Restoration of Rocky Mountain Elk Habitat through Prescribed Burning in Lytton, B.C.

Abstract

The Mill Yard prescribed burn was conducted on March 30, 2016, in an effort to reduce forest fuels and monitor the effects of prescribed fire on wildlife habitat values near Lytton, B.C. The project was undertaken jointly between the Lillooet Fire Zone (Ministry of Forests, Lands and Natural Resource Operations) and myself. The 11.5-hectare study area is located on crown land south of Lytton on a fluvial terrace of the Fraser River. Fire suppression over the last century has altered these forests by increasing forest density and causing changes to hydrology, biodiversity, and fire regime. The in-growth of young trees in this historically open stand has lead to the loss of habitat value to an introduced herd of Rocky Mountain Elk (Cervus elaphus). Regular habitat enhancement is required to keep the land in a productive state for the elk (Chris Proctor, pers. Comm., March 7 2016). The prescribed burn goals were to increase wildfire protection to the Village of Lytton; monitor the changes in elk browse species after the reintroduction of low-intensity fire; and provide training in prescribed fire to wildfire crews. The site was divided into three polygons based on ecosystem structure: an low shrub/herb ecosystem (0.54ha), a mature Pinus ponderosa forest mechanically treated in 2012 (6.96ha), and a dense maturing Pseudotsuga menziesii forest that had not received fuel management treatments (3.15ha). In addition, a 0.83ha control area was set up within the study area. Forest measurements were taken at 5 plots. Data collected at these plots included tree mensuration (tally of live and dead trees, species, height, and diameter) and understory vegetation species and percent cover. The burn was conducted on March 30, 2016. After guarding the site, the fire was ignited with drip torches at approximately 13:00, and continued until about 18:00. By the end of the day, 70% of the site had successfully been burned. The mature Ponderosa pine forest burned most uniformly, while the dense Douglas-fir forest at the toe of the slope didn’t ignite well, except for within a few feet of the ignition strips. Post burn monitoring conducted 1 week after the burn showed that tree mortality was low overall, with no mortality in conifer trees over 30cm diameter, and 43% mortality in trees under 30 cm diameter. This mortality rate was lower than what we had aimed for, and as a result we weren’t able to create any wildlife trees or coarse woody debris. Grasses regenerated strongly within a week, and the cover of grass species increased from the pre-burn cover by approximately 20%. After the fire, I detected a number of understory species that weren’t detected before the burn, including trace amounts of Lomatium macrocarpum, Lithospermum ruderale, and Prunus pensylvanica. Lomatium macrocarpum is an important food plant for the Nlaka’pamux, so it is exciting to see the response of that species to prescribed fire.