Acid Hydrolysable Components Released from Four Decomposing Litter in an Alpine Forest in Sichuan, China

Acid hydrolysable components have been thought to release from plant litter at early periods of decomposition and to be sensitive to hydrological change. Variations in snow depth and timing may alter the release of acid hydrolysable components from decomposing litter in seasonally snow-covered ecosystems. Here, we measured the release of acid hydrolyzable components from four foliar litters (fir, cypress, larch and birch) in deep and shallow snow plots during winter (snow formation, snow coverage and snowmelt stages) and growing seasons in an alpine forest from 2012 to 2016. We found that the content of acid hydrolysable components was 16-21% in fresh litter across species, and only 4-5% of these components remained in the litter after four years of decomposition when 53-66% of litter mass was lost. The content of acid hydrolysable components greatly decreased within 41 days and during the growing seasons of the fourth year of decomposition, suggesting that acid hydrolysable components in plant litter are not only released at early periods but also at a very late period during litter decay. However, the content of acid hydrolysable components increased significantly at snowmelt stages. Reduced snow cover increased the content and remaining level of acid hydrolysable components during the four years of decomposition by altering leaching, microbial biomass and stoichiometry. We propose that more effective partitioning of chemical fractions should be incorporated to distinguish the carbon and nutrient release during litter decomposition within a complex context of the changing environment.

Automated summary

This study found that acid hydrolysable components in plant litter are released not only in the early stages of decomposition but also in the very late stages. The content of these components significantly increased at the snowmelt stages. Reduced snow cover increased their content and remaining level during the four years of decomposition by altering leaching, microbial biomass, and stoichiometry. Therefore, considering the effects of changing environmental factors on chemical partitioning is important in studying litter decomposition.