Dissertations / Theses on the topic 'Above- and belowground'
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Wilson, Gail T. "Mycorrhizal symbiosis in the tallgrass prairie : above-and belowground linkages /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Barberis, Ignacio Martín. "Above- and belowground competition for seedlings in a Panamanian moist forest." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620174.
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Jonas, Jayne Louise. "Nutrient resources and stoichiometry affect the ecology of above- and belowground invertebrate consumers." Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/404.
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Hahn, George Eugene III. "Wildland Fire in the Central Appalachian Mountains: Impacts on Above- and Belowground Resources." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/102606.
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Prescribed fire use in Virginia and West Virginia has increased over the past ten years as forest managers on public lands have increasingly used prescribed fire to meet management goals. These goals include hazardous fuel reduction, wildlife habitat restoration and management, and control of less desired vegetation. Research is needed to better understand the effects of wildland fire on forest ecosystems. In this study, we addressed wildland fire's effects on water, vegetation, and soil resources in the central Appalachian Region. Moreover, the long-term efficacy of various types of timber harvests on forest fuel reduction was analyzed.
Over fifty peer-reviewed articles were evaluated to characterize the effects of prescribed fire on physical, chemical, and biological water quality parameters throughout the eastern United States. It was determined that fires of low to moderate intensity and severity may cause short-term sediment and nutrient increases in nearby waterbodies, but these effects often dissipate within 2-3 years. Effects on biological organisms are more transient, frequently lasting from a few weeks to a few months. Regeneration following wildfires at three sites in Virginia and West Virginia varied due to fire behavior and time since fire. Preferred and undesired species responded differently at each site. Follow-up treatments and continued monitoring are needed to obtain desired vegetative compositions post-fire. Two dormant season prescribed fires on the Fishburn Forest near Blacksburg, Virginia were studied for mineral soil chemistry effects. Both treatment and time affected macronutrient levels, but no differences were present 6 and 14 months post-fire between burned and unburned locations. Forest fuels were quantified approximately 20 years following different silvicultural harvests on the George Washington-Jefferson National Forest. Fuels of different size classes responded differently to different harvests as fine fuels were reduced by the high-leave shelterwood treatment, and coarse woody fuels were reduced by the clearcut and low-leave shelterwood treatments. Overall, low intensity and low severity fires induce minimal, potentially negative changes in water and soil quality. In contrast, wildfires of high intensity and severity may potentially contribute to changes in species composition and forest floor properties. Furthermore, varying levels of overstory removal may reduce extreme wildfire risk for decades. The findings of this study reinforce the need for continued research and monitoring of both wildfire effects and prescribed fire use in the central Appalachian Region.Doctor of Philosophy
It is well-documented that fire has occurred in forested ecosystems for millennia. In addition to natural ignitions, indigenous peoples used fire for various reasons, such as understory reduction, hunting, and crop cultivation. As European settlers arrived and advanced across North America, they continued to use fire as a tool to shape the landscape to fit their societal needs. The use of fire by humans in North America all but ceased in the early 20th century. Large fire events in the western United States motivated the newly created United States Forest Service to restrict fire from the landscape. The fire exclusion policy of the early 20th century had unintended consequences, such as increased fire risk due to fuel accumulation and a shift from fire-tolerant species, such as oaks and pines, to fire-intolerant species. More recently, the perception of wildland fire has been re-examined due to ecological and societal issues. Although federal and state agencies are burning more acres, the public's wariness towards wildland fire is prevalent. As attitudes about wildland fire have changed, so have the research needs. Information regarding the effects of both wild and prescribed fires on forest ecosystems is needed throughout the United States, including the eastern United States, and more specifically, within the central and southern Appalachian Mountains. This dissertation discusses the effects of both wild and prescribed fires on various forests processes within these regions. In this dissertation, 1) the impacts of prescribed fire on water quality, 2) the responses of forest vegetation to wildfire, and 3) and the effects of prescribed fire on soil nutrients were investigated. Additionally, different timber harvests were studied to determine their long-term effects on potentially hazardous fuel loads. The results indicated that water quality is generally not impacted by low intensity and severity prescribed fires in the eastern United States. It was determined that vegetation often responds vigorously to wildfires, and subsequent species composition varies based on factors such as fire severity, site conditions, time since fire, and overstory species composition. When examining soil nutrients for 14 months following prescribed fires, nutrient changes occurred in both unburned and burned locations. When fuel loads were compared between timber harvests of varying intensities, woody fuels were reduced in the long-term. This reduction may minimize potential wildfire behavior and effects. While both wild and prescribed fires impact forest processes, they generally do so in different ways. This is mainly due to differences in fire behavior between these fire types. Effects of wildfires on water quality, soil chemistry, and vegetation tend to last longer than prescribed fire. Additionally, prescribed fire, when used in conjunction with other forest management activities, may reduce potentially negative wildfire impacts. Monitoring post-fire effects is critical to understanding the best way to use prescribed fire as a forest management tool.
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Jonas, Jayne. "Nutrient resources and stoichiometry affect the ecology of above- and belowground invertebrate consumers." Diss., Kansas State University, 2007. http://hdl.handle.net/2097/404.
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Doctor of PhilosophyDepartment of Biology
Anthony Joern
Aboveground and belowground food webs are linked by plants, but their reciprocal influences are seldom studied. Because phosphorus (P) is the primary nutrient associated with arbuscular mycorrhizal (AM) symbiosis, and evidence suggests it may be more limiting than nitrogen (N) for some insect herbivores, assessing carbon (C):N:P stoichiometry will enhance my ability to discern trophic interactions. The objective of this research was to investigate functional linkages between aboveground and belowground invertebrate populations and communities and to identify potential mechanisms regulating these interactions using a C:N:P stoichiometric framework. Specifically, I examine (1) long-term grasshopper community responses to three large-scale drivers of grassland ecosystem dynamics, (2) food selection by the mixed-feeding grasshopper Melanoplus bivittatus, (3) the mechanisms for nutrient regulation by M. bivittatus, (4) food selection by fungivorous Collembola, and (5) the effects of C:N:P on invertebrate community composition and aboveground-belowground food web linkages. In my analysis of grasshopper community responses to fire, bison grazing, and weather over 25 years, I found that all three drivers affected grasshopper community dynamics, most likely acting indirectly through effects on plant community structure, composition and nutritional quality. In a field study, the diet of M. bivittatus was dominated by forbs with grasses constituting only a minor fraction of their diet under ambient soil conditions, but grass consumption approximately doubled as a result of changes in grass C:N:P. M. bivittatus was found to rely primarily on selective consumption of foods with varying nutritional quality, rather than compensatory feeding or altering post-ingestive processes, to maintain C:N homeostasis in a laboratory experiment. In a soil-based mesocosm study, I show that Collembola feed on both saprophytic and AM fungi, in some cases exhibiting a slight preference for AM fungi. In the final study, although I did not find the expected indirect relationship between soil Collembola and aboveground herbivory as mediated through host plant quality, there were significant effects of root C:N and AM colonization on Collembola density and of plant C:N on aboveground herbivory. Overall, this research shows that host plant C:N:P stoichiometry can influence both above- and belowground invertebrate population, community, and food web dynamics.
