广西大瑶山保护区不同森林类型凋落物的持水与失水特性

Water-holding and water-losing characteristics of litter in different forest types in Dayaoshan Reserve, Guangxi

关键词:  广西大瑶山, 森林水文, 凋落物, 持水量, 有效拦蓄量, 水文效应

Key words:  Guangxi Dayaoshan, forest hydrology, litter, water-holding capacity, effective interception capacity, hydrological effect

摘要:

森林凋落物持水与失水特性是调控森林生态系统水文过程的关键环节,但当前对不同森林类型的凋落物层水文功能的定量表征与解析仍显不足。为明确广西大瑶山国家级自然保护区主要森林类型凋落物的持水与失水特性,该研究通过野外样地调查与室内控制试验相结合的方法,对保护区内常绿阔叶林(EBF)、针阔混交林(MCBF)及山顶矮林(MEF)3种典型森林类型的凋落物现存量、持水动态过程及失水动态过程进行测定,进而评估其水源涵养能力。结果表明:(1)3种森林类型凋落物总储量介于2.28～5.33 t·hm^-2之间,表现为EBF>MCBF>MEF。(2)凋落物持水量(Q)、吸水速率(V)与浸水时间(t)关系式分别为Q=aln(t)+b、V=ktⁿ; 失水量与风干时间呈显著对数关系(R²>0.95,P<0.05),失水速率与风干时间呈显著幂函数关系(R²>0.95,P<0.05)。(3)有效拦蓄率变化范围为49.46%～116.13%,有效拦蓄量为0.41～3.09 t·hm^-2,其中EBF和MCBF均显著高于MEF(P<0.05)。综上,广西大瑶山保护区不同森林类型凋落物在水文调节效能上存在显著性差异,EBF不仅具有最高的降雨截留容量且表现出更优的持水与释水协调性。该研究结果可为亚热带山地森林水源涵养功能的精准评估、生态效益量化及保护管理决策提供实证依据与参数支撑。

Abstract:

The water-holding and water-losing characteristics of forest litter are critical components regulating hydrological processes in forest ecosystems. However, the quantitative characterization and mechanistic analysis of the hydrological functions of the litter layer across different forest types remain largely inadequate to date. To clarify the water-holding and water-losing characteristics of litter in major forest types in the Dayaoshan National Nature Reserve, Guangxi, this study employed a combination of field plot surveys and laboratory-controlled experiments to determine the litter standing crop, dynamic water-holding processes, and dynamic water-losing processes of three typical forest types in the reserve, namely evergreen broadleaf forest(EBF), mixed coniferous-broadleaf forest(MCBF), and montane elfin forest(MEF). Furthermore, their water conservation capacity was evaluated. The results were as follows:(1)The total litter accumulation of three forest types ranged from 2.28 to 5.33 t·hm^-2, with the order of EBF> MCBF> MEF.(2)The relationship between water-holding capacity(Q)and immersion time(t)followed the logarithmic function [Q=aln(t)+b], and the relationship between water-absorption rate(V)and immersion time(t)followed the power function(V=ktⁿ); there was a significant logarithmic relationship between water-losing capacity and seasoning time(R²>0.95, P<0.05), whereas a significant power function relationship was found between water-losing rate and seasoning time(R²>0.95, P<0.05).(3)The effective interception rate ranged from 49.46% to 116.13%, and the effective interception capacity ranged from 0.41 to 3.09 t·hm^-2. Among them, the effective interception capacity of EBF and MCBF was significantly higher than that of MEF(P<0.05). In conclusion, there were significant differences in the hydrological regulation efficiency of litter among different forest types in the Dayaoshan Reserve, Guangxi. EBF not only had the highest rainfall interception capacity but also exhibited better coordination between water-holding and water-release. The results of this study can provide empirical basis and parameter support for the accurate evaluation of water conservation functions, quantification of ecological benefits, and protection and management decisions of subtropical montane forests.