Study On Comprehensive Competition Stress Index Of Cyclobalanopsis Glauca Secondary Forest

There is a total area of 16.72 million hm2 Cyclobalanopsis glauca(Thunb.)Oerst.in China,Including a area of 16.1 million hm2 is natural,they are widely distributed throughout the country,with a area of 10.15%of the total area of China’s forest resources,hold 13.7%of the total area of China’s natural forests,Quercus L.forest management is the key areas of natural forest protection in China.Trees competition is a common phenomenon in forest ecological system,it’s the main power to shape the plant morphology and life history,it has a great influence in plant community and dynamic,also,it is one of the core problems of ecology.This article used the Cyclobalanopsis glauca(Thunb.)Oerst.secondary forest of LuTou state forest farm as the research object,based on the purpose of studying the trees competition of Cyclobalanopsis glauca(Thunb.)Oerst.,learn the competition structure law of forest stand,built the canopy model of dominant tree by dominant tree data,and elicited the open-growing tree canopy model of Cyclobalanopsis glauca(Thunb.)Oerst,according to the Circle of influence and the height of tree,combined Competition Stress Index came up with the Comprehensive-Competition Stress Index,a new index to evaluate trees competition,compared and analyzed the CSI and C-CSI of different sample plots and different trees.Based on the value of C-CSI,got a different grade to the forest trees,carried out a simulating forest thinning analysis to the Cyclobalanopsis glauca(Thunb.)Oerst.secondary forest according to the classification results.The main conclusions are as follows:(1)It worked out the canopy model of dominant tree of Cyclobalanopsis glauca(Thunb.)Oerst.was CW=0.1589+0.2509*D got the open-growing tree canopy model was CW=0.1773+0.2799*D by the method of the percentage of average deviation adjustment.Coming up with the cylinder of influence to express the three-dimensional space of plant growth,based on the cylinder of influence,created the comprehensive-competition stress index and got the measure model was C-CSIi = 100(?)。(2)There were some difference in expressing trees competition by CSI and C-CSI,according to the reasons and the results of the competition,chose neighborhood comparison,health index,space density index,competition index based on intersection angle to compare the CSI and C-CSI,the results showed that the C-CSI was more accurate than CSI while evaluating trees competition.Compared the CSI and C-CSI in different diameter class and high order,it indicated that the larger the tree was,the weaker pressure of competition the tree got,at the same time,the greater the difference was between CSI and C-CSI.Analyzed the relation between the competition index of CSI,C-CSI,CI and the growth factor of DBH and height,it showed the imitative effect of C-CSI was more appropriate than CSI and CI,C-CSI can evaluate the pressure of tree competition more accurate than CSI and CI,also it indicated the necessity of considering the height of trees while evaluating the trees competition.(3)There were some different between the results of forest classification based on the CSI and C-CSI,the result of forest classification based on the C-CSI was better than CSI,in terms of the overall condition of four sample,dominant trees took the most,the competition pressure was not fierce,the growth condition was good,only a few forest tree cluster growth,belong to the suppressed tree and intermediate tree.(4)According to the results based on C-CSI,carried out a simulating forest thinning analysis to the sample plot Ⅲ and Ⅳ,the result showed that the average neighborhood comparison and average health index of the forest kept the same after intermediate cuttings,but the average growth space of trees increased obviously,there were no suppressed tree and intermediate tree in the forest.