A Neighborhood Analysis of Herbivory in Bouteloua Gracilis
1989
This study examined whether an individual plant's risk of herbivory was affected by its nearest neighbor. Individually potted tillers of Bouteloua gracilis were placed in a natural habitat with one of two neighbors (B. gracilis conspecifics or Aristida spp.), and in one of two cover treatments (high: in center of neighbor canopy, and low: at periphery of canopy). After one month, the experimental tillers were collected and scored for herbivory. We found that the less palatable neighbor, Aristida spp., reduced the probability that herbivores would feed upon experimental tillers in one of the two years of our study, but in both years increased the amount of feeding on those tillers that were attacked. The amount of cover did not alter the proportion of plants fed upon, but did affect the number of feeding marks for plants that were fed upon. Our results demonstrate that small—scale spatial pattern within a community is an important determinant of herbivory. A tiller's neighbor exerted a stronger effect on the amount of herbivory it experienced than did either history of previous herbivory or larger scale spatial effects. Our study also reveals that the ways in which neighbors affect herbivory are complex and may vary from year to year.
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