南亚热带季风常绿阔叶林锥栗-荷木-黄果厚壳桂群落发展趋势探讨

DYNAMICS OF THE CASTANOPSIS CHINENSIS-SCHIMA SUPERBA-CRYPTOCARYA CONCINNA COMMUNITY OF MONSOON EVERGREEN BROADLEAVED FOREST IN DINGHUSHAN NATURE RESERVE IN LOWER SUBTROPICAL CHINA

根据广东省中部鼎湖山自然保护区季风常绿阔叶林锥栗_荷木_黄果厚壳桂 (Castanopsischinensis_Schimasu perba_Cryptocaryaconcinna)群落 8年的监测 ,用成对双样本均值分析的方法对群落个体数、生物量等进行了对比研究 ,初步揭示了群落真正时间意义上的变化 :1 )群落个体数呈逐年递减的趋势 ,1 992、1 994、1 999年分别为 3 979、3 82 2、3 531株·hm-2 ,1 994、1 999年比 1 992年分别减少了 3 .9%、1 1 .3 % ,经t_检验 ,差异极显著。类似的 ,群落生物量大体上也呈下降的趋势 ,1 992、1 994和 1 999年分别为 2 93 .1、30 4 .3和 2 4 8.5t·hm-2 ,1 994、1 999年分别为 1 992年的1 0 3 .8%、84.8% ,差异不显著。 2 )不同径级树木个体数和生物量年间存在差异。胸径≤ 30cm的树木个体数年间差异极显著。胸径 90cm以上的树木个体数在 1 992～ 1 999年间减少 50 %。胸径 40cm以下和 90cm以上树木生物量年间差异不显著。 1 994、1 999年中径级 (尤其是 40～ 50cm)树木的生物量有一定的发展 ,分别增长了 1 .36 %、8.7%。 3)黄果厚壳桂、云南银柴物种个体数极显著减少 ,锥栗 1 992～ 1 999年间生物量减少 31 .1 % ,黄果厚壳桂 1 999年生物量显著低于 1 992年。 4)鼎湖山季风常绿阔叶林正朝着中生顶级群落演替。

The monsoon evergreen broad_leaved forest, located in Dinghushan, near the Tropic of Cancer is well protected and has been considered as a climax comm unity in lower subtropical area, with the Castanopsis chinensis_Schima superba _Cryptocarya concinna community as the representative community. The structure , function and dynamics of this community have been well documented in previous studies. Most studies reported that a climax community generally viewed fluctuates spat ia lly and temporally. However, few studies have quantitatively analyzed its chan ges over time. Therefore, our study aimed to i) monitor the dynamics of the Ca stanopsis chinensis_Schima superba_Cryptocarya concinna community; ii) examine the fluctuations of plant density and biomass of this community and iii) try to provide information for forest resource managers and policy makers to promote long_term ecosystem sustainability. Based on the plant density and biomass obtained from three consecutive sites (19 92 t o 1999), a comparative study and paired_samples t_test were conducted. The r esul ts demonstrated: 1) plant density generally declined, indicated by 3 979, 3 822 and 3 531 individuals·hm -2 in 1992,1994 and 1999, respectively, with stat istical difference between 1994 and 1992 (p<0.05), 1999 and 1992 (p<0.05 ). Similarly, biomass fluctuated from 293.1 in 1992 to 248.5 t·hm -2 in 19 99,with no statistical difference. 2) Plant density and biomass also differed in various DBH (Diamet er at Breast Height) classes. Individuals with DBH≤30 cm, including DBH ≤10 cm, 10 cm<DBH≤20 cm and 20 cm<DBH≤30 cm, differed statistically between 1999 and 1992, 1994 an d 1992. Individuals with DBH>90 cm decreased by 50% from 1992 to 1999. The b ioma ss for trees of DBH ≤40 cm and DBH >90 cm did not differ statistically. For mid dle DBH trees, especially for 40 cm<DBH≤50 cm trees, individuals increa sed by 1.3 6% in 1994 and 8.7% in 1999, compared with that in 1992. 3) Individuals for Cr yptocarya concinna and Aporosa yunnanensis decreased statistically in 1994 and in 1999, respectively. Biomass for Castanopsis chinensis decreased by 31.1% in 1999. Biomass for Cryptocarya concinna decreased statistically by 1 7.8 % in 1999. Integrated analyses showed that Castanopsis chinensis_Schima superba_Cryptocar ya concinna community tends to the climax dominated by neutral species. The co mmunity fluctuation resulted from succession, natural thinning and death induced by disaster.