Water Holding Capacity of Bryophytes and Litter in Subalpine Forest in Western Sichuan,China
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/hm2 and an effective interception capacity of 7.1-34.2 t/hm2.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.
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