the evidence concerning the differing nature of wood accumulations in rivers of different size and style, and it has demonstrated the importance of large wood for retaining organic matter and plant propagules, resources essential for riparian vegetation succession and for the success of river restoration efforts.
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Nave, André Gustavo. "Banco de sementes autóctone e alóctone, resgate de plantas e plantio de vegetação nativa na fazenda Intermontes, município de Ribeirão Grande, SP." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-02062005-153506/.
Abstract:
O acúmulo significativo de conhecimento sobre a ecologia de restauração nos últimos anos tem conduzido a mudanças na orientação dos programas de manejo e restauração florestal. A escolha ou criação de um modelo de restauração é um processo em constante aprimoramento, exigindo a necessidade de estudos que não apenas diminuam os custos envolvidos, mas também, que garantam a efetividade do objetivo proposto. Neste sentido, este trabalho testa novas metodologias de restauração visando a obtenção de informações técnicas sobre: A) a expressão do banco de sementes autóctone e alóctone na restauração florestal de diferentes situações de degradação antrópica.; B) o resgate de plântulas e indivíduos de espécies arbustivo-arbóreas regenerantes; C) a eficiência de um modelo de plantio que utiliza conceitos de Preenchimento e Diversidade e; D) a evolução da paisagem. Para análise dos bancos de sementes autóctone e alóctone foram feitos levantamentos da densidade e das espécies arbustivo-arbóreas regeneradas. No resgate de indivíduos de espécies arbustivo-arbóreas regenerantes, as plântulas e indivíduos jovens foram resgatadas em uma floresta e levadas para adapatação em viveiro, onde tiveram seus indivíduos e espécies contabilizados em termos de densidade e sobrevivência. No modelo de plantio estudado, as espécies foram reunidas em grupos de Preenchimento e Diversidade e tiveram a cobertura de copa de cada indivíduo quantificada. A evolução da paisagem foi realizada através de fotointerpretação e principalmente checagem de campo periódica. Os principais resultados dessas metodologias foram: A) As situações identificadas na Fazenda Intermontes apresentaram diferentes expressões de regeneração natural em função do número de indivíduos germinados banco de sementes autóctone. O aproveitamento dessa expressão poderá ser realizado através de metodologias diferenciadas de restauração para cada situação estudada: B) No estudo do Banco de sementes alóctone, a densidade dos indivíduos germinados se foi de 409.334 indivíduos/ha, revelando a possibilidade de uso no programa de restauração. Os indivíduos arbóreos apresentaram na área adubada um acréscimo de 137,3 % em sua altura média em relação aos indivíduos da área não adubada. C) No resgate de plântulas e indivíduos de espécies arbustivo-arbóreas regenerantes, a densidade dos indivíduos foi muito próxima para as duas épocas do ano, sendo 38.700 ind./ha e 37.900 ind./ha, mas com uma diferença significante para os indivíduos sobreviventes que apresentaram 16.500 ind./ha e 26.600 ind./ha para os meses de julho e dezembro de 2002, respectivamente. A técnica de resgate utilizada se mostrou viável uma vez que foi possível alcançar até 70,9% de sobrevivência para os indivíduos resgatados; D) No estudo sobre o modelo de plantio foram amostrados 143 espécies, demonstrando que a função do grupo da diversidade vem sendo mantida e aumentando as chances de efetivação dos processos de sucessão. Os resultados mostraram que o grupo de Preenchimento apresentou-se com uma porcentagem de cobertura significativamente maior que a do grupo de Diversidade, sendo 73,6% e 83,3% para 1,5 e 2,5 anos respectivamente.Significant accumulation of know-how about restoration ecology has been changing forest restoration management programs trends during the last years. Choosing or elaborating a restoration model is a process that requires constant improvement and ecological studies that not only reduces the costs involved but also warrants the achievement of the aimed proposal. This study explores new restoration methodologies, searching for technical information about: A) autochthonous and allochthonous seed bank expression on forest restoration at different situations degraded by anthropogenic disturbances; B) seedlings and woody growing individuals rescue; C) efficiency of a planting model based on fulfillment and diversity concept; D) landscape development. The autochthonous and allochthonous seed bank were analyzed through regenerating woody species and density scouting. For the rescue of regenerating woody species, seedling and young individuals were taken from a forest and transferred to a plant nursery for adjustment, where number and species were counted regarding density and survival. In this studied planting model, species were organized and gathered into a fulfillment or diversity group, and each individual had its crown area quantified. Landscape development was analyzed by photointerpretation and specially by periodical field checking. Results from these methodologies showed that: A) Identified degraded situations at Intermontes farm displayed distinguished natural regeneration expression, influenced by the number of germinated seeds of the autochthonous seed bank. Advantage can be taken from these different outcomes by using distinct restoration methodologies for each studied situation. B) For the autochthonous seed bank study, germinated seed density was 409,334 ind./ha, indicating its potential role on restoration programs. Woody individuals at fertilized sites had a medium height enhancement of 137,7% when compared to those at non fertilized sites. C) For seedlings and woody growing individuals rescue, individual density was similar for both seasons (38700ind./ha and 37900ind./ha) but significantly distinct for individual survivor, with values of 16500ind./ha for July and 2600ind./ha for December. Rescue technique turned out to be a viable possibility since it achieved survival of 70,9% for rescued individuals. D) This planting model study registered 143 species, indicating that the diversity groups role has been maintained and enhances the chance of successional process success. The fulfilling group had a significant higher percentage of crown area than the diversity group, with 73,6% and 83,3% for 1,5 and 2,5 years, respectively.
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Bobowski, Benny R. "Identification of Belowground Woody Structures Using Molecular Biomarkers." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/6540.
Abstract:
Within the last two decades substantial progress has been made in understanding seed bank dynamics and the contribution of the soil seed bank to a post-disturbance plant community. There has been relatively little progress, however, in understanding perennial bud bank dynamics and the contribution of the soil bud bank to secondary succession. This lack of information is due primarily to the inability to reliably identify roots, rhizomes, and lignotubers that lie dormant beneath the soil surface. This scientific investigation, therefore, addressed the issue of identification of belowground woody structures.
The first objective was to develop a methodology that utilizes molecular tools to reliably identify woody plant species from subsoil tissue samples. The second objective was to create a key in which molecular markers serve as criteria for identification and differentiation of selected tree and shrub species common to the mountains of northeast Oregon and southeast Washington. Application of restricted fragment length polymorphism (RFLP) analysis on polymerase chain reaction (PCR)-amplified rbcL gene products proved to be a reliable method to identify and differentiate 15 plants to the genus level. Two restriction enzymes, DPN II and Hha I, cut (or do not cut) the PCR-rbcL product into one to six fragments. Fragment number and length are used to develop an identification key. Plants not analyzed in this key may share the same banding patterns , resulting in a false-positive identification of unknowns. Future research needs and management implications are discussed.
