西南岩溶地区天然次生林群落不同层次的构建机制

以西南岩溶地区天然次生幼龄林、中龄林和近熟林为研究对象,采取以空间代替时间的群落生态学方法,研究不同林分结构特征的变化规律和森林群落不同层次的构建机制.结果表明:岩溶地区天然次生林恢复过程中,林分的结构特征发生了显著变化.由幼龄林、中龄林到近熟林,林冠层(林木胸径DBH>5 cm、树高H>5 m)的个体密度、胸高断面积...

Construction Mechanism of Natural Secondary Forest Communities at Different Forest Strata in a Karst Area of Southwest China

Taking natural secondary young-aged, middle-age and near-mature forests in a Karst area of southwest China as the research object, the community ecology method with space instead of time was adopted to study the change rule of different stand structure characteristics and the construction mechanism of forest community at different forest strata.The results showed that the structural characteristics of forest had changed significantly during restoration process of natural secondary forests in karst areas.The individual density, basal area and aboveground biomass in the young-aged, middle-age and near-mature forest had increased significantly in the canopy layeri.e.DBH (diameter at breast height) >5 cm and tree height >5 m], while those indexes in the understory layer had decreased significantly (i.e.DBH <5 cm and tree height <5 m).Different strata of natural secondary forest communities in Karst areas had different construction mechanisms.In the young-aged forest, the species composition was very similar in the canopy and understory communities.This was related to the extreme high individual density, no obvious differentiation, high rock exposure rate and low soil bulk density, which stunted the settlement and growth of plants.The main performance was the driving mechanism of habitat filtering.In the middle-age forest, the soil properties and stand structure were improved, which could provide more diverse habitats for plants.At this time, the canopy plants had a climate-dominated niche, while the understory plants had a soil-microhabitat dominated niche, leading to the difference in plant composition between canopy and understory layer.In the near-mature forest, the effect of habitat filtering was weakened, and the effect of biological factors was enhanced.The aboveground biomass and canopy coverage had become the main driving factors for the differentiation of plant composition in canopy and understory.