Professor Emeritus, Fisheries and Biology; Adjunct Professor, Civil Engineering, Environmental Health and Public Affairs
jrkarr@u.washington.edu, 360-681-3163

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ecology and public policy, watershed management, tropical forest ecology, conservation biology

Publications

This professor is no longer available as a faculty advisor for graduate students.

My major areas of research span the range from tropical forest ecology to aquatic ecology and watershed management. I am particularly interested in fostering use of ecological knowledge to resolve complex natural resource and environmental disputes. My research in recent years has concentrated on the ecology of fish and invertebrate in streams, on plants and invertebrates in shrub steppe, and the demography of tropical forest birds. I evaluate the influence of human-induced disturbances on biological systems using the index of biotic integrity (IBI) as a biologically based approach to evaluate the condition of living systems. IBI is used widely to evaluate the condition of water resource systems. Assessments of resource condition based on biological evaluations require detailed knowledge of the ecology of streams and rivers.

My research on forest birds has emphasized subjects such as habitat selection, niche partitioning, and demography. Recent work on avian demography has shown that, in contrast to long-held assumptions, differences in survival rates between tropical and temperate birds are not as extreme as once thought. Furthermore, demographic and other data for tropical birds prove valuable in interpreting information on extinction probability in small isolated populations of those species. Studies of avian extinction on Barro Colorado Island (BCI), Panama, provide insight into the number, identity, and attributes of species susceptible to local extinction. Extinction is not random at the species or guild level. Obvious patterns include disproportionate losses of large and specialized species and of species from undergrowth and foothill forest. In addition to these factors, demographic attributes (fecundity, rates of adult survival and recruitment, and population variability) interact in complex ways to vary the risk of extinction among species. Life histories that balance susceptibility to nest predation with the ability to replace clutches are essential for persistence on BCI. Differential extinction rates on the mainland and island demonstrate the importance of the local and regional habitat mosaic as determinants of extinction probability. Genetic factors do not seem to be important, at least over ecological time scales. Environmental factors increasing the mortality rate at any life stage should be the focus for management on insular reserves.

Select Publications

Chu, E. W., and J. R. Karr. 2001. Environmental Impact, Concept and Measurement of. Pages 557-577 in S. A. Levin, editor. Encyclopedia of Biodiversity, Vol. 2. Orlando, FL; Academic Press.

Kimberling, D. N., J. R. Karr, and L. S. Fore. 2001. Measuring human disturbance using terrestrial invertebrates in the shrub-steppe of eastern Washington (USA). Ecological Indicators 1: 63-81.

Karr, J. R. 2002. What from ecology is relevant to design and planning? Pages 133-172 in B. R. Johnson and K. Hill, editors. Ecology and Design: Frameworks for Learning. Island Press, Washington, DC.

Morley, S. A., and J. R. Karr. 2002. Assessing and restoring the health of urban streams in the Puget Sound Basin. Conservation Biology 16: 1498-1509.

Karr, J. R. 2002. Understanding the consequences of human actions: Indicators from GNP to IBI. Pages 98-110 in P. Miller and L. Westra, editors. Just Ecological Integrity: The Ethics of Maintaining Planetary Life. Rowman and Littlefield, Lanham, Maryland.