49 research outputs found

    Vegetation dynamics following grazing cessation on the Channel Islands, California

    Get PDF
    European introduction of grazing livestock converted large areas of perennial-dominated native plant communities to exotic, mostly annual-dominated communities in much of the arid and semiarid western U.S. Grazing-induced type conversions of vegetation are particularly widespread in the Mediterranean-climate ecosystems of California, where exotic annual grasslands have largely replaced native shrublands and grasslands. Land managers are increasingly retiring arid and semiarid lands from grazing in an effort to reverse these changes and promote native vegetation recovery, but such recovery is often slow or nonexistent. Exotic grasslands can exhibit remarkable compositional stability even where native propagules are available. Where spontaneous recovery of native plant communities does occur, it tends to be spatially and temporally variable and seemingly unpredictable. Why some exotic-dominated communities are rapidly recolonized by native species upon release from grazing while others persist indefinitely is poorly understood. Long-term vegetation monitoring at the California Channel Islands provides an opportunity to determine factors associated with spontaneous recovery of native vegetation following the removal of nonnative herbivores. This study used time-series vegetation data and environmental data to identify patterns in post-grazing native vegetation recovery among taxa and environments, assess the utility of certain ecological theories in predicting recovery, and develop hypotheses about factors controlling native vegetation recovery. Site environmental characteristics explained post-grazing succession on the Channel Islands better than did ecological theories invoking biodiversity as a predictor or correlate. Exotic species richness and abundance consistently correlate with fine-grained substrates, and more generally with higher site heat load. Results suggest that competition for soil moisture is an important control on native vegetation recolonization. Response to grazing cessation also differed among taxa. Theoretically invasive traits did not predict differences in response among native woody species, but drought dormancy did, suggesting the importance of drought-coping strategies among taxa. Differential response among exotic species indicates possible post-grazing environmental changes and can inform prioritization of eradication efforts. Application of this type of trend analysis to the development of restoration goals and strategies is discussed

    Economic Development in Indian Country: Redefining Success

    Get PDF
    In this paper we draw from lessons learned in four research projects to suggest effective strategies for building successful economies in Indian Country. Current thinking about economic development in Indian Country often focuses on the challenges of implementing successful models from outside Indian Country in a location considered deficient in the cultural, social, financial, and human preconditions necessary for successfully growing jobs and businesses. Recent research from the North Central Regional Center for Rural Development, Heartland Center for Leadership Development, and United Tribes Technical College counters this perception in three ways. First, despite some reports to the contrary, many successful entrepreneurs live in Indian Country. Second, while reservation communities do experience higher levels of poverty and unemployment than their non-reservation counterparts, Indian country abounds in unacknowledged and often uninvested natural, cultural, human, and social capital assets. Traditional mainstream approaches to job and business development typically overlook these assets. Third, our data indicates that many Native people define wealth in non monetary ways suggesting that successful economic development in Indian Country must be measured by the indicators that matter most to the people involved

    Survey Committee Report, June 19, 1954

    Get PDF
    A report of the Survey Committee detailing the findings of a questionnaire that attempted to outline the future development of law libraries in the Southeast and to determine how interlibrary loan service might be facilitated . The questionnaire results were inconclusive

    Clinical and Experimental Applications of NIR-LED Photobiomodulation

    Get PDF
    This review presents current research on the use of far-red to near-infrared (NIR) light treatment in various in vitro and in vivo models. Low-intensity light therapy, commonly referred to as “photobiomodulation,” uses light in the far-red to near-infrared region of the spectrum (630–1000 nm) and modulates numerous cellular functions. Positive effects of NIR–light-emitting diode (LED) light treatment include acceleration of wound healing, improved recovery from ischemic injury of the heart, and attenuated degeneration of injured optic nerves by improving mitochondrial energy metabolism and production. Various in vitro and in vivo models of mitochondrial dysfunction were treated with a variety of wavelengths of NIR-LED light. These studies were performed to determine the effect of NIR-LED light treatment on physiologic and pathologic processes. NIRLED light treatment stimulates the photoacceptor cytochrome c oxidase, resulting in increased energy metabolism and production. NIR-LED light treatment accelerates wound healing in ischemic rat and murine diabetic wound healing models, attenuates the retinotoxic effects of methanol-derived formic acid in rat models, and attenuates the developmental toxicity of dioxin in chicken embryos. Furthermore, NIR-LED light treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. The experimental results demonstrate that NIR-LED light treatment stimulates mitochondrial oxidative metabolism in vitro, and accelerates cell and tissue repair in vivo. NIR-LED light represents a novel, noninvasive, therapeutic intervention for the treatment of numerous diseases linked to mitochondrial dysfunction

    The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

    Get PDF
    Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades
    corecore