Burn Baby Burn - Can Prescribed Fire Be a Tool for Pasture Rejuvenation and Improved Soil Health?

Background

Fire has been a part of natural disturbance and used by Indigenous communities for millennia. Fire’s ability to clear deadfall and keep encroachment at bay improves the health and productivity of grasslands. However, negative associations with fire spark fear and interrupt this beneficial traditional and historical practice. The loss of natural and managed fires has caused brush encroachment and a lack of natural disturbance leading to a loss of available pastureland and a decrease in productivity in those that remain. At the same time, the risk of wildfires also increases with accumulation of highly susceptible wildfire fuel in grazing systems paired with increasing likelihood of drought and higher ambient temperature. Managed fire can be used as a management tool to remove build-up of dead forage and dry brush that are highly susceptible fuel for wildfires and improve the health and productivity of clapped-out pastures.

Some other perceived risks of fire management include the risk of soil carbon depletion, but this is only seen when fire frequency is higher than the natural/historical rate.

Objectives

• Evaluate if prescribed fire can be used as a tool for pasture rejuvenation
• Evaluate the impact of prescribed fire on soil health particularly, how it impacts carbon storage and cycling

What they will do

Four comparisons of burning and grazing – unburned/ungrazed, unburned/grazed, burned/ungrazed, and burned/grazed will be evaluated at ranches and community pastures in the Peace Region of northern BC. Each site will implement a pre-approved prescribed fire plan developed by Northern Fire WoRx and producers to ensure burning is safe and legal.

The following metrics will be evaluated with data collected pre-fire, immediately post-fire and over subsequent years.

Forage Production: forage clippings will be collected from 1/4 meter squares to determine dry biomass and forage nutrient composition.

Plant Diversity and Composition: vegetation surveys will be conducted from forage clipping. These factors will be used to compare forage production and quality across all sites.

Soil Data: Baseline soil data will be collected through large soil coils collected at one meter depth and will be analyzed for temperature, root depth, moisture, horizons, colour, bulk density, and texture. Smaller surface cores (30 cm depth) will be collected at each site to record the soil’s chemical (carbon, organic matter (OM), nitrogen, phosphorous etc.) and biological (microbial biomass, enzyme activity etc.) properties. Smaller cores will be taken following the fire and in subsequent years and analyzed for the same properties as above.

Grazing Management: number of head, weight (or average weight), size of pasture and the timing of grazing to allow the calculation of stocking rates, stocking density and rest periods will be recorded to evaluate grazing management impacts and differences. These variables will be included to understand how management impacts the microbiome, forage quality and quantity, and soil carbon stocks.

Knowledge & Technology Transfer:  The Peace Region Forage Association will share information about this project through multiple avenues: field days, webinars, checklist for ranchers, fact sheets, online resource page, and educational videos. They will also coordinate a prescribed fire mentorship program. 

Implications

Managed/prescribed fires can be a useful tool to mitigate fire risk and improve the productivity of forage stands. Not only will this research be able to provide practical information to producers seeking to improve grazing management and productivity using prescribed fire but will also inform how fire impacts soil carbon cycling. Gaining insight into this practice will be essential for producers and policy makers to make informed decisions and has the potential to stimulate adoption and approval of managed fires.