PARENT SESSION
Oral Session #54: Vegetation: Controls on NPP, Global Climate Change. Presiding: W. Oechel.
Wednesday, August 8, 2001. 1:00 PM to 5:00 PM. Hall of Ideas G.
Diversity, productivity, and scale: a case study of Wisconsin vegetation.
Scheiner, Samuel 1,2, Jones, Sharon2, 1 2
ABSTRACT- We examined how species richness of terrestrial vascular plants varies with net primary productivity in 901 stands scattered across the state of Wisconsin, U.S.A., based on a comprehensive examination of the components of scale (grain, focus and extent) across a geographic (spatial) hierarchy and two, overlapping ecological hierarchies (provinces and community types). We found no single relationship between species richness and productivity. Instead, the relationship depends on the components of scale (grain, focus or extent) and hierarchy (ecological or geographic). For the state as a whole, the relationship was U-shaped. For the geographic hierarchy, with increasing extent the relationship went from hump-shaped, to negative, to U-shaped. Increasing the grain resulted in the opposite pattern, the relationship went from U-shaped, to negative, to hump-shaped. With increasing focus, the relationship became negative. For the ecological hierarchy among community types, increasing the grain changed the relationship to negative, while for the among-province hierarchy, increasing the grain eliminated any relationships. In contrast, increasing the focus among community types strengthened the U-shaped relationship, but similarly eliminated it among provinces. Decreasing the extent ¿ examining individual provinces or communities types ¿ generally eliminated the relationship, although a negative relationship were found for prairies and sand barrens, a positive relationship was found for bracken grasslands, and U-shaped relationships were found for northern upland forests.
KEY WORDS: productivity, diversity, scale, Wisconsin