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Klein, Débora Kestring [UNESP]. "Ecologia do banco de sementes de trecho de floresta estacional semidecidual e germinação de sementes de Peltophorum dubium (Sprenge) Taubert (Fabaceae: Caesalpinioidea) em diferentes condições de alagamento." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/104005.
Abstract:
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klein_dk_dr_botib.pdf: 427517 bytes, checksum: 69b36be9a11ed0b66d6a420111b90ee9 (MD5)Para um melhor entendimento dos processos que determinam a dinâmica das florestas tropicais, estudos que investigam tanto a vegetação (parte aérea) como o banco de sementes do solo, são necessários. Através de estudos de banco de semente pode-se avaliar, por exemplo, a capacidade de regeneração natural de uma dada vegetação, a viabilidade das sementes existentes no solo e sua influência na estrutura da vegetação. No entanto, pouco se sabe sobre os processos que podem provocar variações na estrutura do banco de sementes, especialmente em florestas semideciduais. O presente estudo teve como objetivo conhecer a composição do banco de sementes do solo em um trecho de Floresta Estacional Semidecídual, bem como investigar possíveis processos capazes de gerar variações em sua estrutura. Além disso, determinou-se o grau de similaridade entre a parte aérea e o banco de sementes. Primeiramente, a densidade (número de plântulas), a riqueza, a diversidade e a composição de espécies foram comparadas entre áreas em diferentes estágios sucessionais, bem como entre diferentes profundidades do solo e estações do ano (chuvosa e seca). Em seguida, a similaridade entre o banco de sementes e a vegetação local foi comparada. Constatou-se que a principal fonte de variação do número de plântulas, da riqueza e da diversidade de espécies presentes no banco de sementes foi a profundidade na qual as sementes foram amostradas. De forma geral, as amostras obtidas da serrapilheira continham, significativamente, um maior número de plântulas, uma maior riqueza e maior diversidade de espécies do que as amostras provenientes das profundidades de 0-10cm e 10-20cm, tanto na estação chuvosa como seca. Comparações da riqueza e da diversidade de espécies entre a estação seca e chuvosa...
For a better understanding of the processes that determine tropical forest dynamics, studies that investigate vegetation both above and below ground are needed. By studying seed banks it is possible to determine, for example, the natural regeneration capacity of vegetation, the viability of the soil seed bank as well as its influence at structuring plant communities. However, little is known about the processes that can generate variation in the seed bank structure, particularly in semideciduous forests. The main aim of this study was to know the soil seed bank composition in a semideciduous seasonal forest fragment, and also to investigate some processes that may generate variations in this structure. Besides, it was determined below (seed bank) and above ground (vegetation) similarity. Firstly, the density (seedling numbers), the richness, and the diversity and species composition were compared among areas of different sucessional stages, and among different soil depths and season (rainy and dry season). After that, the similarity between the soil seed bank and local vegetation was compared. It was observed that the main source of variation of seedling numbers, richness, and species diversity was the depth at which seed samples were obtained. In overall, samples from the litterfall had significantly higher seedling numbers, species richness and diversity than the other depths (0-10cm and 10-20cm); this difference occurred at both in the rainy and dry season. Comparisons of species richness and diversity between the rainy and dry season showed that both significantly differed between seasons, and higher values were observed in the rainy season. Seedling numbers did not differ between seasons. Species composition was more similar between pairs of samples from depths near to each other; for example, for both seasons... (Complete abstract click electronic access below)
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Auffret, Alistair G. "Seed mobility and connectivity in changing rural landscapes." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89105.
Abstract:
The success or failure of many organisms to respond to the challenges of habitat destruction and a warming climate lies in the ability of plant species to disperse between isolated habitats or to migrate to new ranges. European semi-natural grasslands represent one of the world's most species-rich habitats at small scales, but agricultural intensification during the 20th century has meant that many plant species are left only on small fragments of former habitat. It is important that these plants can disperse, both for the maintenance of existing populations, and for the colonisation of target species to restored grasslands. This thesis investigates the ecological, geographical and historical influences on seed dispersal and connectivity in semi-natural grasslands, and the mobility of plants through time and space. Seed dispersal by human activity has played a large role in the build-up of plant communities in rural landscapes, but patterns have shifted. Livestock are the most traditional, and probably the most capable seed dispersal vector in the landscape, but other dispersal methods may also be effective. Motor vehicles disperse seeds with similar traits to those dispersed by livestock, while 39% of valuable grasslands in southern Sweden are connected by the road network. Humans are found to disperse around one-third of available grassland species, including several protected and red-listed species, indicating that humans may have been valuable seed dispersers in the past when rural populations were larger. Past activities can also affect seed mobility in time through the seed bank, as seeds of grassland plant species are shown to remain in the soil even after the grassland had been abandoned. Today however, low seed rain in intensively grazed semi-natural grasslands indicates that seed production may be a limiting factor in allowing seeds to be dispersed in space through the landscape.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Accepted. Paper 4: In press. Paper 5: Manuscript.
36
Klein, Débora Kestring. "Ecologia do banco de sementes de trecho de floresta estacional semidecidual e germinação de sementes de Peltophorum dubium (Sprenge) Taubert (Fabaceae: Caesalpinioidea) em diferentes condições de alagamento /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/104005.
