Plant development affects arthropod communities: Opposing impacts of species removal

Amy Martin Waltz, Thomas G. Whitham

Research output: Contribution to journalArticle

82 Scopus citations

Abstract

We examined the hypothesis that developmental phase changes from juvenile to mature growth in plants affect the distribution of common herbivores, which in turn affect the rest of the arthropod community. Using naturally occurring clones of cottonwoods, we compared the arthropod communities found in the mature zones of upper tree canopies, in juvenile zones at the base of mature trees, and in juvenile ramets that have suckered from the roots of mature trees. Mature zones were shown to support 23% greater species richness and 108% greater relative abundance than juvenile ramets. Of 17 Common arthropod taxa, 8 showed significantly higher abundances on one developmental zone over another; 4 had higher abundances on mature zones, and 4 had higher abundances on juvenile ramets. The juvenile zones of mature trees resembled a transition zone, supporting intermediate species richness and relative abundance. We also detected a significant clone effect on arthropod relative abundance, indicating that plant development varies among clones. Because developmental-based resistance directly affects the distributions of the two dominant insect herbivores, we then removed these insects to quantify the indirect impacts of development on the rest of the arthropod community. The gall-forming aphid Pemphigus betae was removed from susceptible mature branches (juvenile branches and ramets are resistant), and the leaf-feeding beetle Chrysomela confluens was removed from susceptible juvenile ramets (mature branches are resistant). We found opposite impacts of removal: aphid removal decreased species richness and abundance in mature zones by 32 and 55%, respectively, while beetle removal increased species richness and abundance on juvenile ramets by 120 and 75%, respectively. These studies suggest that plant development is an important factor that contributes to the structuring of insect communities, and that the indirect impacts of plant development acting through common herbivores may rival direct impacts (e.g., competition and predation) in their overall importance. Furthermore, the habitat mosaic created by developmental processes provides a mechanism for understanding the commonly observed pattern of higher biodiversity in mixed-aged stands of trees and forest edges than in even-aged stands or forest interiors.

Original languageEnglish (US)
Pages (from-to)2133-2144
Number of pages12
JournalEcology
Volume78
Issue number7
DOIs
StatePublished - Jan 1 1997

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Keywords

  • Biodiversity
  • Chrysomela confluens
  • Cottonwoods
  • Herbivory
  • Insect communities
  • Mixed-aged tree stands
  • Ontogeny
  • Pemphigus betae
  • Phase change
  • Plant development
  • Populus sp.

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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