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Kafle, Dinesh [Verfasser]. "Plant-mediated interactions between spatially and temporally separated above- and belowground herbivores / Dinesh Kafle." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1117028496/34.
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Paris, Carolina Ivon. "Above-belowground effects of the invasive ant Lasius neglectus in an urban holm oak forest." Doctoral thesis, Universitat Autònoma de Barcelona, 2007. http://hdl.handle.net/10803/3680.
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Las hormigas invasoras desplazan a las especies de hormigas nativas y otros artrópodos. Como consecuencia, las interacciones biológicas del sistema invadido y los servicios ecológicos prestados por las especies nativas son modificados. El objetivo de este trabajo fue investigar los efectos de la hormiga invasora Lasius neglectus sobre algunos de los componentes superficiales y subsuperficiales de un encinar urbano y compararlos con los efectos de las hormigas nativas, en particular con Lasius grandis. Lasius neglectus visita principalmente árboles aislados donde permanece más meses atendiendo áfidos. Por el contrario, las hormigas nativas no visitaron los árboles según su ubicación (aislado, borde o centro del bosque). Excepto en el caso de la hormiga nativa Lasius grandis, que permaneció más tiempo en los árboles aislados cuando Lasius neglectus no estaba presente en el fragmento. La riqueza de especies nativas de hormigas y su visita a los árboles fue menor en fragmentos de bosque con Lasius neglectus. Crematogaster scutellaris, Temnothorax lichtensteini y Lasius grandis lograron coexistir con la hormiga invasora. La estructura de la comunidad de hormigas nativas en fragmentos con o sin Lasius neglectus mostró un patrón aleatorio.
Entre Mayo y Octubre, en las encinas se encontraron dos especies de áfidos, Hoplocallis picta, ocasionalmente atendido por las hormigas, y Lachnus roborisun un mirmecófilo obligado. En encinas visitadas por la hormiga invasora, se observó que la abundancia de Lachnus roboris tendió a duplicarse, como así también su producción de melaza, porcentaje de colonias atendidas comparado con los resultados obtenidos en encinas visitadas por la hormiga nativa Lasius grandis. Consecuentemente, durante el periodo estudiado la hormiga invasora duplicó su colecta de melaza por encina respecto de la hormiga nativa. Las colonias de Lachnus roboris se ubicaron principalmente sobre las bellotas. Sin embargo, no se detectó ningún efecto en la producción o calidad de bellotas y en la emergencia o calidad de las plántulas.
Ambas especies de hormigas capturaron principalmente Pscópteros y Hoplocallis picta como fuente de proteínas. El porcentaje de obreras que llevaba insectos o trozos de artrópodos entre sus mandíbulas fue superior para Lasius grandis.
La comunidad de artrópodos y el nivel de herbivoría no fueron modificados por la presencia de una u otra especie de hormiga. Sin embargo, en las encinas visitadas por Lasius neglectus las arañas, los curculiónidos y los áfidos tendieron a incrementar su abundancia mientras que las larvas de coccinélidos (predadores de áfidos) disminuyeron marcadamente.
La melaza que no es recogida por las hormigas puede incorporarse al suelo disuelta en el agua de trascolación de la copa como carbono orgánico disuelto (COD). La colecta de melaza de Lasius neglectus disminuyó el COD disuelto en el agua de trascolación de las encinas lo cual indicaría una interrupción del flujo de materia y energía entre la copa de las encinas y el suelo aledaño.
En relación a los efectos subsuperficiales se observó que el contenido de nutrientes en el suelo aledaño a las encinas visitas por Lasius neglectus fue mayor respecto del encontrado en encinas visitadas por hormigas nativas. Asimismo, la comunidad de microorganismos se diferenció según la presencia de hormigas nativas o de la invasora; tendiendo la biomasa microbiana del suelo a ser mayor en el caso de la presencia de Lasius neglectus. Según la localidad estudiada, la calidad de la hojarasca producida fue menor en los árboles visitados por Lasius neglectus. Sin embargo, la descomposición de la hojarasca de encina no fue modificada por la presencia de la hormiga invasora.
Se concluye que la presencia de Lasius neglectus modifica aquellos componentes, superficiales y subsuperficiales, del sistema de la encina que están directa o indirectamente relacionados con la colecta de melaza.
Invasive ants displace native ant species and other arthropods. As a consequence, at the invaded system biological interactions and ecological services provided by native ant species are modified. The aim of this study was to investigate some of the above-belowground effects of the invasive ant Lasius neglectus in an urban holm oak forest and to compare these effects with those of native ant species, in particular related to Lasius grandis.
Lasius neglectus mainly visited isolated trees where workers remained more months tending aphids and other insects. On the contrary, native ant tree visitation was not related to tree position in the fragments (isolated, edges or core trees). The only exception was the native ant Lasius grandis which remained more months at isolated trees in fragments where Lasius neglectus was not present. Native ant species richness and its tree visitation were lower at fragments where Lasius neglectus was present. Crematogaster scutellaris, Temnothorax lichtensteini y Lasius grandis were able to coexist with the invasive ant specie. Community structure of native ants did not differ from a random pattern with or without Lasius neglectus.
Some effects of the ant presence were investigated in detail at the holm oak (Quercus ilex) since this tree was the most abundant at the studied forest fragments.
Between May and October, two aphid species were found feeding at holm oak canopy: Hoplocallis picta, which was occasionally tended and Lachnus roboris which was the main tended species. At holm oaks visited by the invasive ant, the abundance of Lachnus roboris tended to increase twice, as well as their honeydew production related to results obtained at holm oaks visited by the native ant Lasius grandis. The percentage of tended colonies tended by Lasius neglectus was higher compared to the percentage tended by Lasius grandis. As a consequence, at the studied period, the invasive ant collected two fold of honeydew per tree related to the native ant. At holm oaks visited by Lasius neglectus or Lasius grandis colonies of Lachnus roboris fed mainly on acorn petiole or on their cap. However, there was not any difference of acorn production acorn or quality and sapling emergency or quality between these holm oaks.
Both ant species mainly captured Pscoptera and Hoplocallis picta as source of proteins. The percentage of workers carrying insects or pieces of arthropods in its jaws was higher for Lasius grandis.
Arthropod community and herbivory level was not modified due the presence of the invasive or the native ant. However, some particular groups showed differences of its abundance. At holm oaks visited by Lasius neglectus, spiders, weevils and aphids tended to increase its abundance while ladybird larvae (aphid predators) decreased markedly.
Honeydew production that was not collected by ants may reach the soil dissolved in throughfall as dissolved organic carbon (DOC). Honeydew collection by Lasius neglectus decreased DOC content in throughfall. This result suggests that the invasive ant interrupts the flux of energy and matter between canopy and the soil surrounding holm oaks.
