The Stand Non-spatial Structure And Forest Health Assessment Of Different Altitudes In Hunan Mangshan

Mangshan Nature Reserve is the largest natural forest region in Hunan province, and source of the Pearl River. Unfortunately there were some incorrect policy decision, made the natural forest has been extensive damage especially in middle and low mountain. After a lapse of establishment of nature reserve, there has been for more than 30 years. So it is necessary to find out the Mangshan Nature Reserve natural forest resources current situation. And the study of the stand structure is helpful to reserve plant diversity and to improve the capacity of water conservation. In this research we set sample plots with altitudinal gradient, and quantify the stand structure factors, using the species composition, diameter structure, tree height structure and accumulation structure analysis to analysis the information of stand growth, and the diversity of tree, shrub and herb layer. Then we based on the results give the forest health assessment. The main conclusions of the research are as follows.(1) Analysis of stand structure. The results showed that in Mangshan Nature Reserve the evergreen broad-leaved forest is the temperate zone climax communities, this type of forest can adjust to maintain a balanced nutrition and keep generation update in a long time. With the altitude of 1200 m as the dividing line, the distribution can be divided into evergreen broadleaf forest, conifer and broad-leaved mixed forest and deciduous broad-leaved mixed forest.Natural forests are mostly young in Mangshan, and the average diameter and diameter increases with altitude rising constantly, the average tree height and maximum height are also increasing. Although the quantity of younger woods is many, the yield is not high. So it is not optimistic that those destroyed forest is difficult to recovery.In the fitting of the diameter structure and height structure of natural forest, we found weibull distribution fitting is better, it seems that weibull distribution has the wider applicability, so it cloud be the first choice to analysis forest structure.(2) Analysis of plant diversity. There is evergreen broad-leaved forest to the coniferous and broad-leaved mixed forest to the evolution of the mountain forest from low to the high in Mangshan. And species diversity also have a greater volatility, tree layer and shrub and herb layers alpha diversity showed the opposite trend, tree layer the overall decline with increasing altitude, but the shrubs in high altitude occupy the main position, so alpha diversity is higher. On the other hand, the change rate of species is fast with the increase of altitude.(3) Forest health assessment. In this paper, we use the single tree as the object to build the health evaluation system based on the previous research results. The results showed that in Mangshan nature reserve, except for the history of large area cutting, there is a lack of scientific and rational management, let the tree growth in savage, makes natural forest is not every healthy and the sub-health and genera healthy trees are more than 60%, the remaining health than unhealthy slightly more, Mangshan forest restoration work is a heavy responsibility work.