Impact/Purpose:

The goal of this research is to evaluate stream ecosystem function at three levels of watershed disturbance intensity in four regions of the continental United States. As a secondary objective, we will assess intra- and inter-annual variability in measures of stream ecosystem function. We predict that any amount of watershed disturbance by logging will affect energy flow in the system by depressing community metabolism, increasing nutrient uptake lengths and disrupting ecosystem stability.

Description:

The objective of the proposed study is to assess the responsiveness of indicators of ecosystem function to three intensities of watershed disturbance in four regions. An integrated assessment of abiotic and biotic condition of streams will be conducted to assess streams affected by different silviculture practices and associated physical habitat degradation. Despite advances in stream research on ecosystem function, regulatory assessment and monitoring of streams are still limited to collection of structural data. Although structural metrics are easily applied and employ standardized methods, within-community variability hampers their ability to assess stream ecosystem integrity. Functional metrics, such as community metabolism or nutrient spiraling, are also variable. But their ability to integrate diverse populations into a single attribute allows comparisons within a system through time (temporal heterogeneity), among diverse systems (spatial heterogeneity) and at broad regional scales. This research will provide a detailed assessment of the responses of functional measures of stream ecosystems to varying intensities of a watershed stressor across several ecoregions.

We predict that any level of logging activity in a watershed will impair energy flow in aquatic systems. Functional indicators of ecosystem processes will be able to detect early states of ecosystem recovery. The results of the proposed study will contribute to a conceptual model of ecosystem function and responsiveness to anthropogenic disturbances. We propose that this model will contribute to the incorporation of functional measures of ecosystem integrity in bioassessment, monitoring and biocriteria development.

Record Details:

Record Type:PROJECT

Start Date:11/30/2000

Completion Date:10/01/2002

Record ID: 56162

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Project Information:

Progress :Twenty-five sites have been selected controlling for harvest regime, history and prescriptions, and structural features (geology, soils, aspect, and watershed area). Due to limitations of harvest regime and watershed size, four watersheds paired for treatment history, elevation, watershed area and aspect have been sampled at the Coweeeta Hydrology Laboratory. Five watersheds have been sampled at the Ouachita National Forest and on an adjacent industrial forest. Two streams in the industrial forest have been heavily harvested; one is being treated with fertilizer to enhance tree growth, the other is a control. As part of a forest restoration study, two watersheds in the ONF are being harvested according to two treatment regimes - selective thinning and burning, and clear thinning. Eight sites have been sampled in both the HJ Andrews Experimental Forest and the Redwood National Forest. All are paired old-growth vs. clearcut treatments.

Preliminary data suggest that nutrient spiraling studies may be successfully applied at stream discharges of up to 200 L/s. Data from Coweeta Hydrology Laboratory sites are presented in Figure 1. Preliminary indications are that we will be able to detect significant differences in nutrient uptake lengths between old growth and harvested watersheds. Similar results have been obtained at sites in the Redwood National Forest and HJ Andrews Experimental Forest.

Relevance :The research described in this proposal will provide important information on the relationship of stream ecosystem dynamics to watershed disturbance. The data will allow resource managers to determine the impact of past management practices on aquatic systems and predict which of those management practices will lead to more rapid recovery of the ecosystem. This information will help scientists and managers prioritize their restoration needs within a watershed. The indicators used in the assessment of stream ecosystems are also effective criteria for assessing the incremental improvement of ecological conditions following restoration efforts, as well as providing quantitative endpoints against which to measure restoration success or failure.

Clients :US Dept. of Agriculture-Forest Service, Agriculture Research Service, USEPA Office of Water

Project IDs:

ID Code :4846

Project type :OMIS