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1
Ascarrunz, Nataly Lorena. "Topography, elemental ratios, and nutrient limitation in tropical montane ecosystems." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337070.
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Vélez, Caicedo María Isabel. "A contribution of diatom analysis to lateglacial and holocene environmental reconstructions of Colombian lowland and montane ecosystems." [Amsterdam] : Amsterdam : Universiteit van Amsterdam/IBED ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/66945.
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Uhlig, David [Verfasser]. "The deep Critical Zone as a source of mineral nutrients to montane, temperate forest ecosystems / David Uhlig." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/117663657X/34.
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Young, Laura May. "Seed dispersal mutualisms and plant regeneration in New Zealand alpine ecosystems." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/6992.
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The New Zealand alpine zone has many fleshy-fruited plant species, but now has a relatively depauperate animal fauna. The key question is, therefore, are native alpine plants still being dispersed, if so where to and by what? I first measured fruit removal rates among nine common species using animal-exclusion cages to compare natural fruit removal by all animals, and by lizards only. Over two years, mean percent of fruit removed by early winter ranged from 25–60% among species. Speed of fruit removal also varied depending on species. Secondly, I quantified which animals disperse (or predate) seeds of those fruits, into which habitats they deposit the seeds, and the relative importance of each animal species for dispersal, in two ways. A 2-year study using fixed-area transects to monitor faecal deposition showed that introduced mammals (especially possums, rabbits, hares, sheep, pigs and hedgehogs) were abundant and widespread through alpine habitat. Of the 25,537 faeces collected, a sub-sample of 2,338 was dissected. Most mammals dispersed most (> 90%) seeds intact. However, possums (numerically the important disperser) moved most seeds into mountain beech (Nothofagus solandri) forest, while rabbits, hares, and sheep dispersed seeds mainly into open grassland dominated by thick swards of exotic grasses (e.g. Agrostis capillaris and Anthoxanthum odoratum); all are less suitable microsites. Kea (Nestor notabilis), the largest and most mobile of only three remaining native alpine bird species, are potentially useful as a long-distance seed disperser, even though parrots are typically seed predators. I found that kea are numerically more important than all other birds combined, damage very few seeds, and are probably responsible for most dispersal of seeds between mountain ranges. Finally, I investigated the effects of seed deposition microsite (shady/high-light), pulp-removal (whole/cleaned), competition (soil dug/not-dug) and predation (caged/ not) on germination, growth and survival of eight subalpine plant species. There were strong positive effects of shady microsites for seed germination and seedling survival to 3.5 years for six of the eight species. Effects of other treatments were less important and varied among species and stages. Hence, both native birds and introduced mammals are dispersing alpine seeds, but the mammals often deposit seeds in habitats unsuitable for establishment. Any evaluation of the dispersal effectiveness of frugivores must consider their contribution towards the long-term success for plant recruitment through dispersal quantity and quality.
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Sánchez, Galindo Laura Margarita [Verfasser]. "Impacts of leaf litter diversity and root resources on microorganisms and microarthropods (Acari, Collembola) during early stages of decomposition in tropical montane rainforest ecosystems / Laura Margarita Sánchez Galindo." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1229192638/34.
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Bale, Adam M. Guyette Richard P. "Fire effects and litter accumulation dynamics in a montane longleaf pine ecosystem." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6553.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 16, 2009). Thesis advisor: Dr. Richard P. Guyette. Includes bibliographical references.
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Barrento, Maria João Hortas. "Influence of soil parameters on ectomycorrhizal diversity in montado ecosystems." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5305.
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Mestrado em Engenharia Florestal e dos Recursos Florestais - Instituto Superior de AgronomiaThis study characterized the composition and the diversity of macrofungal communities associated with four plots of montado situated in Grândola Hills, Southern Portugal, and evaluated the influence of soil parameters on ectomycorrhizal fungal diversity and abundance. Phosphorus, potassium, total nitrogen, organic matter concentrations and soil pH were the parameters determined. Differences in soil chemical features were found between studied plots. A total of 132 species of macrofungi were found in the study area being Laccaria, Russula and Cortinarius the most abundant genera. Also dissimilarities on macrofungal communities, particularly, on abundance and diversity, were registered among plots. The influence of soil parameters on ectomycorrhizal diversity and abundance was studied in the plots with values of biological spectrum higher than one, and in particular for the most frequent species Laccaria laccata, Cortinarius trivialis, Russula amoenolens and Russula subfoetens. Results showed that ectomycorrhizal diversity is negatively correlated with the increasing of extractable phosphorus concentration, and the abundance of ectomycorrhizal species responds differently to soil chemical characteristics. The present study allows us to understanding the influence of some soil features on ectomycorrhizal fungal diversity and abundance. Finally, the effects of management practices on ectomycorrhizal fungal diversity in this Mediterranean ecosystem are discussed.
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Stein, Claudia. "Biodiversity and ecosystem functioning: regional and local determinants of plant diversity in montane grasslands /." Leipzig : UFZ, 2008. http://www.ufz.de/data/ufzdiss_11_2008_9590.pdf.
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Burgoyne, Tricia. "Free living nitrogen-fixation in ponderosa pine/Douglas-fir forests in western Montana." The University of Montana, 2007. http://etd.lib.umt.edu/theses/available/etd-05302007-085002/.
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Nitrogen (N) is a primary limiting nutrient in all ecosystems. Therefore, a thorough understanding of N cycling processes in forest ecosystems is required to minimize N losses to fire, harvesting, and other forms of land management. The influence of fire, fire exclusion and forest restoration treatments on non-symbiotic N-fixation in the forest ecosystem has been poorly studied. Over the past 100 years, fire has been greatly excluded from low elevation, fire maintained forests as a result of active fire suppression as well as land management activities that create discontinuities in landscape fire patterns. Previous studies have shown this activity to inhibit recolonization of sites by symbiotic N-fixing plant species. The lack of these important N fixing species may make non-symbiotic, free-living N fixing bacteria a more important source for N recovery in these forest ecosystems following disturbance. Recent studies also suggest that free-living N-fixing bacteria colonizing decomposing woody roots have the capacity to fix large amounts of N. The purpose of these studies was to investigate the effect of fire, fire exclusion, and forest restoration on the N contribution of non-symbiotic N-fixing bacteria (colonizing soil, woody roots, and soil crusts) to the forest ecosystem and how their contribution compares to symbiotic N-fixers in Western Montana. Studies were conducted in the laboratory and at numerous field sites throughout western Montana. In order to determine the N-fixation activity of organisms in these systems, we used the acetylene reduction technique. Neither time since fire, nor restoration treatment had any direct influence on free living N-fixation in soil or woody roots. Moisture and N availability were the potent drivers of free living N-fixation in western Montana. Nitrogen-fixation rates were low in decomposing woody roots in these ecosystems and woody roots do not contribute a significant amount of N to low elevation ponderosa pine/Douglas-fir forests in western Montana. Free-living N-fixing bacteria in soils were found to make a significant, yet modest N contribution to the forest ecosystem. Nitrogen demand by trees and shrubs are being maintained by residual soil organic N, symbiotic N fixation, and wet and dry N deposition in the Inland Northwest
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Amish, Stephen Joseph. "Ecosystem engineering beaver and the population of Columbia spotted frogs in western Montana /." Connect to this title online, 2006. http://etd.lib.umt.edu/theses/available/etd-01172007-105600/.
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Williams, Thomas James. "Estimating organic carbon on avalanche paths in Glacier National Park, Montana." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4795.
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Avalanche paths are unique ecosystems that represent a significant portion of the landscape in the northern Rocky Mountains. Frequent avalanche disturbance results in vegetative cover that is unlike the adjacent coniferous forest. These high relief environments have the potential to remove carbon from the atmosphere at rates differing from those of the surrounding forest, and to regulate matter and/or energy fluxes to downslope ecosystems.
This thesis attempts to estimate organic carbon on south-facing avalanche paths in the southern portion of Glacier National Park, Montana. I am specifically interested in total organic carbon density, compartmental carbon density, and change in organic carbon over time as a function of shrub and tree diameter. Using an integrated sampling method, estimates of total organic carbon on avalanche paths appear to be different than those of the adjacent forest and similar to those of other shrub formation types in the area. However, the potentially moveable litter compartment is consistently larger. Organic carbon from shrub and trees growing on paths appears to be increasing at a continuous rate leading up to disturbance, while a typical individual's rate of increase appears to be slowing. The organic material temporarily stored on avalanche paths could serve as an important outside carbon source for near and distant aquatic ecosystems.
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Griffin, Kathleen Ann Pletscher Daniel H. "Spatial population dynamics of western painted turtles in a wetland ecosystem in northwestern Montana." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05272008-135912/.
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Thesis (Ph. D.)--University of Montana, 2007.Title from title screen. Description based on contents viewed Aug. 14, 2008. Includes 2 appendices: Potential effects of highway mortality and habitat fragmentation on a population of painted turtles in Montana, and Fencing methods and efficacy for minimizing turtle road kill and directing turtles to crossing structures, both by Kathy Griffin and Daniel H. Pletscher. Includes bibliographical references.
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Epperly, Joshua A. "The Effects of Enhanced Flows on Community Structure and Ecosystem Functioning in a Montane Utah River System." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7223.
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Due to growing human demands for freshwater within the last century, manmade flow alterations are now a common characteristic of rivers worldwide. Alterations to the volume and timing of flows in rivers are known to negatively impact aquatic biodiversity, biological productivity and ecosystem functions such as nutrient cycling. While previous research has focused on the effects of flow reductions and spates, there is a lack of knowledge on how high flows across longer timespans (i.e. ‘enhanced flows’) impact the structure of river communities and the integrity of ecosystem functions.
The Utah Reclamation, Mitigation and Conservation Commission has expressed interest in reducing enhanced flows in a central Utah river so as to benefit aquatic habitat and native game fish. With their funding support, I collected aquatic invertebrate and ecosystem function data under natural and enhanced flow conditions throughout Sixth Water Creek and Diamond Fork River. These data were supplemented with historical invertebrate data collected by BIO-West, Incorporated. For each river segment, I tested whether flow volume and variation had relationships with the density and health of streambed invertebrate communities. I also sought to determine how these flow metrics affected leaf litter breakdown, primary production and stream metabolism (i.e. the production and respiration of organic matter).
Here, I demonstrate that enhanced flows impact streambed invertebrate communities differently in each river segment, in addition to suppressing stream metabolism system-wide. While streambed communities were mostly unaffected by enhanced flows in Sixth Water Creek, density and community health exhibited negative relationships with flow metrics in Diamond Fork River. In the Lower Diamond Fork mainstem, proportions of pollution-tolerant taxa increased as peak flows increased, while streambed invertebrate density decreased as mean monthly flows increased. Moreover, enhanced flows appeared to severely impact the production of organic matter in Sixth Water Creek and Lower Diamond Fork River. This disproportionate suppression of production over respiration shifted the river towards greater reliance on out-of-stream energy sources. These results demonstrate the importance of considering spatial gradients when investigating community responses to flow alterations, and also reveal how river ecosystems are threatened with losses of in-stream energy supplies under enhanced flows.
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Thormann, Birthe [Verfasser]. "Biodiversity of leaf beetles (Coleoptera: Chrysomelidae) in a tropical montane rainforest ecosystem assessed with DNA barcoding / Birthe Thormann." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1113688246/34.
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Davidson, Diedre P., and University of Lethbridge Faculty of Arts and Science. "Sensitivity of ecosystem net primary productivity models to remotely sensed leaf area index in a montane forest environment." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2002, 2002. http://hdl.handle.net/10133/155.
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Net primary productivity (NPP) is a key ecological parameter that is important in estimating carbon stocks in large forested areas. NPP is estimated using models of which leaf area index (LAI) is a key input. This research computes a variety of ground-based and remote sensing LAI estimation approaches and examines the impact of these estimates on modeled NPP. A relative comparison of ground-based LAI estimates from optical and allometric techniques showed that the integrated LAI-2000 and TRAC method was preferred. Spectral mixture analysis (SMA), accounting for subpixel influences on reflectance, outperformed vegetation indices in LAI prediction from remote sensing. LAI was shown to be the most important variable in modeled NPP in the Kananaskis, Alberta region compared to soil water content (SWC) and climate inputs. The variability in LAI and NPP estimates were not proportional, from which a threshold was suggested where first LAI is limiting than water availability.xii, 181 leaves : ill. ; 28 cm.
