How well does forestry in Ontario’s boreal forest emulate natural disturbances from the perspective of birds?

Abstract

Emulating natural disturbance has become a paradigm for biodiversity retention in forest management. This study evaluates the extent to which harvest management practices have created stands that emulate natural fire disturbance from the perspective of bird communities in Ontario, Canada. We compared the relative abundance of forest landbirds at the stand level in mature forest (> 80 years old) with that in early-regenerating (0-20 years) and midregenerating (21-80 years) forests originating from fire or timber harvest across the boreal forest of Ontario using over 7000 point counts. Our results indicate that forest harvest management practices in Ontario have created stands that only partially emulate natural fire disturbances in terms of the bird community composition. Total bird abundance and species richness were significantly lower postharvest than postfire in midregenerating forests, although they did not differ in early-regenerating stands. Species-level comparisons revealed several differences between postharvest and postfire stands, as well as among age classes. Although no species was completely missing from any stand type, 8% of species in early-and 34% in midregenerating stands were detected significantly less often in postharvest than postfire forests. Some other species were found significantly more often in postharvest stands, while the majority of species detected (84% and 71% in early-and midregenerating stands, respectively) showed no significant difference between disturbance types. Collectively, these results suggest that widespread replacement of fire with logging as the dominant disturbance type will shift the relative abundance of species within Ontario's boreal forest bird community. Quantifying the population-level implications of these shifts requires extrapolating these stand level effects to the landscape level, while considering the actual or anticipated abundance and distribution of forest age classes across the province under different forest management regimes.