Abstract:
Orientador: Marcelo Nogueira RossiCoorientador: Renata Cristina Batista Fonseca
Coorientador: Vera Lex Engel
Banca: Maria Tereza Grombone Guaratini
Banca: Wesley Augusto Conde Godoy
Banca: Rita de Cássia S. Maimoni Rodella
Banca: João Nakagawa
Resumo: Para um melhor entendimento dos processos que determinam a dinâmica das florestas tropicais, estudos que investigam tanto a vegetação (parte aérea) como o banco de sementes do solo, são necessários. Através de estudos de banco de semente pode-se avaliar, por exemplo, a capacidade de regeneração natural de uma dada vegetação, a viabilidade das sementes existentes no solo e sua influência na estrutura da vegetação. No entanto, pouco se sabe sobre os processos que podem provocar variações na estrutura do banco de sementes, especialmente em florestas semideciduais. O presente estudo teve como objetivo conhecer a composição do banco de sementes do solo em um trecho de Floresta Estacional Semidecídual, bem como investigar possíveis processos capazes de gerar variações em sua estrutura. Além disso, determinou-se o grau de similaridade entre a parte aérea e o banco de sementes. Primeiramente, a densidade (número de plântulas), a riqueza, a diversidade e a composição de espécies foram comparadas entre áreas em diferentes estágios sucessionais, bem como entre diferentes profundidades do solo e estações do ano (chuvosa e seca). Em seguida, a similaridade entre o banco de sementes e a vegetação local foi comparada. Constatou-se que a principal fonte de variação do número de plântulas, da riqueza e da diversidade de espécies presentes no banco de sementes foi a profundidade na qual as sementes foram amostradas. De forma geral, as amostras obtidas da serrapilheira continham, significativamente, um maior número de plântulas, uma maior riqueza e maior diversidade de espécies do que as amostras provenientes das profundidades de 0-10cm e 10-20cm, tanto na estação chuvosa como seca. Comparações da riqueza e da diversidade de espécies entre a estação seca e chuvosa... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: For a better understanding of the processes that determine tropical forest dynamics, studies that investigate vegetation both above and below ground are needed. By studying seed banks it is possible to determine, for example, the natural regeneration capacity of vegetation, the viability of the soil seed bank as well as its influence at structuring plant communities. However, little is known about the processes that can generate variation in the seed bank structure, particularly in semideciduous forests. The main aim of this study was to know the soil seed bank composition in a semideciduous seasonal forest fragment, and also to investigate some processes that may generate variations in this structure. Besides, it was determined below (seed bank) and above ground (vegetation) similarity. Firstly, the density (seedling numbers), the richness, and the diversity and species composition were compared among areas of different sucessional stages, and among different soil depths and season (rainy and dry season). After that, the similarity between the soil seed bank and local vegetation was compared. It was observed that the main source of variation of seedling numbers, richness, and species diversity was the depth at which seed samples were obtained. In overall, samples from the litterfall had significantly higher seedling numbers, species richness and diversity than the other depths (0-10cm and 10-20cm); this difference occurred at both in the rainy and dry season. Comparisons of species richness and diversity between the rainy and dry season showed that both significantly differed between seasons, and higher values were observed in the rainy season. Seedling numbers did not differ between seasons. Species composition was more similar between pairs of samples from depths near to each other; for example, for both seasons... (Complete abstract click electronic access below)
Doutor
37
Navarra, Jennifer J. "Species composition and spatiotemporal pattern of the seed bank and vegetation in native and degraded Florida rosemary scrub." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4645.
Abstract:
Due to large pulses of recruitment immediately after fire and population decline with time-since-fire, I predicted seed density with time-since-fire would follow a unimodal function with low density in early and late years post-fire, and highest density at intermediate time-since-fire. I compared seed density data among sites with different time-since-fire: two sites each of three, six, ten and 24 years time-since-fire and three long-unburned sites (greather than]24 years). Variability in seed bank composition and density increased with time-since-fire and only recently burned stands were distinctly different from the other time-since-fire age classes. Some species and functional groups did exhibit a quadratic or cubic association to time-since-fire (ruderal herbs, subshrubs, Ceratiola ericoides, Lechea cernua, Paronychia chartacea, Phyllanthus tenellus); however, timing of the peak in seed density varied depending on life span and age of reproductive maturity. Scrub herbs were the most abundant functional group in the seed bank and showed highest density in the first ten years post-fire. This pattern corresponds to the pattern of aboveground species abundance and suggests abundances above- and belowground are closely linked. Understanding the dynamics of the seed bank in both naturally and anthropogenically disturbed communities in Florida rosemary scrub is important for the restoration of scrub habitat and management of existing populations of endangered and threatened scrub species endemic to the Lake Wales Ridge in central Florida.; The soil seed bank plays a dynamic role in the regeneration of plant communities after natural and anthropogenic disturbance. In this thesis, I addressed how disturbances influence the vegetation and seed bank of Florida rosemary scrub. In Chapter One I evaluated changes in species composition and spatiotemporal pattern of the vegetation and seed bank along a gradient of disturbance. During the summers and winters of 2007-2009 percent ground cover and seed bank species composition were assessed among replicates of three vegetation types subjected to minimal, moderate, and extreme anthropogenic disturbance (native rosemary scrub, degraded scrub, and agriculturally improved pasture, respectively). These vegetation types shared the same soil and topographic characteristics but differed in disturbance history. I found that species composition and spatial pattern varied with disturbance. In pastures the compositional and structural characteristics of rosemary scrub were lost and only native scrub species able to evade herbivory persisted in this community. Native and degraded scrub differed most from each other in species abundances and spatial pattern. Degraded scrub showed highest abundance of subshrubs and a spike moss species, while rosemary scrub was dominated by shrubs. The seed banks of scrub herbs in degraded scrub had a tendency towards a random spatial distribution that lacked association with aboveground cover. Conversely, rosemary scrub seed banks tended to have an aggregated distribution and were associated with occurrence of conspecific species aboveground, litter, and shrub cover. These results indicated a change in the spatial heterogeneity of the seed banks of scrub herbs in degraded scrub. In Chapter Two I evaluated changes in seed bank density with time-since-fire in native rosemary scrub.ID: 028917091; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 108-123).
M.S.
Masters
Department of Biology
Sciences
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Delong, Michael. "Metapopulations and metacommunities in dry forest openings in southern Illinois." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/dissertations/90.
Abstract:
The type of regional dynamics of a species can provide information on how to manage the species, and may be the only way that some rare species may persist in a given region. A metapopulation is a type of regional dynamic in which local extinction is counterbalanced by recruitment from nearby patches. Metapopulation studies were originally conducted on animals, but have been adapted to plants, and are generally restricted to single-season studies. Plant species may persist as a metapopulation in patchy habitats, such as in forest openings. Forest openings (commonly called barrens, hill prairies, or glades) are habitats found on ridgetops which are characterized by having thin or nutrient-poor soil, high sunlight exposure, and relatively low soil moisture when compared to nearby forest habitats. Forest openings commonly contain plant species more frequently found in prairies, and are often maintained by natural fires that prevents woody species encroachment. In the absence of natural fires due to human management and suppression, woody species have invaded some forest openings, dividing them into a series of patches. To determine whether it is possible for each species to persist as a metapopulation in forest openings, five studies were carried out at each of three sites within the Shawnee National Forest in southern Illinois: a plant survey and ordination using environmental variables, the use of incidence function models to determine which of the species had the potential to form a metapopulation, a metacommunity study to examine overall patterns at each site, a seed bank study, and a seed dispersal study. Forest openings were found to be separate habitats from the surrounding forest based upon canopy openness. Approximately 30% of the species fit the metapopulation model, and the metacommunities at each of the sites exhibited a Clementsian pattern, characterized by groups of co-occurring species that replace each other over the region due to turnover between the groups of species. Species that fit the metapopulation model tended to have seeds that emerge more frequently from the seed bank if annuals and less frequently in the seed bank than species not fitting the metapopulation model (non-metapopulation species) if longer-lived. Species fitting the metapopulation model dispersed equal numbers of seeds as non-metapopulation species at short (5m) and medium (10m) distances, and in some cases dispersed more seeds to longer distances than non-metapopulation species. These studies show that forest openings can be treated as islands of suitable habitat for some species, and that numerous (~30%) species (such as Scleria pauciflora, Stylosanthes biflora, and Manfreda virginica) may assume a metapopulation dynamic in any given year. Many species may have incidence patterns consistent with those of a metapopulation in multiple years; however, the exact habitat patches in which species occur in any given year may change from year to year. Species in forest openings tend to co-occur in groups (a Clementsian pattern), which means that management plans should consider the entire community rather than a single species.
