Managing for Biodiversity and Livestock

In the western Great Plains (semiarid rangelands west of the 100th meridian and east of the Rocky Mountains), millions of acres of native grasslands remain intact. With benefi cial management, these grasslands have great potential to revive populations of grassland birds1 (such as the Mountain Plover, Lark Bunting, Upland Sandpiper, Long-billed Curlew, and McCown’s Longspur), which have declined over the last 30 years. To help reverse this decline, land managers can implement strategies to improve grassland bird habitat while maintaining the productivity of their livestock operations. Wildlife conservationists and agencies recommend managing grasslands for vegetation heterogeneity to improve grassland bird habitat and recover declining populations.2 Vegetation heterogeneity refers to variability in the structure and composition of plant communities over space and time. Grassland plant communities are inherently heterogeneous because of plant species diversity, which results from differences in physical characteristics (climate, soils, topography) as well as disturbance processes (e.g., livestock grazing, prescribed fi re, burrowing mammals, and ant hills). Grasslands with more vegetation heterogeneity support a greater number of plant and animal species because they contain additional structural complexity and/or diverse plant communities, which provide added spatial and temporal niches.3 For example, western Great Plains grasslands grazed at a range of intensities harbor more bird species than purely ungrazed or heavily grazed grasslands. This occurs because grasslands managed for a gradient of grazing intensities contain a wider variety of vegetation heights, which provide a diverse suite of nesting and feeding habitats4 (Fig. 1). Compared to other ecosystems, western Great Plains grasslands are relatively simple structurally and compositionally, making the maintenance and improvement of vegetation heterogeneity even more important. To increase habitat diversity for wildlife, management strategies should maintain or maximize inherent vegetation heterogeneity. However, many management practices tend to emphasize livestock production through more homogeneous use of plant communities, which results in decreasing vegetation heterogeneity and wildlife diversity.5 In contrast, grassland management practices that promote vegetation heterogeneity involve the application of techniques that increase variability in vegetation structure and/or composition. Managing for vegetation heterogeneity can be a win– win approach for wildlife and livestock managers alike, because it can maintain livestock production levels while increasing biodiversity. We suggest using a simple, scale-dependent framework to promote vegetation heterogeneity on western Great Plains grasslands. Our approach is designed to facilitate land management decisions that maintain or improve vegetation heterogeneity and biodiversity on these grasslands. We intend to help land managers consider appropriate scales at which to address vegetation heterogeneity, suggesting important management considerations at each scale, and providing examples of land management practices that can improve vegetation heterogeneity at each scale. Our approach is most useful for grassland managers in the western Great Plains endeavoring to maintain or increase vegetation heterogeneity for grassland wildlife or overall grassland health in general, and not for those implementing species-specifi c management. In cases of species-specifi c management, the objective(s) will be narrower, heterogeneitypromoting management may or may not be appropriate, and the scale of management decisions may be defi ned specifi cally by habitat needs of the target species.