Large Experiments and Permanent Plot Studies
It is essential to undertake experiments and manipulations under controlled conditions in order to:
- evaluate infrequent though historically important processes
- anticipate ecosystem response to predicted climatic and chemical stresses
- test basic hypotheses concerning the mechanisms underlying observed ecological changes.
Over the past few decades we have undertaken a series of long-term measurements on experimental manipulations. These focus on important, though contrasting disturbances and stresses, including:
- simulation of windthrow from a major hurricane
- enhanced deposition of nitrogen
- soil warming as a component of climate change
- the removal of hemlock by logging or the hemlock woolly adelgid
- alteration of above-and below-ground inputs of organic matter to soils
- early successional habitat dynamics in former plantations
Often the results of these studies can be compared directly to long-term measurements on "natural experiments," such as the 1938 hurricane or historical logging. Other manipulations can be compared to parallel experiments in other ecosystems. In all cases, the integrated measurements of ecosystem structure and pattern enable comparison among these important manipulations.