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Baker, Corey Ryan. "Mapping and change detection of wetland and riparian ecosystems in the Gallatin Valley, Montana using landsat imagery." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/baker/BakerC1204.pdf.
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McCaffery, Magnus. "The influence of an ecosystem engineer on nutrient subsidies and fish invasions in Southwestern Montana." Diss., [Missoula, Mont.] : University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-03102010-102211.
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Lopes, Cláudia Maria Gomes. "Barn swallows' diet in the montado." Master's thesis, Universidade de Évora, 2018. http://hdl.handle.net/10174/23686.
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As aves são um grupo importante no equilíbrio dos ecossistemas devido aos
serviços que proporcionam. A andorinha-das-chaminés é uma ave insectívora
geralmente associada a actividades humanas, com a sua dieta baseada em estádios
voadores de insectos, principalmente Diptera, Hymenoptera e Coleoptera. Neste estudo,
avaliámos a dieta de uma população de andorinha-das-chaminés nidificante num
ecossistema seminatural – o montado –, aplicando o método do colar em crias.
Avaliámos se existiam diferenças na composição da dieta entre períodos de amostragem
ao longo de Abril e Maio de 2012, bem como entre dípteros de diferentes funções
ecológicas. Os resultados confirmaram a preferência pelas três ordens insectívoras
descritas, com Diptera totalizando 65%. Não foram registadas diferenças na biomassa
média consumida entre períodos, idade das crias e funções ecológicas, mostrando um
equilíbrio no consumo energético, embora haja consumo de diferentes tipos de presas; Barn swallow’s diet in the montado
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Birds are an important group in the equilibrium of the ecosystems due to the
services they provide. The barn swallow is an insectivorous bird generally associated to
human activities, with their diet being based on winged life stages of insects, mainly
Diptera, Hymenoptera and Coleoptera. We evaluated the diet of a barn swallow
population breeding in a semi-natural ecosystem – the montado –, applying the ligature
method on nestlings. We evaluated if there were differences in the diet among sampling
periods along the months of April and May (2012), as well as among different
ecological functions of Diptera. Results confirmed the preference for the three main
insect orders, with Diptera reaching 65% of the total. There were no differences in mean
biomass consumed throughout periods, nestling’s age and ecological functions, showing
equilibrium of the energetic intake despite the different types of prey consumed.
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Bison, Marjorie. "Approches taxonomique et fonctionnelle des interactions trophiques entre grands herbivores et communautés végétales dans un écosystème de montagne." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV068/document.
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Etant donné le rôle clé des grands herbivores sur la diversité végétale spécifique et fonctionnelle, notre objectif était de mieux comprendre la relation entre l'herbivorie et les communautés végétales principalement à une échelle spatiale fine, afin de concilier des objectifs de gestions des populations et de conservation de la flore. Pour cela, nous avons abordé cette problématique en intégrant des approches taxonomiques et fonctionnelles, et en étudiant les interactions aux niveaux inter- et intra-spécifiques. Nous avons combiné les informations de trois bases de données : (1) des données de régime alimentaire issus d'analyses d'ADN metabarcoding réalisées sur des faeces de chamois (Rupicapra rupicapra), chevreuil (Capreolus capreolus) et mouflons (Ovis gmelini musimon) du Massif des Bauges, (2) des données sur les caractéristiques des communautés végétales (composition floristique, biomasse, phénologie), (3) des données de traits fonctionnels des plantes. L'analyse de variabilité intra-spécifique des trois grands herbivores nous a permis de valider l'hypothèse de variation de niche (NVH) de Van Valen au niveau intra-spécifique mais aussi au niveau inter-spécifique, soit une relation positive entre la largeur de niche de l'espèce et sa variabilité intra-spécifique. Ensuite, grâce à deux populations de chamois d'alpage, l'une vivant en sympatrie avec le mouflon et l'autre vivant en allopatrie, nous avons pu mettre en évidence l'absence d'effets négatifs de la population introduite de mouflon sur le régime alimentaire de la population native de chamois, autant au niveau de la niche alimentaire taxonomique que fonctionnelle. L'analyse des critères de sélection alimentaire nous a finalement permis de mettre en avant des différences de critères de choix entre les deux espèces à certaines saisons, expliquant ainsi partiellement le partitionnement des niches taxonomiques et fonctionnelles entre les deux espèces. Par ailleurs, les scénarios proposés d'évolution de la sélection alimentaire au cours de l'année pour les deux espèces concordaient avec les caractéristiques morphologiques spécifiques à l'espèce d'ongulé. Finalement, contrairement à la littérature où aucune étude n'était capable de discriminer les effets directs et indirects des traits fonctionnels à cause de corrélations, nous avons pu, grâce à des analyses de pistes, démontrer que, dans la plupart des cas, les traits biomécaniques avaient un effet direct sur le choix alimentaire alors que les traits chimiques n'avaient qu'un effet indirect. Enfin, d'un point de vue méthodologique, nous conseillons l'utilisation d'indices d'azote fécaux uniquement dans l'étude de la variation à long terme de la qualité des régimes de manière spécifique à chaque espèce et chaque site, et non pas pour comparer des qualités de régime entre espèces ni pour étudier les variations fines à l'échelle intra-saisonnière. La complémentarité des approches nous a permis de mieux appréhender la structuration des communautés d'herbivores, et devrait nous aider à mieux évaluer l'état actuel et l'évolution des relations entre individus, entre espèces et avec leur environnement.Mots-clés : ongulés, interactions intra- et inter-spécifiques, approche taxonomique et fonctionnelle, ADN metabarcoding, NIRS, massif des Bauges, sélection alimentaireGiven the key role of large herbivores on species and functional plant diversity, we aimed at better understanding the relationship between herbivory and plant communities mainly at a fine-scale, in order to reconcile objectives of population management and plant conservation. For this purpose, we used both taxonomic and functional approaches, and studied interactions at the inter- and intra-specific levels. We combined information coming from three databases: (1) diet data from DNA-metabarcoding applied on chamois (Rupicapra rupicapra), roe deer (Capreolus capreolus) and mouflon (Ovis gmelini musimon) faeces from the Bauges Massif, (2) characteristics of plant communities (plant composition, biomass, phenology), (3) plant functional traits. Analyses of intra-specific variability of the three large herbivores allowed us to upscale the niche variation hypothesis (NVH) of Van Valen from the intra- to the inter-specific level, i.e. we observed a positive relationship between the species niche breadth and among-individual variation. Then, based on two chamois subpopulations living in pastures, one living in sympatry with the mouflon and the other living in allopatry, we revealed the absence of negative effects of the introduced mouflon population on native chamois population diet, both for the taxonomic and functional dietary niche. Analyses of diet selection criteria allowed us to highlight differences in choice criteria between chamois and mouflon in some seasons, which helped to explain the taxonomic and functional niche partitioning of the two species. Furthermore, the proposed scenario of the evolution of diet selection over the year for both species were consistent with ungulate-specific morpho-physiological features. Finally, contrary to the literature where no studies could discriminate the direct and indirect effects of functional traits on diet selection because of correlations, we used path analyses, which allowed us to show that in most cases, biomechanical traits had a direct effect on diet choices, whereas chemical traits had an indirect effect. Furthermore, from a methodological point of view, we advised to use nitrogen fecal indices only to study the evolution of species-specific and location-specific population long-term diet quality, but not to compare diet quality between species, nor to study slight fluctuations at the intra-seasonal level. The complementarity of the approaches allowed us to better account for the structuration of herbivore communities, which should help to better assess the actual state and the evolution of relationships among individuals, species and their environment.Key-words: ungulates, intra- and inter-specific interactions, taxonomic and functional approach, DNA metabarcoding, NIRS, Bauges Massif, diet selection
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Lieberherr-Gardiol, Françoise. "Pratiques et représentations en montagne : le pays d'Enhaut : Suisse." Paris, EHESS, 1986. http://www.theses.fr/1986EHESA004.
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Etude anthropologique des rapports societe-ecosysteme naturel, c'est-a-dire d'un groupe social a l'espace environnement - territoire a travers les pratiques et les representations des habitants, revelant leurs systemes de valeurs specifiques. Region agro-touristique du pays-d'enhaut (vaud). Methode d'etude multidimensionnelle (questionnaire sur echantillon stratifie de 306 personnes, 53 entretiens stastistique demographique et socio-economique, etude documents et archives, analyse des correspondance, et. ) pour conprehension - explication globale et endogene. Themes : paysannerie, interconnaissance villageoise, identite, appartenance montagnarde, ruralite, tradition modernite tourisme, loisirs, perception ville, heterogeneite socio-culturelle, comportements eco-anthropologiques. Tendances d'evolution des regions alpestres suisses ou "modernisation de la montagne" par premiere phase d'acculturation urbaine. Deuxieme phase de reacculturation rurale en 3 courants interactifs : ruralite paysanne, ruralite reinventee, urbanite montagnardeAnthropological study of relationships between society - natural ecosystem, between a social group with space - environment - territory by practices and representations of mountainers, revealing specific value systems. Agro-tourist region of pays-d'enhaut (vaud). Method of multidimensional study (questionary on stratified sample of 306 inhabitants, 53 interviews demographic and socio-economic statistics study documents and archives, "correspondance - analysis", etc. ) for global and endogenous understanding-explanation. Themes : paesantry, face-to-face comunity, identity, mountain membership feeling, rurality, tradition modernity, tourism, perception of town, socio-cultural heterogeneity, eco-anthropological behaviours. Evolution tendencies in swiss moutain regions or "mountain modernization" by first phase of urban acculturation. Second phase of rural reacculturation with 3 interactive trends : paesant rurality, reinvented rurality, mountain urbanity
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Michaels, Amanda Paige. "Land Use and Land Cover Change in the Crown of the Continent Ecosystem, Montana, USA from 1992-2011." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/72842.
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In recent decades land use and land cover change (LULCC) has occurred throughout the Intermountain West. The Crown of the Continent Ecosystem (CCE) extends along the Rocky Mountains adjacent to the Canada-U.S. International border. In the U.S. portion of the CCE, located in northwestern Montana, development has increased since the 1990s, largely because of urban to rural migration. The CCE has become an amenity-based destination, which in turn is likely to threaten its terrestrial and aquatic ecological diversity (Quinn and Broberg 2007). Specifically, development pressures on private lands surrounding federally protected lands, are intensifying and thus threatening core habitat of native species and connectivity of forested areas. By characterizing the spatial and temporal patterns of LULCC, we can better understand landscape-scale changes influenced by human-environment interactions.
Using National Land Cover Database (NLCD) products, I identified areas that have experienced land cover change for three time periods: 1992-2001, 2001-2006, and 2006-2011. Additionally, I used case studies to further investigate LULCC in the study area. The findings suggest that the highest rates of development in proximity to Glacier National Park were dependent on existing urban land cover, meaning existing roadway infrastructure and established urban areas saw the greatest urban development. Additionally, communities adjacent to Glacier National Park were hotspots for urban development. Based on the results, areas in proximity to federally protected lands are likely to experience continued urban intensification over the next few decades.Master of Science
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Srinivasan, Madhusudan P. "THE ECOLOGY OF DISTURBANCES AND GLOBAL CHANGE IN THE MONTANE GRASSLANDS OF THE NILGIRIS, SOUTH INDIA." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/213.
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Biodiversity rich regions worldwide face threats from various global change agents. This research quantifies environmental influences on vegetation, and the impacts of exotic woody plant invasion and anthropogenic nitrogen (N) deposition in a global biodiversity hotspot. The study was conducted in the montane grasslands of the Nilgiris, Western Ghats, and outlines potential management options for this region. Specifically, I examined (1) the role of environmental factors in influencing native plant distribution and ecosystem properties, (2) the status and impact of exotic shrub (Scotch broom, henceforth broom) invasion, (3) the role of disturbances in the success of broom, (4) the role of fire in restoring invaded grasslands, and (5) the impacts of terrestrial N loading on the grassland ecosystem. I used experiments and surveys to assess these. Distributions of several key species were explained by a few complex environmental gradients. In invaded-grasslands, broom populations consisted mainly of intermediate size and age classes, with no clear indication of population decline. Invasion negatively impacted plant community structure and drastically changed composition, favoring shade-tolerant and weedy species. However, invasion did not greatly alter ecosystem function. Fire successfully eliminated mature broom stands, but resulted in a short-term increase in broom seedling recruitment. At the end of 18 months, the fire effects on uninvaded-grasslands were not apparent, but there was no conclusive evidence of the formerly invaded patches attaining the composition of uninvaded-grasslands following burning. N fertilization strongly influenced soil N dynamics, and shoot N concentrations, but effects on aboveground production were weak. Surprisingly, N enrichment had positive effects on diversity in the short-term. It is clear that these grasslands need immediate management intervention to forestall degradation from invasion. Fire could be used to eliminate mature broom stands and deplete persistent seedbanks, which will facilitate colonization by shade-intolerant grassland plants. Active restoration should be mindful of environmental preferences of framework species. Long-term studies of the impacts of N deposition in the context of disturbances will help determine realistic critical thresholds and utilize disturbances to buffer the potential adverse effects of increasing N loading.
