| Site classification and site quality evaluation are the basis of matching tree species with site and fully developing the potential of productivity.Moso bamboo(Phyllostachys edulis)forest is one of the most important forests in southern China.The current Moso bamboo forest site classification mainly adopts three-level or four-level classification system and is still not wholly connected with China forest site classification.Diameter at breast height(D)and bamboo height(H)are the commonly used indicators of site quality evaluation,but it is difficult to accurately evaluate the site quality for its singleness.Zhejiang Province is the main producing area of bamboo forest in China,thus study on site classification and site quality evaluation of Moso bamboo forest can provide a theoretical basis for cultivating effectively high-quality bamboo forests.Aiming at the current issues existing in site classification and site quality evaluation of bamboo forests,the study chose the Moso bamboo forests in Zhejiang Province as the object,based on the national forestry inventory data and the data obtained by surveying 115 temporary sample plots scattering in 10 counties that within the eastern,southern,western,northern and central part of Zhejiang Province,using the measured data of individual stem volume and biomass,to establish the stem volume and biomass models and quantitative models for predicting the site quality combining GIS technology.The main results were as followed:(1)The Moso bamboo site classification system was built and the forestland in Zhejiang Province was divided into 5 site regions,8 site sub-regions,20 site type districts,65 site type groups and 110 site types.(2)Drainage method was an effective approach to measure the stem volume by establishing and evaluating the stem volume models.(3)Using the log-regression fitting,the best bamboo stem volume model was binary based on the diameter at breast height(D)and the internode length at breast height(L),while the optimum model of stem biomass was a trigram-based one that contained D,L and bamboo age(A).And the model adjusted coefficient of determination of the two models were 0.964 9 and 0.900 4,respectively.(4)Stem volume and biomass of dominant individual bamboo were chosen as the dependent variables of quantitative site quality predicting models,which reached significance level by test(P<0.05).Stem volume of dominant individual was taken as the evaluation index of site quality in Moso bamboo forests from the conclusions of analysis,and it could be used to evaluate the site quality and site potential of forestland.(5)According to the stem volume and biomass of dominant individual and average bamboo of forestland,based on site quality predicting models,all sites in the study area were divided into five quality grades,five suitability grades and five site potential grades.Above 74% forestland and 79%bamboo forests within the province were suitable for bamboo growth,but the area with high site potential was merely up to 28%.The high-quality area of the bamboo forests in the province was distributed in the west,northwest and southwest of Zhejiang.(6)The average ratio of area with suitable productivity and high site potential of all site sub-regions in Zhejiang Province was 73.28% and 24.62%,inspectively.For the suitable area ratio,the sub-regions of mountainous area in southwestern Zhejiang was the highest,namely 93.87%,while the sub-regions of coastal hills in eastern Zhejiang was the lowest,namely 58.52%.Meanwhile,the area with high site potential at sub-regions of middle and low mountains in Western Zhejiang was up to43.19%,while the ratio of that was merely 5.15% at sub-regions of northern plain of Zhejiang. |
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