黎母山引进外来树种对森林群落物种多样性的影响

Effects of Introducing Exotic Tree Species on Species Diversity of Forest Communities in the Limu Mountain

采用样地调查法对黎母山片区内28 a和15 a加勒比松群落、20 a和26 a马占相思群落、16 a和21 a橡胶群落、10 a和3 a桉树群落、20 a次生林群落进行调查,通过树种重要值和物种多样性指数反映林地森林植被群落特征。结果表明:1)乔木层树种种类最多的是次生林群落40个种,20 a马占相思群落乔木层树种共29个,21 a橡胶和3 a桉树群落未调查到乔木;灌木种类最多为20 a马占相思群落,共5个种,草本种类最多为3 a桉树群落,共7个种。2)次生林优势种为贡甲和青梅,重要值分别为17.87%和14.76%;28 a加勒比松群落乔木树种重要值最大为鸭脚木38.94%,15 a加勒比松群落乔木树种重要值最大为中平树37.99%,20 a马占相思群落乔木树种重要值最大为细齿叶柃18.80%,26 a马占相思群落乔木树种重要值最大为八角枫30.86%,16 a橡胶群落乔木树种重要值最大为白楸31.63%,10 a桉树群落乔木树种重要值最大为细基丸45.74%;森林群落内灌木树种与草本种类比较少。3)黎母山不同外来树种与次生林群落Simpson指数、Shannon-Wiener指数均表现为乔木层>灌木层>草本层,乔木层Pielou指数低于灌草层。4)森林群落更新层未调查到外来树种自主更新幼树,但加勒比松和马占相思群落均生长海南乡土树种。黎母山引进不同外来树种对森林群落优势树种种类具有差异,不同程度上减少了森林群落物种多样性,改变了森林群落乔灌草层次物种组成结构,降低了群落结构复杂性。

In order to explore the effects of the introduction and construction of different exotic tree species on the forest community characteristics in the Limu Mountain,the sample plot survey method was used to investigate the communities of 28-and 15-year-old Pinus caribaea,20-and 26-year-old Acacia mangium,16-and 21-year-old Hevea brasiliensis,10-and 3-year-old Eucalyptus spp.,and 20-year-old secondary forest occurring in the Limu Mountain area.The characteristics of the forest community were reflected by the tree species importance value and species diversity index.The survey results showed that 1)the most abundant plant species with a number of 40 were found in the tree layer of secondary forest community.There were a total of 29 tree species in 20-year-old A.mangium community.No tree species were found in 21-year-old H.brasiliensis and 3-year-old Eucalyptus spp.communities.Shrub species were the most(5 species)in 20-year-old A.mangium community.Herbaceous species were the most(7 species)in 3-year-old Eucalyptus spp.community.2)Dominant species of secondary forests were Maclurodendron oligophlebium and Vatica mangachapoi,with the importance values of 17.87%and 14.76%,respectively.The largest important value(38.94%)of the tree species in the 28-year-old P.caribaea community was Schefflera heptaphylla.The largest important value(37.99%)of the tree species in 15-year-old P.caribaea community was Macaranga denticulata.The largest importance value of the tree species in the 20-year-old A.mangium community was 18.80%of Eurya nitida.The largest importance value(30.86)of the tree species in 26-year-old A.mangium community was Alangium chinense.The largest importance value(31.63%)of tree species in 16-year-old Hevea brasiliensis community was Mallotus paniculatus.The largest importance value(45.74%)of tree species in 10-year-old Eucalyptus spp.community was of Polyalthia cerasoides.Less shrub species and herb species were found in forest communities.3)Simpson index and Shannon-Wiener index of different exotic tree species and secondary forest communities in Limu Mountain showed tree layer>shrub layer>herb layer,and Pielou index showed tree layer was lower than shrub layer.4)There was no self-renewal saplings of exotic tree species in the regeneration layer of forest community,but P.caribbean and A.mangium communities grew native species in Hainan.The introduction of different exotic tree species in the Limu Mountain had differences between the dominant tree species of forest community,which reduced the species diversity of forest community to varying degrees,and changed the species composition structure of tree layer,shrub layer and herb layer in forest community,and thus reduced the complexity of community structure.