天宝岩不同类型长苞铁杉林枯落物持水特性

Water-holding characteristics of litter in different types of Tsuga longibracteata forests in Tianbaoyan National Nature Reserve

为了解长苞铁杉林枯落物的持水特性以及水文变化过程,进一步揭示长苞铁杉林幼苗天然更新困难的内在机制,以天宝岩国家级自然保护区4种类型长苞铁杉林为对象,对其枯落物层持水特性进行研究.结果表明:(1)4种类型长苞铁杉林枯落物层平均厚度在19~34 mm,枯落物蓄积量为10.22~24.98 t·hm^(-2),枯落物蓄积量以长苞铁杉和猴头杜鹃为建群种的类型Ⅰ最大;(2)枯落物最大持水率为149.94%~223.47%,最大持水量为11.91~34.42 t·hm^(-2),最大拦蓄量为15.32~48.84 t·hm^(-2),有效拦蓄量为8.38~18.43 t·hm^(-2);(3)不同林分类型枯落物持水量与浸泡时间以及吸水速率与浸泡时间的动态变化规律基本一致,枯落物浸泡6 h后,其持水量基本达到最大值,吸水速率明显减缓;(4)枯落物的持水量与浸泡时间呈明显的对数关系(R2>0.96),吸水速率与浸泡时间呈明显的幂函数关系(R2>0.99).

Forest litter plays a central role in water inception, nutrient cycling and soil conservation. To elucidate the regeneration problem of Tsuga longibracteata seedling, a preliminary study on water-holding characteristics of litter in 4 types of T.longibracteata-based mixed forests was carried out in Tianbaoyan National Nature Reserve. Results showed that average litter thickness ranged from 19 to 34 mm, and storage capacity varied between 11.91 and 34.42 t·hm^-2 , with the thickest litter and largest storage capacity be-ing in forest that dominated by mix forest of T.longibracteata and Rhododendron simiarum hance. Variations in water-holding capaci-ty, water absorption rate and immersion time of litter were basically similar among 4 forest types, which was that water-holding ca-pacity of litter peaked 6 hours after immersion and after that absorption rate slowed down. Maximum water-holding rate, water-hold-ing capacity, interception capacity and modified interception capacity of litter in 4 forest types approximated at 149.94%-223.47%, 11.91-34.42 t·hm^-2 , 15.32-48.84 t·hm^-2 and 8.38-18.43 t·hm^-2 , respectively. Water-holding capacity of litter had a visible logarithmic correlation with immersion time （R^2〉0.96）, and there existed a significant power function relationship between water absorption rate and immersion time （ R^2〉0.99） .