Habitats all over the globe have been extensively degraded by human activity. This is particularly the case in the American Midwest where 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 requires prescribed fire and often the removal of invasive species. There is also growing support for “adaptive management” where goals shift through time to meet the evolving priorities of relevant stakeholders, which further complicates the evaluation of community response to applied treatments. The response of prairie specialist taxa to these adaptive management techniques is particularly relevant to the large-scale implementation of these processes throughout pasturelands in the Midwest. Of these taxa, butterflies are particularly sensitive to management, making them and their floral partners ideal taxa in studying community responses to several adaptive management techniques. We present here butterfly and floral resource community response since 2014 to four site-level adaptive management types: burn only, patch-burn graze, graze and burn and herbicide (burning, grazing, and invasive plant treatment with herbicide) and herbicide only (invasive plant treatment with herbicide without burning or grazing).
Results/Conclusions
Butterfly and floral resource communities varied among adaptive management types in terms of abundance, species richness, and Shannon diversity, but did not change over time significantly despite the continued monitoring over the four study years. Additionally, the “best” (i.e. most abundant, speciose, and diverse) adaptive management types differed between butterflies and flowers indicating that diverse butterfly communities may not be as tightly linked to hyper-abundant floral resources as we initially hypothesized. In multivariate analyses of each year’s community data, the two grazed treatments were usually non-significantly different from one another and were different from the burn-only treatment, but the herbicide only treatment demonstrated much higher year-to-year variability. This may be due competition among the broader pool of potential species in each year (as neither burn-tolerance nor grazing tolerance is a necessary pre-requisite to successful colonization of those sites. When comparing abundances of the most abundant floral and butterfly communities, among-treatment patterns emerge that differ from the whole-taxon results previously explained, indicating that managers interested in promoting certain groups of taxa of interest may rely more on a treatment that does not have the same effect across the whole taxon.