Location: Livestock and Range Research Laboratory
Project Number: 3030-21630-005-005-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Mar 31, 2020
Objective:
Determine wildfire and post-fire management effects on mixed prairie-ponderosa pine communities in the Lodgepole Wildfire Complex.
Approach:
Burned Ponderosa pine sites will be identified for grazing and rest treatments during the first post-fire growing season (2018). This work will be carried out on cooperating private lands because federal policy will not allow grazing treatments during 2018 and 2019. Area selection will be based on apparent fire intensity (severe, moderate, low) and similarity in landscape, soils, and likely pre-burn vegetation. One of the paired study plots within each fire intensity class will be fenced to exclude cattle and the other left open to grazing. Because of the elk population in the area exclosure size must be minimized to limit elk use within the exclosure. Therefore, we will use the same 0.01ha sized exclosures used in our study of northern mixed grass prairie response to wildfire and grazing (Gates et al. 2017). In cooperation with the participating landowner stocking rate and grazing rotations will target 50% utilization of the emerging herbaceous forage crop.
Plant community diversity, standing crop, and species will be measured at the end of the grazing period in the grazed and ungrazed (exclosures) plots. These measures have been selected to address: 1) answer agency and conservation organization concerns about loss of biotic integrity if grazing is allowed too soon, 2) forage available to grazing livestock, and 3) the likely impact to long term sustainability of the system. To objectively describe the response of each of these ecosystem indices to grazing or rest measurements will be collected near peak production (July) during 2018 and 2019 following the methods of Gates et al (2017). During the 2019 study period livestock grazing will be deferred until sampling can be completed to better ascertain the impact of grazing and rest on community recovery.
A second set of exclosures will be established near the previously described paired plots to assess season of defoliation effects following the methods of Gates et al (2017). This investigation will provide a picture of when grazing could begin immediately following wildfire. Plots will be mowed during June, July, or August to a height approximating 50% biomass removal. Companion protected plots will not be mowed during 2018 and 2019. Diversity, biomass production, and species composition will be measured in mowed and untreated control plots near peak production (July) during 2019. Two years of repeated seasonal defoliation will provide an informed picture of plant community response to season of grazing use.
This study will provide area specific information for developing post-fire grazing management in burned ponderosa pine habitat types of north central Montana. Outcomes from grazing and defoliation (mowing) studies will provide resolution to the confusion over which set of recommendations best apply to the Montana condition. Sideboards for achieving the necessary rest periods for recovery of herbaceous plant communities can then be factored into long term grazing plans for private, state and federal rangelands.
