川西亚高山森林苔藓与枯落物持水特征

Water Holding Capacity of Bryophytes and Litter in Subalpine Forest in Western Sichuan,China

森林苔藓和枯落物在水土保持、水分涵养方面具备重要作用,但现有研究多单一关注苔藓或枯落物,对苔藓-枯落物层的整体效应的认识较少,尤其针对高海拔西南森林林下的苔藓-枯落物层,更为鲜见。本文以川西贡嘎山针叶林和阔叶林地被层(苔藓、枯落物)为研究对象,通过野外调查、采样瓶取样浸水试验,分析了单一苔藓、单一枯落物及苔藓-枯落物整体的持水特征。结果表明:(1)贡嘎山苔藓和枯落物最大持水率为327.9%~432.6%,最大持水量为16.6~79.4 t/hm^(2),有效拦蓄量为7.1~34.2 t/hm^(2)。针叶林比阔叶林具有更大的持水能力和水分拦蓄能力。(2)不同地被组分中,苔藓-枯落物层持水率、有效拦蓄率、持水量和拦蓄量最大,苔藓显著提高了针叶林地被层的水源涵养能力;(3)地被层持水量与时间呈对数关系,吸水速率与时间呈幂函数关系,不同组分持水量和持水率均在0~2 h内迅速增长,2~12 h内缓慢增长,12 h时几乎达到饱和状态。(4)与单一苔藓或枯落物层相比,苔藓-枯落物整体的吸水速率更快,具有更高效的短期降水拦蓄能力。本研究结果可为亚高山森林水源涵养和生态水文研究与保护提供参考和理论基础。

Forest bryophyte and litter jointly plays an important ecological role in soil and water conservation.Most of previous studies paid attention to bryophyte or litter alone on its eco-hydrological role,but neglected the comprehensive function of bryophyte-litter layer as a coupling component of forest ecosystem;especially for the bryophyte-litter layer in some high-altitude southwest forest of China,the related research was rare.Forest in the Gongga Mountain is a type of alpine ecosystem with rich coniferous and broad-leaved vegetation in western Sichuan of China,enriched by an abundance of bryophyte and litter under forest canopy.Examining the hydrological impact of the bryophyte-litter layer can provide valuable insights into the water conservation capacity of the forest floor.This study aimed to investigate the water-holding capacity of bryophyte and litter on the forest floors of the Gongga Mountain,which has coniferous and broad-leaved vegetation cover.The study was conducted through field research and immersion tests using sampling bottles.The study revealed following facts:(1)The maximum water-holding capacity of bryophyte and litter in the Gongga Mountain ranged from 327.9%to 432.6%,with a maximum water retention capacity of 16.6-79.4 t/hm^(2) and an effective interception capacity of 7.1-34.2 t/hm^(2).As compared with broad-leaved forests,coniferous forests exhibited more significant water-holding and interception capabilities.(2)Among the ground layer components,bryophyte and bryophyte-litter layer demonstrated the highest water retention capacity and effective interception rate,and hence the bryophyte-litter and litter layer displayed the highest water holding and interception capacities.Bryophyte significantly enhanced the water conservation capacity of the ground layer in coniferous forests.(3)The water-holding capacity of the ground layer exhibited a logarithmic relationship with time,and the water absorption rate indicated a power function relationship with time.The water-holding capacity and absorption rate of different ground layer components increased rapidly within 0-2 h,followed by a slow increase within 2-12 h,and then nearly reached saturation after 12 h.(4)The overall water-holding capacity of the bryophyte-litter layer was equivalent to the sum of the water holding capacities of the bryophyte and litter layer.However,the water absorption rate of the bryophyte-litter layer was higher,rendering it more efficient in intercepting short-term precipitation.Our findings provide reference and a theoretical basis for further research and practices related to water conservation and ecological hydrology in subalpine forests.