Dynamics of forest canopy and major tree populations over nine years in a subalpine old-growth coniferous forest, central Japan

Abstract

:From 1991-2000, we examined the dynamics of the forest canopy and major tree populations in a 2-ha permanent plot of subalpine old-growth coniferous forest dominated by Picea jezoensis var. hondoensis, Abies mariesii, Tsuga diversifolia, Abies veitchii, and Betula ermanii in the Ontake Forest Reserve, central Japan. During the 9-y study period, the rates of canopy gap formation and closure were 0.89%·y-1 and 0.63%·y-1, respectively; mortality and recruitment rates were 2.74%·y-1 and 1.02%·y-1, and the rates of basal area loss and gain were 1.26%·y-1 and 0.80%·y-1. The rates of mortality and recruitment of P. jezoensis var. hondoensis, T. diversifolia, and B. ermanii were clearly lower than those of A. mariesii and A. veitchii. Plots of mortality rate versus size class showed different patterns among species. Mortality of all stems was lower in the canopy and higher in the understory, while the proportion of stems killed by disturbances increased with height. The spatial pattern of dead stems in the upper layer was related to new gaps, but recruited stems were not concentrated in either old or new gaps.