In the American Midwest, 99% of historic tallgrass prairie has been lost due to extensive conversion to agriculture and urbanization. Pastureland has promise in the use of working landscapes as refugia for threatened prairie taxa but often requires a combination of fire and grazing. The response of prairie-dependent taxa to such management must be quantified to better inform large-scale restoration strategy in the region. Of these prairie taxa, butterflies are particularly sensitive to management, making them, and the floral resources upon which they depend, ideal taxa in studying community response to management techniques. There is growing interest in assessing how community composition varies in response to habitat changes (as opposed to more frequently used metrics such as species richness or diversity indices) to ensure that species identity post-management is as similar as possible to reference conditions. We present here butterfly and floral resource community response to five years of three management types: burn only, patch-burn graze, and graze and burn.
Results/Conclusions
Butterfly and floral resource community species richness did not vary in a management-dependent fashion through time, or individually among either sampling years or management type. However, butterfly community composition varied significantly among management types in three of the five sampling seasons. Interestingly, the two years without significant among-management variation in butterfly community composition were the two years following burns on all study sites; this seems to be suggestive of a conserved post-burn community even when the communities pre-burn are significantly different. Despite the significant variation in butterflies, floral resource communities did not vary significantly among management types in any year. This apparent disconnect between butterfly and floral resource communities may be indicative of an effect of management on caterpillar resources rather than on the nectar resources more likely to affect adult butterflies. We also observed differences in which butterfly family were most abundant in each management type, which may be why community composition varied among management types. Taken together, the results presented here indicate that while pastureland can be managed for butterflies generally, desired communities may only be possible under particular management plans.