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Meireles, Leonardo Dias. "Estudos floristicos, fitossociologicos e fitogeograficos em formações vegetacionais altimontanas da Serra da Mantiqueira Meridional, sudeste do Brasil." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315023.
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Orientador: George John ShepherdTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A Serra Fina é o nome de umas das áreas da Serra da Mantiqueira Meridional, uma cadeia montanhosa na divisa geográfica entre Minas Gerais, São Paulo e Rio de Janeiro, sudeste do Brasil. A Serra Fina compreende um dos maciços de rochas alcalinas que forma uma das áreas de maior altitude dessa região com mais de 2.500 metros de altitude em vários locais. Ela apresenta um destacado gradiente altitudinal que permite a ocorrência de diferentes formações vegetacionais altimontanas. Sua vegetação apresenta-se ainda relativamente conservada, mas pouquíssimo conhecida. Nós objetivamos analisar a composição florística de suas formações vegetacionais altimontanas, descrever a estrutura fitossociológica das florestas nebulares, verificar a similaridade dessa floresta com outras florestas montanas brasileiras e verificar como mudanças climáticas quaternárias influenciaram a distribuição geográfica das espécies que as compõem. Nos campos de altitude, matas de candeias e nas florestas nebulares foram coletadas 393 espécies das quais sete são provavelmente novas para a ciência. As famílias Asteraceae, Poaceae, Melastomataceae, Rubiaceae, Cyperaceae, Fabaceae, Myrtaceae, Orchidaceae e Ericaceae apresentaram as maiores riquezas específicas. Duas espécies novas da família Asteraceae restritas aos campos de altitude acima de 2.500 metros de altitude foram descritas e ilustradas e as demais necessitam de estudos detalhados por especialistas. A riqueza específica amostrada denota a importância das áreas de altitude na diversidade da Floresta Atlântica e denotam a importância fitogeográfica da Serra Fina por apresentar um grande número de espécies endêmicas ou com distribuição geográfica restrita e comportar espécies com fortes relações com a flora dos Andes, oeste da América do Sul. As florestas apresentaram características típicas de florestas nebulares como menor riqueza, elevada densidade e um dossel reduzido. Myrsinaceae, Myrtaceae, Symplocaceae e Cunoniaceae foram as famílias de maior valor de importância. As florestas alto-montanas da Serra da Mantiqueira apresentaram alta similaridade florística com florestas nebulares sulinas e em parte com as florestas alto-montanas do interior de Minas Gerais e do topo da Serra do Mar em São Paulo, que apresentam uma composição florística relativamente diferenciada. A similaridade dessas florestas com florestas em altitudes mais baixas é relativamente menor. Os modelos de distribuição potencial para espécies florestais montanas destacaram intensas modificações na área de ocupação dessas espécies em cenários climáticos para o Quaternário Tardio e sugerem que estas espécies possam ter ocorrido em altitudes e latitudes menores e longitudes maiores do que atualmente observado. Esses resultados sugerem que florestas com composição florística similar às atuais florestas alto-montanas possam ter ocupado uma área mais extensa no passado, formando em algumas regiões florestas mais extensas que foram posteriormente fragmentadas e confinadas ao topo de cadeias montanhosas na região leste ao sul do Brasil.
Abstract: The "Serra Fina" is the name given to a block of the Serra da Mantiqueira, a mountain chain that forms the boundary between the states of Minas Gerais, São Paulo, and Rio de Janeiro, southeastern Brazil. The Serra Fina largely corresponds to a massif of alkaline rocks and forms the highest part of the range, rising to more than 2500m at several points. It offers an exceptionally extensive altitudinal gradient, with the occurrence of several high-montane vegetation formations. These formations are still relatively well-conserved, but are very poorly known. The main objectives of the present study were to analyze the floristic composition of some of the high-montane vegetation types, describe and analyze the phytosociological structure of the cloud forests, determine the degree of similarity between these forests and other montane forests in Brazil and to investigate possible explanations of the patterns seen, especially with regard to climate changes in the quaternary. A total of 393 species, of which seven are probably new to science, were collected in the grasslands, "candeia" scrub and cloud forests. The greatest species-level richness was found in the families Asteraceae, Poaceae, Melastomataceae, Rubiaceae, Cyperaceae, Fabaceae, Myrtaceae, Orchidaceae and Ericaceae. Two new species of Asteraceae, confined to grasslands above 2500m have been described and illustrated, and the remainder await more detailed studies by specialists. The species richness encountered demonstrates the importance of the contribution of high altitude areas to the overall diversity of the Atlantic Forest of eastern Brazil, and the phytogeographic importance of the Serra Fina with a large number of endemic species or species with restricted distributions with strong links to the Andean flora of western South America. The forests showed a number of characteristics typical of cloud forests, such as low richness, high density and a reduced canopy, with Myrsinaceae, Myrtaceae, Symplocaceae and Cunoniaceae as the most important families. The Serra da Mantiqueira upper montane forests showed their greatest floristic similarity to be with the cloud forests of southern Brazil and to some extent with the upper montane forests of the interior of Minas Gerais and the crest of the coastal range ("Serra do Mar") in São Paulo, though with a somewhat differentiated floristic composition. Similarities with the surrounding forest matrix at lower altitudes were much less. Models of potential distribution for montane forest species using scenarios for Late Quaternary conditions suggest that extensive modifications of currently observed distributions are likely to have occurred, with many species occupying much lower altitudes and latitudes, together with much greater longitudes. These results suggest that forests similar in composition to current upper montane forests may have occupied much more extensive areas in the past, forming an almost continuous forest that has subsequently been fragmented and confined to high mountain areas in the east-south Brazil.
Doutorado
Doutor em Biologia Vegetal
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Mlotha, McArd Joseph. "Analysis of Land Use/Land Cover Change Impacts Upon Ecosystem Services in Montane Tropical Forest of Rwanda: Forest Carbon Assessment and REDD+ Preparedness." Antioch University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=antioch1527773591460797.
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Girardin, Cécile A. J. "Ecosystem carbon dynamics from Andes to Amazon : investigating the effects of environmental parameters on productivity and carbon cycling of an Andean tropical montane forest." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551278.
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The productivity and carbon cycling of tropical forests are an important aspect of the global carbon cycle. These variables have been investigated in lowland tropical forests, but they have rarely been studied in tropical montane forests. This thesis examines spatial and temporal patterns of above- and below-ground forest ecosystem carbon cycling along a transect of study sites ranging from lowland Amazonia (194 m) to the high Andes in S.B. Peru (3025 m), with a mean annual temperature ranging from 26.4 QC (194 m) to 11.8 QC (3020 m) and an annual rainfall ranging from 3086 mm yr" (1000 m) to 1706 mm yr" (3025 m). Measurements of above-ground (stem, canopy litterfall) and below-ground (fine roots, soil respiration, soil organic matter) carbon stocks and CO2 fluxes were made at nine one-hectare forest plots along the elevational gradient extending from lowland forest, through pre-montane, lower montane and upper montane forest, with relatively homogeneous stand structure, geological substrate and topography. I began by documenting the spatial and temporal patterns of above-ground carbon allocation along the elevational gradient. In particular, I analysed net primary productivity allocation to canopy components (leaf, twigs, flowers, fruit, bromeliads, epiphytes) along the elevational gradient in detail and observe the effects of seasonal variation on each component of above-ground production. Consistently lower values of mean annual above-ground productivity were observed in the cloud immersion zone of the montane forest. Then, the below-ground components of the ecosystem were recorded through spatial and temporal measurements of soil CO2 efflux and fine root dynamics (carbon stocks, net primary productivity and residence time). CO2 efflux did not show a significant trend along the elevation gradient, with the range of soil C02 efflux values similar to that observed in lowland tropical forest sites, despite the large variation in mean annual temperatures. Below-ground, a step change in fine root productivity was recorded at the base of the mountain (~1 000 m) between most lowland plots and tropical montane forest plots, although there was no significant change in fine root productivity with elevation above 1000 m. These measurements allowed for a comparison of the allocation of net primary productivity above- and below-ground along the elevational gradient. I combined the data obtained in this D.Phil thesis with data from recent lowland studies to examine the spatial patterns of above- and below-ground carbon dynamics along the elevational transect. The ratio of fine root biomass to stem biomass increased significantly with increasing elevation, whereas the allocation of net primary productivity above- and below-ground remained approximately constant at all elevations. Although net primary productivity declined in the tropical montane forest, the partitioning of productivity between the ecosystem sub-components remained the same in lowland, pre-montane and montane forests. Further, most processes driving the internal carbon cycle (net primary productivity, carbon stocks, autotrophic respiration) showed evidence of a step change at the base of the cloud immersion zone (1500 - 1855 m), and no significant change within the cloud immersion zone. These patterns imply that cloud forest characteristics (such as increased and year-long moisture resulting from frequent cloud cover immersion, a decrease in PAR incidence and slower soil nutrient uptake rates) combine with cooler temperatures to drive the internal carbon cycle.
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Menezes, Viviane Costa de. "Composição e estrutura da comunidade fitoplanctônica a montante e a jusante das Cataratas do Iguaçu, Parque Nacional do Iguaçu, Paraná, Brasil." Universidade Estadual do Oeste do Parana, 2012. http://tede.unioeste.br:8080/tede/handle/tede/718.
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This work aimed to analyze the composition variation and structure of phytoplankton community upstream and downstream of the Iguaçu Falls, Iguaçu River, investigating the influence of these waterfalls and environmental variables on this community. Samples of phytoplankton material were carried out in two sampling stations in Iguaçu River (25° 35' S; 54° 23' W e 25° 38' S; 54° 27' W), from May 2010 to May 2011 (except November). A total of 408 taxa were identified, and Bacillariophyceae was the best represented group. There was a large difference in phytoplankton composition between the sampled stations. The total richness and density of phytoplankton groups were very low in both collection sites, and it was represented by the classes Bacillariophyceae, Chlorophyceae and Cyanobacteria. The Shannon diversity was classified as very low. The equitability, in general, was high. The Multivariate Analysis of Variance showed no significant spatial or seasonal difference for total density, total richness, equitability and Shannon diversity. However, when measured densities and richness classes (Bacillariophyceae, Chlorophyceae, Cyanobacteria) separately, significant seasonal differences were observed. The heterogeneity of the characteristics of the Iguaçu River between the sampling sites did not cause a longitudinal compartmentalization of the river regarding to the attributes of the phytoplankton community, while the seasonal variation of weather conditions influenced in a significant way the composition and structure of this community in the studied environment.
Este trabalho objetivou analisar a variação da composição e estrutura da comunidade fitoplanctônica a montante e a jusante das Cataratas do Iguaçu, rio Iguaçu, observando a influência destas quedas d água e das variáveis ambientais sobre esta comunidade. As coletas do material fitoplanctônico foram realizadas em duas estações de amostragem no rio Iguaçu (25° 35' S; 54° 23' W e 25° 38' S; 54° 27' W), entre maio de 2010 e maio de 2011 (exceto novembro). Um total de 408 táxons foram identificados, sendo Bacillariophyceae o grupo melhor representado. Observou-se uma grande diferenciação na composição do fitoplâncton entre as estações amostradas. A riqueza total e densidade dos grupos fitoplanctônicos foram muito baixas em ambos os locais de coleta, estando representadas pelas classes Bacillariophyceae, Chlorophyceae e Cyanobacteria. A diversidade de Shannon foi classificada como muito baixa à média. A equitabilidade, de uma maneira geral, foi alta. A Análise Multivariada de Variância mostrou que não houve diferença sazonal nem espacial significativa para densidade total, riqueza total, equitabilidade e diversidade de Shannon. No entanto, quando avaliadas as densidades e riquezas das classes (Bacillariophyceae, Chlorophyceae, Cyanobacteria) separadamente, diferenças sazonais significativas foram observadas. A heterogeneidade das características do rio Iguaçu entre os locais amostrados não causaram uma compartimentalização longitudinal do rio no que diz respeito aos atributos da comunidade fitoplanctônica, enquanto que a variação sazonal das condições climáticas influenciou significativamente a composição e estrutura dessa comunidade no ambiente estudado.
