三峡库区残存的常绿阔叶林及其意义

THE REMAINING EVERGREEN BROADLEAVED FOREST AND ITS SIGNIFICANCE IN THE THREE GORGES RESERVOIR AREA

三峡库区世坪森林公园的常绿阔叶林处在中亚热带北部，群落中４８．６５％的物种具热带性质，３５．１４％的物种具温带性质；３３．７８％的物种集中在忍冬科（Ｃａｐｒｉｆｏｌｉａｃｅａｅ）、壳斗科（Ｆａｇａｃｅａｅ）等７个科，全部３８个科中８１．５８％的科仅有１～２种植物在群落中出现；群落含有具先锋意义的伴生种。这些都反映出该地带的次生常绿阔叶林的一般特点。栲树（Ｃａｓｔａｎｏｐｓｉｓｆａｒｇｅｓｉ）的重要值在乔木层和灌木层均居第一，特别是在乔木层该值显著高于其它种，说明此处的常绿阔叶林是以栲树为建群种的单优群落，而且栲树种群径级结构符合其正常发育规律，因而群落相对稳定。该群落对于中亚热带地带性植被的生态学和生物多样性的基础研究具有重要意义，对于退化生态系统的恢复和三峡水库的水源涵养具有典范作用。

The evergreen broadleaved forest at Shiping in the Three Gorges Reservoir Area was studied. The results show that tropical and temperate plant species respectively amounted to 48 65% and 35 14%,that 1/3 of all species belonged to 7 families such as Caprifoliaceae,Fagaceae etc. And more than 80% of all 38 families just had 1～2 species observed in the community. Some pioneer trees were common in tree layer. These reflect the main characteritics of the secondary evergreen broadleaved forest in the north of central subtropics nearby the warm temperate zone. The importance value of Castanopsis fargesii was the highest in both the tree layer and the shrub layer, especially in the tree layer, suggesting that the forest was community of monodominant of C.fargesii (edificato). The community was relatively stable with a normal DBH distribution of the dominant population. The important significance of the community was discussed in the context of ecology and biodiversity research of zonal vegetation in the central subtropics, restoration of retrograded ecosystems, and conservation of water and soil in the Three Gorges Reservoir Area.