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311.
Prioritizing Pacific Salmon Stocks for Conservation 总被引:3,自引:1,他引:2
Fred W. Allendorf David Bayles Daniel L. Bottom Kenneth P. Currens Christopher A. Frissell David Hankin James A. Lichatowich Willa Nehlsen Patrick C. Trotter & Thomas H. Williams 《Conservation biology》1997,11(1):140-152
Over 300 native stocks of Pacific salmon, steelhead, and coastal cutthroat trout (Oncorhynchus spp.) are at risk of extinction in the Pacific Northwest. With only limited resources available for conservation and recovery, prioritization of these stocks may become necessary if meaningful measures are to be implemented. We propose criteria by which prioritization may be guided. First, we rank stocks for risk of extinction, either by population viability analysis or by a set of surrogate measures. Then we rank stocks for biological consequences of extinction, using sets of questions designed to establish the genetic and evolutionary consequences and the ecological consequences if a stock were to become extinct. Together, these rankings allow stocks to be prioritized for a range of possible actions, with those stocks at highest risk and bearing the greatest biological consequences of extinction receiving attention first. Application of the prioritization process to 20 Pacific anadromous salmonid stocks worked as intended, although data limitations are considerable. The process is most likely to work successfully when applied to many stocks on which data exist, when several experts carry out the prioritization, and when the results are peer reviewed. 相似文献
312.
313.
Tamim Younos Fred W. Kaurish Terri Brown Raymond de Leon 《Journal of the American Water Resources Association》2001,37(2):327-334
ABSTRACT: Karst terrane provides a linkage between surface water and ground water regimes by means of caves, sinkholes and swallets, and sinking streams, and facilitates the inter‐watershed transfer of water and contaminants through these subsurface systems. The goal of this study was to develop procedures to identify the sources of degradation of a creek situated in a complex karst‐water system. The study approach consisted of using dye tracing technique to determine subsurface flow paths through the karst system, a water‐sampling network to identify and characterize pollution sources within the surface watershed and subsurface flow regime, and evaluation of analytical data for several water quality parameters. The results of this study provide an interesting perspective of water and contaminant movement in karst‐water systems and pinpoint the sources of stream contamination for a case study site in southwest Virginia where two springs supply water to a contaminated freshwater stream. 相似文献
314.
Most European goose populations have increased exponentially, and this has increasingly brought them into conflict with human activities. To manage this conflict, we used multi-criteria decision analysis to help set population targets for a super-abundant population of greylag geese (Anser anser). We relied on expert elicitation to assess the consequences of varying goose abundance on nine ecological, economic, and societal objectives. Representatives from national governments and from non-governmental organizations then weighted the objectives based on their perceived relative importance, and we used a consensus-convergence model to reach stakeholder agreement on the tradeoffs among objectives. The preferred population targets for two management units represent about a 20% reduction from current abundances, which from a management perspective would require considerable effort above and beyond current population-control measures. We believe that multi-criteria decision analysis can provide a systematic and transparent framework for building consensus among diverse stakeholders in a wide array of human-wildlife conflicts. 相似文献
315.
To better understand the role of herbivory and fire as potential disturbance processes in sagebrush communities, we examined
responses of a grazing ungulate, elk (Cervus elaphus), following prescribed burning of sagebrush (Artemisia
tridentata ssp. vaseyana) in south-central Montana (USA.) with concurrent monitoring of changes in plant production, nutritional quality, and community
diversity from 1989–1999. Burning transformed low-diversity, sagebrush-dominated communities into high-diversity, graminoid-forb
communities that persisted for 10 years without significant reestablishment of sagebrush. Elk increased use of burned sites
one year after burning, but elk use returned to pre-burn levels over the next two to nine years. Forage biomass and nutritional
quality declined after initial increases that coincided with increased elk use. Increases in elk use appeared to be influenced
by increases in combined graminoid and forb production and changes in structural vegetation characteristics that permitted
greater foraging efficiency. Declines in use were associated with loss of nutritional enhancement and declines in combined
graminoid and forb production. Managers may observe only short-term responses from grazing ungulates to prescribed fire in
sagebrush communities, but can expect longer-term increases in plant diversity and establishment of graminoid-forb communities. 相似文献