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Lafond, Valentine. "Sylviculture des forêts hétérogènes de montagne et compromis production-biodiversité : une approche simulation." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV019/document.
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Les changements globaux et l'évolution du contexte socio-économique renforcent les attentes vis-à-vis d'une gestion multifonctionnelle des forêts. En France, la communauté forestière s'est accordée sur la définition du double objectif de « produire plus de bois, tout en préservant mieux la biodiversité […]» (Grenelle de l'Environnement, 2007). Cet objectif s'accompagne d'une volonté de maintenir des attributs favorables à la biodiversité d'une part, et de « dynamiser » la sylviculture d'autre part. La comptabilité entre ces mesures est toutefois controversée et il est aujourd'hui nécessaire de mieux comprendre leurs effets sur les services écosystémiques, afin de pouvoir définir les conditions d'une gestion forestière multifonctionnelle et durable.L'objectif de la thèse est d'explorer de manière fine l'effet de la sylviculture sur la structure des peuplements, la production de bois et la préservation de la biodiversité. Le travail s'articule autour de deux hypothèses générales : (1) celle que les indicateurs de ces deux services répondent de manière différente à la gestion; (2) celle qu'une gamme intermédiaire d'intensités de sylviculture est favorable au compromis entre production et biodiversité. Le travail a porté sur le cas des sapinières-pessières irrégulières de montagne, qui présentent une longue tradition de gestion en futaie irrégulière et sont jugées favorables à la fourniture d'un certain nombre de services écosystémiques. Nous avons opté pour une approche par simulation s'appuyant sur le couplage d'un modèle de dynamique forestière, d'algorithmes de sylviculture et de modèles et indicateurs de production et de biodiversité. Le travail de thèse a nécessité la mise en place d'une démarche complète d'expérimentation par simulation impliquant les étapes (i) de formalisation des variables de contrôle et de réponse, (ii) de développement et d'évaluation de modèles, (iii) de définition de plans d'expérience, (iv) d'analyse de sensibilité et (v) d'analyse de la réponse des indicateurs à la gestion. Une analyse complète du modèle Samsara2 nous a permis de vérifier la cohérence des dynamiques forestières simulées et la fiabilité des prédictions. Un algorithme de sylviculture a été développé pour modéliser la gestion en futaie irrégulière de manière fine. Deux modèles de biodiversité ont été implémentés à partir de modèles issus de la littérature : un modèle de stockage et de décomposition du bois mort et un modèle de prédiction de la richesse spécifique de la strate herbacée. Une analyse de sensibilité du système nous a tout d'abord permis d'analyser l'influence des paramètres d'entrée (sylvicoles, démographiques ou état initial) sur un ensemble d'indicateurs de structure, production et biodiversité, puis d'identifier et de fixer les paramètres peu influents. Une approche par régression a ensuite permis d'établir la fonction de réponse (métamodèle) de chaque indicateur aux principaux leviers de gestion, en interaction avec la démographie et l'état initial. Nous avons ainsi observé un effet négatif de l'intensification de la gestion sur la biodiversité, bien que cet effet varie en fonction des indicateurs. Les mesures de conservation de la biodiversité peuvent toutefois servir de leviers de compensation dans certains cas, permettant ainsi de concilier les deux objectifs. Des situations de compromis entre indicateurs de production et/ou biodiversité ont été détectées, mais leur analyse fine nécessite désormais de se tourner vers les méthodes d'analyse multicritère.Ainsi, l'analyse couplée des de la réponse des indicateurs de services écosystémiques à la gestion et des scénarii de gestion situés sur la zone de compromis devrait permettre d'alimenter les échanges avec les gestionnaires forestiers et de discuter des recommandations de gestion à l'échelle de la parcelle ou du massif forestierGlobal change and the evolution of the socio-economic context reinforce the expectations for multifunctional forest management. In France, the forest community agreed on the definition of the double objective of “improving timber production while preserving biodiversity better” (Grenelle 2007). This objective goes along with a will of maintaining the natural attributes favoring biodiversity on one hand, and of increasing management intensity on the other hand. The compatibility between both objectives is however controversial and it seem nowadays necessary to better understand their effects on ecosystem services, so as to enable the definition of multifunctional and sustainable forest management. The objective of this PhD thesis is to explore the effect of silviculture on stand structure, timber production and biodiversity preservation. This works involves two main hypotheses: (1) the fact that ecosystem services indicators present different responses to silvicultural drivers, thus leading to trade-offs situations; (2) the fact that management scenarios of intermediate intensity may enable satisfactory production-biodiversity trade-offs to be reached. This work addressed the case of uneven-aged spruce-fir mountain forests, which present a long tradition of uneven-aged management (selection system) and are judged favorable to the provision of several ecosystem services. We used a simulation approach coupling a forest dynamics simulation model (Samsara2), a silviculture algorithm, and ecosystem services models and indicators (for timber production and biodiversity). This however required a complete simulation experiment approach to be set up, with several steps: (i) formalization of control and response variables, (ii) model development and evaluation, (iii) experiment designs definition, (iv) sensitivity analysis, and (v) study of indicators' response to management. A complete analysis of the Samsara2 model enabled the consistency of simulated forest dynamics and the reliability of predictions to be checked. A silviculture algorithm has been developed to accurately model uneven-aged management. Two biodiversity models have been implemented from the literature: a dead wood decay model and an understory diversity model.A sensitivity analysis of the system first enabled us to assess the influence of input parameters (silviculture, demographic and initial state) on structure, timber production and biodiversity indicators, and then to identify and fix those with low influence. Then, a regression approach enabled the establishment of the response function (metamodels) of each indicator to the main silvicultural factors, in interaction with demography and initial state. This revealed the negative effect of increased management intensity on biodiversity indicators, although its effect depended on the indicator. Biodiversity conservation measures could however be used as compensation drivers in some cases, therefore enabling both objectives to be concealed. Trade-offs situations have also been detected between timber production and/or biodiversity conservation indicators, but their analysis now require specific multi-criteria analysis to be used.The combined analysis of ecosystem services response to silvicultural drivers and of management scenarios located on the trade-offs area would then supply the discussion with forest managers with new elements and enable management recommendations to be discussed at the stand or landscape scale
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Devaux, Caroline. "Résilience des services écosystémiques à l’échelle du paysage : un cadre conceptuel et une analyse pour un socio-écosystème de montagne." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV002/document.
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L’intérêt que porte la communauté scientifique ainsi que politique aux les services écosystémiques et à leur résilience face aux changements globaux (environnementaux ou sociétaux) en cours est grandissant, ce qui se reflète par le nombre d’études à ce sujet, le rapport d’évaluation des écosystèmes pour le millénaire et la mise en place d’un groupe de travail sur la résilience (« Resilience Alliance »). Les définitions de la résilience sont elles aussi très variées, avec des concepts tels que la résistance, la résilience spécifique (« de quoi à quoi ? »), la résilience générale, l’adaptabilité et la transformabilité, que nous nous sommes appropriés dans le but de développer un cadre conceptuel et méthodologique pour étudier la résilience de la fourniture de services écosystémiques, en particulier dans le but de comparer les potentiels de résilience des différents types de prairies subalpines du col du Lautaret (Hautes-Alpes, France) pour un ensemble de services sélectionnés. Nous avons proposé deux approches pour évaluer les potentiels de résilience des différents états dans lequel peut se trouver un socio-écosystème, en considérant la résilience comme la capacité d’un système à maintenir une fourniture stable de services écosystémiques (composante résistance) mais aussi sa capacité à l’adapter (différentes composantes selon le degré d’adaptation : résilience, transition, transformation). Une première étape d’évaluation d’un ensemble de services d’intérêt sur la zone d’étude est suivie d’une première analyse de la résilience de chacun de ces services spécifiquement, basée sur l’évaluation de « gammes opérationnelles » pour chaque service, définies comme les gammes de valeurs que peut prendre le dit service dans un état donné du socio-écosystème. L’échelle organisationnelle à laquelle ces gammes sont évaluées les relie aux différentes composantes de la résilience. Les résultats confirment l’intérêt de s’intéresser à la résilience spécifique de chaque service, car leur profil de résilience sont différents, c’est-à-dire que les prairies aux plus forts potentiels ne sont pas les même d’un site à l’autre, bien que dans tous les cas les potentiels de résilience soient plutôt forts, au contraire des autres potentiels.La deuxième analyse part de l’hypothèse théorique que la diversité des traits de réponse (hétérogénéité et redondance) améliore la résilience. Nous avons fait l’hypothèse que, lorsque les traits de réponse sont ceux utilisés pour modéliser les services écosystémiques, la diversité fonctionnelle d’une communauté végétale peut-être reliée à sa résilience générale en termes de services écosystémiques. Nous avons relié plusieurs mesures de la diversité fonctionnelle aux potentiels de résilience (entropie et diversité fonctionnelle dans leur dimension α et β, redondance et complémentarité des groupes fonctionnels). Cependant, les résultats obtenus par l’analyse des prairies du Lautaret nous amènent à réfuter l’hypothèse proposant que la diversité fonctionnelle des communautés végétales permet d’expliquer le profil de résilience des services écosystémiques analysés, car ils ne concordent pas avec les profils de résilience trouvés par l’approche des gammes opérationnelles. Au final, nous préconisons d’utiliser l’approche des gammes opérationnelles, qui permet de connaître le profil de résilience de chaque service, dans le cadre d’étude portant sur la capacité d’un socio-écosystème à maintenir la fourniture de ses services écosystémiques. Cette approche peut de plus être enrichie d’une approche de scénarisation qui permettrait de déterminer « à quoi » la fourniture de chaque service est résilienteAs evidenced by the number of studies on the subject, the recent millennium ecosystem assessment and the establishment of a working group on resilience (« Resilience Alliance »), the interest of the scientific community in ecosystem services and their resilience in the face of global change (environmental or social) is steadily increasing. Definitions of resilience are highly varied, and we used concepts such as resistance, specific resilience (« of what to what ? »), generalised resilience, adaptability and transformability to develop a conceptual and methodological framework to study the resilience of ecosystem service provision. This conceptual framework was applied to compare the potential resilience of differing sub-alpine grasslands types in three local government areas in the area of the Col du Lautaret (Hautes-Alpes, France) for a number of locally and regionally important ecosystem services. We proposed two approaches for evaluating the potential resilience of the different states in which a socio-ecosystem can exist, by considering resilience as the capacity of a system to maintain a stable provision of an ecosystem service (resistance component), as well as its capacity to adapt this provision if needed (components of resilience, transition, transformation depending on the degree of adaptation). A first stage of the quantification of ecosystem services was followed by an initial analysis of each of these services via the evaluation of their « operating ranges », defined as the range of values that a service can take given a particular state of the socio-ecosystem. The organizational scale at which these ranges are evaluated links them to other components of resilience. Our results confirm the utility of considering the specific resilience of each service, as the profiles of their resistance are different. In particular, the types of grasslands with the highest resilience component potential are not the same from one site to another, even though in all cases these resilience component potentials are rather high as compared to other components potentials. The second analysis is based on the theoretical hypothesis that it is the increasing diversity of response traits (heterogeneity and redundancy) which increases resistance. We hypothesised that, when it is response traits that have been used to model ecosystem services, the functional diversity of a plant community can be linked to its overall resistance in terms of ecosystem services. We linked a number of measures of functional diversity to resilience potential, including the α and β dimensions of entropy and functional diversity, and the redundancy and complementarity of functional groups. The obtained results for the grasslands at Lautaret lead us to reject the hypothesis which proposes that the functional diversity of plant communities can be used to predict the patterns of resilience of the analysed ecosystem services, as these do not correspond to the patterns of resistance obtained from the approach using operating ranges. Finally, we suggest that to assess the capacity of a socio-ecosystem to maintain the provision of ecosystem services, our approach using operating ranges is preferable as it allows for the quantification of the resistance profile of each service. This approach could be further developed using scenario building so as to determine « to what » the provision of each service is resistant
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Tosca, Claude. "Structure, dynamique et fonctionnement des ecosystemes prairiaux supra-forestiers des pyrenees-centrales." Toulouse 3, 1986. http://www.theses.fr/1986TOU30197.
