Additive Partitioning Reveals Spatial Patterns Of Plant Species Diversity In A Sagebrush Steppe

The premise of this study is that plant diversity is a neglected aspect of the North American sagebrush steppe, a once expansive biome that is now highly degraded. What kind of plant diversity is expected in the sagebrush steppe when it is not regularly physically disturbed? What ecological gradients most affect how plant diversity changes over large spatial scales? The answers to these questions could have implications for invasive plant management and the reclamation and restoration of the sagebrush steppe. Methods included sampling four regions of the sagebrush steppe in the northeastern portion of this biome. The Pryor Mountains, the Charles M. Russell National Wildlife Refuge, and the region of the Yellowstone Plateau were sampled in mostly Montana. These high-native-cover sagebrush sites were compared with those sampled in the Upper Snake River Plains region of southeastern Idaho. One hectare transects were established in high-native cover sagebrush steppe. These were paired with transects established in immediately adjacent disturbance-prone settings (e.g., roadsides) where sagebrush steppe vegetation remained intact. Geographically adjacent transects were sampled where they differed in at least one important ecological attribute. Key findings included that mountain big sagebrush steppe is evolutionarily distinct from Wyoming big sagebrush steppe and that the maximum temperature during the warmest month of the year was an important gradient for shaping species and phylogenetic beta diversity. Geographical proximity also had a large influence on the local species composition. The degree of disturbance also had less of an effect perhaps because of the influence of geography. The effects of physical disturbance were still detectable using descriptive approaches that compared infrequent with frequently disturbed transects. Regardless, native species diversity was distinctly diminished by physical disturbance, which is argued to be evidence that the sagebrush steppe is inherently ecologically stable. The implications of this research include the identification of specific taxonomic groups at and above the species level that may serve as benchmarks for sagebrush steppe reclamation or restoration. Long term stable conditions (infrequent disturbance regimes) are very much required for the successful restoration of the sagebrush steppe.

Here is a thorough presentation and critique of the sampling approaches, designs and field techniques for measuring plant diversity. Ecologists interested in assessing landscapes and ecosystems must measure biomass, cover, and the density or frequency of various key species. Recently, sampling designs for measuring species richness and diversity, patterns of plant diversity, species-environment relationships, and species distributions have become finer-grained, as it has become increasingly important to accurately map and assess rare species for conservation. This book lays out the range of current methods for mapping and measuring species diversity, for field ecologists, resource managers, conservation biologists, and students, as a tool kit for future field measurements of plant diversity.

The sagebrush steppe ecosystem of the Columbia Plateau has become degraded by a long history of alternative land use and associated perturbations. Protection of remnant stands of intact sagebrush steppe currently relies upon their preservation within the nation's network of parks and protected-areas. The John Day Fossil Beds National Monument, located in central Oregon, and Craters of the Moon National Monument and Preserve, located in southeast Idaho provided a unique opportunity to examine the pattern of plant species distribution and invasion dynamics in two Columbia Plateau protected-area landscapes with a mixed history of alternative land management and protection. Non-metric multidimensional scaling and nonparametric multiplicative regression were applied to data from the National Park Service's Inventory and Monitoring program to investigate correlations of native and non-native plant species to environmental and landscape variables. Understanding how these patterns change at the landscape scale and identifying variation in these patterns between landscapes may improve efficacy in resource management planning. Principle native species reviewed included sagebrush species (Artemisia spp.), broom snakeweed (Gutierrezia sarothrae), currants (Ribes spp.), desert sweet (Chamaebatiaria millefolium), dwarf goldenbush (Ericameria nana), green rabbitbrush (Chrysothamnus viscidiflorus), bluebunch wheatgrass (Pseudoroegneria spicata), bluegrass species (Poa spp.), sandberg bluegrass (Poa secunda.), wheatgrass species (Agropyron spp.), Great Basin wildrye (Lymus cinereus), and squirreltail (Elymus elymoides). Principle non-native invasive species reviewed included cheatgrass (Bromus tectorum), medusahead (Taeniatherum caput-medusae), and bulbous bluegrass (Poa bulbosa), tumble mustard (Sisymbrium altissimum), and tansy mustard (Descurainia spp.). The distribution and relative cover of principle species within the John Day Fossil Beds National Monument were found correlated to combined effects of slope and aspect, representing a transition from steep south-facing slopes to steep north-facing slopes. Species cover and distribution were also found to be correlated to crop year precipitation, the amount of rain and snow falling between October and May. Individual species response along topographic gradients revealed higher relative cover of B. tectorum on the more xeric, south-facing slopes and an increase in the cover of P. spicata on more mesic, north-facing slopes. The relative cover of G. sarothrae and T. caput-medusae were found to increase with increasing crop year precipitation. The distribution and relative cover of principle species within Craters of the Moon National Monument were found correlated to a north to south spatial separation of sampling frames. This gradient represented a transition from higher elevation to lower elevation, decreasing moisture availability, and increasing proximity to alternative land use (i.e. grazing, agriculture) and transportation corridors. Individual species response along these topographic and environmental gradients revealed higher relative cover of non-native invasive species in southern portions of the monument and with positive correlation to the more xeric and disturbed portions of the Monument. The results of this study have increased the understanding of species cover distribution across environmental and topographic gradients within protected sagebrush steppe landscapes while providing insight into the applicability of resilience theory to Columbia Plateau ecology.

