Marsh Project Summary

WE ARE NO LONGER ACCEPTING APPLICATIONS FOR 2010
If you would like to be placed on a waiting list for this year, please contact Cornelia Harris at (845) 677-7600 x321 or harrisc@caryinstitute.org

Tidal freshwater wetlands on the Hudson River and elsewhere have a demonstrated capacity to retain and transform elements. The proposed research asks questions about appropriate scales for predicting their performance. Ecosystems may transform or retain significant proportions of material inputs, and we would like to understand what factors influence the degree of alteration. Clearly certain elements are more susceptible to retention or processing than others, and this will partially depend on whether those elements are at limiting concentrations and whether those elements participate in several biogeochemical reactions.

For elements such as the major nutrients (N,P) and reactive gases (O2) we expect that the characteristics of the ecosystem will strongly affect whether or not there is net retention or transformation. Prediction of ecosystem capacity to act as net sources or sinks for elements and compounds has been examined at multiple scales including comparisons across large spatial scales, across time, and within a class of ecosystems. IN these and many other examples, the questions have progressed from first quantifying that a net transformation has occurred and then turning to the issue of what ecosystem characteristics predict the magnitude of transformation. For the tidal wetlands we propose to study there is strong evidence that a variety of constitutents show large changes in concentration during tidal exchange, so there is a clear capacity for transformation. However, our ability to account for the magnitude of transformation is only fair, raising the possibility that better prediction hinges on finer spatial scales than the wetland-averaged attributes we have considered to now. For example, it is well-accepted that wetlands within a watershed can be important sources of dissolved organic carbon to surface waters exiting the drainage. However, it is not clear what predicts the amount of DOC export. Some studies have shown that the amount of wetland cover is important, while others have indicated that it is not enough to simply know how many wetlands exist, but where the wetlands were located, how old they are, how large the tidal range is, and what the upland forests of the watershed were like.

Thinking about ecosystems as mosaics rather than homogenous entities has grown in importance, and there is work going on to determine if individual patches can interact in a way that affects ecosystem behavior. Our study represents a study of lateral transfers, asking whether information on within-system configuration and other fine-scale variability improves predictive ability. We want to find out how much vegetation cover type affects ecosystem performance, how the range in tides and location of the patches affect connectivity, and whether the different types of measurements matter in terms of predicting the ability of the wetlands to transform nutrients.