Typical Forest Community Structure And Fallen Log Characteristics In Inner Mongolia Greater Khingan Mountains

The Greater Khingan Mountains forest zone is the only temperate coniferous forest in China,located in the northern frontier of China.The area is in the high latitude permafrost regions,the permafrost and the island frozen soil distributed in the forest region,wetland area is wide,it has strong sensitivity to environmental change.Forest structure determines forest function,structure directly determines the nature of the system,only the structure is clearly visible, it is possible to implement effective regulation,only the structure of the fores is reasonable, all the function is possible to implement.Fallen log is one of the important structural and functional components of forest ecosystem and played many important and unique ecological function in the forest ecosystem. Therefore, it is of great significance to study the structure of forest community and the study of the characteristics of the forest trees.Based on this theory,this research study on the community structure and the characteristics of the tree species in 6 typical forest communities in Inner Mongolia Greater Khingan mountains,to provide a theoretical basis for forest management in Greater Khingan mountains. The main results are as follows:(1) The species of the tree layer of the six typical forest communities have a simple composition, tree species include Larix gmelinii、Betula platyphylla and Populus davidiana. Stand density difference is relatively large, the distribution range is 984to 2360 trees per hm2. The total basal area of the stands was different,but the difference is not obvious,with a changing range from 13.44-22.04m2 per hm2.(2) The diameter class structure as well as the structure analysis of tree height show that the distribution curves of diameter class of forest communities have five main types: normal distribution、approximate normal distribution、single peak mountain distribution、 double peak、many peak mountain distribution.the distribution of the tree height is dominated by the normal distribution,double peak、many peak mountain distribution.(3) (3) The six typical forest communities have varied distribution patterns.Larix gmelinii population distribution pattern is mainly with aggregated distribution in the whole scale research、aggregation distribution of small and medium scale.Betula platyphylla is also have this trend,other with random distribution.Populus davidiana is mianly with aggregation distribution.Interspecific relationship presented competitive relationship in Larix gmelinii-Betula platyphylla mixed forest and Betula platyphylla-Larix gmelinii mixed forest.It has a fierce competition in Populus davidiana-Betula platyphylla mixed forest.Tree layer biomass and community biomass is the most in.Larix gmelinii virgin forest,least in the.Larix gmelinii clear cutting forest. Forest volume is the most in clear cutting forest,and least in Populus davidiana-Betula platyphylla mixed forest.(4)The number of fallen log is most in Betula platyphylla- Larix gmelinii mixed fores,least in Larix gmelinii-Betula platyphylla mixed forest,The fallling direction is mainly in the southeast and northeast directions, the cause of fallen log is correlated with nature and wind.Larix gmelinii fallen log distribution pattern is mainly with aggregated distribution in the whole scale research、aggregation distribution of small and medium scale.Betula platyphylla fallen log is also have this trend,other with random distribution.Populus davidiana fallen log is mianly with aggregation distribution.Existing quantity is most in virgin forest,least in Populus davidiana-Betula platyphylla mixed forest.The storage of organic C is the largest in fallen log, followed by total N storage, and the total P storage is the least.Fallen log existing quantity have positive correlation with age of sand,have negative correlation with stand density,Fallen log volume storage have positive correlation with forest volume.