The widespread conversion of natural habitat to row-crop agriculture in the Midwestern United States has come at a great cost to soil, water quality and biodiversity. Establishing perennial vegetation has been shown to improve ecosystem health and expand the ecosystem services provided by row-crop dominated landscapes. Since it may not be feasible to transform large areas of row-crops to perennials, we designed an experiment to test the hypothesis that small amounts of diverse prairie targeted within watersheds will produce disproportionate improvements in ecosystem functioning, and species richness and abundance in major taxa, specifically breeding birds. We have conducted spot-mapping surveys for breeding birds in 15 small experimental watersheds (0.5-3.2 ha) with five treatments of varying proportions and configurations of prairie and crop cover (0% prairie, 10% prairie at base of watershed, 10% prairie in multiple strips on the contour, 20% prairie in multiple strips on the contour, and 100% prairie).
Results/Conclusions
We have observed a total of 52 species within the watersheds for all five years of surveys (2007-2011), with an average of 31 species observed each year. Eleven species have been documented nesting in the sites, including birds listed in Iowa as Species of Greatest Conservation Need (Sedge Wren, Dickcissel, and Field Sparrow). Community composition was affected by year (P = 0.011), and block (P=0.002), but was not significantly different between treatments. Species richness was greater in sites with 10-20% prairie than in sites with 0% prairie, with significant differences for treatment (P < 0.05) and year (P < 0.001). Our results indicate that birds respond positively to the presence of small prairie strips within row-crop fields, demonstrating large shifts between the planting year and post-establishment years, and between watersheds with no prairie and watersheds with small amounts of prairie.