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Potential of Water Quality Wetlands to Mitigate Habitat Losses from Agricultural Drainage Improvements
Citation:
Mitchell, Mark E., T. Newcomer-Johnson, J. Christensen, W. Crumpton, S. Richmond, B. Dyson, Timothy J. Canfield, M. Helmers, D. Lemke, M. Lechtenberg, D. Green, AND Kenneth J. Forshay. Potential of Water Quality Wetlands to Mitigate Habitat Losses from Agricultural Drainage Improvements. Joint Aquatic Sciences Meeting, Grand Rapids, MI, May 14 - 20, 2022.
Impact/Purpose:
Iowa is responsible for a large portion of crops grown in the U.S., but has lost at least 90% of its historic wetland habitat while also exporting nutrients to the Gulf Coast where they contribute to harmful algal blooms. A group of Iowa stakeholders representing agricultural producers, land managers, and researchers identified the importance and relevance of a small watershed analysis of a collection of environmental benefits associated with wetlands installed to intercept and treat water leaving the agricultural watershed, in combination with improvements in the agricultural drainage system. In this presentation we will focus on the habitat implications of improving drainage and installing water quality wetlands, and will present results from InVEST habitat models for amphibians, grassland birds, and wild bee pollinators.
Description:
Agricultural wetlands designed to provide wetland and grassland habitat and water quality benefits, hereafter referred to as water quality wetlands (WQW), are an emerging restoration solution that may mitigate habitat declines in intensively farmed areas. Installation of WQW in the Upper Midwest, USA, when considered alongside the repair and modification of aging agricultural tile drainage infrastructure, may reduce nutrient loads from agricultural systems while also improving crop yields. While the water quality improvements associated with WQW are well established, the capacity of these restored systems to provide habitat within the wetland pool and in grassland habitat that surrounds them is not well studied, particularly with respect to potential habitat changes resulting from drainage infrastructure upgrades. For the current study, we produced spatially explicit wildlife habitat models of 37 catchments distributed throughout an important region for agriculture and biodiversity, the Des Moines Lobe of Iowa, for scenarios with and without improved drainage, and with and without WQW. Habitat model results indicate that drainage modification alone will likely result in moderate direct losses of suitable amphibian habitat and large declines in overall amphibian habitat quality, but inclusion of WQW at the catchment scale may offset these amphibian habitat losses while also increasing grassland bird and wild bee habitat. WQW are also likely to offset any losses to permanent and semi-permanent waterfowl habitat in our model catchments due to drainage improvements, but the effects on temporary and seasonally inundated depressions require additional study.