This best-selling majors ecology book continues to present ecology as a series of problems for readers to critically analyze. No other text presents analytical, quantitative, and statistical ecological information in an equally accessible style. Reflecting the way ecologists actually practice, the book emphasizes the role of experiments in testing ecological ideas and discusses many contemporary and controversial problems related to distribution and abundance. Throughout the book, Krebs thoroughly explains the application of mathematical concepts in ecology while reinforcing these concepts with research references, examples, and interesting end-of-chapter review questions. Thoroughly updated with new examples and references, the book now features a new full-color design and is accompanied by an art CD-ROM for instructors. The field package also includes The Ecology Action Guide, a guide that encourages readers to be environmentally responsible citizens, and a subscription to The Ecology Place (www.ecologyplace.com), a web site and CD-ROM that enables users to become virtual field ecologists by performing experiments such as estimating the number of mice on an imaginary island or restoring prairie land in Iowa. For college instructors and students.

This book provides case studies and general views of the main processes involved in the ecosystem shifts occurring in the high mountains and analyses the implications for nature conservation. Case studies from the Pyrenees are preponderant, with a comprehensive set of mountain ranges surrounded by highly populated lowland areas also being considered. The introductory and closing chapters will summarise the main challenges that nature conservation may face in mountain areas under the environmental shifting conditions. Further chapters put forward approaches from environmental geography, functional ecology, biogeography, and paleoenvironmental reconstructions. Organisms from microbes to large carnivores, and ecosystems from lakes to forest will be considered. This interdisciplinary book will appeal to researchers in mountain ecosystems, students and nature professionals. This book is open access under a CC BY license.

The question "Why are there so many species?" has puzzled ecologist for a long time. Initially, an academic question, it has gained practical interest by the recent awareness of global biodiversity loss. Species diversity in local ecosystems has always been discussed in relation to the problem of competi tive exclusion and the apparent contradiction between the competitive exclu sion principle and the overwhelming richness of species found in nature. Competition as a mechanism structuring ecological communities has never been uncontroversial. Not only its importance but even its existence have been debated. On the one extreme, some ecologists have taken competi tion for granted and have used it as an explanation by default if the distribu tion of a species was more restricted than could be explained by physiology and dispersal history. For decades, competition has been a core mechanism behind popular concepts like ecological niche, succession, limiting similarity, and character displacement, among others. For some, competition has almost become synonymous with the Darwinian "struggle for existence", although simple plausibility should tell us that organisms have to struggle against much more than competitors, e.g. predators, parasites, pathogens, and envi ronmental harshness.

This book provides a coherent review of NDVI including its origin, its availability, its associated advantages and disadvantages, and its possible applications in ecology, environmental monitoring, wildlife management, and conservation.