Old-growth forest dynamics in the Sierra Nevada

Lab members past and present collaborated on a recent paper documenting ecosystem dynamics and tree demography over the past half-century. In the mid-1950’s Professor Frederick Baker (former Cal Forestry School Dean) established a 4 ha mapped stand of old-growth mixed conifer forest in northern California. In 1996, Jolie-Ann Ansley re-established the “Baker Plot” and we have been following the dynamics since.

Changes in relative dominance of trees >24 cm DBH by species (1957-2013) and the total basal area increase over the 56-year study period. Relative dominance is defined as the proportion of total basal area for that species.

The most recent paper in the Canadian Journal of Forest Research, Levine et al. (In press) found that despite a warming climate, stand density, basal area, and carbon have increased over 56 years. Fir recruitment and growth significantly exceeded the community-level median rates, while pine recruitment and growth was significantly lower than the community-level median. Shifts in species composition from a well-mixed stand to a more dense fir-dominated stand appear to be driven by low growth and recruitment rates of pines relative to firs.