三峡库区常绿落叶阔叶混交林的监测研究

生物多样性的长期动态监测是生物多样性研究的热点之一。陆生植物监测实验站作为长江三峡工程生物与环境监测系统的重点站，完成了大量的野外监测样地建立工作，为今后的长期研究打下了良好的基础。以米心水青冈及曼青冈组成的常绿落叶阔叶林的相关研究为例，介绍了陆生植物观测实验站现阶段关于监测方面的部分研究工作。在多个尺度下对米心水青冈及曼青冈两种优势种进行格局分析，结果表明两者均为聚集分布，米心水青冈的聚集强度高于曼青冈。按1 ～4 cm, 4 ～ 8 cm及8 cm以上3个径级对曼青冈分布格局进行比较，各径级间聚集强度相似，这与群落年龄、特殊的地形环境及种群的生态习性有关。群落的地形异质性研究表明0.96 hm2范围内坡度及坡向存在明显的差异，研究范围内样方的平均坡度在18.2°～ 74.6°之间。坡向可以分为南坡、西南坡及东南坡3部分。地形的异质性影响着群落的内部结构，植物与地形因素的相关分析表明不同的种对地形的适应性不同，群落中的24种主要植物可以分为4个生态种组。

ECOLOGICAL INVESTIGATION OF THE MIXED BROAD LEAVED DECIDUOUS AND EVERGREEN FOREST IN THREE GORGES RESERVOIR AREA

The plant species observation and experimental station was an important component of the biological and environmental monitoring system for the Three Gorges Project. 5 one hectare permanent plots were established from 1996~2002, including broad leaved evergreen forest, mixed broad leaved deciduous and evergreen forest, deciduous forest and evergreen conifer forest. All the permanent investigation plots provide the basis for the long term biodiversity dynamic research. In this paper, some achievements in the research stations were introduced. The distribution of a mixed broad leaved deciduous and evergreen forest patterns were detected. Two dominated species, Fagus engleriana and Cyclobalanopsis oxyodon, were all clumped. The oxyodon population was divided into three size classes as DBH 1 ~4 cm, DBH 4 ~8 cm and DBH > 8 cm, all of which were clumped, and might be influenced by the age of the forest and the topographic factors. Micro site heterogeneity was one of the important mechanisms in maintaining species diversity in plant community. To examin the heterogeneity of the topography, a DEM was built using the interpolation method. The slope and aspect driven form DEM showed strong heterogeneity. The slope varied from 18.2° to 74.6°, and from south, to southwest and southeast. Twenty four species were chosen to calculate correlation coefficients between slope, aspect and position. The topographic adaptation of these species was different, for example Fagus engleriana was positively associated with slope, and Sorbus alnifolia was positively associated with other aspects and so on. According to topography, these species were classified into six groups using a hierarchical cluster analysis. All the achievements in the research station will contribut to the biodiversity reservation in the future.