Aerial overview survey of the mountain pine beetle epidemic in British Columbia: Communication of impacts

Abstract

In western Canada, the current outbreak of mountain pine beetle (Dendroctonus ponderosae) is of unprecedented proportions. Annual aerial overview surveys (AOS) are the primary means of accounting for the area and severity of mountain pine beetle impacts. Typically, reports of impacted areas do not consider severity—the proportion of trees killed within a given area. A common misconception is that all impacted areas will experience 100% pine mortality.
We examined a time series of AOS data collected in British Columbia from 1999 to 2005. The year-toyear trends indicated that the AOS data effectively captured the infestation's increasing area, severity, and spatial variability. The cumulative area impacted between 1999 and 2005 was estimated at 11 million ha; 39% of this area was attacked in only one year. The approximate year of death was estimated by assuming a 50% severity threshold. Approximately 6.5 million ha experienced mortality. The results of this study emphasize the importance of reporting severity, as well as considering the cumulative effects of the infestation over time.