MORTALITY, RECRUITMENT, AND GROWTH-RATES OF MONTANE TROPICAL RAIN-FOREST CANOPY TREES ON MOUNT BELLENDEN-KER, NORTHEAST QUEENSLAND, AUSTRALIA

To better understand the physiognomy and dynamics of tropical forest c anopy trees, the mortality, recruitment, and growth rates of trees gre ater-than-or-equal-to 30 cm DBH were quantified on a montane tropical rain forest hillslope over the 10-yr period 1982-1992. The results ind icate that the smaller stature of canopy trees growing on or near ridg e-crests of montane rain forests is a consequence of higher turnover r ates, not slower growth rates. The annual canopy tree turnover rate of approximately 1.7 percent in the upslope section of the sample area w as two times greater than in the downslope section. The DBH growth inc rements in the upslope and downslope sections also were significantly different (P < 0.05), but it was the upslope trees that grew at the fa ster rate (upslope = 3.1 mm yr-1; downslope = 2.4 mm yr-1). The mean D BH growth increment of 2.7 mm yr-1 for the entire plot is relatively h igh compared to other montane tropical rain forests. Interspecific var iation among the 23 tree species also was notable, with mean DBH incre ments ranging from 0.4 to 7.8 mm yr-1. Ceratopetalum virchowii and Ela eocarpus ferruginiflorus were the most dominant species in 1982: C. vi rchowii increased its dominance over the 10-year period with a higher rate of recruitment than mortality and a change in relative importance from 22.7 percent in 1982 to 28.4 percent in 1992; E. ferruginiflorus , in contrast, experienced the most significant change of all the spec ies examined, with a decrease in relative importance from 14.1 percent in 1982 to 5.3 percent in 1992 as a result of its high mortality, its slow growth rates, and its failure to recruit any individuals into th e greater-than-or-equal-to 30 cm DBH size-class; the local demise of t his species may be part of a shifting floristic mosaic associated with natural disturbance events or perhaps part of an irreversible trend. It is recommended that more attention be directed to the growth patter ns of co-occurring species and the life histories of individual trees to obtain a clearer sense for the long-term dynamics of montane tropic al rain forest canopy tree populations.