9806473 Likens This LTREB research will continue to support long-term ecological and biogeochemical studies at the Hubbard Brook Experimental Forest in New Hampshire to evaluate patterns and trends in the chemistry of atmospheric deposition, stream water and lake water, and to support efforts at synthesis and ecological integration of this information. Biogeochemical data that have been collected over the past 34 years and that will continue to be collected will be used to test critical hypotheses on (i) atmospheric deposition of strong acids and surface water acidification, (ii) the role of atmospheric deposition of nitrogen, nitrogen uptake by vegetation, and climatic factors on ecosystem nitrogen loss, and (iii) the effects of changing land-use on water quality. We will use long-term measurements of biogeochemistry and hydrology, the small watershed-ecosystem approach, and simulation models to test these hypotheses. An important aspect of the long-tern studies at Hubbard Brook is to separate the effects of local human-caused, land-use changes and natural forest succession from the impacts of regional disturbances, such as acid rain and climate changes.