In relation with belowground effects of Lasius neglectus soil nutrient content was higher beneath holm oaks visited by the invasive ant in relation to those trees visited by native ants. Soil microbial community was characterized by the presence of Lasius neglectus and microbial biomass tended to increase beneath holm oaks visited by this invasive ant. Depending on the study site, litter quality was lower at holm oaks visited by Lasius neglectus. Litter decomposition was not modified by the presence of the invasive ant.
I conclude that Lasius neglectus presence modifies those below-aboveground components of the holm oak system that are directly or indirectly related to honeydew collection.
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Kobiela, Breanna Lyn Paradeis. "Above and Belowground Effects of Nutrient Applications and Mowing Treatments on Restored North Dakota Grasslands." Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/25187.
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Although more than half of the annual production within North American grasslands occurs beneath the soil surface, this portion is oftentimes overlooked in ecological studies. In this study, we investigated the above- and belowground responses in restored grassland plots that were subjected to different nutrient and mowing treatments. This study was conducted at two locations in North Dakota: the Dickinson Research Extension Center (DREC); and the Albert K. Ekre Grassland Preserve (Ekre). We evaluated the above- and belowground responses using visual surveys, biomass harvesting, and minirhizotrons.
At the DREC site, we found the belowground variables to be relatively unresponsive to the nutrient and mowing treatments ? there were no significant differences in root length, surface area, number of tips, or branches. The aboveground variables did exhibit responses to repeated nitrogen applications (200 kg/ha?yr). Nitrogen applications were found to increase aboveground biomass over the control (660 g/m2 vs. 265 g/m2, respectively) and decrease the species richness in comparison to the control (3.25 vs. 7.29, respectively). There was a decrease in the ratio of root volume to average aboveground biomass in the DREC nitrogen plots that resulted from the increase in aboveground biomass despite no apparent changes in the root systems, indicating that the root systems in the nitrogen plots were able to support significantly more aboveground biomass than similarly sized root systems in plots that did not receive nitrogen.
At the Ekre site, there were no significant differences in the belowground variables attributed to mowing. However, aboveground biomass was higher in the mowed sub-plots (xM=530 g/m2) than in the control sub-plots (xC=485 g/m2). Species richness was lower in the nitrogen (xN=4.46) than in the phosphorus plots (xP=5.66). Species richness was also lower in the plots that received the high application rates (200 kg/ha?yr nitrogen or 40 kg/ha?yr phosphorus) (xH=4.30) than the low application rates (20 kg/ha?yr nitrogen or 4 kg/ha?yr phosphorus) (xL=5.90). Root growth was highest in the low phosphorus and the high nitrogen plots. There were different responses in the root variables throughout the growing season as a function of nutrient type and application rate.National Science Foundation (NSF) (DEB-9627928)
USDA-NRICGP (93-0051 and 99-00979)
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Cope, Colin G. "Understanding above- and belowground interactions within invasion biology: An integrative approach across a forest community." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1528202331073491.
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Keith, Aidan Marischal. "Links between above and belowground communities : tree-driven impacts on food webs and ecosystem processes." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485397.
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Examining mechanistic links between above and belowground communities IS important to understand how land-use change may influence belowground food webs and ecosystem processes. Native woodland expansion is encouraged by conservation policy in the United Kingdom, but consequences of tree regeneration for belowground communities are poorly understood. This thesis examined mechanisms by which the plant community may control nematode community structure, and decomposition. In a correlative field study, changes in plant community structure were related to changes in nematode abundance, trophiq''structure and diversity, indicating treedriven impacts on litter inputs may determine belowground community structure. Increased nematode abundance and prevalence of higher trophic levels (Le. predators) were associated with more productive plant communities, and nematode diversity was positively related to plant diversity. A manipulative field experiment established that plant litter diversity generally had limited effects on the decomposer system, while plant litter identity had strong effects on decomposition, microbial biomas~ and the abundance of different nematode trophic groups. Collectively, these data demonstrate that plant species composition is more important than plant species diversity in determining belowground community structure and ecosystem processes. A mesocosm experiment tested the relative importance of above and belowground tree inputs on belowground community structure and decomposition. Litter addition, even at unnaturally high levels, had limited effects on the soil nematode community, whereas the presence of tree roots markedly altered nematode abundance and trophic structure, and microbial biomass. Changes in nematode community structure, particularly increases in predatory nematode abundance, in the presence of roots, indicate that belowground tree inputs may be more important than aboveground litter inputs in determining soil food web structure and complexity. This thesis established that trees can have a considerable impact on belowground community structure and ecosystem processes by controlling detrital inputs, both directly, and indirectly via changes in plant community composition. Consequently, it has demonstrated how land-use change may influence the belowground system, and thus improved our understanding of mechanisms by which above and belowground communities are linked.
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Ögren, Amanda. "Is above- and belowground phenology of Eriophorum vaginatum in sync in a peatland underlain by permafrost?" Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-132877.
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The phenology of plants in northern ecosystems is currently changing. Roots have a key role in these ecosystems, though the phenology of roots is still poorly understood. The aim of this report was to investigate if above- and belowground phenology of the circumpolar sedge Eriophorum vaginatum was synchronized in a subarctic peatland underlain by permafrost, and to investigate which abiotic factors are limiting root growth. Additionally, the length of the belowground growing season was examined. The study was performed with a non-destructive in situ method (minirhizotrons and NDVI measurements) in the northernmost part of Sweden. Both above- and belowground phenology was measured biweekly during the whole growing season in 2016. The depth of the active layer, air temperature, soil temperature and soil moisture were measured to investigate the determinants of root growth. Root growth and aboveground activity was asynchronous, as peak in root growth occurred on average 21 days before maximum NDVI was reached. Soil temperature and thaw depth seem to be important factors regulating root growth in this peatland. The result highlight that solely studying the aboveground parts of plants can give a misleading interpretation about the phenology of the entire plant and thus during which time periods important ecosystem processes take place. Hence, to more accurate forecast ecosystem responses to global warming, both aboveground and belowground phenology should be considered.
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Johnson, Brittany Anne. "Acidic deposition effects on above- and belowground wood biomass and nutrient status in a young hardwood forest." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10704.
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Thesis (M.S.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains vii, 119 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Pugliese, Jennie Y. "Above- and Belowground Response to Managing Kernza (Thinopyrum intermedium) as a Dual-Use Crop for Forage and Grain." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494000853982965.
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Rubilar, Rafael Alejandro. "Environmental constraints on growth phenology, leaf area display, and above and belowground biomass accumulation of Pinus radiata (D. Don) in Chile." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-12062005-135049/.
