杉木人工林单木断面积生长动态模拟

Individual Tree Basal Area Growth Dynamics of Chinese Fir Plantation

应用面板数据固定效应模型对杉木人工林单木断面积生长规律进行模拟,在模拟过程中,将胸径(DBH)和活冠比例(LCR)作为自变量,又分别加入密度因子和不同类型的竞争指数,同时引入立地条件和林龄效应来解释单木断面积生长过程中的异质性。结果表明:虽然密度因子与竞争指数有较强的相关性,但是在单木断面积生长中都具有不可忽略的重要影响。立地条件与林龄对单木断面积的拟合偏差在不同的林分密度下略有不同,随立地指数或者林龄增加,其对平均单木断面积拟合偏差的影响也增大。

The fixed-effect model for individual tree basal area growth modeling for Chinese fir（Cunninghamia lanceolata） in spacing plantations was developed using panel data.The heterogeneity of individual increment basal area among the different blocks was analyzed with independent variables（diameter of breast height（DBH） and live-crown ratio（LCR））,dummy variables with stand planting density,competition indices,and site and stand age effects.The result indicates that there is a strong relationship between stand planting density and competition indices,but both of them are important factors impacting individual increment tree basal area growth.The impact of site condition and stand age varies with different stand density.The fitting deviation of the average individual increment basal area increases along with site indices and stand ages.