Content area
Full Text
ABSTRACT.-Selective herbivory by animals can have significant effects on the succession of a plant community. Damage resulting from major insect outbreaks has been shown to alter species dominance and competitive balance of woody plants in temperate North America. In this study we examine the effects over three seasons of a visually striking herbivory event: periodical cicada (Magicicada cassini) oviposition into an early successional tree community in the prairie-forest ecotone in eastern Kansas. Oviposition damage during cicada emergence in 1998 was large in overall magnitude, highly variable in space and varied by host tree species. From 1998-2000 we monitored four measures of tree growth on individuals of each tree species on the study site, and infructescence production on the dominant species (rough leaved dogwood, Corpus drummondii). Cicada damage in 1998 was regressed against each measure of tree performance in following years. Only a few statistically significant results were found. Overall, we concluded that the widespread oviposition damage from periodical cicadas did not have any important effects on successional dynamics of the host plants, suggesting that the trees appeared to compensate sufficiently for physiological damage during the emergence. We suggest that documenting the absence of substantial impacts from episodes of herbivory is useful in gauging the general significance of herbivory in succession.
INTRODUCTION
In many ecosystems, selective herbivory can lead to important changes in plant community dynamics (Crawley, 1983; Samson et al., 1992). Highly dynamic communities, such as those undergoing secondary succession, appear to be notably sensitive to herbivory (Weltzin et al., 1997; Ostfeld et al., 1997; Schweiger, 1998). Recently, we (Cook et al., 2001) documented spatial variation in oviposition damage on tree saplings by the periodical cicada (Magicicada cassini) in 1998 in an old field undergoing succession. The overall damage was extensive, with >87% of sampled individuals being attacked, often heavily. We suggested that this dramatic episode of insect herbivory could affect tree community dynamics. In this paper we evaluate the impacts of cicada emergence on tree community dynamics by documenting inter- and intraspecific changes in individual growth rates over the next 2 y, and variation in reproductive output for the dominant tree species, rough-leaved dogwood (Cornus drummondii).
Major insect outbreaks can have important effects on plant communities. In the eastern United States the introduced...