不同劈草时间毛竹林的生长特征

The Growth Characteristics of Phyllostachys pubescens Forest at Different Operation Time

林分结构是林分各项功能正常发挥的保证,探索经营时间梯度上的竹林结构特征,可以为制定合理的结构调整技术提供理论支持。本文对不同劈草时间毛竹林的生长特征及其影响因子进行了调查研究。结果表明,胸径、树高和新生竹株数与经营时间显著或极显著相关。随着经营时间的延长,毛竹林胸径、树高呈先上升后下降的趋势,新生竹株数呈下降趋势。经营10 a后毛竹林平均胸径从8.52 cm增加到11.24 cm,提高了31.92%;随着经营时间的进一步延长,毛竹林平均胸径逐渐降低,到经营30 a时胸径下降到9.71 cm,下降了13.61%。经营10 a后毛竹树高达到14.79 m,比未经营毛竹林平均树高提高了19.18%;随着经营时间的延长,平均树高逐渐降低,30 a时降低为13.65 m,比10 a时的树高降低了7.71%,为长时期经营毛竹林生产力退化提供了重要证据。通径分析表明,经营时间对毛竹林胸径和树高的直接和间接通径系数均最大,胸径和树高可以作为反映毛竹林退化的指标。

The function of forest stand is based on the structure of forest.To explore the bamboo structure at operating time can provide theoretical support for the reasonable structure-adjustment technology.The growth characteristics and influence factors were investigated in bamboo forest.The results showed that there was extremely significant correlation between the operation time and the DBH,height of bamboo as well as the number of new bamboo.The DBH and height of bamboo increased in the first ten years,and then decreased with the operation time.The number of new bamboo decreased with the operation time.The DBH reached the maximum 11.24 cm,and the height of bamboo reached the maximum 14.79 cm within ten years.Afterwards,both the DBH and the height of bamboo decreased gradually.30 years later,the DBH decreased by 13.61% and the height of bamboo decreased by 7.71%.The results can be evidence for the argument of productivity degradation of bamboo forest with operation time.The path analysis showed that both direct path coefficient and indirect path coefficient of operation time to DBH and height of bamboo were largest.Therefore,the index of DBH and height of bamboo can reflect the productivity degradation of bamboo with operation time.