海南岛尖峰岭两类热带山地雨林次生群落在15年演替过程中的林木消长(英文)

TREE POPULATION MORTALITY, RECRUITMENT AND GROWTH DURING A 15-YEAR PERIOD OF SECONDARY SUCCESSION IN TROPICAL MONTANE RAINFORESTS AT JIANFENGLING ON HAINAN ISLAND, CHINA

以两块对照固定样地 (840 1和 840 2 )为对象 ,研究了海南岛尖峰岭热带山地雨林两类采伐迹地次生群落在过去 15年的演替过程中胸径≥ 7.0 cm林木种类、个体数及胸高断面积的消长格局 ,结果表明 :1)常遭台风及一些人为活动干扰、源于大面积采伐迹地的 840 1群落比位于保护区核心区、源于小面积采伐迹地的 840 2群落具有较高的物种多样性 ,但两样地林木的个体密度随演替进程的变化均较缓慢 ,前者减少 3.9% ,后者增加 14.2 %。2 )常见种(即 1984年在 0 .2 hm2样地中个体数≥ 5的种类 ,绝大多数为群落优势种或先锋树种 )在 15年演替过程中种类数量保持不变 ,非常见种种类数量增加 31% ,常见种与非常见种个体密度在时间上的变化呈显著的负相关。3)林木死亡率总体上随胸径增大而减少。常见种的林木死亡率显著高于非常见种的林木死亡率 ,与此相反 ,林木的个体增补主要来自非常见种 (占 89.3% ) ,840 2样地的个体置换率 (增补数量 /死亡数量 )比 840 1高 90 % ;不同观测年份个体增补数量的变化与死亡数量的变化存在显著的正相关。4)林分胸高断面积的相对增长量主要受常见种的消长及样地总置换率的影响 ,总体上看 ,840 2样地的相对增长量高于 840 1样地 ,前者为 2 .48% ,后者为 1.6 9%。5 )热带山地雨林次生群落?

Trees greater than 7.0 cm DBH were censused from 1984 to 1999 in two permanent plots in secondary growth tropical montane rainforests to determine tree mortality, recruitment, and basal area growth. The two plots are regrowth from large (Plot 8401) and small scale cuts (Plot 8402). The 248 trees tagged in 1984 were grouped into two species types: common (≥5 trees/0.2 hm 2 ) and uncommon, and were sorted according to DBH into three size groups: small, medium and large. Plot 8401, which suffered greater damage from typhoons and disturbance from human activities, showed higher species diversity than did Plot 8402. Tree density decreased by 0.3% per year in Plot 8401, but increased by 0.9% in Plot 8402. The common species contributed to 10.7% and 10.6% of recruitment, but accounted for 82.4% and 90.0% of mortality in Plot 8401 and Plot 8402, respectively. Tree mortality tended to decrease with tree size. Mortality of large trees (>17.7 cm DBH) was significantly lower than for the all other trees. When different census periods were considered, there was a positive and significant relationship between the number of trees recruited and the number of trees that died, suggesting that tree recruitment was more frequent at times of greater tree mortality. Growth in total basal area was mainly affected by mortality of the common species and the rate of replacement that took place in the plots. The annual growth rate of total basal area was higher in Plot 8402 than in Plot 8401. We conclude that tree mortality, recruitment, and growth appeared to be dependent on the species type as defined. Population studies confined only to trees of dominant or pioneer species would probably fail to detect some important successional effects, such as we found in this study.