|Jacobs, James - MONTANA STATE UNIV|
Submitted to: Ecological Restoration
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 7, 2003
Publication Date: December 1, 2003
Citation: Jacobs, J.S., Sheley, R.L. 2003. Combination of burning and herbicides may favor establishment of weedy species in rangeland restoration (Montana). Ecological Restoration Notes. 21(4):138-139. Interpretive Summary: Since burning can create open niches for weeds, we wanted to determine if burning combined with herbicide application could prevent weed establishment. It appears that the increased soil nutrients associated with combining burning and herbicides may leave a site susceptible to establishment of unwanted and difficult to control weeds, such as Dalmatian toadflax, that respond to high fertility. Therefore, restorationists using this approach should consider seeding desirable species that can exploit the increased nutrients.
Technical Abstract: Technical abstract for 'Combination of burning and herbicides may favor establishment of weedy species in rangeland restoration (Montana)' Our objective was to determine the effects of burning combined with herbicides on soil disturbance and nutrient content. We hypothesized that combining the two treatments would create the greatest amount of bare-ground and would increase soil nutrient content. The study was conducted on two adjacent Artemisia tridentata-Agropyron spicatum community types being restored for elk habitat. We divided each area in burned (Site 1 and Site 3) and unburned (Site 2 and Site 4). Site 1 and 3 were burned in April 2000 and April 2001, respectively. Five herbicide treatments, each replicated four times were applied to all four sites. Herbicides were: an untreated control (1), picloram (0.56 kg/ha applied in the (2) fall prior to the burn or (3) spring after the burn, and chlorsulfuron (0.085 kg/ha) applied in the (4) fall before each burn and (5) spring after the burn. Bare-ground percent cover increased from about 65 to about 37 on sites that were burned. However, burning and herbicides did not interact to influence bare-ground as hypothesized. We found that neither fire nor herbicides influenced soil pH or organic matter. Electrical conductivity increased by 16% on burned sites. Phosphorus increased in plots burned and sprayed with chlorsulfuron in the fall. Burning or herbicides, especially chlorsulfuron, increased NO3, but not NH4. The increased soil nutrients that result from combining burning and herbicides may leave a site susceptible to difficult to control perennial weeds, such as Dalmatian toadflax that respond well to high fertility. Restorationists using this approach may need to introduce desirable species that can exploit the increased nutrients.