Four tree species (i.e. Pinus ponderosa, Juiperus scopulorum, Quercus Gambelii, and Ceanothus velutinus were chosen for this study. Ten individuals of each species were selected and their associated understory communities and adjacent non-understory communities sampled. Data taken included biotic and abiotic parameters. The data was subjected to similarity index analysis, cluster analysis, discriminant analysis, and x^2 analysis. The results were confirmed by all tests. The forest canopy was shown to directly influence the understory community. The understory community is a shrub-grass dominated type while the non-understory community is an annual-forb dominated type. The different tree species were also shown to differentially influence their associated understory communities.

No description available.

Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 85-91). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Les paysages français sont de plus en plus soumis aux pressions anthropiques. Ces pressions engendrent des modifications de la qualité et de la configuration des habitats, y compris forestiers, et ont des effets sur les plantes. Cette thèse aborde le rôle de la composition et de la configuration de la mosaïque paysagère extra- et intra-forestière sur la diversité de la flore en forêt. Il s'appuie sur 1932 relevés de l'Inventaire Forestier National répartis dans 19 départements de la moitié nord de la France. Les indices paysagers ont été calculés à partir de fonds cartographiques et d'images aériennes photo-interprétées. L'étude de terrain a été consacrée à la portée de l'effet d'un élément linéaire particulier du paysage : la route forestière. Le paysage a un effet important au-delà de la qualité de l'habitat local. La flore répond à trois principaux gradients paysagers : le premier est lié à la nature forestière ou non forestière du paysage, le second à la présence de coupes et peuplements jeunes, et le dernier reflète la composition en essences (feuillus ou résineux). L'effet des ouvertures paysagères (extra-forestière cultivée, coupe, peuplement jeune) sur la flore passe par la quantité, et surtout le nombre de taches et la longueur d'interfaces. Cet effet est positif sur la plupart des espèces, ce qui confirme le rôle des ouvertures dans le maintien de la diversité floristique. Les traits des espèces discriminés sont l'épi-zoochorie et l'anémochorie, la masse x longueur des semences et certaines stratégies de Grime. Ce travail montre qu'il est primordial d'appréhender le paysage sur un rayon de plus d'1 km. En comparaison, la route a un faible impact sur la flore, et plus souvent un effet positif que négatif. Les mécanismes sous-jacents à l'influence du paysage sont discutés à la lumière d'un effet temporel sur les plantes. Les implications pour la gestion des habitats en faveur de la biodiversité sont abordées. / French landscapes are submitted to increasing anthropogenic pressures. These pressures can affect plant species diversity by modifying the quality and spatial configuration of habitats, including forest habitats. This project addressed the role of the composition and configuration of the forest and non forest landscape mosaic on forest plant diversity. It was based on 1932 plots from the National Forest Inventory located in 19 "départements" of Northern France. Landscape indices such as fragmentation were measured or calculated from aerial photographs and existing national forest maps. A specific field study was devoted to analyse the depth of the effect of a particular linear landscape feature: the forest road. Landscape patterns had a significant impact in addition to local habitat quality. Plant composition was influenced by three main landscape gradients: (1) forest or non-forest habitat, (2) presence of fellings and young stands and (3) species composition (broadleaves or coniferous). The openings in the surrounding landscape (agricultural lands, forest felling and young stands) had an effect on plants through their quantity, number of patches and edge length. This effect was positive for most species, which confirms the role of the openings in maintaining plant diversity. The species traits discriminated were epi-zoochory and anemochory, mass x length of seeds and some Grime adaptive strategies. This work also underlined the importance to analyse landscape pattern effect within a buffer zone of more than 1 km around the plots. In contrast, we found that forest roads had a short depth of edge influence on plants (< 5 m) and road effect was more often positive than negative. The mechanisms underlying the influence of landscape mosaic are discussed in light of a temporal effect on plants. The implications for habitat and forest management to protect biodiversity are presented.

How plants from a common species pool form community has been considered from a variety of approaches. A promising approach involves the search for assembly rules based on plant functional traits. This approach has potential to provide insight into community and ecosystem processes In this research. a general and simple conceptual model based on life forms and independent of species is used as a framework for assessing the internal structure of plant communities. Plant functional traits are used to identify patterns within and between plant communities in the contrasting environments of Camp Williams, Utah, and Camp Grayling, Michigan. The conceptual model has three different functional types formed by one to three functional groups. A functional group, made up of species with similar life form, is analogous to a vegetation stratum. A functional type, consisting of one or more functional groups. is analogous to a community or vegetation type. Correspondence analysis (CA) and analysis of variance (ANOVA) indicate that richness, species diversity, and trait diversity are essentially independent of functional type and are, for example, fairly consistent regardless of climatic regime or structural complexity. Cover. on the other hand. increases with the number of functional groups in a functional type. Consistent patterns and trends for sets of functional traits support the view that assembly rules may account for internal structure in plant communities. The consistent association of sets of traits with functional groups even in taxonomically dissimilar communities suggests that the functional traits are related to fundamental ecological processes that shape these communities. Ambiguity in some of the results might be explained by extending the analysis to additional installations that replicate the climatic conditions found at Camp Williams and Camp Grayling.

The diverse lichen flora of the Pacific Northwest is being impacted by population growth and by forest management practices. Accumulating information about our lichen flora will improve our conservation strategies. This dissertation first collects information to improve our understanding of how lichen communities vary among forests of differing structure, and across the western Oregon landscape. It then proposes a method to predict species occurrence in unsampled sites by utilizing the information on forest characters and environmental gradients at sampled sites. Macrolichen communities sampled in coniferous forests revealed that old-growth stands (>200 yrs old) harbored communities that differed from those in young forests (50-110 yrs old). Even more atypical communities occurred in macrolichen hotspots, which were primarily in riparian zones. Many macrolichen species were associated with these hotspots, including numerous nitrogen-fixing cyanolichens. Macrolichen species associated with old-growth forested plots included the nitrogen-fixing lichen Lobaria oregana and several forage-providing alectorioid lichens. The presence of remnant old trees apparently increased the occurrence of old-growth associates in young stands. The calicioids, a group of microlichens investigated only in the Cascades, had a strong association with old growth forest and remnant trees. Diversity of calicioids may also be increased by legacy structures such as old snags and wolf trees. These structures increase continuity between current and previous stands. Macrolichen communities varied between the Coast and Cascade Mountain Ranges, following climatic gradients, particularly annual precipitation. Successional patterns in macrolichen communities appeared to differ between the mountain ranges. The modeling method proposed for using habitat associations to predict occurrence has several advantages over common modeling methods, such as regression. The method is simple, avoids parametric assumptions, provides easy updating of models as additional sites are sampled, and automatically accounts for interactions among predictor variables. It can be linked with GIS data and software to map estimated probability of occurrence across landscapes. The data on calicioids from the Cascades, supplemented with additional stand inventories, were used to test and demonstrate the modeling method. / Graduation date: 2001

Thesis (Dr. rer. nat.)--Universität Regensburg, 2006. / Title from PDF title page (viewed on Apr. 25, 2007). Includes bibliographical references (p. 169-185).

Thesis (M.S.)--University of Pretoria, 1999. / Includes bibliographical references (leaves 122-135).

Thesis (Ph. D.)--University of Kentucky, 2005. / Includes bibliographical references (p. 203-220). Also available in PDF format via the Internet.