Community and Population Dynamics of an Evergreen Conifer-Broadleaf Forest in Southern Taiwan: Recent Trends (1999~2009)

Abstract

Community and population dynamics in a 1-ha permanent plot of an evergreen forest of conifer and broadleaf trees, dominated by Pseudotsuga wilsoniana and Castanopsis carlesii, in southern Taiwan were studied. All live stems with a diameter at breast height of ≥ 1 cm in this area were identified by species, tagged, and measured, first in 1999 and then again in 2009. While no changes in the floristic composition occurred between 1999 and 2009, some slight variations were evident in Shannon's diversity index. Based on a logarithmic model, the mortality, recruitment, loss, and gain rates in basal area during this period were respectively calculated to be 1.7, 0.6, -0.5, and 0.02% yr^(-1). The stem density and especially the basal area (5.06 m^2 ha^(-1)) of P. wilsoniana, the most important conifer, decreased. Although the density of all dominant broadleaf trees slightly declined, 8 gained in basal area. Recent trends suggest that P. wilsoniana trees are now at a competitive disadvantage relative to evergreen broadleaf trees in the permanent plot, but a powerful typhoon on September 2, 2003, had a major impact on the community and population dynamics of this evergreen forest of conifer and broadleaf trees.