- Peinetti, H. P., M. A. Kalkan, and M. B. Coughenour.
- 2002. Long-term changes in willow spatial distribution on the elk winter range of Rocky Mountain National Park. Landscape Ecology 17: 341-354.
The authors determined changes in willow cover in two valleys of the eastern slope of Rocky Mountain National Park in Colorado, and related these changes in suspected causative factors. Changes in vegetation were inferred from digital maps generated from aerial photo interpretation and field studies conducted with a global positioning system. The decrease in riparian shrub cover was approximately 20% in both valleys over the period between 1937/46 and 1996, while the decline in tall willow (> 2m tall) cover was estimated to be about 55% in both valleys. Suppressed willows (< 1.5 m tall) were predominantly located in areas affected by flooding and in areas where major river reductions were observed. Both valleys had sites that were being colonized willows in wet meadows, and open areas created by flood disturbance. The potential causes of willow decline are many. Willow decline was associated with simplification of river spatial pattern, i.e., less complex branching and channelization, and a large flood disturbance. The causes of the reduction in river meanders were not determined, but are likely related to a decline in beavers, and increase in elk, and possibly climatic change. An increase in elk placed increased browsing pressure on willow during the period of willow decline. Other facts such as climate changes and human activities could also have contributed to the willow decline. The persistence of these riparian ecosystems depends in large part on biotic interactions, particularly between willow, beaver, and elk.
- Richter, B. D., R. Matthews, D. L. Harrison, and R. Wigington.
- 2003. Ecologically sustainable water management: managing river flows for ecological integrity. Ecological Applications 13:206-224.
Human demands on the world’s fresh-water supplies continue to grow as the global population increases. In the endeavor to meet human needs, the needs of fresh-water species and ecosystems have largely been neglected and the ecological consequences have been tragic. Healthy fresh water ecosystems provide a wealth of goods and services for society, but our appropriation of fresh-water flows must be better managed if we hope to sustain these benefits and fresh-water biodiversity. We offer a framework for developing an ecologically sustainable water management program, in which human needs for water are met by storing and diverting water in a manner that can sustain or restore the ecological integrity of affected river ecosystems. The six-step process: 1) developing initial numerical estimates of key aspects of river flow necessary to sustain native species and ecosystem functions; 2) accounting for human uses of water, both current and future, through development of computerized hydrologic simulation model that facilitates examination human-induced alterations to river flow regimes; 3) assessing incompatibilities between human and ecosystems needs with particularly attention to their spatial and temporal character; 4) collaborative searching for solutions for resolving incompatibilities; 5) conducting water management experiments to resolve critical uncertainties that frustrate efforts to integrate human and ecosystem needs; and 6) designing and implementing an adaptive management program to facilitate ecologically sustainable water management for the long term. Drawing from case studies from around the world to illustrate our framework, we suggest that ecologically sustainable water management is attainable in the vast majority of the world’s river basins. However, this quest will become far less feasible if we wait until water supplies are further over-appropriated.
- Zedler, J. B.
- 2003. Wetlands at your service: reducing impacts of agriculture at the watershed scale. Frontiers in Ecology and the Environment 1(2):65-72.
In the Upper Midwest region of the US, three ecosystem services (flood abatement, water quality improvement, and biodiversity) declined when about 60% of the region’s historical wetland was drained, mostly for agriculture. Some of the lost services could potentially be regained through wetland restoration measures authorized in the 2003 Farm Bill. Because no single wetland can provide all ecosystem services indefinitely, ecologists can help to identify combinations of projects that will best restore ecosystem services within watersheds. “Strategic” restoration would use an adaptive management approach, targeting former wetlands with marginal crop production, and prioritizing the location, size, and type of wetland needed for a watershed to provide optimal levels of all three services. Given that the Farm bill includes over $1 billion per year to conserve natural resources on agricultural lands, we are in an excellent position to increase the effectiveness of wetland restoration.