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采用标准样地调查法对防护林林分结构指标进行调查,研究河北坝下地区丰宁县小坝子乡不同防护林树种榆树、杨树及油松的动态变化规律.结果表明:该区域榆树、杨树和油松纯林的平均年龄均为10年,杨树纯林的平均胸径和树高分别是榆树纯林的2.3和3.8倍,是油松纯林的2.3和3.0倍.杨树纯林的平均胸径、树高、叶面积指数(LAI)、活枝下高等指标显著大于榆树纯林和油松纯林.与杨树混交林相比,杨树纯林的林分密度高10.8%,纯林平均胸径则低5.2%,平均树高低11.3%;与榆树混交林相比,榆树纯林的林分密度高6.6%,纯林平均胸径、树高分别低7.8%和14.2%;与油松混交林相比,油松纯林的林分密度大4.9%,纯林平均胸径和树高分别低29.3%和31.8%.各林分类型的平均胸径、树高与密度呈显著负相关;平均LAI与密度和活枝下高呈显著正相关,与胸径、树高呈显著负相关;平均活枝下高与密度呈显著正相关.针阔混交林的胸径和树高生长显著优于针叶纯林.该区域防护林综合生长潜力呈上升趋势,而横向生长潜力总体上呈下降趋势.
The standard plot survey was used to investigate the structure of shelterbelts to investigate the dynamic changes of elm, poplar and Pinus tabulaeformis trees in Xiaobazi Township, Fengning County, Hebei Province. The results showed that the elm, poplar and Pinus tabulaeformis The average age of pure forests are 10 years, the average diameter at breast height of pure poplar and tree height were 2.3 and 3.8 times the pure elm trees, respectively, 2.3 and 3.0 times the pure Pinus tabulaeformis pure forest average diameter at breast height, leaf height LAI and live branches were significantly higher than pure stands of elm and pure stands of Pinus tabulaeformis forest.Compared with poplar mixed forest, stand density of poplar pure forest was 10.8% higher than that of pure mixed forest and average forest diameter was 5.2% Compared with the elm mixed forest, the stand density of elm pure forest was 6.6%, and the average DBH of pure forest was 7.8% and 14.2% lower than the tree height respectively. Compared with the mixed forest of Pinus tabulaeformis forest, The mean DBH and tree height were 29.3% and 31.8% lower than the average DBH, and the mean DBH, tree height and density were negatively correlated with each other. The average LAI was positively correlated with the density and live branch height , But negative correlation with DBH and tree height There was a significant positive correlation conifer tree diameter and height growth significantly better than coniferous. Comprehensive Shelter growth potential in the region is rising, while the lateral growth potential decreased as a whole.