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Kalk, Hannah June. "The role of coastal plant community response to climate change: implications for restoring ecosystem resiliency." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/742.
Abstract:
Accelerated sea-level rise and increased intensity of tropical storm events have challenged the conventional approaches to conservation and restoration of coastal ecosystems. In coastal communities, where survival will depend largely on the ability of species to adapt to rapidly shifting conditions or become established farther inland, historic assemblages may be lost. Seed banks may be an important component of resilience and recovery in response to altered inundation regimes, should they contain species able to adapt or migrate inland. This study assess the ability of seed banks to act as ecological buffers to storm surge disturbances and to instill ecological resilience in degraded and vulnerable coastal ecosystems. Above-ground, seed bank and propagule assemblages were surveyed from historic communities at the Grand Bay National Estuarine Research Reserve. Artificial storm surge experiments revealed that that seed banks were not well distributed throughout the coastal transition communities and that seed bank responses following storm surges are likely to vary among the different plant communities. While some relict species are expected to respond following disturbances, ruderal species are especially dominant in the upland seed bank communities and may, at least in the short term, cause shifts away from the historical assemblages. The apparent absence of seaward species in the upland seed banks may make assisted migration an important tool for the survival of communities unable to keep pace. Community response following translocation of propagule bank application onto highly degraded buyout properties suggested that this technique may be an effective tool in introducing resilience into ecosystems already experiencing the effects of climate change. They resulted in the establishment of diverse and variable communities, containing indicator species from a number of historic communities with varying environmental tolerances. Long-term monitoring of community change and reproductive output of target species may indicate the utility of community translocation in creating resilient and future-adapted communities.
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SANTOS, Danielle Melo dos. "Variação espacial na dinâmica do banco de sementes em uma área de caatinga em Pernambuco durante três anos consecutivos." Universidade Federal Rural de Pernambuco, 2010. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4755.
Abstract:
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Danielle Melo dos Santos.pdf: 428920 bytes, checksum: 322bb464473f572f27942b042957d2dc (MD5)Made available in DSpace on 2016-06-15T14:25:03Z (GMT). No. of bitstreams: 1 Danielle Melo dos Santos.pdf: 428920 bytes, checksum: 322bb464473f572f27942b042957d2dc (MD5) Previous issue date: 2010-06-15
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Space-time heterogeneity that occurs in dry forests changes seedling emergence rates and habitat’s species richness by influencing soil seed bank density. Therefore, considering the importance of understanding how these space-time variations influence seed bank dynamics in an area of caatinga, this study aims to answer the following questions: 1. Do soil bank species richness and seed density differ according to the microhabitat type and annual precipitation totals? 2. Is there an interaction between annual precipitation totals and microhabitat types in determining soil bank species richness and seed density? The study was performed in a fragment of caatinga in Caruaru-PE. Three microhabitat types are easily found in the study area. The riparian corresponds to the terrain zone with a smooth inclination on the margins of Olaria stream, not considering the part of the stream bed where water runs during high precipitation periods; the flat microhabitat corresponds to the somewhat flat terrains, with no significant elevations and up to 150 m distant from the stream bed margins; the rocky microhabitat corresponds to the places with small rock outcrops, within an area varying from 2 to 5 m², which occur as distinct patches dispersed in the flat microhabitat. In the interior of the study area there are 105 1 x 1 m randomly placed parcels for the study of herbaceous vegetation, 35 in each microhabitat. Soil was collected around the 1x 1m parcels (35 samples for each microhabitat) in a 5 cm depth considering litter. These collections were performed in the end of rainy and dry seasons during three consecutive years (2006, 2007 and 2008), summing 630 samples. Differences in log-transformed data of species richness and seedling emergence in the soil bank between years and microhabitats were evaluated with a two-way ANOVA, with a 5% probability and using Turkey as a posteriori test. During the three years of the study, a total of 79 species emerged from the soil bank, 63 species in the riparian microhabitat, 43 in the flat one and 42 in the rocky microhabitat. There was a significant difference for both average species richness and average seedling emergence between microhabitats and between monitoring years, with a significant interaction between them. The influence of microhabitat and annual precipitation on the soil bank species richness and seed density was not the same, or at least did not act with the same intensity, since while precipitation explained 48% of soil bank species richness, microhabitat only explained 7%. Regarding seed density, the opposite was recorded, since while microhabitat explained 31% of seedling emergence, precipitation only accounted for 5%. The results of this study showed that, in order to better understand seed bank dynamics of semi-arid environments, it is also necessary to consider variations inducted by microhabitat conditions, which help for a better adjusting of predictions about seed availability in the soil bank for population renewal and conservation of these environments.
