with greater herbivory in tropical than in temperate forests. This observation suggests that the importance of herbivory may differ among communities. Animals can also affect plant community structure indirectly by manipulating the physical environment through activities such as digging or trampling. Pathogens can have effects similar to those of herbivores on plant population and community structure.
Plants defend themselves in a variety of ways. Some plants have tough leaves that resist attack, leaves that
Herbivory and Plant-Pathogen Interactions 231
are covered with defensive hairs, or stems covered with spines. Other plants have leaves that are low in nutrients or contain substances that make it difficult for herbivores to digest them. To defend themselves against herbivores and pathogens, plants produce toxic substances such as phenolics, alkaloids, terpenes, toxic proteins, protease inhibitors, and cyanogenic compounds. As plants have evolved these defenses, herbivores have evolved countermeasures, although the extent to which one-to-one coevolution occurs is unclear.
Additional Readings
Classic References
Tansley, A. G. and R. S. Adamson. 1925. Studies of the vegetation of the English chalk. J. Ecol. 13: 77–223.
Hairston, N. G., F. E. Smith and L. B. Slobodkin. 1960. Community structure, population control, and competition. Am. Nat. 44: 21–425.
Rhodes, D. and R. Cates. 1976. Toward a general theory of plant antiherbivore chemistry. Rec. Adv. Phytochem. 10: 68–213.
Contemporary Research
Agrawal, A. A. 2000. Benefits and costs of induced plant defense for Lepidium virginianum (Brassicaceae). Ecology 81: 804–1813.
Augustine, D. J. and D. A. Frank. 2001. Effects of migratory grazers on spatial heterogeneity of soil nitrogen properties in a grassland ecosystem. Ecology 82: 3149–3162.
Blossey, B., L. C. Skinner and J. Taylor. 2001. Impact and management of purple loosestrife (Lythrum salicaria) in North America. Biodiversity and Conservation 10: 1787–1807.
Gutierrez, J. R., P. L. Meserve, S. Herrera, L. C. Contreras and F. M. Jaksic. 1997. Effects of small mammals and vertebrate predators on vegetation in the Chilean semiarid zone. Oecologia 109: 398–406.
Additional Resources
Burdon, J. J. 1987. Diseases and Plant Population Biology. Cambridge University Press, Cambridge.
Coley, P. D. and J. A. Barone. 1996. Herbivory and plant defenses in tropical forests. Annu. Rev. Ecol. Syst. 27: 305–335.
Karban, R. and I. T. Baldwin. 1997. Induced Responses to Herbivory. University of Chicago Press, Chicago, IL.
Rosenthal, G. A. and M. R. Berenbaum, eds. 1992. Herbivores: Their Interactions with Secondary Plant Metabolites, 2nd ed. Academic Press, San Diego.
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