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Environmental site-specific constraints on shoot, branch, and leaf area growth and phenology were investigated during the third and fourth growing seasons in two-year-old radiata pine plantations established under a factorial combination of soil preparation, fertilization, and weed control at three contrasting textural and climatic soil-site conditions in the Central Valley of Chile. During October 2002 and June 2005, biweekly measurements of foliage accretion, branch, and stem growth were obtained together with periodical evaluations of foliage senescence. At each site, tree growth, aboveground biomass, belowground biomass, total biomass, aboveground:belowground biomass ratio, and leaf area index increased mainly by weed control (WC). The large gradient of tree growth and biomass accumulation among sites, and within sites varying in response to WC, was mainly attributed to large differences in soil water availability and possibly atmospheric water demand differences within sites. A linear relationship was established between LAI and stand growth across sites. The slope of the relationship (stemwood growth efficiency, GE) varied from 2.9 m3ha-1year-1 to 6.8 m3ha-1year-1 per unit of leaf area, with lower growth efficiencies found on sites with the greater water constraints. Phenology of growth was little affected by site or silvicultural treatments. Seasonal differences in the patterns of growth were mainly observed among sites for diameter, with longer growing seasons at sites with lower water limitations. In contrast, strong site and silvicultural treatments effects were observed on tree morphology. Trees where water limitations were more severe exhibited fewer and shorter flushes of height growth. The negative effects of soil water limitations, were at least partially ameliorated by silvicultural treatments that had been applied three years previously. Resource availability constraints during the mid to late growing season affected diameter growth more than height growth. Phenology of fascicle elongation indicated that sites with water and nutritional constraints ended fascicle elongation earlier during a growing season. Phenology of fascicle senescence indicated that maximum needlefall occurred during the summer and autumn seasons. No differences in silvicultural treatments were observed in foliage accretion or senescence patterns. Foliage longevity increased for sites with water and nutrient limitations.
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Gessesse, Tigist Araya [Verfasser]. "Above- and belowground carbon stocks in semi-arid land-use systems under integrated watershed management in Gergera watershed, Ethiopia / Tigist Araya Gessesse." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1122285841/34.
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Jones, Thomas Michael. "Integrating above and belowground components of biodiversity across spatial scales : the role of host plants in the distribution of Arbuscular Mycorrhizal fungi." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/17086/.
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The Arbuscular Mycorrhizal (AM) fungi are a group of obligate plant root endosymbionts, which form associations with an estimated two thirds of terrestrial plant species. Their extra-radical mycelium extends throughout the soil and absorbs nutrients that are transferred to their host plant in exchange for a purely phytogenic carbon supply. Due to their ubiquity and their functional importance, they are the subject of much research into their community ecology, yet much is still unknown. For instance: whether or not AM fungi display preference for certain host plant species; how environmental heterogeneity and energy availability affect communities; and the relative influence of niche and neutral processes. This thesis describes experiments which profile AM fungal communities and environmental properties of their habitat at different spatial scales in different plant species. Network analysis revealed patterns indicative of niche-based processes structuring AM fungal communities more than neutral processes, phenotypic trade-offs between AM fungi, and of priority effects influencing diversity and unevenness. Difference between plant species in the heterogeneity of surrounding soil was dependent on spatial scale. The effect of decreased carbon allocation on AM fungal communities is greater in more heterogeneous habitats. These results suggest that the detection of host plant preference in AM fungi is dependent on spatial scale of sampling, driven by interspecific variation in plant root architecture, soil physical properties and AM fungal vital rates.
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Müller-Haubold, Hilmar [Verfasser], Dietrich [Akademischer Betreuer] Hertel, Christoph [Akademischer Betreuer] Leuschner, and Markus [Akademischer Betreuer] Hauck. "Climate response of above- and belowground productivity and allocation in European beech / Hilmar Müller-Haubold. Gutachter: Christoph Leuschner ; Markus Hauck. Betreuer: Dietrich Hertel." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1071713604/34.
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Mahon, Michael B. "Soil litter and soil-dwelling invertebrate response to experimental removal of white-tailed deer (Odocoileus virginianus) and Amur honeysuckle (Lonicera maackii)." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1563282959616797.
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Weidlich, Emanuela Wehmuth Alves [Verfasser], and Vicky M. [Akademischer Betreuer] Temperton. "Testing theories for ecological restoration: effects of plant-plant interactions and plant order of arrival on assembly and on above- and belowground productivity / Emanuela Wehmuth Alves Weidlich ; Betreuer: Vicky M. Temperton." Lüneburg : Universitätsbibliothek der Leuphana Universität Lüneburg, 2018. http://d-nb.info/1154307328/34.
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Akgul, Alper. "Performance of slash pine (Pinus elliottii Engelm.) containerized rooted cuttings and bare-root seedlings established on five planting dates in the flatlands of western Louisiana." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2230.
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The forest product industry is keenly interested in extending the normal planting season, as well as in the comparative field performance of standard nursery bare-root seedlings and containerized rooted cuttings. The effect of seasonal planting dates on survival, above and belowground biomass allocation, water relations, gas exchange attributes and foliar carbon isotope composition (δ13C) of two stock types of slash pine (Pinus elliottii Engelm.) were examined. Slash pine bare-root seedlings (BRS) and containerized rooted cuttings (CRC) were hand planted in September, November, January, March and April in three consecutive planting seasons (2000-2001, 2001-2002 and 2002-2003) on three sites with silt loam topsoils in southwestern Louisiana. First-year mean survival of CRC across all planting dates and sites was consistently high at 96 to 98%, whereas BRS survival was significantly (P < 0.0001) lower at 59 to 81% and highly variable among study sites and dates through three planting seasons. Generally, there was a negative relationship between soil moisture at the time of planting and first-year survival of BRS planted September through March in 2001-2002 and 2002-2003 planting seasons, whereas the opposite was observed only for BRS planted in April 2002 and 2003. Survival of CRC was affected very little by the variation in soil moisture. Containerized rooted cuttings had higher early above and belowground biomass, and height and diameter than did BRS. However, three years after planting the size differences between stock types disappeared or became negligible. Early size differences among trees planted September through March also decreased after three years, although September trees were tallest. Growth of the April-planted trees was poor compared to trees planted in other months. Late-planted April trees had higher δ13C values, and higher water-use efficiency in the first growing season compared to earlier planted trees. Differences in δ13C values among the planting dates disappeared in the second growing season. Net photosynthesis rates did not differ considerably between stock types or among planting dates in the second and third growing seasons. This study indicates that it is possible to extend the planting season to as early as September and as late as March by using CRC.
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Walbert, Katrin. "Ectomycorrhizal communities associated with a Pinus radiata plantation in the North Island, New Zealand." Lincoln University, 2008. http://hdl.handle.net/10182/658.
