Study on accurate dominant tree selection method in Cunninghamia lanceolata mountain plantation | 山地杉木人工林优势木选择方法的研究

Chinese. 比较9种优势木选择方法的选择效果，以精确评价山地人工林的立地质量。基于福建邵武卫闽林场连续观测26年的杉木密度试验林数据，比较最高株法和分层法2类共9种优势木选取方法对山地杉木人工林林分立地指数的影响；分析初植密度对林分蓄积的影响，并以林分蓄积作为评价立地质量的依据，对9种方法所确定的优势高与5，10，14，20，24和26年生时杉木人工林的林分蓄积进行相关分析。分层法所确定的优势木在样地内分布的均匀性明显优于最高株法；选择的优势木株数相同时，最高株法所确定的立地指数均高于分层法；随着林龄的增加，初植密度对林分蓄积影响的差异逐渐减小，24年生时林分蓄积趋于相等；随着林龄的增加，林分蓄积与9种方法所确定立地指数的相关性均逐渐增大，从10年生起达到显著水平，20年生起达到极显著水平，在26年生时相关系数达到最大；以20年生作为杉木人工林林分的基准年龄，此时采用分层法确定的优势高与林分蓄积的相关性均优于最高株法，且此时采用9种方法确定的优势高与26年生时的林分蓄积均达到了极显著相关。选择20年为基准林龄评价杉木人工林的立地质量是合理的；优势木在样地内分布的均匀性对山地杉木人工林立地质量的准确评价有重要影响，分层法确定的优势木在林分中的分布更均匀，同时考虑野外调查时的便捷性，推荐采用分层法中的5株法和固定6株法来选择山地林分中的优势木。

English. For the purpose of valuing site quality accurately, effects of several dominant trees selestion methods were compared. Based on data from 26-year-old Cunninghamia lanceolata density experimental stands in Weimin forestry farm, Shaowu city, Fujian Province, effects of the two types of dominant tree selestion methods, highest-tree method and layer methods (total 9 methods), on site indices of plots in mountain were analyzed. The impact of planting density on stand volume growth was analyzed, and the stand site quality was valued in terms of stand volume. The correlations between dominant height from 9 methods and Chinese fir plantation volume at stand age of 5, 10, 14, 20, 24, 26 years were analyzed. The uniformity of dominant trees by layer methods is better than that by highest-tree method; When the number of dominant tree is uniform, the site index by highest-tree method is higher than that by layer method; The stand volume in stand with the same site index and different planting density was analyzed. The effects of planting density on stand volume decrease with stand age, and the volume tends to be equal at 24 years old; The correlation between stand volume and site index by 9 methods increases gradually with stand age, significant at 10 years old, very significant at 20 years old and the correlation coefficient is the biggest at 26 years old. So, 20 years old is taken as base-age in Chinese fir plantation, and at this stand age, the correlation between dominant height by layer method and stand volume is better than that by highest-tree method, the correlation between dominant height by 9 methods and stand volume at 26 years old is very significant. So choosing 20 years as base-age for valuing the site quality of Chinese fir plantations is reasonable. The uniformity of the dominant trees is very important for valuing mountain Chinese fir stand quality accurately. Dominant trees chosen by layer method scatter more uniformly than that by highest-tree method. In consideration of measure convenience, we think the methods of F5 and GD6 are better than the other methods, and should be applied to forest management in the future.