Sensitivity of berry productivity to climatic variation in the cabinet-yaak grizzly bear recovery zone, Northwest United States, 1989-2010

Berry-producing shrubs are culturally, economically, and ecologically important for both people and animals in the Pacific Northwest of the United States. We examined huckleberry (Vaccinium membranaceum) and serviceberry (Amelanchier alnifolia) productivity across the Cabinet-Yaak grizzly bear recovery zone in Northern Idaho and Western Montana. An index of annual berry productivity was measured at field plots from 1989 to 2010. Temperature, precipitation, and snow indices were derived from nearby Snowpack Telemetry (SNOTEL) stations. Huckleberry production was highest during cool springs with high July diurnal temperature ranges. April-June growing-degree days and July temperature range explain 70% of the inter-annual variability in huckleberry productivity. Serviceberry production was correlated with maximum snow-water equivalent and April-June growing-degree days, which explained 86% of the variance in annual serviceberry production. These models show potential to forecast annual berry production and to anticipate potential bear-human interactions. Further development of models is essential to better predict the potential changes in important wildlife resources in the context of climate change.