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Aboveground and belowground ectomycorrhizal (ECM) communities associated with different age classes of the exotic plantation species Pinus radiata were investigated over the course of two years in the North Island of New Zealand. ECM species were identified with a combined approach of morphological and molecular (restriction fragment length polymorphism (RFLP) and DNA sequencing) analysis. ECM species richness and diversity of a nursery in Rotorua, and stands of different ages (1, 2, 8, 15 and 26 yrs of age at time of final assessment) in Kaingaroa Forest, were assessed above- and belowground; furthermore, the correlation between the above- and belowground ECM communities was assessed. It was found that the overall and stand specific species richness and diversity of ECM fungi associated with the exotic host tree in New Zealand were low compared to similar forests in the Northern Hemisphere but similar to other exotic plantations in the Southern Hemisphere. Over the course of this study, 18 ECM species were observed aboveground and 19 ECM species belowground. With the aid of molecular analysis the identities of Laccaria proxima and Inocybe sindonia were clarified. In the aboveground study, five species were found associated with P. radiata that were previously not reported with this host in New Zealand (Inocybe sindonia, Lactarius rufus, Lycoperdon gunii, Rhizopogon pseudoroseolus and Wilcoxina mikolae). Belowground, the species Psudotomentella sp., P. tristis, R. luteorubescens, Tomentella sp., Wilcoxina mikolae were found as new associates of P. radiata in New Zealand, additionally nine ECM types were found that could not be identified with molecular analysis. There was little correlation between the species fruiting and the species colonising root tips. Only seven species were found in common between the above- and belowground communities, furthermore the dominant species aboveground were not observed in the belowground ECM communities. The influence of host age on the above- and belowground ECM communities of different age classes of P. radiata plantations was investigated. The aboveground species richness increased from the nursery to the oldest age group investigated (26 yrs), while diversity increased to the 15 yr old age group and decreased slightly to the oldest stand. A clear sequence of ECM species changes was observed to be related to stand age with a growing complexity over the chronosequence. The belowground ECM communities showed a different picture and richness and diversity initially decreased from the nursery to the outplanting but increased thereafter. Belowground no change in ECM composition that was directly related to the age of the host was observed, but two distinct groups of ECM species were found – a 'young' and a 'plantation forest' group, with the respective discriminating species being Rhizopogon rubescens and Type unknown Basidiomycete/Amanita muscaria. Another aspect of the study was the fate of the nursery ECM species in the outplanting and the arrival of non-nursery species. The ECM communities of seedlings in the nursery were investigated in 2006 and these seedlings were followed up over eight assessments in the field for one year, furthermore data from the 1-, 2 and 8 yr old plantation stands was analysed. It was found that the nursery species do survive the first year of outplanting and are dominant in the first year. The first non-nursery species occurred six months after outplanting but was only in minor abundance. Nursery ECM were dominant for two years after the seedlings were planted, and were completely replaced after seven years. Rhizopogon rubescens was found to be the most persistent and dominant species in the outplanting, facilitating the successful establishment of the seedlings in the plantation forest.
22
Lin, Yue. "The role of different modes of interactions among neighbouring plants in driving population dynamics." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-105119.
Full textAbstract:
The general aim of my dissertation was to investigate the role of plant interactions in driving population dynamics. Both theoretical and empirical approaches were employed. All my studies were conducted on the basis of metabolic scaling theory (MST), because the complex, spatially and temporally varying structures and dynamics of ecological systems are considered to be largely consequences of biological metabolism. However, MST did not consider the important role of plant interactions and was found to be invalid in some environmental conditions. Integrating the effects of plant interactions and environmental conditions into MST may be essential for reconciling MST with observed variations in nature. Such integration will improve the development of theory, and will help us to understand the relationship between individual level process and system level dynamics.
As a first step, I derived a general ontogenetic growth model for plants which is based on energy conservation and physiological processes of individual plant. Taking the mechanistic growth model as basis, I developed three individual-based models (IBMs) to investigate different topics related to plant population dynamics:
1. I investigated the role of different modes of competition in altering the prediction of MST on plant self-thinning trajectories. A spatially-explicit individual-based zone-of-influence (ZOI) model was developed to investigate the hypothesis that MST may be compatible with the observed variation in plant self-thinning trajectories if different modes of competition and different resource availabilities are considered. The simulation results supported my hypothesis that (i) symmetric competition (e.g. belowground competition) will lead to significantly shallower self-thinning trajectories than asymmetric competition as predicted by MST; and (ii) individual-level metabolic processes can predict population-level patterns when surviving plants are barely affected by local competition, which is more likely to be in the case of asymmetric competition.
2. Recent studies implied that not only plant interactions but also the plastic biomass allocation to roots or shoots of plants may affect mass-density relationship. To investigate the relative roles of competition and plastic biomass allocation in altering the mass-density relationship of plant population, a two-layer ZOI model was used which considers allometric biomass allocation to shoots or roots and represents both above- and belowground competition simultaneously via independent ZOIs. In addition, I also performed greenhouse experiment to evaluate the model predictions. Both theoretical model and experiment demonstrated that: plants are able to adjust their biomass allocation in response to environmental factors, and such adaptive behaviours of individual plants, however, can alter the relative importance of above- or belowground competition, thereby affecting plant mass-density relationships at the population level. Invalid predictions of MST are likely to occur where competition occurs belowground (symmetric) rather than aboveground (asymmetric).
3. I introduced the new concept of modes of facilitation, i.e. symmetric versus asymmetric facilitation, and developed an individual-based model to explore how the interplay between different modes of competition and facilitation changes spatial pattern formation in plant populations. The study shows that facilitation by itself can play an important role in promoting plant aggregation independent of other ecological factors (e.g. seed dispersal, recruitment, and environmental heterogeneity).
In the last part of my study, I went from population level to community level and explored the possibility of combining MST and unified neutral theory of biodiversity (UNT). The analysis of extensive data confirms that most plant populations examined are nearly neutral in the sense of demographic trade-offs, which can mostly be explained by a simple allometric scaling rule based on MST. This demographic equivalence regarding birth-death trade-offs between different species and functional groups is consistent with the assumptions of neutral theory but allows functional differences between species. My initial study reconciles the debate about whether niche or neutral mechanisms structure natural communities: the real question should be when and why one of these factors dominates.
A synthesis of existing theories will strengthen future ecology in theory and application. All the studies presented in my dissertation showed that the approaches of individual-based and pattern-oriented modelling are promising to achieve the synthesis.
23
Payne, Michelle Jennifer. "Above- and belowground competition in Savanna systems." Thesis, 2008. http://hdl.handle.net/10413/10749.
Full textAbstract:
The structure and composition of savanna vegetation is influenced by resource availability
and disturbance. Grasses, a major component of savannas, influence this resource
availability by competing directly with trees for light, water and soil nutrient resources.
The direct causes of bush encroachment are not always apparent, but are commonly
ascribed to overgrazing and consequent decreased grass competition. The interaction, both
above and belowground, between tree and grass seedlings and the surrounding grass sward
is dependant on many factors, such as soil depth, seedling species and sward composition.
