Reversing the Woodland Steady State: Vegetation Responses During Restoration of Juniperus-Dominated Grasslands with Chaining and Fire

Abstract

Junipers (Juniperus spp.) are native woody shrubs that have expanded beyond their normal historical ranges in the western and southwestern United States since the late 1800s (Johnson 1962; Burkhardt and Tisdale 1976; Gehring and Bragg 1992; Ansley et al. 1995; Miller and Tausch 2001; Ueckert et al. 2001). The most likely reason for this is the change in the disturbance regimes associated with these communities and the lengthening of the time between disturbances that removed juniper. Increases in juniper can be attributed to fire suppression, climate change, and overgrazing by livestock. Overgrazing had the dual effect of weakening the competitive ability of grasses against emerging juniper seedlings and reducing the amount of herbaceous fine fuel that normally supported fires (Archer et al. 1995; Van Auken 2000). Junipers have encroached upon 8.8 million ha of rangeland in Texas and 1.4 million ha in Oklahoma and negatively influenced land use (SCS 1983, 1988; Snook 1985). Increases in density and distribution of these species has increased remarkably in the last 50 to 60 years. For example, from 1948 to 1982, redberry juniper (Juniperus pinchotii Sudw.) distribution in northwest Texas increased from 2.5 to 4 million ha, or 61% (Ansley et al. 1995). Distribution of eastern redcedar (Juniperus virginiana L.) and Ashe juniper (Juniperus ashei Buchholz) in Oklahoma has increased from 1.4 to 2.4 million ha, or 71%, during the short period of 1985 to 1994 (McNeill 2000).