Background/Question/Methods  Selection management, which maintains an uneven-aged stand structure and high canopy cover, has been promoted as an ecologically sustainable form of forest management. Although retention harvesting may immediately preserve integral forest structural characteristics, adequate evaluation of stand responses will determine the success or failure of such treatments. In previous work, we quantified a temporal spike in stem mortality following retention harvest. While the mechanisms underlying this increase in post-harvest mortality (PHM) are generally understood, the patterns of mortality are unclear, particularly in operational stands. Here we analyzed the influence of the cut block edge on the rate and spatial pattern of PHM for four different mortality classes in Yukon boreal forest. The different mortality classes relate closely to specific mechanisms by which stems die, such as by wind throw and fungal attack. Using 20m radius sample plots set along the forest edge of retention plots, we computed the frequency and spatial-dependency of mortality for each class.

Results/Conclusions  Distance from the edge of the cut block influenced the rate of mortality for stems located within intact forest along the boundary of retention plots. The rate of mortality differed among the four mortality classes, suggesting that the mechanisms influencing PHM are spatially heterogeneous. Our results indicate that efforts to mitigate the negative impacts of selection management can be improved by recognizing how the major drivers of PHM change with the spatial proximity, and possibly the shape characteristics, of the cut block edge.