These factors, as well as the presence or absence of defoliation, in the form of grazing or
fire dictate whether the system will remain in a transition state as savanna or move towards
a stable woodland state. The major competitive effects experienced by the tree seedlings
were dependant on grass species and nutrient level. A. nilotica was affected by
aboveground competition while A. karroo was affected by belowground competition. E.
capensis caused the greatest decrease in A. karroo plant biomass. Both E. capensis and H.
hirta had large competitive effects on the aboveground biomass of A. nilotica, while S.
africanus had the greatest effect on belowground biomass. Increasing nutrient availability
resulted in an increase in the competitive effect exerted on A. karroo, while little to no
change was seen in the competitive effect exerted on A. nilotica. Soil depth constrained
plant size in both tree species. The intensity of belowground interactions on tree biomass
was unaffected by soil depth, while aboveground competition had a significant effect on
shallow soils. Belowground competition was also of greater importance than aboveground
competition in dictating tree seedling height. Grass seedlings growing on all three soil
depths differed in mean mass, with E. racemosa having the least mass and T. triandra
having the greatest. Simulated grazing by cutting the surrounding sward resulted in
biomass increases in all three grass species. Changes in savanna composition and structure
are thus likely to be influenced by initial species composition and soil depth and soil
nutrient composition. While grazing creates niches for grass seedling establishment, heavy
grazing has been observed to increase grass seedling mortality. Encroachment is thus more
likely to occur on intensively grazed shallow and deep soils than on medium depth soils.
This highlights the importance of ensuring the grass sward remains vigorous by resting and
monitoring stocking rates to ensure veld is not over-utilized. It is then possible to maintain
some form of tree-grass coexistence at a level where available grazing is not compromised.Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
24
Hsieh, Chia, and 謝嘉. "Above-belowground interactions on soil ecosystem functioning in Taipei urban parks." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/378m6x.
Full textAbstract:
碩士國立臺灣大學
地理環境資源學研究所
105
Soil ecosystem functions in urban green infrastructures (GIs) could help mitigate the impact of human activities on soil biodiversity and biochemical cycle in urban ecosystems. However, plant-soil interactions on soil ecosystem processes in GIs, especially urban parks, are unclear. In this study, the above-belowground properties and soil dissolved organic matter (SDOM) properties of two habitat types, namely tree with grass (TG) and grass (G), from three subtropical urban parks in Taipei City were investigated from December 2015 to January 2017. Ultraviolet-visible spectroscopy and three-dimensional excitation-emission matrix fluorescence spectroscopy were used to characterize SDOM. The differences between the above-belowground properties in TG and those in G were investigated. The relationships between SDOM properties and soil microbial extracellular enzyme activities were also analyzed. With identical litter removal, grass clipping intensities, and similar recreational activities intensities, there were no significant differences in plant compositions, the physicochemical properties of surface soils (0-10 cm), and soil food web compositions. Between two habitat types, ground arthropod compositions were not significantly different. In addition, G had higher soil water content, soil microbial extracellular hydrolases activities, decomposed humic acid-like substances in SDOM, nutrients levels, and SOM content than TG did. Furthermore, the former four parameters had strong positive correlations with each other. The results of this study suggest the formation of soil food web and the rate soil ecosystem processes could correspond to vegetation planting under different land use histories in the field. With the woody litter removal, ground grass cover becomes an important factor in the composition of ground habitat structure, soil organic resources input, and the soil water retention in two habitat types. Between two habitat types, the comparable composition of grass plants could form similar soil food web compositions in two habitat types, and the rates of decomposition and mineralization could be majorly induced by soil water content. From this study, if we want to promote the soil biodiversity or the soil organic matter content by plant planning and management in GIs, the effect of plant diversity and management intensity on soil ecosystem functioning should be further investigated.
25
Müller-Haubold, Hilmar. "Climate response of above- and belowground productivity and allocation in European beech." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5FFB-6.
Full textAbstract:
Die Rotbuche (Fagus sylvatica L.) ist die bestimmende Baumart der potentiell natürlichen Vegetation in den Wäldern Mittel- und Westeuropas die ökonomisch bedeutsamste Laubbaumart Deutschlands. Obwohl diese spät-sukzessionelle Baumart über eine hohe physiologische Toleranz gegenüber einem weiten Spektrum klimatischer Wuchsbedingungen verfügt, wird die Buche gegenüber anderen temperaten Laubbaumarten als relativ trockensensitiv eingeschätzt. Da im Zuge des globalen Klimawandels mit einer Verschlechterung der klimatischen Wasserbilanz und mit einer Zunahme sommerlicher Trockenperioden gerechnet wird, wird die zukünftige Rolle der Rotbuche in der europäischen Forstwirtschaft derzeit intensiv diskutiert. Diese Studie hatte zum Ziel, hydrologische und klimatische Einflüsse auf die Produktivität und die Vitalität der Rotbuche zu untersuchen. Hierdurch sollen grundlegende Mechanismen der Trockenstressantwort bei dieser trocken-sensitiven Art identifiziert, und Rückschlüsse auf zukünftige Klimaantworten von Buchenbeständen ermöglicht werden. Zu diesem Zweck wurde die ober- und unterirdische Biomasseproduktion von 12 Buchenaltbeständen im Norddeutschen Tiefland entlang eines natürlichen Niederschlagsgradienten (543-816 mm a-1) auf einheitlichem geologischen Substrat ermittelt. Um den zusätzlichen Einfluss der Wasserspeicherkapazität der Böden zu berücksichtigen, wurden Paare von Buchenbeständen untersucht, die unter nahezu identischen klimatischen Bedingungen, jedoch auf Böden unterschiedlicher Textur (sandige versus lehmig-sandige Böden) stockten. Einflüsse der Wasserverfügbarkeit und klimatischer Variationen auf das Wachstum wurden untersucht unter Berücksichtigung (i) der gesamten ober- und unterirdischen Biomasseproduktion, (ii) der Dynamik von Ressourcen-Allokation und Kohlenstoff-Partitionierung, sowie (iii) der Morphologie wasseraufnehmender und -abgebender Oberflächen.
Unerwarteterweise zeigte sich die gesamte Produktivität von Buchen-Altbeständen nur geringfügig von Veränderungen der hydrologischen Regime entlang des Gradienten beeinflusst. Trotz deutlicher Unterschiede in der jährlichen Wasserverfügbarkeit nahmen die oberirdische und die gesamte Biomasseproduktion auf den trockeneren Flächen des Transektes nicht ab. Allerdings führten ausgeprägte früh-sommerliche Wasserdefizite (in den Monaten Juni und Juli) zu deutlichen Einbußen der oberirdischen Biomasseproduktion, und insbesondere der Stammholzproduktion. Entlang des untersuchten Gradienten konnte eine ausgeprägte, kontinuierliche Verschiebung der Allokationsmuster festgestellt werden: Mit abnehmender Wasserverfügbarkeit nahm die Feinwurzelproduktion zu und das Verhältnis von oberirdischer:unterirdischer Biomasseproduktion ab. Anders als oberirdische Komponenten zeigte die Feinwurzelproduktion eine hohe Sensibilität gegenüber Unterschieden hinsichtlich hydrologischer Regime. In Übereinstimmung mit der Optimalitätstheorie der pflanzlichen Ressourcennutzung konnte dieses Allokationsverhalten in sowohl in Reaktion auf veränderte Niederschläge, als auch in Antwort auf auch veränderte Wasserspeicherkapazitäten beobachtet werden. Allokative Anpassungsmechanismen an Wassermangel wurden im Feinwurzelbereich zusätzlich durch morphologische Plastizität (Zunahme im Verhältnis von Oberfläche: Biomasse) und durch Regulierung der räumlichen Verteilung (zunehmende Konzentrierung von Feinwurzeln in der organischen Auflage) komplementiert. Im Gegensatz zu diesen komplexen unterirdischen Trockenheits-Antworten konnten keinerlei Anpassungen der Blattmorphologie an veränderte hydrologische Bedingungen festgestellt werden.
