Comparison of the biodiversity of lepidoptera within three forested ecosystems

Abstract

Lepidopterans function in the dynamics of forested ecosystems by serving as defoliators, decomposers, prey or hosts to carnivores, and pollinators. The biodiversity of Lepidoptera is thus linked into the ecosystem by influencing nutrient cycling, plant population dynamics, and predator-prey population dynamics. Two important measures of biodiversity are species richness and abundance of individuals. However, values for these measures require an ecosystem context for insightful interpretation of ecological function. We propose that such an ecosystem context is gained by an assessment of host resource requirements; in the case of Lepidoptera, this means larval host plants. The flora that contributes to the biodiversity of Lepidoptera can be grouped into 3 major vegetation types: (1) conifers, (2) hardwood trees and shrubs, and (3) herbs and grasses. We compared the macrolepidopteran biodiversity of 3 forested ecosystems: (1) western Oregon, (2) eastern Oregon, and (3) West Virginia. In respective order of the above locations, totals of 463, 385, and 475 species were found. Conifers supported 9, 10, and 1% of the species richness. By contrast, hardwoods supported 57, 45, and 61% of the species richness, whereas herbs and grasses supported 31, 42, and 31% of the species richness. The patterns in abundance of individual moths were different from species richness of moths and butterflies considered together. Comparisons of moth abundance showed conifers supported 18,5, and 1%; hardwoods supported 69,39, and 77%; and herbs and grasses supported 11,55, and 8%. Practices involved in the management of forested ecosystems are discussed in the context of how Lepidoptera may be used as an indicator taxon for the assessment of land management practices, and how biodiversity of Lepidoptera could be considered in plans for habitat restoration with a specific focus on food web relationships.