GWERD Research on Ecosystem Restoration & Nitrogen Management

RESTORATION & NITROGEN;
MANAGEMENT OF A MULTI-MEDIA AND MULTI-SCALE STRESSOR

At NRMRL, we are identifying opportunities and developing technologies for improving the ability of terrestrial ecosystems to retain and sequester nitrogen, for the direct purpose of reducing nitrogen loading to the Nation's waters. We are particularly concerned about effects of chronic exposure to atmospherically deposited nitrate to the ability of landscapes to maintain their ability to retain and sequester nitrogen. We are seeking means to identify ecosystems at risk from chronic exposure to atmospherically deposited nitrate and we are identifying and developing means for restoring the functionality of ecosystems whose ability to retain and sequester nitrogen is already compromised. Finally, we are investigating means for restoring and increasing the ability of terrestrial ecosystems to retain and sequester nitrogen; an ability that will improve their function as filters and intermediaries between atmospheric and aquatic systems.

The presence and distribution of undesirable quantities of bioavailable nitrogen in the environment is an issue of long- standing concern. Deleterious effects associated with high loadings of nitrogen are frequent news events. Excess nitrogen in the environment is associated with many large-scale environmental concerns, including; eutrophication of surface waters, toxic algae blooms, hypoxia, acid rain, nitrogen saturation in forests, and global warming.

Nitrogen is the essential multi-media stressor. Its ubiquity in the environment and necessity to life assures its ease of transport through biotic and abiotic cycles and interaction with aquatic, atmospheric, and terrestrial systems. Currently, nitrogen loading to the Nation's waters is a concern to the Agency: currently, the contribution of nitrogen to acid rain is a concern to the Agency: currently, unintended and unforeseen interactions with biota contribute to toxic algae blooms and hypoxia in estuarine ecosystems that are concerns to the Agency.

Contrary to expectation, environmental problems associated with Nitrogen are occurring with greater frequency, over larger spatial scales, and with increasing levels of acute severity despite decades of effort aimed at limiting its release. Further, releases are projected to increase into the foreseeable future. It is prudent risk management to address the growing suite of nitrogen related environmental and health problems more fully now.

How does restoration tie in with nitrogen management? First, even today many waters in the eastern United States receive excess loading of nitrogen: thus, a restoration goal for today is to restore water quality through implementation of risk management technologies that will reduce the amount of nitrogen that leaches to the Nation's waters. Second, even today the contribution of atmospherically deposited nitrogen to acid rain and forest nitrogen saturation is recognized: thus, a restoration goal for today is to improve the ability of forests in particular to retain, sequester, and cycle nitrogen to improve forest health and reduce nitrogen leaching to surface waters. Restoring ecosystems frequently means restoring their ability to retain and sequester nitrogen.

As the examples of water quality and acid rain teach, the health of the land and the quality of the Nation's water resources are ultimately tied to the ability of terrestrial ecosystems to retain and sequester nitrogen; an ability that will directly affect loading of nitrogen to streams, lakes, and estuaries and interact with the pool of bioavailable nitrogen in the atmosphere.

Recent Hightlights

Jorgensen, E.E., S. Holub, G. Silva, P.M. Mayer, A.E. West, M.E. Gonsoulin, S.J. Tunnell, J.E. Clark, J.L. Parsons, D.M. Engle, and E.C. Hellgren. 2003. Sources and estimated load of bioavailable nitrogen attributable to chronic nitrogen exposure and changed ecosystem structure and function. Pages 614-618 In Proceedings of the First Interagency Conference on Research in the Watersheds, Benson, AZ.

Clark, J.E., E.C. Hellgren, E.E. Jorgensen, S.M. Tunnell, D.M. Engle, and D.M. Leslie, Jr. 2003. Population dynamics of hispid cotton rats (Sigmodon hispidus) across a nitrogen amended landscape. Canadian Journal of Zoology 81:994-1003.

Jorgensen, E.E. 2002. Opportunities in nitrogen management research; improving applications for proven technologies and identifying new tools for managing nitrogen flux and input in ecosystems. Advances in Restoration Science; Number 2. USEPA. EPA/600/S-02/003.

Jorgensen, E.E., T.J. Canfield, and P.M. Mayer. 2002. Research needs in riparian buffer restoration. Advances in Restoration Science; Number 1. USEPA. EPA/600/S-02/002.

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