湘中丘陵区南酸枣阔叶林群落特征及群落更新

Abstract

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.