ASSEMBLY OF ARTHROPOD COMMUNITIES IN RESTORED PRAIRIE, OLD FIELD AND MONOSPECIFIC STAND OF PHALARIS ARUNDINACEA: A FUNCTIONAL PERSPECTIVE
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Effects of prairie restoration on arthropod diversity was investigated at Gabis Arboretum, Valparaiso, Indiana. A total of 35,408 arthropods belonging to 13 taxa in the restored prairie (RP1 and RP2), old field (OF), and monoculture stand of Phalaris arundinacea (reed canary grass – RCG) sites, were captured, counted, and compared. The enhanced plant species diversity in the restored prairies did not appear to promote the diversity of arthropod taxa. However, the restoration led to a more balanced composition of arthropod functional groups and thus elevated the diversity of functional groups. The arthropod assemblages in the three sites diverged clearly according to my canonical correspondence analysis (CCA) ordination. Pollinator abundance was greatest at RP and least at RCG site, positively correlating with greater forb diversity, and suggesting greater potential for nectar feeding and pollination potential at RP sites. Herbivore abundance was greatest at the RP sites, positively correlating with increasing plant species diversity. Predator abundance was significantly greater at the RCG site compared to the OF and RP sites; it was positively correlated with greater C3 grass cover, a characteristic of the structurally homogenous RCG site, and negatively correlated with increasing plant diversity and forb cover, a characteristic of the diverse and more structurally complex RP sites. Given the apparent non-random distribution of arthropods among the field types, my results suggest plant species composition has a significant effect on arthropod assembly. The monoculture grass stand was found to have a predator dominated arthropod community supported by a small, diverse herbivore community. It is concluded that the prairie restoration has resulted in alteration of arthropod communities supporting greater pollinator and herbivore abundance and a more balanced ratio of herbivores to predators due, in part, to increased plant structural diversity.