The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008 - 10:40 AM
Response of South Texas Coastal Prairie Rangeland to Management of Non-Native, Invasive Bluestems
Marvin E. Ruffner, Forestry, University of Kentucky, 123 TP Cooper Building, Lexington, KY 40536 and Thomas G. Barnes, Department of Forestry, University of Kentucky, 214 Thomas Poe Cooper Building, Lexington, KY 40546.
Non-native bluestems (Bothriochloa and Dichanthium spp.) are perennial, C4 grasses introduced to the southern Great Plains in the early 1900’s for soil erosion control, livestock forage, and revegetation of roadsides. Non-native bluestems were preferred over native bluestems because they establish rapidly, produce abundant seed, and are tolerant of drought and persistent grazing. Presently, many rangeland professionals consider non-native bluestems extremely problematic because they hinder the conservation of native grasslands in the southern Great Plains. A study was conducted at the Welder Wildlife Refuge near Sinton , Texas with the purpose of quantitating the response of a south Texas native coastal prairie plant community to management of non-native, invasive bluestems. A two-way factorial treatment design, with mowing and herbicide as the two factors, was implemented in a split-plot randomized complete block design. Each block (n=4) contained eight experimental units and half of each unit was mowed ten days prior to herbicide treatments. Seven herbicide treatments and untreated check were assigned to each block. Pre-treatment non-native bluestem, native grass, and forb canopy cover averaged 90%, 4%, and 3%, respectively. Three months after treatment (3 MAT, mid-October 2006), all herbicide treatments had significantly reduced non-native bluestem canopy cover. Furthermore, mowing in combination with herbicide reduced herbicide efficacy to control non-native bluestems. One year after treatments (July 2007), non-native bluestem canopy cover had recovered to pre-treatment and control levels in most treatment plots. However, forb abundance was significantly higher in imazapyr (Arsenal®) 5 pts/acre and imazapyr 3pts/ac + glyphosate (RoundUp Pro®) 2qts/ac mixture plots compared to other treatments. Moreover, native grass response to treatments was poor. In general, mowing and herbicide treatments only provided short-term control of non-native bluestems. These findings indicate that an aggressive and integrative management strategy should be assessed for long-term control of non-native, invasive bluestems in south Texas coastal prairie rangeland.