Although the management practice of retaining forest structural elements is modelled on the propensity for fires to leave behind a variety of biological legacies or structural elements, the comparison of post-fire and post-harvest residual forest structure and diversity has received little attention. We compared coarse woody debris (CWD) attributes to determine the similarity between anthropogenically created residuals to wildfire residuals. During the spring of 2021, 30 sites (15 harvest and 15 fire) in northern Alberta were selected that experienced a harvest or fire between the years of 2009-2011 and left residuals that possessed a patch size >0.45 ha and was >60% deciduous. Each site included a reference (larger matrix of forest bordering the same disturbance) area and a disturbance area. Within these 3 areas of a site an interior (location not bordering another area) plot and an edge (location bordering another area) plot were surveyed. CWD data was gathered during the summer of 2021 from an 11.28 metre radius plot containing 6 overlapping transect lines at every 60 degrees. Using the line-intercept method CWD ≥7.5 cm in diameter was counted, assigned a decay classification and identified by species (if possible): the same information was gathered for standing dead ≥9.1 cm. Post-fire island edge, disturbance edge and disturbance interior plots expressed higher recent (decay classes 1 and 2) CWD volumes. The CWD attributes of reference edge, reference interior and island interior plots were similar between post-fire and post-harvest sites. Decay class distribution, also, presented similarities between the disturbance types. The wildfire sites contained a larger proportion of small CWD (≥7.5 cm < 20 cm) but showed no variation in other size categories. The disparity in the disturbances was to be expected due to the strategy of harvesting being vastly different from a wildfire. The greater volume in wildfire island edges is likely due to the edge gradient that is present compared to a definite harvest edge. It is probable that sampling bias influenced these results. Overall, it appears that harvesting companies have been able to effectively mimic the retention patches created by natural disturbances.
About the Author
Lance was born and raised in the Southwest portion of Missouri in the US. His interests in biology, specifically botany, was influenced by his high school teacher. During these years he worked at a landscape nursery where his passion for plants was solidified. He obtained his BSc in Biology with an emphasis in botany at Northwest Missouri State University. While completing this degree he diverted a year of his studies to the University of Eastern Finland where he explored courses specifically related to forest ecology within the boreal forests. His passion for botany has influenced him to study Quercus spp. regeneration in Connecticut with the Connecticut Agricultural Experiment Station, Vaccinium spp. diversity in with the University of Eastern Finland, long-term vegetation surveys in West Virginia with the Eastern Rivers and Mountain Network and, currently, coarse woody debris dynamics in northern Alberta.
Land Acknowledgements
I would like to acknowledge that research for my project and subsequent work at the University of Alberta was conducted on lands taken from Indigenous peoples. As an international student it is easy for me to remove myself from the evils that occurred on this land, but I would like to be cognisant of the fact that injustices, such as what happened in Canada, have occurred all over the world and to give recognition for the lives, livelihoods and cultures that were stifled. My research was conducted on Treaty 8 territory that the Cree, Dené, Chipewyan, Beavers, Slaveys, Dogribs and Yellowknives collaborated with for centuries. My continued analysis at the University of Alberta was conducted on Treaty 6 territory that was utilised by Cree, Blackfoot, Métis, Nakota Sioux, Iroquois, Dene, Ojibway/ Saulteaux/Anishinaabe, and Inuit peoples. Words do not express the injustices these peoples faced. May the survivors and their families receive peace and carry on the traditions of their peoples.