A heterogeneidade espaço-temporal que ocorre nas florestas tropicais secas, altera a taxa de emergência de plântulas e a riqueza de espécies dos habitats por influenciar a densidade do banco de sementes do solo. Deste modo, considerando a importância de se entender como estas variações espaço-temporal vão influenciar a dinâmica do banco de sementes de uma área de caatinga, este estudo objetiva responder as seguintes perguntas: 1. A riqueza de espécies e a densidade de sementes no banco do solo diferem em relação ao tipo de microhabitat e os totais de precipitação de cada ano? 2. Existe interação entre os totais de precipitação anuais e os tipos de microhabitats na determinação da riqueza de espécies e densidade de sementes do banco do solo? O estudo foi realizado em um fragmento de caatinga, em Caruaru, PE. Na área de estudo, três tipos de microhabitats são facilmente visualizados, o ciliar corresponde à faixa de terreno com inclinação suave às margens do riacho Olaria, sem considerar a parte do leito onde corre água do riacho na época de maior precipitação; o microhabitat plano corresponde aos terrenos razoavelmente planos, sem maiores elevações e que distam até 150 m das margens do leito do Riacho; o rochoso corresponde aos locais com pequenos afloramentos rochosos, com área variando de 2 a 5 m2 e altura 0,1 a 1 m, que ocorrem como manchas distintas dispersas no microhabitat plano. No interior da área estudada existem aleatoriamente alocadas 105 parcelas de 1x1 m para o estudo da vegetação herbácea, sendo 35 em cada microhabitat. O solo foi coletado no entorno das parcelas de 1x1 m (35 amostras em cada microhabitat), a 5 cm de profundidade e considerando a serrapilheira. Estas coletas foram realizadas nos finais das estações chuvosas e secas, durante três anos consecutivos (2006, 2007 e 2008), totalizando 630 amostras. Diferenças nos dados logaritmizados de riqueza de espécies e de emergência de plântulas do banco do solo entre anos e microhabitats foram avaliadas através de uma Anova-two way, a 5% de probabilidade com teste a posteriori de Tukey. Durante os três anos de estudos, um total de 79 espécies emergiu do banco do solo, sendo 63 espécies no microhabitat ciliar, 43 no plano e 42 no rochoso. Houve diferença significativa tanto na riqueza média de espécies bem como na emergência média de plântulas entre microhabitats e entre anos de monitoramento, com interação significativa entre os mesmos. A influência do microhabitat e da precipitação anual sobre a riqueza de espécies e a densidade de sementes do banco do solo não foi à mesma, ou pelo menos não atuou na mesma intensidade, pois enquanto a precipitação explicou 48% da riqueza de espécies do banco do solo, microhabitat explicou apenas 7%. Já em relação à densidade de sementes, o inverso foi registrado, pois enquanto microhabitat explicou 31% da emergência de plântulas, precipitação explicou apenas 5%. Por fim, os resultados deste estudo mostram que para compreender bem a dinâmica do banco de sementes de ambientes semi-áridos torna-se necessário também considerar as variações induzidas pelas condições de microhabitats, as quais possibilitam ajustar melhor as predições sobre a disponibilidade de sementes no banco solo para renovação das populações e conservação destes ambientes.
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Hacker, Molly. "ASSESSING SEED BANK CONTRIBUTION TO LANDWARD EXPANSION OF COASTAL WETLAND COMMUNITIES AND RESPONSES TO FIRE AND TRANSLOCATION ALONG COENOCLINE." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2332.
Abstract:
Land loss is a major threat to coastal wetlands of the northern Gulf of Mexico due to the impacts and interactions of sea level rise, regional subsidence, and anthropogenic changes to land cover and sediment supply. Here, coastlines are rapidly converting to open water due to an inability of coastal systems to keep pace with sea level rise via marsh migration due to barriers in the landscape, including dense shrub encroachment from fire suppression of inland communities. Fire may play an important role in promoting resiliency by in two ways, first by reducing or removing woody encroachment, allowing species to be released to migrate inland, second, by promoting primary productivity of herbaceous vegetation, which in turn, may promote vertical expansion. Where elimination of barriers is not possible (i.e., roads, industry and infrastructure), assisted migration of coastal communities landward (via translocation) may be also be a viable solution to bypass these barriers. This research is focused on the potential contribution of seed banks in landward migration of species, the role that fire plays in compositional change, and how seed banks compare to translocated communities when introduced into new environments. Here, seed bank dynamics were assessed and compared to aboveground vegetation of naturally regenerating and reciprocally transplanted (translocated) sods through time, with and without fire. The objectives of this study were to examine: 1) richness and abundance of species in the seed bank among vegetation zones of the coastal transition gradient; 2) effect of fire on expression of the soil seed bank; 3) emergence patterns and the degree of mixing/dispersion of dominant species within the seed bank among zones; 4) similarity of species composition of seed bank to that of the standing vegetation, pre- and post-fire; 5) similarity of species composition of the seed bank to that of the inter-zonally transplanted sods, with and without fire; and 6) fire behaviors through fuel loads and fire temperatures across zones. Results demonstrate the effect of zone on the composition, species richness and propagule density of the seed bank, and differences in similarity of the composition of the seed bank and standing vegetation. Fire did not appear to affect the composition of the seed bank. Ordinations indicate that seed bank communities are more widely distributed than standing vegetation assemblages. An overlap of communities was observed in each zone of the seed bank except salt marsh. Reciprocally transplanted sods that were burned prior to translocation were more similar to seed bank composition than no-fire transplants. Similarity, related to habitat preference, was most retained when sods were transplanted one zone away, and when transplanted upslope. A series of Procrustes analyses was conducted for combinations of seed bank treatments to standing vegetation of naturally regenerated and reciprocally transplanted plots of varying survey periods. Results showed that seed bank composition was most similar to the standing vegetation of the same survey period, and least similar for no-fire seed bank to transplanted plots surveyed 15 months after transplant. That the no-fire transplant plots were less similar to seed bank than burned transplant plot indicate that similarity between the seed bank and standing vegetation may be retained with fire. Comparisons of the Jaccard’s Similarity Coefficient of transplanted plot to seed bank with and without fire showed that overall, plots that had been burned were more similar to their source plots than those that had not been burned, across all zones. This study provides insight to zonation patterns of the seed bank across the coastal coenocline of the northern Gulf of Mexico, and compositional similarity of the seed bank to both naturally generated and reciprocally transplanted propagules, in order to understand the how these communities respond to sea level rise, how they may be managed with fire, and how plant species respond to conditions across zone, thereby the potential contribution of the seed bank to landward migration and the promotion of resiliency of coastal communities through facilitation of lateral migration in response sea level rise.
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Camara, Armando Tadeo Rodriguez da 1985. "Armazenamento de sementes pré-germinadas de Inga vera Willd. /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/99770.
