ORDINATION OF FOREST INSECT AND PLANT COMMUNITIES IN WEST CENTRAL INDIANA

The objective of this research was to sample forest insect and plant communities and objectively analyze the results by community ordination techniques. In addition, an attempt was made to quantify the site relationships in the insect ordinations through the use of multiple regression techniques. Some 11,588 individuals representing 103 insect species from the families Scarabaeidae, Elateridae, Cerambycidae, and Chrysomelidae were collected from 16 forest communities during the summers of 1966 and 1967. In each community one omnidirectional light trap was operated which consisted of two 2-watt argon glow lamps powered by three 45 volt batteries. Bait traps were also operated during 1967. The trees, saplings, and seedlings were identified and tallied for a 0.5 acre circular plot surroundng each trap. Eighteen environmental variables were measured at each site. The insect and plant communities were subjected to community ordination analysis. Importance and prominence values were calculated for the plants and insects respectively for each stand by means of FORTRAN IV computer programs. Ordination of importance values by the program ORDCOM resulted in a cluster of sites dominated by sugar maple with fewer numbers of shagbark hickory, white ash, red oak, white oak, and red elm. Several sites showed shifts in their relative stand positions for the tree, sapling, and seedling ordinations. The four insect families were ordinated separately and collectively for each year. Except for the Chrysomelidae, each family was represented by a large number of infrequently collected species and a half dozen or so that were collected with increasing frequency and abundance. The relative densities and therefore the relative prominence values for the dominant species were dependent upon the date of trap operation. Even the most abundant species were present for only a short period. Kendal\u27s tau coefficient of rank correlation was calculated to compare the insect and plant communities. The low values indicated little or no affinity of the insects for a specific plant community. When the 19 most abundant species were considered, coefficients of association between sites were very high indicating that the same dominant species were present at all sites. Thus the site relationships in the insect ordinations were the result of different relative densities for basically the same group of species. . . . (Author\u27s abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UM