Ecosystem services and disservices of bear foraging on managed timberlands

The literature on ecosystem services has been criticized for inadequately acknowledging culture values and for de-emphasizing economic disservices. While economic loss due to tree damage by American black bears (Ursus americanus, hereafter bears) may negatively affect timber production, it also alters forest structure and habitat that may contribute to forest wildlife diversity, including culturally significant species. We examined the relationship between bear damage to Douglas-fir trees (Pseudotsuga menziesii var. menziesii) and response of cavity-nesting birds on the Hoopa Valley Indian Reservation. We measured disservices from bear damage by calculating current and future timber revenue loss, and ecosystem services by calculating forest structural complexity, abundance and diversity of cavity-nesting birds, and woodpecker activity. Bear damage was correlated negatively with tree growth and positively with estimated timber loss. Forest structural complexity was positively correlated with bear damage, and cavity-nester abundance and woodpecker foraging activity were positively correlated with forest structural complexity and bear damage. Pileated woodpeckers (Dryocopus pileatus) and red-breasted sapsuckers (Sphyrapicus ruber) used bear-damaged trees out of proportion to their availability, and pileated woodpeckers selected for more structurally complex sample units. Information from this study advances our understanding of the potential for bear foraging to negatively affect economic revenue and the trade-offs with habitat conditions favoring other important wildlife species. Understanding the costs and benefits of bear damage can help guide management decisions vital to forest managers both on and off tribal lands.