Ecosystem recovery

Uhl, C, C. F, Jordan, K. Clark, H. Clark, and R. Herrera. 1982. Ecosystem recovery in Amazon caatinga forest after cutting, cutting and burning and bulldozer clearing treatments. Oikos 38 313-320. 

Kelly, J.R. and M.A. Harwell. 1990. Indicators of ecosystem recovery. In Recovery of Lotic Communities and Ecosystems Following Disturbance Theory and Application, J.D. Yount and G.J. Niemi, Eds. Environ. Manage. 14(5) 527-546. 

Lemly AD. 1997. Ecosystem recovery following selenium contamination in a freshwater reservoir. Ecotoxicol Environ Saf 36 275-281. 

To date, emissions targets set in the United States and Europe have been met or exceeded. There are widespread decreases in surface water concentrations of sulfate and some waters are showing increases in ANC. Nevertheless, data suggest that these targets may not be sufficient to achieve the full recovery of sensitive ecosystems. In order to evaluate the extent to which historic and future emissions reductions will facilitate ecosystem recovery from acidic deposition, it is necessary to use acidification models to project the future relationship between emissions, deposition, and chemical recovery of acid-sensitive forest watersheds (see Box 3.5). 

The impact of the emission cuts is beginning to be noticed, although more with respect to deposition than ecosystem recovery. The U.S. Environmental Protection Agency soon reported declines in wet sulphate deposition in the order of 10 to 25% across the eastern United States. There are also possible improvements with respect to dry deposition of sulphates, fine particulate matter concentrations, and visibility. Aquatic and terrestrial ecosystems respond slowly, and it is not surprising that evidence of ecosystem improvements would trail behind trends in reduced atmospheric transport and deposition. The EPA, while modest in its assessment of the environmental benefits to be accrued from reduced acidification, has been rather bullish about the investment in human health benefits represented by acid rain controls. It expects SO emission cuts to reduce American health costs by 10 billion annually, through reduced morbidity and mortality, and these savings are projected to rise to 40 billion annually by 2010 (EPA 1995). 

We have the opportunity here in the northeastern United States to use our extensive information to document that ecosystem recovery is not only possible, but that through conscious action, we made it happen. For those areas in the world that may not be able to invest in such extensive monitoring networks to detect change, this effort could provide exceptionally important information to guide decision making in other regions that may suffer similar impacts but lack the resources to assess the effectiveness of their actions. 

Several researchers aU over the world have shown that severely disturbed soils are very slow to recover and in turn, have significant long-term effects on ecosystem recovery and functioning [67-69]. 

Another added feature in ecological risk assessments is the risk description component of risk characterization. In this component, the nature and intensity of effects, their spatial and temporal scale, and the potential for ecosystem recovery are all addressed. This component partially serves to identify ways to remedy effects at a site. 

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