Abstract:
Orientador: Edson Seizo MoriBanca: Marcia Balistiero Figliolia
Banca: Edvaldo Aparecido Amaral da Silva
Resumo: Sementes recalcitrantes sempre apresentam dificuldades em seu armazenamento, tornandose um problema para produtores de mudas que muitas vezes não têm como realizar a semeadura logo após a colheita das sementes ou necessitam produzir mudas em diferentes épocas do ano, além de dificultar a conservação de germoplasma. As sementes de ingá, depois de colhidas, perdem sua viabilidade rapidamente, geralmente não ultrapassando 15 dias. As espécies de sementes recalcitrantes normalmente não utilizam bancos de sementes como estratégia de regeneração em condições naturais. Observações ecológicas têm mostrado que é mais comum sua regeneração natural ser por meio de bancos de plântulas. O objetivo do trabalho foi avaliar o armazenamento de sementes pré-germinadas de Inga vera Willd., provenientes de frutos em dois estádios diferentes de maturação, em três condições diferentes de umidade de substrato e em baixa temperatura. Os frutos de Inga vera Willd. colhidos foram separados em duas categorias, de acordo com sua coloração de casca, entre verdes e maduros. Após seu beneficiamento, as sementes foram prégerminadas e armazenadas em substrato sem adição de água (testemunha), com 30 e 60% de umidade sob baixa temperatura (10°C), por um ano. O armazenamento feito a 30 e 60% de umidade mostrou-se com melhor eficiência, tanto para plântulas provenientes de frutos verdes, como as de frutos maduros. Entre os dois tipos de frutos, observou-se que as plântulas obtidas de vagem verde, obtiveram melhor desempenho sob as condições de armazenamento, em relação àquelas obtidas de vagem madura. Podem ser armazenadas por até quatro meses, mantendo 50% de sobrevivência das plântulas do lote, quando o armazenamento é feito sob baixa temperatura (10 ± 5°C) e em substrato com 30 e 60% de umidade. Após um período de armazenamento... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Recalcitrant seeds always present difficulties for storage procedures, becoming a problem for seedling producers that often have no choice to sow them immediately after seed harvest or when they need to produce seedlings through different times by the year. Inga seeds, once harvested, lose quickly their viability, often not exceeding a period of 15 days. Species of recalcitrant seeds do not use seed banks as regeneration strategy into the natural environment. Ecological observations have shown that is common occur their natural regeneration through seedling banks. The objective of this work was to evaluate pregerminated seed storage of Inga vera Willd. from two fruit maturation stages, under different conditions of substrate humidity, and under low temperature. The collected fruits of I. vera 9were splited into two types, according to their color, between unripe and ripe. After the processing of those seeds, they were pre-germinated on substrate and stored in substrate with no water addition (control), 30, and 60% humidity under low temperature (10°C) for a year. The storage made under 30 and 60% humidity showed to be the best for both, seedlings from unripe and ripe fruits. Between two types of fruits, we observed that the seedlings from unripe fruits, presented better performance under storage conditions, when compared to those obtained from mature fruits. They can be stored for until four months, with 50% of seedling survivals when stored under low temperature (10 ± 5°C) and with 30 and 60% of substrate humidity. After a year of seedling storage it was possible to get until 10% of survival... (Complete abstract click electronic access below)
Mestre
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Postma, Froukje M. "Selection during Early Life Stages and Local Adaptation in Arabidopsis thaliana." Doctoral thesis, Uppsala universitet, Växtekologi och evolution, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302862.
Abstract:
Organisms are often adapted to their local environment, but the role of early life stages in adaptive differentiation among populations remains poorly known. The aim of my thesis was to investigate the contribution of early life stages to the magnitude and genetic basis of local adaptation, and to identify the underlying adaptive traits. For this, I used two natural populations of the annual plant Arabidopsis thaliana from Italy and Sweden, and a Recombinant Inbred Line (RIL) population derived from a cross between these populations. By combining greenhouse and field experiments, Quantitative Trait Loci (QTL) mapping, and path analysis, I examined (1) the genetic basis of seed dormancy, (2) the contribution of differential seedling establishment to local adaptation, (3) among-year variation in selection during seedling establishment, (4) direct and indirect effects of seed dormancy and timing of germination on fitness, and (5) the adaptive value of the seed bank. I found that both the level and the genetic basis of seed dormancy were affected by the maternal environment. One major-effect QTL was identified in all maternal environments, which overlaps with the dormancy gene DELAY OF GERMINATION 1 (DOG1). Selection through seedling establishment success contributed strongly to local adaptation and genetic tradeoffs, and varied among years. Variation in seedling establishment and overall fitness among RILs could be explained by genetically based differences in seed dormancy and timing of germination. Seed dormancy affected fitness throughout the life cycle, by affecting the proportion of germinated seeds, and indirectly via effects on timing of germination, plant size and flowering time. My results suggest that a considerable portion of A. thaliana seeds enter the seed bank. I found genetic differences in dormancy cycling behaviour between the two populations, which could contribute to local adaptation. The value of a seed bank should be higher at the Swedish study site than at the Italian study site due to lower rate of seed mortality in the soil. Overall, the results of this thesis demonstrate that early life stages contribute strongly to both the magnitude and the genetics of local adaptation.
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VanderWeide, Benjamin Lee. "Grazing and drought in tallgrass prairie: the role of belowground bud banks in vegetation dynamics." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16622.
Abstract:
Doctor of PhilosophyDepartment of Biology
David C. Hartnett
Grazing and drought are instrumental in the development and maintenance of perennial grasslands. In this research I tested the belowground bud bank contribution to tallgrass prairie resistance and resilience when perturbed by grazing and drought. First, I tested the bud bank role in vegetation response to and recovery from severe drought (Chapter 2). I compared above- and belowground responses of experimentally droughted plots to ambient controls and irrigated plots during two years of severe drought and two years of recovery. I found that although aboveground net primary productivity declined 30-60% during drought, bud bank density and demography were insensitive to drought. These results suggest that grassland resistance and resilience when perturbed by drought may be mediated by stability of belowground bud banks. Second, I investigated vegetation and soil nutrient legacies following release from long-term grazing (Chapter 3). I documented a relatively rapid shift in aboveground vegetation within four years of grazer exclusion, with productivity, stem density, and diversity becoming relatively more similar to ungrazed than grazed prairie. The density and composition of the belowground bud bank and soil seed bank shifted more slowly, remaining more similar to grazed than ungrazed prairie. Responses of soil nutrients to removal of grazers varied, and in some cases was affected by recent fire history. These results demonstrate the contribution of belowground propagules to the maintenance of a diverse plant community both during grazing and after grazers are removed. Finally, I examined short-term vegetation responses to both drought and grazing (Chapter 4). Despite extreme drought and simulated grazing that reduced productivity and increased mortality of individual stems, the dominant C4 grasses maintained a stable bud bank. Aboveground net primary productivity and bud bank density of sedges and forbs, however, were reduced by both drought and grazing. This differential response of species to extreme drought and grazing led to shifts in community composition and species diversity over one growing season. Across drought and grazing treatments, live rhizome biomass was highly correlated with bud bank density and may be a useful, more easily measured index of bud bank density.
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Nielsen, Michele Erin. "Seed and seedling dynamics of the seagrass, Zostera japonica Aschers. and Graebn. and the influence of Zostera marina L." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30172.
