All weather data was collected from the CCNHA weather station, located [less than]2 km from Field B.
Another source of interaction might be effects of shading by the higher biomass of fertilized plants on soil temperatures and egg development, as fertilized plots at CCNHA with canopies opened by pocket gopher (Geomys bursarius) soil disturbances contained twice the density of grasshoppers (Huntly and Inouye 1988).
Herbivory of woody species might explain why tree invasion of old fields and prairies at CCNHA is so slow (Inouye et al.
Consequently, indirect herbivore effects on plant resources might explain why succession in CCNHA grassland occurs through mechanisms other than shifts in resource ratios, e.
Because CCNHA features nitrogen-poor soils and nitrogen-limited aboveground production, our results support the hypothesis that herbivores should have decelerating effects on N cycling in nitrogen-limited systems.
To test for herbivore and nutrient effects, we measured abundance of all legume species within parts of five existing long-term experiments established in either 1982 or 1989 as part of the Long-Term Ecological Research (LTER) program at CCNHA (summarized in Table 1).
While addition of nitrogen has either no effect or a negative effect on legume abundance at CCNHA (Tilman 1988), our results suggest that potentially dominant legume species may be limited by nutrients other than nitrogen (Tilman 1982, Fenner and Lee 1989).
All above- and below-ground litter bags were placed randomly in a common location in a CCNHA
field dominated by Schizachyrium and Poa.