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Deux toposequences majeures, en liaison avec la granulometrie des sols, sont identifiees; le rayonnement energetique associe aux variations de l'hygrometrie de l'air entraine la creation d'hygroseres en ombree et de xeroseres en soulane. Sur substrat caillouteux s'installent divers groupements a festuca eskia tandis que sur terre fine on peut identifier plusieurs associations a nardus stricta. On observe neanmoins une evolution chimique identique des sols, a savoir une acidification generale descendante liee aux phenomenes de percolation
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Viguier, Clément. "Dynamiques des prairies de montagne : intégration de la plasticité phénotypique dans un nouveau modèle à base d'agents." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV057/document.
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Les prairies de montagne offrent de nombreux services ecosystémiques qui sont menacés par le changement global. Les traits fonctionnels constituent un outil prometteur pour caractériser les réponses des communautés à des changements de conditions environnementales et leurs répercussions sur les services associés. Cependant, des résulats de plus en plus nombreuses soulignent l’importance de la variabilité intra-spécifique des traits a également été mise en évidence. Pour étudier ces effets, je propose un nouveau modèle à base d’agents, MountGrass, qui combine la modélisation de communautés végétales riches en espèces avec des processus de plasticité phénotypique. Ces deux éléments au coeur du modèle sont associés grâce à des compromis d’allocation basés sur des patrons empiriques établis de stratégies d’utilisation des resources.Avec MountGrass, j’ai exploré l’impact de la plasticité phénotypique sur la croissance individuelle et les propriétés principales des communautés prairiales. À l’échelle individuelle, le modèle paramétré a révélé un fort impact positif de la plasticité phénotypique sur la croissance mais aussi sur la niche fondamentaledes espèces. Des phénomènes de convergence et de réduction de la sensibilité aux variations de conditionsexpliquent ces effets. À l’échelle des communautés, les simulations ont confirmé de forts effets de la plasticité sur la structure des communautés et leur diversité spécifique. Ces effets sont expliqués par l’effet combiné de la réduction du filtre abiotique et de la réduction des différences de compétitivité. Cependant, aucun effet majeur sur la stratégie dominante ou la productivité n’a pu être mis en évidence.Des implémentations alternatives ou des extensions du modèle devraient permettre de tester la robustesse des résultats obtenus et d’analyser d’autres schémas de dynamiques des communautés. En conclusion, ce travail ouvre la voie à une meilleure considération et une meilleure compréhension du rôle des variabilités intra-spécifiques dans les dynamiques des communautés végétalesMountain grasslands provide numerous ecosystem services that are likely to be impacted by global change. Plant functional traits hold great promise to succinctly characterise plant community response to changing environmental conditions and its effect on associated services; with growing evidence of the importance of intra-specific trait variability. I propose here a novel agent-based model, MountGrass, that combines the modelling of species rich grassland communities with phenotypic plasticity. These two key components are integrated via allocation trade-offs based on established empirical patterns of strategic differentiation in resource-use.With MountGrass, I explored the impact of phenotypic plasticity on individual plant growth and on main properties of grassland communities. At the individual level, the parametrised model revealed a strong impact of plasticity on growth and species’ fundamental niches, with potentially large impacts on community properties. These effects are explained by the convergence of species’ strategies and the reduction of the sensitivity to variable conditions. At the community level, simulations confirmed the strong effect of plastic allocation on community structure and species richness. These effects are driven by the cumulative effect of a reduction of both abiotic filtering and fitness differences between species. However, no clear effect on the dominant strategy or productivity could be detected.Going further, the robustness of these findings and other patterns of community dynamics should be analysed with alternative or extended implementations of MountGrass. In sum, this work opens a door towards a better integration and understanding of the role of the intra-specific variability in complex plant community dynamics
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Cherpeau, Aline. "Télédétection et agroécologie : un essai de cartographie destinée à la gestion des milieux herbacés de haute montagne : application au Parc national des Ecrins." Grenoble 1, 1996. http://www.theses.fr/1996GRE10106.
Full textAbstract:
Les espaces proteges francais (parcs nationaux) sont demandeurs de methode d'inventaire des milieux naturels sur de grandes superficies (superieures a 50 000 ha) pour, notamment, gerer les alpages. L'objectif de cette these est de rechercher une methode de cartographie des milieux naturels du parc national des ecrins par teledetection. L'application s'interesse essentiellement a discriminer les formes vegetales du domaine supraforestier sur des images satellitaires spot et landsat tm. La demarche est basee sur une double approche: 1/ agroecologie pour une description precise des espaces pastoraux, 2/ teledetection pour les identifier de maniere spatiale. Les descripteurs communs a ces deux entrees portent sur la physionomie de la vegetation. Il en resulte une typologie physionomique (14 types), spatialisee par les techniques de classification dirigee. Sur les images classees obtenues par pixel, dont on analyse l'heterogeneite spatiale et thematique, on procede a un decoupage de l'espace en unites physionomiques. Les traitements en zone a fortes contraintes (relief marque et mosaique de vegetation) necessitent des corrections geometriques prealables (precision de 1 a 2 pixels) et plusieurs etapes de controles pour verifier leur pertinence ecologique et proposer une validation quantifiee des resultats (environ 70% de correspondances satisfaisantes entre les unites cartographiees et la realite de terrain). Ces resultats permettent de repondre a des besoins de cartographie ecologique a moyenne echelle (1:25 000, correspondances avec les nomenclatures europeennes). Obtenus sur les ecrins, ils contribuent a enrichir la reflexion methodologique en proposant des traitements d'images adaptes aux zones heterogenes de montagne (emploi de descripteurs physionomiques) et une demarche reproductible (double approche construite avec un modele ecologique et un outil de spatialisation de l'information)
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Reckin, Rachel Jean. "Mountains as crossroads : temporal and spatial patterns of high elevation activity in the Greater Yellowstone ecosystem, USA." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278102.
Full textAbstract:
In the archaeological literature, mountains are often portrayed as the boundaries between inhabited spaces. Yet occupying high elevations may have been an adaptive choice for ancient peoples, as rapidly changing elevations also offer variation in climate and resources over a relatively small area. So what happens, instead, if we put mountain landscapes at the center of our analyses of prehistoric seasonal rounds and ecological adaptation? This Ph.D. argues that, in order to understand any landscape that includes mountains, from the Alps to the Andes, one must include the ecology and archaeology of the highest elevations. Specifically, I base my findings on new fieldwork and lithic collections from the Absaroka and Beartooth Mountains in the Greater Yellowstone Ecosystem (GYE) of the Rocky Mountains, which was a vital crossroads of prehistoric cultures for more than 11,000 years. I include five interlocking analyses. First, I consider the impacts of anthropogenic climate change on high elevation cultural resources, focusing on the diminishing resiliency of ancient high elevation ice patches and the loss of the organic artifacts and paleobiological materials they contain. Second, I create a dichotomous key for chronologically typing projectile points, suggesting a methodological improvement for typological dating in the GYE and for surface archaeology more broadly. Third, I use obsidian source data to consider whether mountain people were a single, unified group or were represented by a variety of peoples with different zones of land tenure. Fourth, I consider high elevation occupation in both mountain ranges as part of the seasonal round, using indices of diversity in tool types and raw material to study how the duration of those occupations changed through time. And, finally, I test the common contention that ancient people primarily used mountains as refugia from extreme climatic pressure at lower elevations. Ultimately, I find that, in both mountain ranges, increased high elevation activity is most highly correlated with increased population, not with hot, dry climatic conditions. In other words, the mountains were more than simply refugia for plains or basin people to occupy when pressured by climatic hardship. In addition, between the Absarokas and the Beartooths the evidence suggests two different patterns of occupation, not a monolithic pan-mountain adaptation. These results demonstrate the potential contributions of surface archaeology to our understanding of prehistory, and have important implications for the way we think about mountain landscapes as peopled spaces in relation to adjacent lower-elevation areas.
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Madrigal, Martínez Santiago. "Land-change dynamics and ecosystem services using expert-based assessment and GIS: methodological implications for improving decision-making." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/172369.
Full textAbstract:
Tesis por compendio[ES] Los servicios ecosistémicos de montaña han adquirido importancia entre los científicos, los administradores y los encargados de formular políticas de todo el mundo; sin embargo, las actividades humanas están amenazando su conservación, en particular los cambios en el uso del suelo debido al aumento de la urbanización, la expansión agrícola y la deforestación. La Puna Altoandina es un ecosistema montañoso representativo que enfrenta estos serios y crecientes desafíos. La Puna Altoandina, cuyos principales socioecosistemas consisten en pastizales naturales, matorrales y zonas agrícolas, puede proporcionar múltiples servicios ecosistémicos influenciados por el tipo de cobertura terrestre y sus dinámicas. En este contexto, se han explorado las dinámicas entre los usos representativos de la superficie terrestre y su potencial para proporcionar servicios ecosistémicos en la Puna húmeda Altoandina a lo largo del tiempo. Asimismo, se ha completado un análisis espacio-temporal que describe cómo diferentes patrones de 6 dinámicas de cambio del uso del suelo impactan en la provisión de 7 servicios ecosistémicos durante un período de 13 años (de 2000 a 2013), y en el territorio de 25 provincias. Además, con el fin de mejorar la gestión de los servicios ecosistémicos, abordamos los efectos de aplicar dos análisis "clúster" (estáticos y dinámicos) para evaluar los conjuntos de servicios ecosistémicos en cuatro escalas de observación diferentes (dos ámbitos administrativos y dos tamaños de pixel geográfico: 0.25 y 9 km2). En general, este estudio proporciona un enfoque para facilitar la incorporación de los servicios ecosistémicos a múltiples escalas que permite una interpretación fácil del desarrollo de la región y que puede contribuir a mejorar las acciones para la gestión del uso del suelo y las decisiones de política ambiental.
[CA] Els serveis ecosistèmics muntanya han adquirit importància entre els científics, els administradors i els encarregats de formular polítiques de tot el món; no obstant això, les activitats humanes estan amenaçant la seua conservació, en particular els canvis en l'ús del sòl a causa de l'augment de la urbanització, l'expansió agrícola i la desforestació. La Puna Altoandina és un ecosistema muntanyenc representatiu que enfronta aquests seriosos i creixents desafiaments. La Puna Altoandina que els seus principals soci-ecosistemes consisteixen en pasturatges naturals, matolls i zones agrícoles, pot proporcionar múltiples serveis ecosistèmics influenciats per les diferents categories de cobertura terrestre y els seus dinàmiques. En aquest context, s'han explorat les dinàmiques entre els usos representatius de la superfície terrestre i el seu potencial per a proporcionar serveis ecosistèmics en la Puna humida Altoandina al llarg del temps. Així mateix, s'ha completat una anàlisi espai-temporal que descriu com diferents patrons de 6 dinàmiques de canvi de l'ús del sòl impacten en la provisió de 7 serveis ecosistèmics durant un període de 13 anys (de 2000 a 2013), i en el territori de 25 províncies. A més, amb la finalitat de millorar la gestió dels serveis ecosistèmics, abordem els efectes d'aplicar dues anàlisis "clúster" (estàtics i dinàmics) per a avaluar els conjunts de serveis ecosistèmics en quatre escales d'observació diferents (dos àmbits administratius i dues grandàries de píxel geogràfic: 0.25 y 9 km2). En general, aquest estudi proporciona un enfocament per a facilitar la incorporació dels serveis ecosistèmics a múltiples escales que permet una interpretació fàcil del desenvolupament de la regió i que pot contribuir a millorar les accions per la gestió de l'ús del sòl i les decisions de política ambiental.
[EN] Mountain ecosystem services have gained relevance among scientists, managers, and policy-makers worldwide; but, human activities are threatening its conservation, particularly land changes due to increased urbanization, agricultural expansion and deforestation. The high-Andean Puna is a representative mountain ecosystem that is facing these serious and growing challenges. The high-Andean Puna, whose main socialecosystems consist of natural grassland, shrubland and agricultural areas, can provide multiple regulating ecosystem services influenced by the land cover/use type and their dynamics. In this context, we explored the dynamics between the representative land-cover classes and its potential to provide ecosystem services in the high-Andean moist Puna over time. We completed a spatiotemporal analysis that describes how different patterns of 6 landchange dynamics impact on the supply of 7 ecosystem services over a period of 13 years (from 2000 to 2013), and across 25 provinces. Moreover, in order to improve the management of ecosystem services, we addressed the effects of applying two cluster analyses (static and dynamic) for assessing bundles of ecosystem services across four different scales of observation (two administrative boundaries and two sizes of grids: 0.25 and 9 km2). Overall, this study provides an approach to facilitate the incorporation of ES at multiple scales allowing an easy interpretation of the region development that can contribute to land management actions and policy decisions.