Abstract:
The seagrass Zostera japonica Aschers. and Graebn. occurs as pure populations and in mixture with Zostera marina L. along the intertidal regions of southwest British Columbia. At the Roberts Bank study area seed and seedling dynamics were studied in three vegetation zones: a landward monospecific zone of Z. japonica, a zone of co-existing Z. japonica and Z. marina, and a seaward monospecific zone of Z. marina. Many more seeds were produced than were found in the sediment, and even fewer germinated. Zostera japonica seeds were most abundant in the seed bank in the upper zones where there is high Z. japonica density. Even though seeds remained in the water column for up to two months, very few seeds dispersed into the lower zone populated by Z. marina. thus limiting Z. japonica's colonization of the lower zones. It is unclear what limits the dispersal of Z. japonica seeds. Of the seeds that were incorporated into the sediment few germinated (5% or less). When seeds were planted in buckets placed into the sediment, with and without Z. marina, Z. japonica was able to germinate, grow, and reproduce in one year throughout the study area. Seedlings that emerged earliest (in April) either did not establish or did not survive as long as those seedlings that emerged later in May and June. Seedlings were often found uprooted, floating in the water. The rim of the buckets and the presence of Z. marina shoots appeared to protect the Z. japonica seedlings, preventing uprooting, but the results were not conclusive. Once seedlings became established, they spread vegetatively at a rapid rate and can persist throughout the winter, either as reduced shoots or as overwintering rhizomes. These overwintering plants contribute greatly to the following year's population.Science, Faculty of
Botany, Department of
Graduate
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McCue, Kimberlie A. "The ecological genetics of rarity : a study of genetic structure, inbreeding and seed bank dynamics in a rare annual plant /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841324.
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Fowers, Beth. "Ecologically-Based Manipulation Practices for Managing Bromus tectorum-infested Rangelands." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1019.
Abstract:
Cheatgrass (Bromus tectorum) is an invasive annual grass common in several semiarid plant communities in the western U.S. B. tectorum presence increases fire frequency and size, reducing species diversity, and leading to annual species-dominated systems with inconsistent livestock forage potential and degraded wildlife habitat value. Most efforts to manage B. tectorum-dominated rangelands have focused on controlling the plant itself rather than addressing the causes of vegetation change. An alternative approach, ecologically-based invasive plant management (EBIPM), identifies treatments that can alter factors associated with the causes of succession, leading to a more desirable vegetation state. This study utilized the EBIPM framework to design a large-scale demonstration project, which implemented a series of manipulation treatments (mowing, prescribed fire, imazapic herbicide, and seeding with perennial species) to suppress B. tectorum and promote desirable species. The treatments were implemented at two semiarid shrubland sites in northwestern Utah. Treatments were evaluated by measuring resident vegetation cover, density, aboveground biomass, and litter and soil seed banks. Herbicide was most effective in reducing B. tectorum cover, density, and biomass, while fire was effective in reducing seed density in the litter seed bank. Treatment interactions were rarely significant; however, by combining fire and herbicide, increased B. tectorum control was achieved. Seedlings of seeded perennial grasses emerged in all treatments; however, establishment by the end of the first growing season was greatest in treatments involving fire. The results of this study indicate that using a decision-making framework to select a series of treatments that alter the causes of succession can improve the management of B. tectroum-dominated rangelands.
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Tilini, Kassie Lorraine. "The Seed Ecology of Rare and Endangered Gibbens' Beardtongue (Penstemon gibbensii) and Blowout Penstemon (Penstemon haydenii)." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4065.
Abstract:
Penstemon gibbensii and Penstemon haydenii are two rare, perennial forbs inhabiting remote areas of the western United States. P. gibbensii is listed as a sensitive species by the Bureau of Land Management (BLM) in Colorado, Utah, and Wyoming (Heidel, 2009). P. haydenii was designated as Endangered by the U.S. Fish and Wildlife Service in 1987 (Heidel, 2012). This thesis research was geared toward helping land managers in their efforts to protect and rehabilitate these species by providing understanding on different aspects of their seed ecology. My first study was a laboratory experiment performed on P. gibbensii and P. haydenii seed germination response to moist chilling and dry after-ripening. Wild harvested seeds were subjected to moist chilling at 2-4 °C for 0, 4, 8, 12, and 16 weeks and held in dry storage for approximately 2 years to determine effective methods for breaking primary dormancy. P. gibbensii seed germination increased consistently with increased length of chilling up to 16 weeks and exhibited habitat-correlated variation in this response. P. haydenii seed germination increased from 1 to 100% germination with 4 weeks of chilling. P. haydenii germination was greatest (96%) when incubated under a cool, diurnally-fluctuating temperature regime (10-20 °C) and responded positively to dry storage, increasing germination from 0 to 15%. My second study was an in situ field study designed to characterize the active seed bank of P. haydenii. We set up a transect line across a P. haydenii population and measured the number of seeds entering the seed bank, lost to predation post-dispersal, and persisting in the seed bank. P. haydenii does not appear to form an ecologically significant seed bank. Approximately 140 seeds/ 10m2 could potentially enter the seed bank but only 1 seed in the upper 10cm of sand persisted. Heavy post-dispersal insect predation resulted in a decrease in viability of nearly 30% in exposed P. haydenii seeds after just 12 hours. My third study explored the effects of burial by sand on P. haydenii. Wild-harvested seeds were planted in pots at 1, 2, 4, 6, 8, and 10cm deep in sand and incubated at 10-20 °C. Seed germination and mortality and seedling emergence were measured. The response of dormant seeds to post-burial incubation was determined. Burial depth decreased seedling emergence and seed germination. Shallow burial appears to induce secondary dormancy for seeds that don't germinate quickly, whereas deep burial appears to impose enforced dormancy in burial.
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Keammerer, Holly Barton 1983. "Community structure, plant interactions, seedling performance and seed bank composition of salt marshes along an estuarine gradient in Coos Bay, Oregon." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11256.
Abstract:
xviii, 160 p. : ill. (some col.)Salt marshes are intertidal communities dominated by halophytic vascular plants that are subjected periodically to tidal inundation. These species have developed various adaptations to this stress, including tolerances of fluctuating salinity, extended periods of inundation and intervals of anoxic conditions. The marshes are divided into zones of different plant communities based on species' tolerances of ambient estuarine conditions. Abiotic stresses change along the estuarine salinity gradient (marine to riverine), potentially altering development and composition of plant communities. Abiotic gradients associated with tides are not the only factors that contribute to development of plant community composition in salt marshes. Both negative (competition) and positive (facilitation) biological interactions are also important. Factors that influence community structure in salt marshes, particularly on the eastern North American seaboard, have been well studied. In contrast, salt marshes along the Oregon coast are smaller and more discrete and have received comparatively little attention. The community structure and seed bank composition of six marshes along an estuarine salinity gradient were evaluated. Four major community types dominated marshes that varied in the salinity of inundating tidal waters. Community types were relatively consistent throughout the estuary despite the distances between the marshes. Unlike the emergent plant communities, marsh seed bank composition was more similar within a marsh than within a community type. The low and high marsh community types were separated by a distinct boundary in the marine marshes. Although abiotic factors influence the physical separation of communities, competitive interactions commonly determine the upper limit of a species. In Metcalf marsh, however, the upper boundary for two dominant low marsh species was not determined by competition with the high marsh dominant species. Positive biotic interactions between seedlings and existing vegetation in a community are important factors in determining species distributions, particularly in stressful estuarine environments. In salt marshes, where abiotic stress can be harsh, presence of existing vegetation can ameliorate these conditions and enhance germination and seedling establishment. However, interaction between seedlings and the emergent marsh community was highly competitive, though germination of one species was enhanced in the presence of existing vegetation. This dissertation includes un-published co-authored material.
