PARENT SESSION
Poster Session 11: Disturbance Ecology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Are mineral soils exposed by wildfires better seedbeds for conifer regeneration?
Kemball, Kevin*,1, Wang, Geoff2, 3, Westwood, Richard3, 1 University of Manitoba, Winnipeg, Manitoba, Canada2 Clemson University, Clemson, South Carolina3 University of Winnipeg, Winnipeg, Manitoba, Canada
ABSTRACT- This study examined germination and establishment of artificially sown jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) on aspen-conifer mixedwood stands following wildfire. Thirty experimental plots were established on three different seedbed types within days following the end of the Black River Fire in Southeastern Manitoba, Canada in May of 1999. Seedbed types were scorched (surface litter only partially consumed), lightly burned (surface litter consumed with little or no duff consumption), and severely burned exposing mineral soil. Seeding was done in the spring of 1999, 2000, and 2001 and each cohort was monitored for three years. Light and microclimate were measured in the field, and the possible toxic effects of ash was examined in the laboratory. Light and microclimate changed considerably over the six years of monitoring and significant differences (ANOVA, p ≤ 0.05) were found between seedbed types. Ash was not found to be toxic. Significant differences in germination were found in each cohort year (ANOVA, p ≤ 0.05). For both species severely burned seedbed was the worst, and scorched was the best for germination in 1999, the reverse was true in 2001. Germination was highest in the second year post fire for jack pine, and third year post fire for black spruce. Three year survival was highest for the 2001 cohort in both cases. Significant differences were also found in age specific survivorship (Chi-square and Fisher exact tests, p ≤ 0.05) between seedbed types and cohort years, and between species. On severely burned seedbed it took 607.5, 243, and 102.9 viable seeds to produce one three year old seedling for the 1999, 2000, and 2001 cohorts respectively. For black spruce it took 2075 and 53.5 viable seeds to produce one three year old seedling on severely burned seedbed for the 1999 and 2001 cohorts; no seedling survived to three years of age for the 2000 cohort. Seedling survival to age three ranged from 7 to 15% for jack pine on severely burned and lightly burned seedbeds and 0 to 14% for black spruce. On scorched seedbed 6% of jack pine and 8% of black spruce seedlings survived to age three for the 1999 cohort. For 2000 and 2001 cohort no seedlings survived to age three on scorched seedbed.
Key words: wildfire, seedbed, conifer, mixedwood