Control and Management of the Exotic Invasive Cyperus entretianus (cyperaceae) in the Coastal Prairie of Texas

Due to fragmentation and land-use changes, less than 1% of the vegetation of the coastal prairie of Texas remains in original condition. Exotic invasive plants are among the greatest threats to the integrity and function of the remaining coastal prairie ecosystem. Cyperus entrerianus Boeck. (deep-rooted sedge) is an exotic invasive plant that has rapidly spread throughout the coastal prairie of Texas during the last 20 years. It often forms homogenous stands, displaces native plant species, produces tremendous volumes of seed, and is effectively altering ecosystem function and stability within the region. Prescribed fire and herbicide treatments, which are key elements of ecosystem maintenance and restoration, are commonly used to control exotic invasive flora. To quantify effects of prescribed fire and herbicide treatments on deep-rooted sedge, 780 permanent 1 m2 plots were established within 84 treatments plots, within 14 treatment blocks among three sites in coastal Texas (i.e., The Nature Conservancy of Texas' Texas City Prairie Preserve, Attwater's Prairie Chicken National Wildlife Refuge, and Anahuac National Wildlife Refuge). Plots were established in May 2005, and percent cover data were collected four times (May/June 2005 and 2006, and December/January 2005 and 2006). Herbicide treatments were randomly applied in May 2006 and August/September 2006 to treatment plots within blocks, such that entire blocks were treated at once within the prescribed fire management program of each site. Preliminary results indicate that deep-rooted sedge cover within prescribed fire treatments decreased 48.58% in May 2005 to 18.08% in May 2006, while in non-burned plots percent cover of deep-rooted sedge remained relatively unchanged (36.13% May 2005 to 38.83% May 2006). During the same period, species diversity (Simpson's index) increased from 0.56 to 0.76 in burned plots, but was relatively unchanged (0.67 to 0.64) in non-burned plots. Species richness in burned plots increased minimally, from 11.2 in May 2005 to 12.7 in May 2006, whereas species richness declined considerably from 21.5 May 2005 to 14.5 May 2006 in non-burned plots. Plots will be read for the first time post herbicide treatment in December 2006. Although preliminary, it appears that some level of prescribed fire negatively impacts percent cover of deep-rooted sedge, although the interaction of fire and herbicide treatments will more clearly demonstrate the effectiveness of these two management strategies to control and remove deep-rooted sedge from the coastal prairie of Texas.