修枝强度和季节对杨树人工林生长的影响

Effects of Pruning Intensities and Pruning Seasons on the Growth Dynamics of the Poplar Plantation

以江苏省泗阳农场 8hm2 的试验林为基础 ,评价了修枝强度和修枝季节对I - 69杨人工林生长及萌枝发生数量的影响。该试验采用裂区设计 ,主处理为修枝强度 ,分为 3种水平(1 /3H、1 /2H和CK) ;副处理为修枝季节 ,分 2个水平 (生长季和非生长季 )。研究结果表明 ,修枝处理后当年 ,不同修枝强度的林分叶面积指数存在显著差异 ,中度修枝 (1 /2H)林分的叶面积指数仅为对照处理的 49% ,弱度修枝林分叶面积指数为对照的 84% ;不同修枝季节对杨树人工林的生长影响不显著 ,但对萌枝发生数量影响显著 ,非生长季修枝林分的萌枝发生数量比生长季修枝林分高出 79.8% ;与对照相比 ,修枝处理 4a后 ,其平均胸径和平均单株材积 ,都略有下降 ,但均未达差异显著水平 ;而不同修枝强度的林分枝下高存在显著差异 ,中度修枝林分枝下高可达 6m ,弱度修枝的林分为 4.5m左右 ,而对照处理仅为 2 .0m。

The effects of pruning intensities and pruning seasons on the growth dynamics and the number of epicormic branches produced for a clone I-69 plantation were evaluated at Siyang Farm, Siyang County, P.R.China. Experimental treatments applied in a split plot design included: three pruning intensities (1/3 H , 1/2 H and CK), and two pruning seasons (growing season and non-growing season). Results indicated that difference in leaf area index (LAI) between the pruning intensities was manifested in the year after pruning. The LAIs of middle pruning intensity (1/2 H ) and slight pruning intensity (1/3 H ) were only 49% and 84% of the CK (unpruned trees) respectively. There was no significant difference in DBH and single-tree volume between two pruning seasons and three pruning intensities at 4 years after pruning. However, the number of epicormic branches was affected considerably by the pruning seacons. The number of epicormic branches in the stands pruned in non-growing season was 79.8% higher than that in growing season. The tree height of non-adhering knot was significantly affected by the pruning intensities at 4 years after pruning, 6.0m for the stand with middle pruning intensity, about 4.5?m for the slight pruning intensity and only 2.0?m for the unpruned stand.