Madrigal Martínez, S. (2021). Land-change dynamics and ecosystem services using expert-based assessment and GIS: methodological implications for improving decision-making [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172369
TESIS
Compendio
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Yavari, Ahmad. "Allocation des ressources naturelles renouvelables et le développement rural dans les milieux montagnards de l'Iran : exemple de modalités du développement rural et la dégradation des ressources naturelles végétales de l'Alborz central." Grenoble 1, 1996. http://www.theses.fr/1996GRE10277.
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Ce travail est une etude en geographie appliquee concernant la gestion des espaces montagnards de pays arides et en voie de developpement ou les montagnes sont des repertoires et lieux de recharge de ressources naturelles et de l'heritage culturel. L'economie de la pluspart des villages de plaines et piedmonts reste dependante des ressources naturelles qui ont subit une degradation intense et de fortes perturbations ecologiques et socio-economiques. La region etudiee est une partie de la chaine d'alborz central choisie de facon a inclure la diversite naturelle et socio-economique de l'espace montagnard de l'iran, tout en restant limitee sur l'etendue (2914 km carres). L'approche adoptee est inspiree par la vision systemique. La gestion de l'espace et son evolution pendant les vingt dernieres annees ont ete etudiees sur place et par des analyses statistiques en tant qu'un systeme uni. L'amenagement de cette region manque d'une gestion rationnelle de l'espace et ceci entraine un rapport desequilibre du developpement entre les montagnes et les pleines adjacentes et la non-integration des specificites montagnardes. Les potentiels agro-sylvo-pastorals sont limites par les contraintes naturelles et par les surexploitations intenses et chroniques. Cependant, il y a des potentiels d'exploitations importants au developpement de la region grace a sa situation geographique exceptionnelle. Le developpement du tourisme, du transport routier, de l'artisanat et de l'industrie legere sont des sources de l'emploi et de revenu et reduisent la pression exercee sur les ressources naturelles mais restent sous-exploites. Etablir l'equilibre (reduction) de l'exploitation de ressources naturelles et le developpement des autres potentiels de l'alborz central sont les premieres mesures indispensables de toutes gestion. La region a besoin d'un amenagement integre base sur les relations complementaires plaines-montagnes au niveau regional dans le respect des specificites des espaces montagnards au niveau local ou micro-regional
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Wahl, Anne-Lena. "Importance des interactions entre plantes et mycorhizes dans le maintien de la productivité des écosystèmes pastoraux montagnards soumis à des forçages climatiques." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS038/document.
Full textAbstract:
Bien que les champignons mycorhiziens arbusculaires (AMF) soient présents des habitats collinaires aux habitats alpins, les recherches sur leur rôle dans l’écosystème montagnard sont encore incomplètes. Les objectifs de cette thèse sont d’analyser l’écologie et le fonctionnement des AMF ainsi que leur réponse au changement global dans les écosystèmes montagnards. Nous tentons de répondre aux questions de recherche suivantes : quels sont les effets de l’altitude sur les AMF indépendamment des effets des autres gradients et de la relation AMF-plante hôte ? Quelles relations de facilitation se développent dans les écosystèmes montagnards et quels bénéfices les plantes tirent-elles des AMF ?Avec l’augmentation d’un stress environnemental la symbiose AMF-plante doit théoriquement devenir plus mutualiste. Nous émettons l’hypothèse d’une modification du fonctionnement des interactions AMF-plante selon un gradient altitudinal dans les conditions environnementales actuelles, puis dans les conditions futures. Afin de vérifier ces hypothèses, une expérimentation in situ a été mise en place dans les Alpes Centrales d’Italie pour évaluer les variations des taux de mycorhization et leur abondance dans la communauté microbienne du sol, étudier la nature des relations entre plantes et mycorhizes ainsi que la productivité végétale le long d’un gradient altitudinal. De plus, les influences d’une augmentation de la température et d’une réduction des précipitations sont analysées séparément dans une chambre de croissance sous conditions contrôlées, ce qui permet de distinguer leurs effets respectifs sur la productivité des plantes et sur les interactions plantes – mycorhizes.Cette thèse montre que les AMF sont omniprésents dans les écosystèmes de montagne et qu’une diminution de leur abondance avec l'altitude dépend du contexte climatique global. D'autre part, la relation des AMF avec les plantes est fortement dépendante de la plante-hôte, ainsi que du contexte biotique et abiotique. Troisièmement, un changement des interactions AMF-plante avec l'altitude est suggéré par des indices indirects, mais est également très probablement dépendant de l'identité de la plante hôte. Cette thèse propose aussi une nouvelle orientation de recherche pour bien évaluer les hypothèses présentées. Il est nécessaire de réaliser des études sur le terrain où la présence des AMF est contrôlée et les interactions AMF-plante peuvent être évaluées. Afin de généraliser les résultats, ces expérimentations doivent être menées à différentes échelles spatiales et représenter différentes aires géographiques.Il est particulièrement important de comprendre et de qualifier ces processus en zone montagnarde pour prévoir leur évolution possible dans un contexte de changement global. Nos expérimentations montrent en effet que le réchauffement est un facteur important car il aggrave les conditions de sécheresse en basse altitude et entraine une baisse de la productivité des plantes. Nous démontrons que la présence de mycorhizes atténue l’impact du changement climatique sur la productivité des plantes mais que le niveau de cette atténuation varie selon les espèces de plantes.Les connaissances actuelles concernant les AMF en milieu montagnard sont peu développées sur les processus en jeu dans les interactions AMF-plantes. Grâce aux hypothèses présentées et à leur approche expérimentale cette thèse offre de nouvelles perspectives sur l’analyse de ces processusEven though arbuscular mycorrhizal fungi (AMF) are present from foothills to all alpine habitats, research on their role in mountain ecosystems remains incomplete. The main objective of this dissertation was to investigate interactions between AMF and plants along altitudinal gradients under both, natural conditions and simulated future climate change conditions.A novel framework is suggested for the functioning of the AMF-plant relationship along altitudinal gradients based on the stress gradient hypothesis. The first hypothesis expects the AMF-relationship to shift along the mutualism–parasitism continuum following changing environmental stress along the altitudinal gradient. The relationship might be most mutualistic at the subalpine zone. In a second hypothesis, this shift along the mutualism-parasitism continuum is predicted to be different under climate change conditions, and the most mutualistic expression of the AMF-plant relationship expected in the montane and alpine zone. Studies to validate the presented hypotheses will help to identify important mechanisms underlying plant-AMF interaction and with that the mediation of plant-plant interactions by AMF. In the scope of this thesis, the framework was addressed in field experiment as well as under controlled conditions in a climate chamber experiment.From a literature review and from a field experiment along a dry inner-alpine altitudinal gradient this thesis proposes the following conclusions: First, AMF are also ubiquitous in mountain ecosystems, but a decrease in their abundance with increasing altitude is dependent on the overall climatic context. Second, their relationship to plants is however strongly dependent on the host plant species as well as the biotic and abiotic context. Third, a shift of the AMF-relationship along with altitude is expected but will quite possibly also depend on the plant species identity. Fourth, to fully assess the suggested working hypotheses for AMF-plant interactions field studies must be conducted at different spatial scales and covering different mountain systems.It is particularly important to understand and investigate the drivers of AMF plant relationship in mountain ecosystems to be able to make sound predictions for AMF-plant interactions under future climate change conditions. The presented field and climate chamber experiments on climate change show that temperature is an important factor because it aggravates the conditions of drought in lowland and a threshold is surpassed. It becomes also clear that whether AMF mitigate climate change effects for plants or not is dependent on the plant species. Altogether this thesis contributes to current research questions in ecology, climate change mitigation and plant–soil interactions, because it addresses the role of AMF in mountain grassland ecosystem, investigates the effects of climate change and provides a new framework concerning the functioning of the AMF-plant relationship ranging from parasitism to mutualism
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Salgueiro, Pedro Alexandre Marques da Silva. "Network analysis of connectivity thresholds in fragmented landscapes. A multi-species approach using birds in pine and oak forests." Doctoral thesis, Universidade de Évora, 2020. http://hdl.handle.net/10174/28598.
Full textAbstract:
Over the last decades, the pervasiveness of human activities has leading landscapes
worldwide to experience unprecedented changes often resulting on the loss,
simplification or fragmentation of habitats. Concomitantly, species diversity and the
self-regulated ecological processes mediated by landscape are severely threatened. This
thesis extends the theoretical considerations of the fragmentation conundrum into realworld
fragmented landscapes to determine the effects of structural and functional
landscape connectivity in mediating the spatial distribution of bird communities. We
describe conceptual approaches to capture landscapes’ heterogeneity on different
forest contexts to uncover the adequate surrogacy of the structural connectivity of the
landscape. Critical ecological thresholds of forest cover are explored to preview
community turnovers and establish the limits where populations are more sensitive.
Finally, we demonstrate how functional connectivity mediates the spatial distribution of
bird species and bird community composition. Our results point out that, though species
reveal overall interdependent behaviour, they show highly specific responses to patch
and landscape cues suggesting differences on how they perceive their quality and
structure, respectively. Consequently, this denotes that the spatial distribution and
composition of bird communities depend on the intrinsic ability of each species to move
across the landscape (functional connectivity) and reach a patch, as well as on the
capacity of patches to provide vital resources for different species. The implications of
our findings leverage concrete and specific management strategies to prevent the
downfall of avian diversity in the two most representative forest systems in Portugal:
pine forest plantations and oak woodlands. We establish the limits beyond which major
changes in community are expected and suggest practices that behold the maintenance
of high bird diversity levels. Overall, we endorse sustainable approaches previewing
exploitation alternatives that reconcile both human interests and the conservation of
natural assets; Resumo:
O impacto das actividades humanas nas paisagens tem promovido alterações sem
precedentes a uma escala global nas últimas décadas, resultando na perda, simplificação
ou fragmentação dos habitats. Consequentemente, a diversidade de espécies e os
processos ecológicos associados à dinâmica paisagística encontram-se profundamente
ameaçados. Nesta tese são explorados os efeitos da conectividade estrutural e funcional
da paisagem na distribuição espacial de comunidades de aves, transferindo para um
contexto de paisagens reais as considerações teóricas formuladas no âmbito da
investigação em fragmentação. Para o efeito, são descritas diferentes abordagens
conceptuais na caracterização da heterogeneidade da paisagem, aferindo a
adequabilidade de descritores de conectividade estrutural, em diferentes contextos
florestais. São explorados os limiares de sensibilidade ecológica e alteração das
comunidades ao longo de um gradiente reflectindo a disponibilidade de recursos. Por
último, é investigado o papel da conectividade funcional na distribuição espacial e a
composição das comunidades de aves. Os resultados demonstram que a percepção da
qualidade de habitat e da estrutura da paisagem é dependente da espécie embora
existam relações de interdependência entre estas. Isto implica que a distribuição
espacial e os processos inerentes à composição das comunidades dependam da
capacidade de cada espécie em alcançar parcelas de habitat adequado (conectividade
funcional), e da disponibilidade de recursos providenciada pelas mesmas em satisfazer
um conjunto diverso de espécies. As implicações dos resultados obtidos estendem-se à
aplicabilidade de estratégias de gestão concretas e específicas que previnem a perda de
diversidade avifaunística nos sistemas florestais mais representativos de Portugal –
plantações de pinheiro e montado –, nomeadamente através da identificação dos
limites além dos quais estão previstas alterações significativas na comunidade, e
sugerindo práticas que contemplam a manutenção de níveis elevados de diversidade.
Abordagens sustentáveis associadas a estratégias alternativas de exploração
contribuirão para conciliar os interesses humanos e a conservação dos valores naturais.
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Genries, Aurélie. "Incendies, dynamique et structure des communautés forestières subalpines à pin cembro (Pinus cembra L. ) dans les Alpes." Montpellier 2, 2008. http://www.theses.fr/2008MON20127.
