摘要
Abstract
In order to establish Lariat principis-rupprechtii structure optimization plan based on spatial structure adjustment,22-and 40-year-old plantations in the central area of Qinling Mountains were selected as the research objects.Through the determination of stand cutting intensity and the application of spatial structure optimization technology,changes of forest stand spatial structure were analyzed quantitatively from the stand dominance and spatial structure characteristics,e.g.,uniform angle index (W),neighborhood comparison (U) and mingling (M) degree.The results showed that L.pricipis-rupprechtii was the dominant and constructive species of the tree layers.Before and after forest managements,the stand domi nance changed little,the tree species diversity remained the same in 22-year-old forest stand,but the stand dominance decreased a little in 40-year-old stand.Through the spatial structure adjustment of stand,in 22-year-old stand,the mean value of uniform angle index turned into 0.478 from 0.490,indicating the stand was more reasonable.The mean value of mingling degree changed form 0.283 into 0.396,meanwhile,the mean value of diameter at breast height (DBH) neighborhood raised from 0.450 to 0.497,and height neighborhood raised from 0.487 to 0.492.The advantage degree of individual tree growth was improved.In 40-year-old stand,the mean value of uniform angle index turned into 0.527 from 0.506,indicating the stand structure changed from slightly aggregative distribution to random distribution and the mean value of mingling degree raised from 0.348 to 0.477,showing that the mingling degree was improved significantly.The mean value of DBH neighborhood raised from 0.497 to 0.492,and height neighborhood raised from 0.493 to 0.498.These suggested that the stand structure was optimized significantly by stand selective cutting scheme based on the stand spatial structure analysis,and the scheme was the effective measure in improving the L.principis-rupprechtii plantation quality in the central area of Qinling Mountains.关键词
华北落叶松人工林/林分结构/优化Key words
Larix principis-rupprechtii plantation/forest stand spatial structure/optimization
