Factors affecting ecosystem recovery after placer mining in northwestern British Columbia
Haig, J. 2017. University of Nothern British Columbia
Abstract
This research sought to determine the attributes affecting unassisted ecosystem
recovery after placer mining. Ninety post-mining sites in 14 creek drainages east of
Atlin Lake, British Columbia, were sampled to represent a range of times since
disturbance (9 to 76 years). The six indicators utilized (vascular species richness, plant
community similarity to undisturbed reference sites, summed plant cover, structural
diversity, A-horizon depth, wildlife activity) exhibited different recovery trajectories
and dependencies. Across all six indicators, the factors most important to ecosystem
recovery were, in order of importance: time since disturbance, microsite relief,
elevation, slope position, and soil texture. Without any reclamation, linear extrapolation
indicates that a mean of 101 years would be needed for disturbed sites to return to
mean undisturbed conditions. Classification and regression tree analysis identified
thresholds of these factors that may promote or hinder recovery. These thresholds
were used to refine recommendations for promoting ecosystem recovery after mining.
