Adapting the Fire-Grazing Interaction to Small Pastures in a Fragmented Landscape for Grassland Bird Conservation

Abstract

In North America, the loss of habitat heterogeneity resulting from homogeneous livestock grazing is one factor contributing to steep population declines of many grassland bird species. Patch-burn grazing is a management technique that uses historic grassland disturbance as a model to create heterogeneous grassland composition and structure, providing for the diverse habitat requirements of grassland birds. Though this management technique has been used successfully in relatively extensive grasslands, its utility on smaller grassland patches is less clear. We examined the efficacy of patch-burn grazing to restore habitat heterogeneity and increase grassland bird diversity in relatively small pastures (15-32 ha) in a grassland landscape fragmented by cultivation and tree encroachment. In 2006, we established 12 experimental pastures in the Grand River Grasslands of southern Iowa and northern Missouri, with 4 pastures in each of three treatments: 1) patch-burn graze, with spatially discrete fires and free access by cattle (the fire-grazing interaction), 2) graze-and-burn, with free access by cattle and a single burn of the entire pasture every third year, and 3) burn-only, with a single burn of the entire pasture every third year and no grazing. Patch-burn grazing in the first phase of the project (2007-2009) did not generate habitat heterogeneity or significant differences in bird diversity. From 2010 to 2013, stocking rates were reduced to increase residual vegetation in unburned patches at the end of the grazing season to increase heterogeneity. Habitat heterogeneity in patch-burn graze pastures subsequently increased relative to other treatments. Concomitantly, diversity of obligate grassland birds also increased in patch-burn graze pastures and was greatest in 2012 and 2013. We conclude that the fire-grazing interaction can be used to restore habitat heterogeneity and increase grassland bird diversity, even in relatively small grassland patches embedded in a highly fragmented landscape.

Disturbance shapes avian communities on a grassland–sagebrush ecotone

“…Grasshopper sparrows are associated with disturbance in the eastern and midwestern portion of their range (Rahmig et al 2009, Duchardt et al 2016), but in semi-arid portions of the Great Plains, this and other mixedgrass associates (e.g., western meadowlark) are Notes: AIC c , Akaike's information criterion adjusted for small sample sizes. Grasshopper sparrows are associated with disturbance in the eastern and midwestern portion of their range (Rahmig et al 2009, Duchardt et al 2016), but in semi-arid portions of the Great Plains, this and other mixedgrass associates (e.g., western meadowlark) are Notes: AIC c , Akaike's information criterion adjusted for small sample sizes.…”

Restoring the fire–grazing interaction promotes tree–grass coexistence by controlling woody encroachment

“…Instituting spatially explicit fires and moderate grazing pressure establishes focal grazing, wherein large herbivores concentrate on the most recently burned patch and uniformly eat the emergent vegetation (Fuhlendorf and Engle , Duchardt et al. ). Over time, these intensively grazed areas are abandoned by large herbivores for newly burned patches (Scasta et al.…”

Managing farm ponds as breeding sites for amphibians: key trade‐offs in agricultural function and habitat conservation

“…, Duchardt et al. ). At these low stocking rates, cattle presence may not result in the severe negative impacts reported in other studies.…”

“…Study ponds were located on pastures grazed at reduced stocking rates (2.5 animal unit months/ha; Duchardt et al. ) to facilitate grassland restoration (Miller et al. , Duchardt et al.…”