Thesis (M.S.)--Southern Oregon University, 2003. / "A thesis submitted to the Department of Biology and the Graduate School of Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science in Environmental Education." Includes bibliographical references (leaves 93-89). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Dec. 7, 2009). Includes bibliographical references.

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Understanding dispersal and gene flow in human-modified landscapes is crucial for effective conservation. Seed dispersal governs colonization, recruitment, and distribution of plant species, whereas both pollen and seed dispersal determine gene flow among populations. This PhD thesis tests the effect of rotational shepherding on seed dispersal and gene flow in fragmented calcareous grasslands. Calcareous grasslands (Gentiano-Koelerietum pyramidatae vegetation) in Central Europe are semi-natural communities traditionally used for rotational grazing that experienced a decline of plant species during the 20th century due to abandonment of shepherding. This PhD profits from a management project started in 1989 in Bavaria, Germany to reconnect previously abandoned calcareous grasslands in three non-overlapping shepherding systems. Two vegetation surveys in 1989 and 2009 revealed colonizations in previously abandoned grasslands reconnected by shepherding. First, I propose a comprehensive approach to identify determinants of community-level patch colonization rates based on 48 habitat specialist plants by testing competing models of pre-dispersal and dispersal effects and accounting for post-dispersal effects. Mean source patch species occupancy in 1989, and structural elements in focal patches related to establishment explained community-level patch colonization rates. Secondly, by adapting the community analysis to all 31 individual species of the same community with sufficient data, I corroborate the role of shepherding to support dispersal for a range of species, even if they lack seed morphological traits related to zoochory. Thirdly, for the habitat specialist Dianthus carthusianorum, I genotyped 1,613 individuals from 64 populations at eleven microsatellites to test the effect of dispersal by sheep on spatial genetic structure at the landscape scale. Genetic distances between grazed patches of the same herding system were related to distance along herding routes, whereas ungrazed patches showed isolation by geographic distance. Lastly, within individual grassland patches, shepherding significantly decreases the degree of relatedness among neighboring individuals (kinship structure) and increases genetic diversity. My thesis contributes towards understanding the effects of zoochory on spatial dynamics in plant populations across scales.