Neben Reaktionen auf Wasserverfügbarkeit wurde die Fruchtbildung als zweiter wesentlicher Einfluss auf das Allokationsverhalten der Buche erkannt. Eine deutliche Ressourcen-Allokation zu Gunsten der Fruchtentwicklung beeinträchtigte maßgeblich das oberirdische vegetative Wachstum, insbesondere den Stammholzzuwachs. Auf Grund einer hohen Attraktionsstärke der Früchte gegenüber C und N führte zunehmende Fruktifizierung auch zu einer Gewichts- (und Größen-) Abnahme der Einzelblätter und somit zu reduzierter Bildung von Blattmasse und Bestandesblattfläche (LAI). Neben dieser Abnahme an assimilierender Blattoberfläche führte auch eine deutliche Senkung der Blatt-Stickstoffgehalte in Folge der reproduktiven Ressourcenwidmung mutmaßlich zu einer Verschlechterung der C-Bilanz, sowohl im Mast- als auch im Folgejahr. Eine Analyse klimatischer Einflussfaktoren auf das Mastverhalten legt nahe, dass die Blütenbildung der Buche durch Überschreitung eines Schwellenwertes der Kohlenstoffassimilation im Frühsommer (Juni-Juli) induziert wird.
Sofern diese Schlüsse zutreffen, unterliegt das zeitliche Muster der Fruktifikations-Antwort auf Witterungsauslöser einer Rückkopplungskontrolle durch pflanzliche Stickstoff-Dynamik. Vor dem Hintergrund anhaltend erhöhter Stickstoffdepositionen ergäbe sich aus diesem Mechanismus eine zusätzliche Belastung für das zukünftige vegetative Wachstum der Buche.
Es ist anzunehmen, dass die in dieser Studie belegte hohe allokative Plastizität in Altbäumen Fagus sylvatica dazu befähigt, ihre hohe Konkurrenzkraft in einem breiten Spektrum hydrologischer Regime zu entfalten. Darüber hinaus werden die hier dargestellten Mechanismen einer langfristigen Trockenheitsanpassung mutmaßlich zu einer gesteigerten Resistenz und Resilienz von Buchen-Altbeständen gegenüber Ereignissen extremer Sommertrockenheit beitragen.
26
Biederman, Lori Ann. "Directing ecological restoration: impact of organic amendments on above- and belowground ecosystem characteristics." 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1371.
Full textAbstract:
Increasing interest among restoration ecologists exists in developing strategies
that stimulate biotic interactions and promote self-regulation in restored systems. These
approaches should target above- and belowground organisms because they interact to
regulate ecosystem pattern and process. In the following dissertation, I compare the
ability of organic amendments to alter above- and belowground biological community
structure and function to promote prairie establishment on Castle Drive Landfill in
Garland, Dallas County, Texas. Treatments included altering the location of organic
amendments in the soil profile, either applied to surface or incorporated, and varying the
amount applied. Plant community composition, grass population dynamics, soil nutrient
conditions, and soil biological parameters were monitored for three growing seasons.
Aboveground, the surface treatments were superior for the establishment of
desired and undesired plant species. Plant density patterns can be attributed to the
amelioration of physical conditions and the accidental burial of seed during
incorporation. Grass population dynamics suggest that surface-amended plots supported establishment, but high-volume incorporated treatments were better for enhancing
survival through seasonal and long-term drought. Belowground biological responses
were affected by the plant community, and not by the amendment treatments. Soil
microbial biomass and carbon mineralization potential were larger in those treatments
with greater plant density. The structure of the nematode community suggests that
decomposition in the surface-amended plots was directed through bacterial channels
while decomposition in the incorporated plots was through fungal channels. It is likely
that the higher rates of plant productivity in surface treatments stimulated root exudation,
thereby favoring bacteria and the nematodes that feed on them. Treatment differences in
decomposition pathway were attenuated after 17 months. The soil quality indicators,
Cmic/Corg, qCO2, nematode family richness and nematode density, were not affected by
the restoration treatments or plant density, but did increase over time. The results of this
study suggest that restoration managers should direct their energies into establishing and
promoting a high-quality plant community. This can be manipulated with amendments,
but care is needed not to exceed thresholds within location treatments.
27
Blue, Jarrod Dwayne. "Soil nitrogen amendments and insect herbivory alter above-and belowground plant biomass in an old-field ecosystem." 2010. http://trace.tennessee.edu/utk_gradthes/688.
Full textAbstract:
Nutrient availability and herbivory can regulate primary production in ecosystems, but little is known about how, or whether, they may interact with one another. Here I investigate how nitrogen availability and insect herbivory interact to alter above- and belowground plant community biomass in an old-field ecosystem. In 2004, 36 experimental plots were established in which soil nitrogen (N) availability (at three levels) was manipulated and insect abundance (at two levels) in a completely randomized plot design. In 2009, after six years of treatment, I measured aboveground biomass and assessed root production at peak growth. Overall, I found a significant effect of soil N availability on both above- and belowground plant biomass while insects affected only aboveground biomass of subdominant plant species and coarse root production; there were no statistical interactions between N availability and insect herbivory for any response variable. Specifically, responses of aboveground and belowground community biomass to nutrients were driven by reductions in soil N, but not additions, indicating that soil N may not be primarily limiting production in this ecosystem. Insect herbivory altered the aboveground biomass of the subdominant plant species and altered allocation patterns to coarse root production belowground. Overall, the results of six years of nutrient amendments and insect removals suggest strong bottom-up influences on total plant community productivity.
28
Horrigan, Emma J. "The Impact of Lesser Snow Goose Herbivory on Above and Belowground Nutrient Dynamics in Two Sub-Arctic Ecosystems." Thesis, 2010. http://hdl.handle.net/1807/24580.
