Macroinvertebrate Community Composition of Temporary Prairie Wetlands: A Preliminary Test of the Effect of Rotational Grazing

摘要

Over half the temporary wetlands in the prairie pothole region of North America (PPR) have been drained for agricultural purposes and nearly all those remaining have agriculturally impacted margins. Cattle grazing is a common practice in the PPR. Rotational grazing utilizes several pastures, with cattle grazing one pasture while the others are rested. The success of this practice in increasing the suitability of rested wetlands for macroinvertebrates has not been evaluated for temporary wetlands. We repeatedly sampled macroinvertebrate communities in 13 rotationally grazed temporary wetlands. Seven wetlands were in an early grazed pasture (i.e., grazed when wetlands were wet), and six wetlands were in an adjacent late grazed pasture (i.e., grazed when wetlands were dry). The communities were examined from two perspectives, traditional taxonomy and an emerging functional traits perspective. Late grazed wetlands contained more abundant and diverse macroinvertebrate communities than early grazed wetlands. Chironomidae were significantly more abundant in late grazed wetlands. Scrapers were more common in the early grazed wetlands, whereas late grazed wetlands contained more gatherers. Our results suggest that rotational grazing may have a positive influence on macroinvertebrate diversity by allowing some wetlands to escape grazing pressure during the wet season.