Thinning a Stand of Goldenrod

Abstract

ECOLOGY Ecologists have long been aware of the potential importance of interactions between species in controlling diversity and community composition. One of the most common of interactions is herbivory—the primary link in almost every food web—so insect herbivores might influence the dynamics of plant communities. In a ten-year study of an old-field habitat dominated by goldenrod ( Solidago altissima ) in the northeastern United States, Carson and Root compared the plant community structure of experimental plots from which insect herbivores were excluded with insecticide, with control plots that were subject to periodic outbreaks of a herbivorous beetle fond of goldenrod. Plant species richness and abundance decreased in the insecticide-treated plots, and the differences persisted for years following the herbivore outbreaks. The levels of light reaching the ground were enhanced by goldenrod defoliation, and this in turn promoted fecundity and productivity of other herbaceous species and, indirectly, the recruitment of tree seedlings. Thus, a specialist interaction between one plant and one insect species can have a clear effect on the trajectory of community composition and succession.— AMS Ecol. Monographs 70 , 73 (2000).