Location: Livestock and Range Research Laboratory
Project Number: 3030-21630-005-004-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 8, 2018
End Date: Aug 7, 2023
Objective:
The 2017 Lodgepole wildlfire complex burned 270,200 acres of northern mixed grass and Ponderosa pine/bunchgrass habitat in north central Montana. Local economic impact was considerable displacing summer and fall grazing for nearly 9,000 head of livestock. As the 2018 grazing season nears Bureau of Land Management (BLM) managers and livestock permittees are concerned about soil health and the interaction of grazing management decisions. Both groups need scientific information to formulate future grazing management decisions. Private landowners are equally interested in this information to direct recovery efforts on their own lands. Embedded within this larger question is a series of questions about the response of woodland and savanna ecosystems to prescribed fire used for treating hazardous fuel conditions.
a) Describe soil organic matter levels in areas treated at different times with prescribed fire and similar landscapes burned under wildfire conditions.
b) Describe native herbaceous and shrub cover, herbaceous biomass, plant height, soil surface litter, soil water content, soil nitrogen and soil texture at the same locations where soil organic matter is measured.
c) Establish the relationship between the selected biological and physical attributes listed in b) and soil organic matter level.
d) Identify those attributes with the highest predictability (R2> 0.60) of soil organic matter levels. These will become grazing management indicators.
Approach:
Eight sites will be selected to monitor the aboveground vegetation response to timing of defoliation after fire and the effects of prescribed fire before wildfire. Defoliation treatments will be June, July and August mowing during the first post-fire growing season. Defoliation treatments will be factorialized with fire history (wildfire or wildfire preceded by prescribed fire. Four paired sites in the wildfire area and four paired sites in the prescribed fire area will be selected to compare grazing to first post-fire growing season rest. ARS will be responsible for biomass, cover and diversity data and will collaborate to incorporate aboveground data with soil variables.
