Corbin, A.T., T.T. Bergsma, G.P. Robertson, K.L. Gross, R.R. Harwood
Presented at the All Scientist Meeting (2003-09-12 )
Above ground net primary productivity (ANPP) is an important measure of the response of ecosystems to explicit management activities as well as to edaphic features within a landscape. At the Kellogg Biological Station LTER, ANPP is measured in systems across a wide gradient of management intensity, including annual crops, perennial crops, and forests in various stages of succession. Here, we compare the productivity of cropped systems and successional forests on an annual basis for the period 1999 to 2002. Within a single landscape, such a comparison helps to emphasize differences in nutrient cycling and energy flow for managed systems versus the systems they replace.Approaches for measurement of ANPP tend to emphasize either woody or herbaceous vegetation. However, many ecosystems have significant annual productivity in both categories; furthermore, the relative significance of woody or herbaceous vegetation may change during a long term experiment. ANPP measurements at the KBS LTER require a combination of sampling strategies as well as an assemblage of data management techniques. Along with our annual cropping systems, we describe two ecosystems where woody growth dominates, one where woody growth is becoming important, one where woody growth is actively suppressed, and one where wood is harvested. Attention is drawn to the potential for inflexible productivity models to overlook key components of ANPP.
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