微生境对华山松人工林天然更新的影响

Effects of microhabitat on natural regeneration of artificial Pinus armandii plantation

【目的】探讨华山松人工林天然更新与微生境因子间的关系,为指导华山松人工林科学经营提供参考依据。【方法】以华山松为研究对象,在甘肃小陇山林区分别在阳坡、阴坡设置20m×20m典型样地各4个,分别调查弱度(20%)、中度(30%)和强度(40%)3种间伐强度处理下,华山松林分的光照强度、空气温度、空气湿度、土壤含水率、凋落物厚度、灌木层盖度、草本层盖度7项微生境因子特性及相应区域的幼苗、幼树更新数量,并采用通径分析法对二者的相关性进行分析。【结果】(1)华山松幼苗更新数量和种群更新潜力随着间伐强度增大而增大,但坡向因子对幼苗幼树数量和种群更新潜力均未产生显著影响。(2)微生境异质性对华山松天然更新有显著影响,土壤含水率和凋落物厚度对幼苗发生数量起主要负向作用,光照强度和灌草层盖度起正向作用。(3)在华山松幼苗向幼树生长的过渡阶段存在明显障碍现象,幼树死亡率较高,林下光照不足是制约华山松完成天然更新的重要原因。【结论】对华山松人工林经营管理时,应采取抚育间伐结合清理林下凋落物的方式,以便为幼苗定居和生长发育提供较好的环境条件,利于种群更新潜力的提升。

【Objective】This paper explored the relationship between microhabitat and natural regeneration in Pinus armandii plantation to provide basis for plantation scientific management.【Method】Four typical sample plots of 20 m×20 m were set for P.armandii in sunny and shady slopes were set in Xiaolongshan forestry area to investigate the microhabitat characters under light（20%）,medium（30%）and heavy（40%）thinning intensities.Seven microhabitat characteristics including light intensity,air temperature,air humidity,soil moisture content,thickness,coverage of shrub,and herbage of coverage were related to number of seedlings and saplings using path analysis.【Result】（1）The number and population regeneration potential of P.armandii seedlings increased with the increase of thinning intensity,but the slope had no significant effect.（2）The P.armandii natural regeneration was significantly affected by microhabitat heterogeneity.Soil water content and litter thickness played a major negative role in seedling germinationnumber,while light intensity and shrub-grass coverage had a positive effect.（3）Difficulties existed in the growth stage that P.armandii seedling transited to sapling,and the sapling death rate was high.Light insufficiency in the understory was a major reason restricting P.armandii natural regeneration.【Conclusion】To provide a better environment for seedling settlement and its growth,intermediate cutting combined with litter cleaning in the understory is suggested for P.armandii plantation operation and management.It is also conductive to the increase of population regenerative potential.