Committee in charge: Dr. Scott Bridgham, Chairperson; Dr. Richard Emlet, Advisor; Dr. Steven Rumrill, Member; Dr. Alan Shanks, Member; Dr. Gregory Retallack Outside Member
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Andrade, Greice Kelly Oliveira. "Avaliação da regeneração natural em áreas de reflorestamento, no município de Laranjeiras-SE." Universidade Federal de Sergipe, 2015. https://ri.ufs.br/handle/riufs/3004.
Abstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESMany researches have been focused on reforestation projects, taking advantages on the self recuperation mechanism of the frorest such as seed rain, soil seed bank and seedling banks. Seed rain is an initial process which develops the dynamic, organization and structuration of the forest. However, the seed bank is one of the most important factors for natural recolonization of affected areas which start the succession process. Through this natural regeneration, a set of individuals are able to be recruited to the upper stages. In this way, the present study was performed aiming to evaluate the plant species establishment strategies through natural regeneration, in an area in the city of Laranjeiras-SE. Thirty plots were installed, and in center of these plots, collectors were installed (1m x 1m) to estimate the seed rain. To characterize the seed bank, was collected from August 2014 (corresponding to the rainy season in the region) to February 2015 (dry season), a soil sample from the center of each subplot (1m x 1m) through a metal jig which was introduced into the soil to remove a 5 cm layer. In the seedling bank evaluation, height and diameter of seedlings were analyzed between August 2014 (rainy season) and Februare 2015 (dry season) in subplots (1m x 1m). In seed rain were found 7,788 seeds, in which Shinus terebinthifollius Raddi (aroeira) presented a higher number of seeds collected with 6,799 samples and its frequency was 87.84% in relation with others species. The autochoric syndrome of dispersion was observed to Centrosema brasilianum (L.) Benth., Fabaceae 2 and Anadenanthera colubrina (Vell.) Brenan, for Asteraceae 1 and Bignoniaceae 1 the dispersion syndrome observed was anemocoric and to Schinus terebinthifollius and Passiflora mansoi (Mart.) Mast, the dispersion syndrome was zoochoric. In the study of seed bank, it was found a total of 171 seeds. The seed bank analyzes by the rainy season and dry season, Schinus terebinthifollius prevailed with more individuals in the rainy season. However, Fabaceae sp prevailed in the dry season. The distribution of species per plot was heterogeneous in both seasons, but presented a better distribution in the rainy season. In the study of seedlings bank, samples were found belonging to seven families and thirteen species. Shinus terebinthifollius represented 28% of total specimen, followed by Genipa Americana L. with 20%. The rainy season showed better seedling distribution along the plots. The processes of natural regeneration at studied area have presented a diversity of species into three regeneration kinds evaluated in different fructification seasons, establishing int this way, a steady supply of seeds, enabling the development of new individuals for future process.
Inúmeras pesquisas têm sido voltadas a projetos de reflorestamentos, aproveitando o próprio mecanismo de recuperação da floresta como chuvas de sementes, bancos de sementes do solo e bancos de plântulas. A chuva de sementes é um processo inicial que desenvolve a dinâmica, organização e estruturação da floresta. No entanto, o banco de sementes é um dos fatores mais importantes para a recolonização natural das áreas afetadas dando início ao processo sucessional. Por meio dessa regeneração natural, um conjunto de indivíduos são capazes de ser recrutados para os estádios superiores. Dessa forma, o presente trabalho foi realizado objetivando avaliar as estratégias de estabelecimentos das espécies vegetais por meio da regeneração natural, numa área em reflorestamento, no município de Laranjeiras-SE. Foram instaladas 30 parcelas, e no centro dessas parcelas foram instalados coletores (1m x 1m) para estimar a chuva de sementes. Para a caracterização do banco de sementes, foi coletada, no mês de agosto de 2014 (correspondente a estação chuvosa na região) e fevereiro de 2015 (estação seca), uma amostra de solo no centro de cada subparcela (1m x 1m), através de um gabarito metálico que foi introduzido no solo para remover uma camada de 5 cm. Na avaliação do banco de plântulas, foram realizadas análises de altura e diâmetro das plântulas, entre agosto de 2014 (estação chuvosa) a fevereiro de 2015 (estação seca), em subparcelas (1m x 1m). Na chuva de sementes foram encontradas 7.788 sementes, dentre as quais a espécie Schinus terebinthifollius Raddi (aroeira) apresentou maior número de sementes coletadas, com 6.799 amostras possuindo frequência de 87,84% em relação as outras espécies. A síndrome de dispersão autocórica foi observada para as espécies Centrosema brasilianum (L.) Benth., Fabaceae 2 e Anadenanthera colubrina (Vell.) Brenan, para Asteraceae 1 e Bignoniaceae 1 a síndrome de dispersão observada foi anemocorórica e para as espécies Schinus terebinthifollius e Passiflora mansoi (Mart.) Mast, a síndrome de dispersão presente foi a zoocórica. No estudo do banco de sementes, foi encontrado um total de 171 sementes. Nas análises por estação chuvosa e seca do banco de sementes, a espécie Schinus terebinthifollius prevaleceu com maior número de indivíduos na estação chuvosa. Contudo, prevaleceu a espécie Fabaceae 1 na estação seca. A distribuição das espécies por parcela foi heterogênea em ambas as estações, porém apresentou uma melhor distribuição no período chuvoso. No estudo do banco de plântulas, foram encontradas amostras pertencentes a sete famílias e treze espécies. A espécie Schinus terebinthifollius representou 28% dos espécimes amostrados, seguida por Genipa americana L. com 20%. Na estação chuvosa houve uma melhor distribuição de plântulas ao longo das parcelas. O processo de regeneração natural da área de estudo apresentou uma diversidade de espécies nas três formas de regeneração avaliadas com diferentes épocas de frutificação, estabelecendo assim, uma constante oferta de sementes, viabilizando o desenvolvimento de novos indivíduos para processos futuros.