The fragmentation of natural habitat caused by anthropogenic land use changes is one of the main drivers of the current rapid loss of biodiversity. In face of this threat, ecological research needs to provide predictions of communities' responses to fragmentation as a prerequisite for the effective mitigation of further biodiversity loss. However, predictions of communities' responses to fragmentation require a thorough understanding of ecological processes, such as species dispersal and persistence. Therefore, this thesis seeks an improved understanding of community dynamics in fragmented landscapes. In order to approach this overall aim, I identified key questions on the response of plant diversity and plant functional traits to variations in species' dispersal capability, habitat fragmentation and local environmental conditions. All questions were addressed using spatially explicit simulations or statistical models. In chapter 2, I addressed scale-dependent relationships between dispersal capability and species diversity using a grid-based neutral model. I found that the ratio of survey area to landscape size is an important determinant of scale-dependent dispersal-diversity relationships. With small ratios, the model predicted increasing dispersal-diversity relationships, while decreasing dispersal-diversity relationships emerged, when the ratio approached one, i.e. when the survey area approached the landscape size. For intermediate ratios, I found a U-shaped pattern that has not been reported before. With this study, I unified and extended previous work on dispersal-diversity relationships. In chapter 3, I assessed the type of regional plant community dynamics for the study area in the Southern Judean Lowlands (SJL). For this purpose, I parameterised a multi-species incidence-function model (IFM) with vegetation data using approximate Bayesian computation (ABC). I found that the type of regional plant community dynamics in the SJL is best characterized as a set of isolated “island communities” with very low connectivity between local communities. Model predictions indicated a significant extinction debt with 33% - 60% of all species going extinct within 1000 years. In general, this study introduces a novel approach for combining a spatially explicit simulation model with field data from species-rich communities. In chapter 4, I first analysed, if plant functional traits in the SJL indicate trait convergence by habitat filtering and trait divergence by interspecific competition, as predicted by community assembly theory. Second, I assessed the interactive effects of fragmentation and the south-north precipitation gradient in the SJL on community-mean plant traits. I found clear evidence for trait convergence, but the evidence for trait divergence fundamentally depended on the chosen null-model. All community-mean traits were significantly associated with the precipitation gradient in the SJL. The trait associations with fragmentation indices (patch size and connectivity) were generally weaker, but statistically significant for all traits. Specific leaf area (SLA) and plant height were consistently associated with fragmentation indices along the precipitation gradient. In contrast, seed mass and seed number were interactively influenced by fragmentation and precipitation. In general, this study provides the first analysis of the interactive effects of climate and fragmentation on plant functional traits. Overall, I conclude that the spatially explicit perspective adopted in this thesis is crucial for a thorough understanding of plant community dynamics in fragmented landscapes. The finding of contrasting responses of local diversity to variations in dispersal capability stresses the importance of considering the diversity and composition of the metacommunity, prior to implementing conservation measures that aim at increased habitat connectivity. The model predictions derived with the IFM highlight the importance of additional natural habitat for the mitigation of future species extinctions. In general, the approach of combining a spatially explicit IFM with extensive species occupancy data provides a novel and promising tool to assess the consequences of different management scenarios. The analysis of plant functional traits in the SJL points to important knowledge gaps in community assembly theory with respect to the simultaneous consequences of habitat filtering and competition. In particular, it demonstrates the importance of investigating the synergistic consequences of fragmentation, climate change and land use change on plant communities. I suggest that the integration of plant functional traits and of species interactions into spatially explicit, dynamic simulation models offers a promising approach, which will further improve our understanding of plant communities and our ability to predict their dynamics in fragmented and changing landscapes. / Die Fragmentierung von Landschaften umfasst die Zerschneidung und den Verlust von Flächen mit natürlicher Vegetationsentwicklung und ist eine der Hauptursachen für den gegenwärtigen drastischen Verlust an Biodiversität. Diese Dissertation soll zu einem besseren Verständnis der Vegetationsdynamik in fragmentierten Landschaften beitragen. Damit verbunden ist das Ziel, Vorhersagen über die Reaktion von Pflanzengemeinschaften auf Fragmentierung zu verbessern. Diese Vorhersagen sind notwendig, um gezielte Naturschutzmaßnahmen zur Verminderung eines weiteren Verlustes an Biodiversität umsetzen zu können. In Kapitel 2 der Dissertation wird mit einem Simulationsmodell untersucht, wie sich die Ausbreitungsdistanz von Samen auf die lokale Artenzahl von Pflanzengemeinschaften auswirkt. Dabei zeigte sich, dass längere Ausbreitungsdistanzen die lokale Artenvielfalt sowohl erhöhen, als auch verringern können. Der wichtigste Einflussfaktor war dabei die Artenvielfalt der über-geordneten Pflanzengemeinschaft, in der die betrachtete lokale Gemeinschaft eingebettet war. Im dritten Kapitel wird die Konnektivität zwischen Pflanzengemeinschaften in Habitat-fragmenten, d.h. der Austausch von Arten und Individuen durch Samenausbreitung, im Unter-suchungsgebiet in Israel analysiert. Dafür wurde ein zweites räumliches Simulationsmodell mit statistischen Verfahren an Felddaten angepasst. Der Vergleich des Modells mit den Daten wies auf eine sehr geringe Konnektivität zwischen den Habitatfragmenten hin. Das Modell sagte vorher, dass innerhalb von 1000 Jahren 33% - 60% der Arten aussterben könnten. In Kapitel 4 wird zuerst analysiert, welche Prozesse die Verteilung von funktionellen Eigenschaften in Pflanzengemeinschaften bestimmen. In einem zweiten Schritt wird dann unter-sucht, wie sich funktionelle Eigenschaften von Pflanzengemeinschaften mit dem Niederschlag und der Fragmentierung im Untersuchungsgebiet in Israel verändern. Der Zusammenhang zwischen den Eigenschaften Pflanzenhöhe, sowie spezifischer Blattfläche und der Fragmentierung änderte sich nicht entlang des Niederschlagsgradienten. Im Gegensatz dazu, änderte sich der Zusammenhang zwischen der Samenmasse bzw. der Samenzahl und der Fragmentierung mit dem Niederschlag. Aus den Ergebnissen der ersten Teilstudie wird deutlich, dass Naturschutzmaßnahmen, die natürliche Habitate stärker vernetzen sollen, die Diversität, sowie die Zusammensetzung der übergeordneten Artengemeinschaft berücksichtigen müssen, um Verluste an Biodiversität zu vermeiden. Die Verknüpfung eines räumlichen Simulationsmodells mit Felddaten in der zweiten Teilstudie stellt einen neuen und vielversprechenden Ansatz für die Untersuchung der Auswirkungen verschiedener Management-Szenarien dar. Die dritte Teilstudie ist die erste Analyse der gemeinsamen Auswirkungen von Klima und Fragmentierung auf funktionelle Pflanzen-eigenschaften und zeigt die hohe Bedeutung der Untersuchung von Synergie-Effekten verschiedener Umweltfaktoren. Für zukünftige Forschung legt diese Dissertation nahe, funktionelle Eigenschaften und Konkurrenz zwischen Arten in räumlichen Simulationsmodellen zu berücksichtigen, um das Verständnis von Artengemeinschaften in fragmentierten Landschaften noch weiter zu verbessern.

The objectives of the study were to identify, classify, describe and map the plant communities in the proposed Highveld National Park, including the degraded Spitskop areas. Vegetation sampling was done by means of the Braun-Blanquet method and a total of 108 stratified random relevés were sampled. A numerical classification technique (TWINSPAN) was used and the result was refined by Braun-Blanquet procedures. The final results of the classification procedure were presented in the form of phytosociological tables and twelve plant communities were described. For indirect ordination, a Detrended Correspondence Analysis (DCA) algorithm was applied to the data set to confirm the phytosociological association and to assess floristic relations between communities. For direct environmental gradient analysis the Canonical Correspondence Analysis (CCA) was applied to the data using the CANOCO software program. The plant communities were combined into six management units based on similarities regarding vegetation composition, habitat, topography and soil characteristics. Characterization of land degradation was done by grouping erosion into different classes and different degrees of severity. Degraded areas in need of rehabilitation and restoration were identified and described. Recommendations were made with regard to rehabilitation and monitoring of all degraded areas in the HNP. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2008.

