Jonathan Tales | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree. This is an ALES MSc Final Exam Seminar by Jonathan Tales. This seminar is open to the general public to attend.

Zoom Link: https://ualberta-ca.zoom.us/j/95659835120

MSc with Dr. Charles Nock      

Thesis Topic: Structure, Understory Vegetation and Edge Dynamics in Forest Remnants of Fire and Harvest Origin

Abstract:

Ecosystem-based-management (EBM) seeks to reduce the negative effects of clear cutting by attempting to emulate the spatial patterns of natural disturbance. In the boreal forests of Canada where wildfire is the dominant natural disturbance, forest managers retain patches of forest within clear cuts to act as analogs of small forest remnants (usually <10 ha) which survive wildfires. Forest remnants within a disturbed area may provide several functions that support biodiversity, including acting as refugia and a source of propagules for interior forest species, casting shade on the adjacent disturbance, and recruiting new snags and coarse woody debris (CWD). Because of their small size, forest remnants may be subject to greater edge effects than larger forest tracts, which could influence their ecological functions, though this question is rarely studied. We sampled nine remnants each of fire and harvest origin approximately ten years after disturbance in the upper foothills sub-region of Alberta’s boreal forest. To understand the ecological functions of remnants in their local context, we describe their structure and floristic communities and compare them to the disturbed area as well as a large forest tract nearby. We estimated edge effects for both remnants and the nearby large forest tract, and measured forest influence of the remnant on the adjacent disturbed area. Structure and plant community in fire remnants was characteristic of moist ecosites with thick organic layers, few snags and little CWD. We found no evidence of edge influence on plant communities in fire remnants, suggesting they maintain very stable habitats. Harvest remnants were dense stands with high numbers of snags and exhibited an increase in ericaceous shrubs and a reduction in water preference of the plant community at the edge. In harvest remnants, we found edge influence up to 20m, but the magnitude of the effect was low. We also observed a decrease in species richness 5-10m within harvest remnants, possibly indicating species loss. Despite these edge effects, harvest remnants had on average an understory community similar to larger forest tracts, demonstrating their potential value as interior forest refugia within the clear cut. To limit edge influence in retention patches, we recommend using large, round patches sited to increase moisture availability and reduce contrasts with the harvested area.