Effects of prescribed fire on fuels, vegetation, and Golden-cheeked Warbler (Setophaga chrysoparia) demographics in Texas juniper-oak woodlands

AbstractThe Golden-cheeked Warbler (Setophaga chrysoparia) is an endangered songbird that breeds in mature juniper-oak woodlands restricted to Central Texas. This habitat is increasingly susceptible to crown fire due to climate change, land use change, and fire suppression. Prescribed fire is a potential tool to reduce the risk of crown fire and may be a management tool to enhance juniper-oak woodlands for breeding warblers. However, no experimental study has been undertaken to investigate how well prescribed fire can meet these goals. We conducted a before-after control-impact study on three plot-pairs within Balcones Canyonlands National Wildlife Refuge, Texas, from 2012 to 2014 to evaluate the response of fuel loads, vegetation structure, and warblers to prescribed fire. We measured fuel loads and vegetation structure in summer 2012 (pre-treatment) and 2014 (post-treatment). We burned one randomly-chosen plot within each plot-pair during February 2013 and measured fire severity in May 2013. We monitored populations of warblers to determine plot abundance and breeding success each season. Impact of the prescribed fires was highly variable across treatment plots with ∼49% of points showing no effects of fire on junipers and ∼9% showing high mortality in the juniper canopy. All 12 fuel and vegetation measures responded to fire in the direction expected; however, only juniper seedling density, juniper sapling density, hardwood sapling density, canopy cover, litter cover, and litter depth were significant (i.e., year×treatment effect P