Full textAbstract:
Dans les Alpes, le changement climatique devrait avoir pour conséquences une baisse des précipitations et une augmentation de la fréquence des perturbations dans les décennies à venir. Or, le feu y est actuellement rare et les forêts subalpines sont particulièrement sensibles aux perturbations. L'objectif de cette thèse est de mieux comprendre les mécanismes d'action du feu et de sa fréquence sur la structure et la dynamique de ces forêts. Dans un premier temps, l'étude paléoécologique de deux lacs de la vallée de la Maurienne (France), a montré l'existence de phases de haute fréquence de feux asynchrones dans la vallée pendant l'Holocène, mais ayant entraîné des dynamiques de végétation similaires. Celles-ci se caractérisent par une ouverture des forêts de pin cembro au profit d'érables et/ou d'aulnes blancs. Ces feux, majoritairement de surface, semblent n'avoir jamais été en mesure de réduire considérablement la population de pin cembro, excepté lors d'une phase à très haute fréquence. Dans un deuxième temps, l'étude comparative d'une parcelle de forêt subalpine ayant brûlée 3 fois lors des 180 dernières années avec une autre n'ayant pas brûlé, révèle que ces feux ont entraîné une augmentation de la densité d'arbres, et que la régénération est plus forte en zone brûlée. Néanmoins, le pâturage aurait été le facteur principal contrôlant la structure de la végétation, et l'abandon des pratiques agricoles dans les années 1950 serait à l'origine d'une régénération du pin cembro aux dépens du mélèze d'Europe. Ainsi, seule une forte augmentation de la fréquence de feu ou un retour au pastoralisme dans les décennies à venir semblent pouvoir limiter la transformation des forêts subalpines mixtes vers des forêts dominées par le pin cembroIn the Alps, the climate change may lead to a decrease in precipitations and an increase in disturbance frequency during the next decades. However, fire is rare in these mountains and subalpine forests are particularly sensitive to disturbances. The aim of this thesis is to study the mechanisms of fire and fire frequency on the structure and the dynamics of these forests. First, the paleoecological of two lakes of the Maurienne valley (France), has shown the occurrence of asynchronous high fire frequencies in the valley during the Holocene, but having triggered similar vegetation dynamics. Those trajectories are characterized by the opening of cembra pine forests, favourable to maples and/or alders. These fires, mainly surface fires, seem to never have endangered the cembra pine population, except during a high frequency period. Second, the comparative study of a stand burned 3 times during the past 180 years with a not burned stand, in a mixed subalpine forest of the Maurienne valley, reveals that those fires have lead to an increase in tree density, and that regeneration is more important in the burned stand. Nevertheless, grazing would have been the main factor controlling the vegetation structure, and the abandonment of farming in the 1950's would have induced the present cembra pine regeneration at the expense of larch. Consequently, only an increase in fire frequency or a reactivation of grazing in the next decades seem to be able to limit the transformation of mixed subalpine forests in pure cembra pine forests
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Moreau, Clémence. "Mettre en débat l’état de référence. Analyse des représentations des dynamiques paysagères au prisme des services écosystémiques." Thesis, Montpellier, 2019. http://oatao.univ-toulouse.fr/23867/1/Moreau_23867.pdf.
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Dans les territoires de montagne en Europe, les paysages évoluent sous l’effet d’une double dynamique : l’augmentation du couvert forestier et l’intensification des paysages agricoles. A partir d’un cas d’étude, le Mont Lozère, nous montrons comment ces deux dynamiques peuvent rentrer en tension, en explorant la question des choix sociaux liés aux dynamiques paysagères. Nous développons dans cette thèse un cadre conceptuel original, qui associe le concept de service écosystémique avec celui de l’état de référence, que nous avons mis en oeuvre par une démarche compréhensive et un dispositif de recherche-action. A travers l’étude des représentations, nous avons mis à jour un glissement de l’état de référence au sein des paysages agricoles, perçu différemment par les acteurs. Nous avons ensuite révélé les mécanismes sous-jacents aux choix liés aux dynamiques des paysages agricoles, ce qui nous a permis d’identifier un besoin de concertation autour de l’état de référence. Nous y avons répondu par une proposition concrète à travers un jeu de rôles, destiné à mettre les acteurs en situation d’apprentissages et à les accompagner vers des choix plus concertés. Notre contribution porte à la fois sur la question de la conciliation de différents objectifs dans les aires protégées, le rôle de l’état de référence dans la gouvernance des paysages et la plus-value scientifique et opérationnelle du concept de service écosystémique.
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Quenta, Herrera Estefania. "Structure multi-échelles de la biodiversité aquatique d'écosystèmes alpins sous l'influence du changement climatique." Thesis, Tours, 2017. http://www.theses.fr/2017TOUR4015/document.
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En combinant des approches empiriques et expérimentales, nous avons évalué les effets de trois composantes du changement climatique sur la biodiversité aquatique alpine: le recouvrement glaciaire, le gradient altitudinal et la température de l'eau. Nous avons montré que: 1) Les niveaux intermédiaires de recouvrement glaciaire génèrent une hétérogénéité environnementale élevée associée à une plus grande diversité locale du zooplancton. 13% de la diversité régionale est limitée aux tourbières aux bassins fortement englacés, et pourrait être amenée à disparaître avec le réchauffement. 2) Les filtres environnementaux et spatiaux impactent fortement la structuration des communautés de zooplancton, avec une influence probable des évènements stochastiques (sécheresse, inondation). 3) La température de l'eau n'a que peu d'influence sur les interactions prédateurs (Anax imperator)- proies (Daphnia magna), la probabilité de capture des proies semblant dépendre principalement de la précision du prédateur. Ce travail suggère une structuration multiéchelle des potentiels effets du changement climatique sur la biodiversité aquatique alpineUsing empirical and experimental approaches, we assessed the effects of three components of climate change on alpine aquatic diversity: glacier’ influence, elevation, and temperature. We found that: 1) intermediate levels of glacial influence on peatland’s catchment resulted in a high environmental heterogeneity and high local zooplankton diversity. Thirteen percent of the total regional aquatic diversity was restricted to peatlands with a high percentage of glacial influence. This diversity might be lost in a context of glacial retreat and a future increasing warming. 2) environmental and spatial filters contributed significantly to the zooplankton community structure at higher spatial scales and the important role of the environmental filter at small spatial scale, likely influenced by disturbance events (e.g. droughts and floods) 3) water temperature did not influence on the prey-predation interaction between Anax imperator and Daphnia magna, and the predator’s capture probability mainly depended on the precision of the predator in capturing the prey. This work suggests that there is a multi-scale structure of the potential effects of climate change on alpine aquatic diversity
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Bowers, Todd Allen. "Forest structure and health trends in the Southern Appalachian montane spruce-fir and northern hardwood ecosystems of the Black Mountains, North Carolina." 2005. http://www.lib.ncsu.edu/theses/available/etd-11262005-132103/unrestricted/etd.pdf.
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Sánchez, Galindo Laura Margarita. "Impacts of leaf litter diversity and root resources on microorganisms and microarthropods (Acari, Collembola) during early stages of decomposition in tropical montane rainforest ecosystems." Doctoral thesis, 2021. http://hdl.handle.net/21.11130/00-1735-0000-0005-1592-E.
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Sierra, Cornejo Natalia. "The role of the fine root system in carbon fluxes and carbon allocation patterns of tropical ecosystems along a climate and land-use gradient at Mount Kilimanjaro." Doctoral thesis, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0005-14AC-3.
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Ribas, Thaís de Toledo. "Payments for environmental services as a policy tool for conserving the portuguese montado ecosystem." Master's thesis, 2011. http://hdl.handle.net/10316/18842.
Full textAbstract:
Dissertação de mestrado em Ecologia, apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraNatural systems provide a multitude of goods and services that benefit human societies, known as environmental services (ES). Most of these ES are currently undervalued, or have no economic value at all, and ecosystem managers have no direct incentives to ensure their provision. The market failure in incorporating the value of natural systems is a major reason behind current ecosystem losses and unsustainable use of resources. The Montado ecosystem in Portugal is an agro-silvo-pastoral system of high conservation value because it sustains high biodiversity and provides important ES. Its ecological stability is depended on traditional management practices, which have become economically unviable due to recent changes in the context for Portuguese agriculture. Montados are current threatened by land use change, and innovative policy tools are needed to maintain the economic viability of these systems. “Payments for Ecosystem Services” (PES) is an incentive-based mechanism considered a new promising policy tool to address environmental problems. It relies on arrangements through which ES beneficiaries pay individuals or communities to undertake practices that increase levels of desired services. PES is a highly variable instrument whose success is determined by choices in policy design combined with implementation context. The aim of this project is to propose PES as a conservation tool for Montados. This project started with literature review of the Montado ecosystem and the instrument PES. Then, Montado’s potential to provide the three major groups of ES sold to date was assessed, as well as the current demand for them. It was concluded that PES schemes should focus on the services biodiversity protection and carbon sequestration and storage, for which demand may come from voluntary buyers or government-funded payments. This insight was complemented with lessons learned from the analysis of three case studies. The mechanisms and case studies selected for biodiversity protection were: Environmental Certification (The Biodiversity and Wine Initiative, South Africa); and Payments for Environmental Stewardship (The Environmental Stewardship Scheme, United Kingdom). For carbon sequestration and storage, The Scolel Te Project (Mexico) was chosen to represent small-scale project targeting voluntary markets. As final outcome, this work analyses potential of the three mechanisms to Montados. It also highlights the main caveats and challenges of implementing these tools, in order to provide guidance and advice to policymakers and project developers. In general, the main requirements for applying PES are: reliable sources of funding; the presence of a strong intermediary; and understanding the science behind ES provision. From this study was concluded that PES is a policy tool with several advantages but its implementation can be complex and costly. The mechanisms analysed are only suitable to very specific situations, where requirements are met and challenges can be overcome. Thus, none of them should be consider a universal solution. Instead, Montados conservation is more likely to be attained through the implementation of several different instruments, each one applied to specific situations where they have greater chances to achieve desired results.
Os ecossistemas naturais são responsáveis por provisionar uma série de bens e serviços que condicionam o bem-estar humano, os quais são conhecidos como serviços ambientais (ES). A maioria deles possui valor econômico nulo ou muito baixo, o que faz com que os gestores dos ecossistemas não tenham incentivo para garantir sua provisão. A falta de reconhecimento do valor dos ES no mercado é uma das principais razões por trás da destruição do meio ambiente e do uso insustentável dos recursos naturais. O ecossistema do Montado, em Portugal, é um sistema agro-silvo-pastoral que apresenta alta biodiversidade e fornece importantes ES. Sua estabilidade ecológica depende de práticas de manejo tradicionais, as quais se tornaram economicamente inviáveis após mudanças no contexto agrícola português. Os Montados encontram-se ameaçados e necessitam de políticas inovadoras para manter sua viabilidade econômica. “Pagamentos por Serviços Ambientais” (PES) é um instrumento baseado em incentivos econômicos considerado uma nova e promissora abordagem para problemas ambientais. Este instrumento consiste em acordos onde beneficiários de serviços ambientais pagam indivíduos ou comunidades pela adoção de práticas que aumentem os níveis dos serviços desejados. PES são altamente variáveis, e seu sucesso é determinado por escolhas feitas durante a sua concepção, bem como por particularidades no contexto de implementação. Este trabalho tem como objetivo propor PES como uma ferramenta de conservação ambiental para os Montado. Este trabalho se inicia com uma revisão literária sobre os Montados e sobre o instrumento a ser proposto. Em seguida, é analisado o potencial do ecossistema-alvo em provisionar os três principais grupos de serviços comercializados atualmente, bem como a demanda por estes serviços. Conclui-se análise que PES em Montados devem focar-se nos serviços proteção da biodiversidade e armazenamento e sequestro de carbono. Demanda para estes serviços deve vir de compradores voluntários e pagamentos financiados pelo governo. Tais descobertas são completadas com lições retiradas da analise de três estudos de caso escolhidos para representar esquemas de PES compatíveis com características do Montado e com suas limitações de mercado. Os mecanismos e estudos de caso selecionados para proteção da biodiversidade foram: Certificação ambiental (The Biodiversity and Wine Initiative, Africa do Sul); e Pagamentos por Manejo Sustentável (The Environmental Stewardship Scheme, Inglaterra). Para armazenamento e sequestro de carbono, o Projeto Scolel Te (México) foi selecionado para representar projetos em pequena escala visando mercados voluntários. Como resultado final, este trabalho analisa a adequabilidade de cada um dos mecanismos para o ecossistema do Montado. No intuito de fornecer orientação para políticos e conservacionistas, são apontados os maiores desafios da implementação destas ferramentas. Os requisitos mais relevantes para a aplicação de PES são: uma fonte de financiamento; um intermediário forte; e compreensão da ciência por trás da provisão de ES. Como conclusão, PES é uma ferramenta com muitas vantagens, porém sua implementação pode ser complexa e custosa. Os mecanismos analisados são apenas aplicáveis a situações muito específicas onde requisitos mínimos são cumpridos e desafios superados. Por isso, nenhum deles deve ser considerado uma solução universal. A conservação dos Montados tem maiores chances de ser alcançada através da implementação de diversos instrumentos concomitantemente, cada um deles aplicado nas situações onde o potencial de alcançar os resultados desejados é maior.
