Density Effect On Biomass Of Pinus Masstniana Plantation In Southern Jiangxi Province

Stand density regulation is the main means of forest management.Reasonable management density is an important way to improve forest quality and maximize the function of forest ecology.Stand biomass is an important indicator to measure forest productivity,and its size is directly affected by stand density.Pinus massoniana is an important timber planting species in southern China,which has high economic and ecological value.Taking Pinus massoniana plantation in Jiangxi Province as the research object,the stand density management diagram and the density regulation diagram of biomass were compiled and the accuracy test was carried out through the data sorting,processing and model construction as well as the biomass density regulation diagram was applied.The research results can provide reference for the scientific management of Pinus massoniana plantation in southern Jiangxi.The main findings and conclusions are as follows:(1)The models of equivalant height curves,equivalent diameter curves,full density curve,forest closeness curves and self thinning curves were established respectively,and the curve was compiled to compose the stand density management diagram.Each management curves conformed to the law of forest density effect.The stock volume corresponding to the height and diameter contours increases with the increase of density.The stock volume which corresponds to the maximum density line and the isosparse density line decreases with the increase of density.The self-thinning line indicates that under the condition of given initial planting density of stand the stock volume increases with the decrease of density.Accuracy testing was carried out with the equivalent height curve and the equivalent diameter curve.The accuracy of equivalent height curve was79.24%,and that of the equivalent diameter curve was 81.94%.(2)The tree biomass data was estimated and the density and the biomass function models of each tree grade and diameter grade were constructed by the conversion relationship between biomass and accumulation.The biomass density regulation diagram of Pinus massoniana forest was also compiled.The biomass corresponding to the height and diameter contours increases with the increase of density.The stand biomass on the maximum density line and the isosparse density line decreases with the increase of density.The self-thinning line indicates that under the condition of given initial planting density of stand,the biomass increases with the decrease of density.The accuracy of the equivalent height curve and the equivalent diameter curve was 76.72%and 82.02%respectively by accuracy testing.(3)Three kinds of different density grades of Pinus massoniana sample plots were selected with a site index of 14 to analyze the application of regulation diagram of biomass density.According to the growth prediction of Pinus massoniana plantation with different densities,the change rule of biomass was that the biomass of individual tree decreased with the increase of density in low,medium and high density stands,and the biomass of tree layer increased with the increase of density in low,medium and high density forests.However,the growth of medium density forests was the largest,which was more reasonable management density,and its density was 1300-1500 plants/hm~2.