Understanding dispersal and gene flow in human-modified landscapes is crucial for effective conservation. Seed dispersal governs colonization, recruitment, and distribution of plant species, whereas both pollen and seed dispersal determine gene flow among populations. This PhD thesis tests the effect of rotational shepherding on seed dispersal and gene flow in fragmented calcareous grasslands. Calcareous grasslands (Gentiano-Koelerietum pyramidatae vegetation) in Central Europe are semi-natural communities traditionally used for rotational grazing that experienced a decline of plant species during the 20th century due to abandonment of shepherding. This PhD profits from a management project started in 1989 in Bavaria, Germany to reconnect previously abandoned calcareous grasslands in three non-overlapping shepherding systems. Two vegetation surveys in 1989 and 2009 revealed colonizations in previously abandoned grasslands reconnected by shepherding. First, I propose a comprehensive approach to identify determinants of community-level patch colonization rates based on 48 habitat specialist plants by testing competing models of pre-dispersal and dispersal effects and accounting for post-dispersal effects. Mean source patch species occupancy in 1989, and structural elements in focal patches related to establishment explained community-level patch colonization rates. Secondly, by adapting the community analysis to all 31 individual species of the same community with sufficient data, I corroborate the role of shepherding to support dispersal for a range of species, even if they lack seed morphological traits related to zoochory. Thirdly, for the habitat specialist Dianthus carthusianorum, I genotyped 1,613 individuals from 64 populations at eleven microsatellites to test the effect of dispersal by sheep on spatial genetic structure at the landscape scale. Genetic distances between grazed patches of the same herding system were related to distance along herding routes, whereas ungrazed patches showed isolation by geographic distance. Lastly, within individual grassland patches, shepherding significantly decreases the degree of relatedness among neighboring individuals (kinship structure) and increases genetic diversity. My thesis contributes towards understanding the effects of zoochory on spatial dynamics in plant populations across scales.

En Amérique tropicale et aux Antilles, le milieu naturel a déjà été l'objet d'une dégradation première de la part des populations précolombiennes: Incas et Mayas sur la terre ferme, Arawaks et Carafbes dans les îles. Cette dégradation n'a fait que s'accentuer lors de la découverte du Nouveau Monde et surtout à la suite de l'introduction des méthodes culturales européennes, il y a trois siècles, par les colons espagnols, portuguais, hollandais, anglais ou français. [...]

An inventory of the vascular flora at Munsee Woods in Delaware County, Indiana revealed 399 species and varieties representing 255 genera and 86 families. The 10 families containing ~52% of the documented species (in order by number of species) were Asteraceae, Poaceae, Cyperaceae, Rosaceae, Brassicaceae, Lamiaceae, Fabaceae, Scrophulariaceae, Polygonaceae, and Liliaceae. Of the documented flora, 300 were native and 99 were exotics. The Floristic Quality Index (FQI) was 47.7, and the mean Coefficient of Conservation (Cav) was 2.4. A plot-based analysis of the woody vegetation was conducted for the southern mesic, upland woodland. Based on the relative importance values (RIV), the important species in order were Acer saccharum, Quercus alba, Celtis occidentalis, Prunus serotina, and Ulmus americana. Relative importance values were used to compare Munsee Woods to Christy Woods in Delaware County, Ginn Woods in Delaware County, and Yuhas Woods in Randolph County. The results of these comparisons were interpreted with regards to the disturbance history of the site, age of the stand, and the stage of succession. / Department of Biology

This study is an effort to provide new information on the effects of isolated tree canopies on understory vegetation composition and soil characteristics of northern Indiana black oak savannas. Temperate savannas in the United States have been greatly altered by human activities. Management of these areas is an important consideration for Midwest natural resource agencies. It is hypothesized that isolated trees within a savanna may alter the soil and plants around them, much in the same way that gaps in a forest canopy alter the plant composition and soil characteristics on the forest floor. In this study, isolated trees were selected in three northern Indiana black oak (Quercus velutina) savannas. Plots were located under the tree canopies and in adjacent open areas, in four directions from the tree stem. Populations of herbaceous plants were inventoried and the soil characteristics analyzed for both inside-canopy and outside-canopy plots. The environmental variables measured accounted for only about 20 percent of the variation in plant community between plots according to a Canonical Correspondence Analysis. Most of the variation in plant composition between plots was explained by pH, the amount of rain throughfall, and the thickness of the A horizon. It is clear that these black oak trees do alter the soil and plant composition around them. This information has implications for the long-term management of northern Indiana savannas. / Department of Natural Resources and Environmental Management