Climate change impacts on forest growth and tree mortality: a data-driven modeling study in the mixed-conifer forest of the Sierra Nevada, California

We evaluated the impacts of climate change on the productivity and health of a
forest in the mixed-conifer region in California. We adapted an industry-standard planning
tool to forecast 30-years of growth for forest stands under a changing climate. Four
projections of future climate (two global climate models and two emission forecasts) were
examined for forests under three management regimes. Forest structural and tree
demographic data from the Blodgett Forest Research Station in El Dorado County were
used to fit our projections to realistic management regimes. Conifer tree growth declined
under all climate scenarios and management regimes. The most extreme changes in climate
decreased productivity, as measured by stem volume increment, in mature stands by 19%
by 2100. More severe reductions in yield (25%) were observed for pine plantations. The
reductions in growth under each scenario also resulted in moderate increases in
susceptibility to non-catastrophic (i.e., non fire) causes of mortality in white fir (Abies
concolor). For the worst case, median survival probability decreased from the baseline rate
of 0.997 year−1 in 2002 to 0.982 year−1 by the end of the century.