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Green, Douglas M. (Douglas Mitchell). "Soil conditions along a hydrologic gradient and successional dynamics in a grazed and ungrazed montane riparian ecosystem." Thesis, 1991. http://hdl.handle.net/1957/36594.
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Kahmen, Ansgar [Verfasser]. "Biodiversity and ecosystem functioning in semi-natural montane grasslands: effects on productivity, nitrogen partitioning and stability / von Ansgar Kahmen." 2004. http://d-nb.info/975196421/34.
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Heimsch, Florian. "Carbon Fluxes and Pools in a Montane Rainforest in Sulawesi, Indonesia." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-15AC-2.
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Červená, Lucie. "Využití laboratorní/terénní spektroskopie a obrazových dat dálkového průzkumu Země pro studium vegetace." Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-391375.
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Dominant vegetation species of two structurally and functionally different montane ecosystems were studied by means of laboratory and field spectroscopy and remote sensing image data: (1) a homogeneous human-influenced evergreen coniferous forest represented by a Norway spruce forest in the Krušné hory Mountains and (2) a heterogeneous natural ecosystem of a relict arctic-alpine tundra in the Krkonoše Mountains with predominance of grasses. The first part dealing with the Norway spruce forest is especially focused on the methods of laboratory spectroscopy. The assessment of Norway spruce stands on a regional and a global scales requires detailed knowledge of their spectral properties at the level of needles and shoots in the beginning, but ground research is very time-demanding. Open spectral libraries could help to get more ground-truth data for subsequent analysis of tree species in forests ecosystems. However, the problem may arise with the comparability of spectra taken by different devices. The present thesis focuses on a comparability of spectra measured by a field spectroradiometer coupled with plant contact probe and/or two integrating spheres (Paper 3) and proves the significant differences in spruce needle spectra measured by the contact probe and integrating sphere, spectra of...
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Guzman-Jacob, Valeria. "Diversity and leaf functional traits of vascular epiphytes along gradients of elevation and forest-use intensity." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-15A0-E.
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Gomes, Marisa Isabel da Silva. "Birds in interface riparian vegetation-woodland matrix: their habitat use and role in ecosystem processes and ecological services." Doctoral thesis, 2017. http://hdl.handle.net/10316/79610.
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Tese de doutoramento em Biociências, na especialidade de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de CoimbraRiparian ecosystems are critical in maintaining biodiversity on a regional scale, which is particularly important for open agroforestry systems. These ecosystems, among the most important and vulnerable habitats, have relatively high biodiversity offering refuge and source areas for prey and predators and consequently providing corridors for migration. These areas provide many fruit resources and attract many animals, such as frugivorous birds, which are the main seed dispersers in the Mediterranean basin. The importance of riparian galleries is well known for the most specialized riparian bird species, but the interface riparian galleries vs. surrounding matrix in terms of importance for passerine bird communities is understudied. This thesis compares the bird composition, diet and feeding ecology and the dynamics of seed dispersal between passerine birds inhabiting the riparian gallery and the surrounding woodland matrix (montado). We also gave the first step in attempting to evaluate the economic value of passerines in seed dispersal. This thesis comprises four data chapters. In the first chapter we analyze bird communities at different distances from the stream in order to describe seasonal and daily variations in the use of riparian galleries and woodland adjacent areas (montado). Furthermore, we assess whether birds move actively from the surrounding matrix into the riparian gallery and their flight direction in three different seasons. Species richness and bird abundance (total number of individuals) in Mediterranean riparian galleries of southern Portugal were strongly influenced by distance to stream and season, and were significantly higher in the riparian gallery than in the adjacent matrix. Species richness was significantly higher during the summer-autumn migration period, and bird abundance significantly lower during the breeding season. There were a significant higher percentage of birds moving from the surrounding matrix into the riparian gallery in mid-summer, but not during the autumn migration and winter. In the second chapter we analyzed the diet of passerines using fecal samples, and trophic ecology using carbon and nitrogen stable isotopes of blood samples of 10 species (5 riparian passerines and 5 surrounding matrix passerine species). We assessed also food availability in two riparian forest areas of Southern Portugal (Évora) during four seasons (spring, summer, autumn and winter). We report consistent differences in the diet and trophic ecology between passerines that inhabit the riparian gallery and the adjacent matrix among seasons, and in relation to the abundance of food resources, particularly during periods with higher species density. In the third chapter we studied seed dispersal patterns by birds in the riparian gallery and in the surrounding forest matrix using a specific type of fruit marking and the conventional seed traps. Seed dispersal was strongly influenced by the abundance of fruits, distance to stream, and seed dimensions. The results of this study present some implications for the colonization of fleshy fruit plants from the riparian gallery into the adjacent matrix, meaning that smaller sized seeds may be dispersed at larger distances, and suggesting that the abundance of each species producing fruits will influence strongly the vegetation composition of the adjacent matrix. In the fourth chapter we set an example and create a precedent using Replacement Cost (RC) analysis to estimate the economic value of the environmental service of seed dispersal performed by the Blackcap (Sylvia atricapilla) dispersing blackberries (Rubus ulmifolius) and wild olives (Olea europaea var. sylvestris) in the riparian gallery and in the immediate adjacent areas of southern Portugal. We discuss that RC varies according to the replacement method used, spreading seeds or planting saplings. A compromise has to be made to replace the service using the most similar method of replacement to seed dispersal performed by birds, however he complexity of factors that affect germination and sapling survival probably resulted in an underestimation of the environmental service provided by blackcap in this study. Taking into consideration that blackcap performs this process freely, this kind of approach can constitute an important tool to achieve better conservation measures and management strategies.
Os ecossistemas ripícolas são fundamentais para manter a biodiversidade à escala regional, sendo particulamente importantes em sistemas agroflorestais abertos. Estes ecossistemas estão entre os mais importantes e vulneráveis, e apresentam uma biodiversidade relativamente elevada, oferecendo refúgio e áreas de alimentação para presas e predadores e consequentemente constituem corredores de migração. Estas áreas fornecem muitos recursos e atraem muitos animais, como aves frugívoras, que são os principais dispersores de sementes na bacia do mediterrâneo. A importância das galerias ripícolas para as comunidades de aves é reconhecida para as espécies ripícolas mas, a interface entre as galerias ripícolas e a matrix envolvente tem sido pouco estudada. Esta tese compara a comunidade de aves em termos de composição, dieta, ecologia alimentar e a dinâmica da dispersão de sementes entre aves que habitam a galeria ripícola e a matriz florestal envolvente (montado). Demos também um primeiro passo na tentativa de estimar o valor económico do serviço de ecossistema “dispersão de sementes” fornecido pelos passeriformes. Esta tese compreende quatro capítulos. No primeiro capítulo analisamos as comunidades de aves a diferentes distâncias da ribeira no sentido de descrever variações sazonais e diárias no uso das galerias ripícolas e das áreas florestais adjacentes (montado). Para além disso, avaliamos se as aves se movimentam activamente da matriz envolvente para a galeria ripícola e a sua direcção de voo em três diferentes estações do ano. A riqueza específica e a abundância de aves (número total de indivíduos) nas galerias ripícolas do sul de Portugal foram fortemente influenciadas pela distância à ribeira e pela estação do ano, e foram significativamente mais elevadas na galeria ripícola do que na matriz adjacente. A riqueza específica foi significativamente mais elevada na galeria ripícola durante a o período da migração (verão-outono), e a abundância de aves foi significativamente menor do que durante o período reprodutor. Verificou-se uma percentagem significativa elevada de movimentos de aves da matriz envolvente para a galeria ripícola no meio do verão mas, não durante a migração outonal e no inverno. No segundo capítulo analisámos a dieta de Passeriformes usando amostras fecais e amostras de sangue, analisadas através de isótopos estáveis de carbono, de 10 espécies de aves; 5 passeriformes característicos da zona ripícola e 5 passeriformes característicos da matriz florestal envolvente. Avaliámos também a disponibilidade de alimento em duas área ripícolas-florestais do sul de Portugal (Évora) em quatro estações do ano (primavera, verão, outono e inverno). Constatámos que a dieta e a ecologia trófica entre passeriformes da galeria ripícola e da matriz adjacente variam entre si de acordo com a estação do ano e com a disponibilidade alimentar, particularmente durante períodos com elevada densidade de aves. No terceiro capítulo estudámos os padrões de dispersão de sementes pelas aves na galeria ripícola e na matriz florestal envolvente usando um tipo específico de marcação de frutos e as convencionais “seed-traps”. A dispersão de sementes foi fortemente influenciada pela abundância de frutos, a distância à ribeira e as dimensões das sementes. Os resultados deste estudo têm implicações na colonização da matriz adjacente pelas plantas de frutos carnudos da galeria ripícola, uma vez que sementes de menores dimensões podem ser dispersadas a maiores distâncias e que a abundância dessas espécies produtoras de frutos vai influenciar fortemente a composição da comunidade de plantas da matriz envolvente. No quarto capítulo demos um primeiro passo no uso do análise do custo de substituição para estimar o valor económico do serviço de ecossistema “dispersão de sementes” levado a cabo pela Toutinegra-de-barrete-preto (Sylvia atricapilla) ao dispersar sementes de amoras silvestres (Rubus ulmifolius) e de zambujeiro (Olea europaea var. sylvestris) na galeria ripícola e na matriz adjacente numa área do sul de Portugal. Discute-se que o custo de substituição da dispersão de sementes varia de acordo com o método de substituição usado, seja ele espalhar sementes ou a plantação de plântulas (alvéolos florestais). Tem de haver um compromisso de forma a substituir este serviço usando o método mais aproximado às dinâmicas de dispersão de sementes pelas aves mas, ainda assim, a complexidade de factores que afectam a germinação e a sobrevivência das plântulas resultou provavelmente numa subestimativa do serviço de ecossitema desempenhado pela toutinegra-de-barrete-preto neste estudo. Tendo em conta que a toutinegra-de-barrete-preto leva a cabo este processo de dispersão de sementes sem qualquer custo económico associado, este tipo de abordagem pode constituir uma importância ferramenta no sentido de desenvolver medidas de conservação e gestão da biodiversidade mais eficientes.
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Peden, Moraig Isobel. "The impact of communal land-use on the biodiversity of a conserved grassland at Cathedral Peak, uKhahlamba-Drakensberg Park, South Africa : implications for sustainable utilization of montane grasslands." Thesis, 2004. http://hdl.handle.net/10413/5448.
Full textAbstract:
South African grasslands are under-conserved and there is a need to expand conservation
efforts beyond the boundaries of protected areas. While communal grasslands have
conservation potential they are generally over-utilized and the impact of communal land-use
on biodiversity is poorly studied. At the same time there is pressure on protected areas to
allow for the sustainable utilization of biodiversity. The aim of this study was to examine the
impact of communal land-use on various components of biodiversity and to make
recommendations regarding communal use of protected areas.
A fence-line study was conducted to assess the impact of eight years of controlled communal
land-use on biodiversity in the uKhahlamba-Drakensberg Park. The communally used land
(referred to as the lease land) which was used for controlled grazing as well as plant collection
was compared with land under formal conservation. Vegetation was sampled using the
importance score method and veld condition assessments. Selected invertebrate taxa were
sampled using sweep netting, colour pan traps and transects and were identified to
morphospecies level.
Multivariate statistics revealed that sites generally grouped according to landscape position
rather than land-use. No significant differences were found in diversity, evenness, richness or
veld condition between the lease and conservation land. However, more than twenty-five
percent of vegetation and invertebrate species were found exclusively in the lease or
conservation land, suggesting that different suites of species were supported by the two landuses.
Four alien plant species were found exclusively in the lease land, while one vulnerable
and one rare plant species were found only in the conservation land.
Further research is required to assess whether biodiversity was diminished by controlled
communal. While the lease concept may offer potential as a low-use buffer zone, localised
damage from cattle paths and weak enforcement of grazing agreements were areas of concern.
Keywords: communal grass)ands, grassland flora, grassland invertebrates, transfrontier park.Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.