湘中丘陵区南酸枣阔叶林群落特征及群落更新

南酸枣阔叶林群落是湘中丘陵区的重要的森林群落类型之一,在森林演替过程中占有重要的地位。在湘中丘陵区长沙县大山冲林场的代表性群落——南酸枣阔叶林群落(The Choerospondias axillaries broad-leaved community)设立1 hm2固定样地,对其群落学特征进行调查,分析其植物多样性和更新动态。结果表明:群落中胸径≥1cm的乔木树种共有25科42属59种。乔木层中南酸枣(Choerospondias axillaries)的重要值最大(23.57),是群落中的建群种;南酸枣胸径和树高结构均呈正态分布,南酸枣幼苗(1.0cm≤DBH1.5cm)只有6株;群落中四川山矾(Symplocos setchuensis)的重要值(10.46)排第二,但胸径小于1.5 cm的幼树数量较多(占种群数量的22.0%),格药柃(Eurya muricata)、千年桐(Aleurites montana)和毛豹皮樟(Lindera coreana)的重要值分别为7.98(幼树数占种群数量的16.8%),5.39(幼树数占种群数量的11.7%),4.17(幼树数占种群数量的11.0%),这4个乔木树种的径级结构均呈倒J型分布;林分的成层结构中,上层木主要为南酸枣,下层木主要为四川山矾、格药柃、千年桐和毛豹皮樟。林下幼苗主要为常绿阔叶树种,且更新良好,并将成为下一个演替阶段的建群种。南酸枣的幼苗更新不良情况说明其在群落中的优势地位在逐年降低,而四川山矾、格药柃、千年桐、毛豹皮樟等树种的优势地位呈上升趋势,表明湘中丘陵区的南酸枣阔叶林群落正在朝常绿阔叶林的方向演替。灌木、草本层中共有植物37种,重要值前5位的种为檵木(Loropetalum chinensis)、满山红(Rhododendron mariesii)、乌饭(Vaccinium bracteatum)、栀子(Gardenia jasminoides)、映山红(Rhododendron simsii)分别为54.59、21.85、4.98、4.63、4.53,其中,檵木和满山红在灌木层中的优势地位明显。

The characteristics and regeneration of the Choerospondias axillaries broad-leaved community in the hilly region of central Hunan Province, China

Broad-leaved forest community dominated by Choerospondias axillaries is one of the main forest community types in the hilly area of central Hunan province, which plays a very important role in forest succession processes in subtropical region. In this study, a large permanent plot with an area of 1 hectares was established in the typical forest community of C. axillaries at the Dashanchong forest farm, Changsha county in the hilly region. The large plot was divided into 100 smaller sample plots of 100 square meters (10m×10m). The characteristics of the C. axillaries community were investigated in detail to analyze biodiversity and regeneration dynamics of the community. In order to investigate the plant diversity of shrub and herb in the smaller plots, 16 small samples were set up and distributed evenly in the sample plots, each small sample with area of 2m×2m. Plant diversity and succession dynamics were analyzed based on these field data. The results showed: (1) in the arborous layer, there were 59 species in total which were more than 1 cm in diameter at breast height (DBH), belonging to 25 families and 42 genera in the community; (2) the dominant species is C. axillaries with the largest important value (IV) of 23.57 in the community. It was characterized with normal distribution in tree heights and DBH for the tree species of C. axillaries, with only 6 saplings of 1.0cm to 1.5 cm in DBH. (3) The IV was 10.46 for Symplocos setchuensis, 7.98 for Eurya muricata, 5.39 for Vernicia montana, and 4.17 for Litsea coreana, respectively. The ratio of saplings, with less than 1.5 cm in DBH, varied with different tree species, which was 22.0% of saplings for the S. setchuensis population, 16.8% for E. muricata, 11.7% for A. montana, and 11.0% L. coreana, respectively. The diameter structures of the 4 tree species showed an inverted J curve type. (4) Considering the stratified structure of forest stands, the overstory were mainly occupied by C. axillaries, the understorey by S. setchuensis, E. muricata, V. montana and L. coreana. (5) Forest seedlings were mainly dominated by evergreen broad-leaved tree species which regenerated well, with exception of C. axillaries saplings. These results indicated that the advantage of C. axillaries in the community was diminishing, whileas the importance of S. setchuensis, E. muricata, V. montana and L. coreana was increasing. Those evergreen broad-leaved tree species should be the dominate species in next succession stages, suggesting the C. axillaries broad-leaved community in hilly region of central Hunan province was developing toward the evergreen broad-leaved forest community succession. (6) There were a total of 37 species in shrub and herb layer. The species with the largest five important values are Oropetalum chinensis, Rhododendron mariesii, Vaccinium bracteatum, Gardenia jasminoides and Rhododendron simsii, with an IV of 54.59, 21.85, 4.98, 4.63 and 4.53, respectively. The Loropetalum chinensis and Rhododendron mariesii were both dominant species in the shrub layer.