Vegetation Response to Timing of Discing to Manage Northern Bobwhite Habitat in Texas

Discing is commonly recommended to improve northern bobwhite (Colinus virginianus) habitat. However, little information exists regarding optimal timing of discing or the duration of discing effects on semiarid rangelands. Our objectives were to evaluate vegetation response to autumn (October 2003), winter (January 2004), and spring (March 2004) discing in two ecoregions of Texas (Rio Grande Plains and Rolling Plains). Our study design was a completely randomized, two-factor (treatment and soil texture) factorial with repeated measures. We collected data on percent bare ground, forb density, visual obstruction, and non-native grass density during pretreatment (September 2003) and six sampling periods post-treatment (March, May, and July 2004 and 2005). Differences in percent bare ground, forb density, and visual obstruction differed (P >0.05) among treatments only during the first year post-discing in all soil textures and ecoregions. The trend was for density of non-native grasses to increase (>60%) on both control and disced plots in the Rio Grande Plains. Density of non-native grasses in the Rolling Plains exhibited no (P <0.05) change. Our findings suggest the positive, structural effects of discing on bobwhite habitat on semiarid rangelands can be short-lived (<1.5 years) and unintended, negative habitat changes may result from an increase of non-native grasses if additional measures such as herbicide application are not taken.

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