Full textAbstract:
In order to determine the impact of lesser snow goose (Chen caerulescens caerulescens) herbivory on above and belowground nutrient dynamics, a grazing and nutrient addition experiment was conducted in two habitat types utilized by snow geese near Churchill, Manitoba. Forage plant nutrition, soil microbial biomass, and inorganic and organic soil nutrients were measured in relation to the timing of grazing, over two consecutive summers. Soil was collected from the rhizosphere to determine the influence of foliar herbivory on root-microbe interactions. Primary productivity in both habitats is co-limited by the availability of both nitrogen (N) and phosphorus (P). Aboveground defoliation either caused a reduction or no change in soil microbial biomass nutrients (carbon (C), N, or P). Defoliated shoots had higher N concentrations and did not show compensatory growth within the season. Root biomass was somewhat reduced with grazing, but higher whole plant N content suggests that grazing does not compromise N-uptake.
29
Valenzuela-Estrada, Luis Rene Eissenstat David M. "Above- and belowground physiology in Vaccinium corymbosum L. (northern highbush blueberry) in response to water stress and reproductive effort." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2853/index.html.
Full text
30
Rubilar, Pons Rafael. "Environmental constraints on growth phenology, leaf area display, and above and belowground biomass accumulation of Pinus radiata (D. Don) in Chile." 2005. http://www.lib.ncsu.edu/theses/available/etd-12062005-135049/unrestricted/etd.pdf.
Full text
31
"Nematode Herbivory as a Mechanism Behind the Influence of Precipitation on the Partitioning of Net Primary Production between Above and Belowground Components." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.49279.
Full textAbstract:
abstract: Aboveground net primary production (ANPP) and belowground net primary production (BNPP) may not be influenced equally by the same factors in arid grasslands. Precipitation is known to affect ANPP and BNPP, while soil fauna such as nematodes affect the BNPP through herbivory and predation. This study on black grama grass (Bouteloua eriopoda) in the Chihuahuan Desert investigates the effects of precipitation and nematode presence or absence on net primary production (NPP) as well as the partitioning between the aboveground and belowground components, in this case, the fraction of total net primary production occurring belowground (fBNPP). I used a factorial experiment to investigate the effects of both precipitation and nematode presence on the components of NPP. I used rainout shelters and an irrigation system to alter precipitation totals, while I used defaunated and re-inoculated soil for the nematode treatments. Precipitation treatment and seasonal soil moisture had no effect on the BNPP and a nonsignificant positive effect on the ANPP. The fBNPP decreased with increasing precipitation and seasonal soil moisture, though without a significant effect. No predator nematodes were found in any of the microcosms at the end of the experiment, though other functional groups of nematodes, including herbivores, were found in the microcosms. Total nematode numbers did not vary significantly between nematode treatments, indicating that the inoculation process did not last for the whole experiment or that nematodes had little plant material to eat and resulted in low population density. Nematode presence did not affect the BNPP, ANPP, or the fBNPP. There were no significant interactions between precipitation and nematode treatment. The results are inconclusive, possibly as a result of ecosystem trends during an unusually high precipitation year, as well as the very low NPP values in the experiment that correlated with low nematode community numbers.Dissertation/Thesis
Masters Thesis Biology 2018
32
Kotowska, Martyna Małgorzata. "Carbon pools and sequestration in vegetation, litter dynamics and hydraulic anatomic properties in rainforest transformation systems in Indonesia." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-863B-9.
Full text
33
Maheux, Lydia. "Impact de Heterodera glycines sur la réaction de défense du soya (Glycine max) et influence sur la gestion de Aphis glycines dans un contexte climatique actuel et futur." Thèse, 2018. http://hdl.handle.net/1866/21318.
Full text
34
Lin, Yue. "The role of different modes of interactions among neighbouring plants in driving population dynamics." Doctoral thesis, 2012. https://tud.qucosa.de/id/qucosa%3A26569.
Full textAbstract:
The general aim of my dissertation was to investigate the role of plant interactions in driving population dynamics. Both theoretical and empirical approaches were employed. All my studies were conducted on the basis of metabolic scaling theory (MST), because the complex, spatially and temporally varying structures and dynamics of ecological systems are considered to be largely consequences of biological metabolism. However, MST did not consider the important role of plant interactions and was found to be invalid in some environmental conditions. Integrating the effects of plant interactions and environmental conditions into MST may be essential for reconciling MST with observed variations in nature. Such integration will improve the development of theory, and will help us to understand the relationship between individual level process and system level dynamics.
As a first step, I derived a general ontogenetic growth model for plants which is based on energy conservation and physiological processes of individual plant. Taking the mechanistic growth model as basis, I developed three individual-based models (IBMs) to investigate different topics related to plant population dynamics:
1. I investigated the role of different modes of competition in altering the prediction of MST on plant self-thinning trajectories. A spatially-explicit individual-based zone-of-influence (ZOI) model was developed to investigate the hypothesis that MST may be compatible with the observed variation in plant self-thinning trajectories if different modes of competition and different resource availabilities are considered. The simulation results supported my hypothesis that (i) symmetric competition (e.g. belowground competition) will lead to significantly shallower self-thinning trajectories than asymmetric competition as predicted by MST; and (ii) individual-level metabolic processes can predict population-level patterns when surviving plants are barely affected by local competition, which is more likely to be in the case of asymmetric competition.
2. Recent studies implied that not only plant interactions but also the plastic biomass allocation to roots or shoots of plants may affect mass-density relationship. To investigate the relative roles of competition and plastic biomass allocation in altering the mass-density relationship of plant population, a two-layer ZOI model was used which considers allometric biomass allocation to shoots or roots and represents both above- and belowground competition simultaneously via independent ZOIs. In addition, I also performed greenhouse experiment to evaluate the model predictions. Both theoretical model and experiment demonstrated that: plants are able to adjust their biomass allocation in response to environmental factors, and such adaptive behaviours of individual plants, however, can alter the relative importance of above- or belowground competition, thereby affecting plant mass-density relationships at the population level. Invalid predictions of MST are likely to occur where competition occurs belowground (symmetric) rather than aboveground (asymmetric).
3. I introduced the new concept of modes of facilitation, i.e. symmetric versus asymmetric facilitation, and developed an individual-based model to explore how the interplay between different modes of competition and facilitation changes spatial pattern formation in plant populations. The study shows that facilitation by itself can play an important role in promoting plant aggregation independent of other ecological factors (e.g. seed dispersal, recruitment, and environmental heterogeneity).
In the last part of my study, I went from population level to community level and explored the possibility of combining MST and unified neutral theory of biodiversity (UNT). The analysis of extensive data confirms that most plant populations examined are nearly neutral in the sense of demographic trade-offs, which can mostly be explained by a simple allometric scaling rule based on MST. This demographic equivalence regarding birth-death trade-offs between different species and functional groups is consistent with the assumptions of neutral theory but allows functional differences between species. My initial study reconciles the debate about whether niche or neutral mechanisms structure natural communities: the real question should be when and why one of these factors dominates.
A synthesis of existing theories will strengthen future ecology in theory and application. All the studies presented in my dissertation showed that the approaches of individual-based and pattern-oriented modelling are promising to achieve the synthesis.