Changes in snow-depth induced by climate change affect biogeochemical cycles through altering the frequency of soil freeze-thaw cycle, soil temperature, soil moisture, soil microbial community structure and leaching effect of melting snow. Accordingly, increases or decreases in snow-depth affect the process of foliar litter decomposition.
As the major constituent of plant litter, the degradation of foliar litter lignin and cellulose is therefore a key factor controlling soil organic matter formation. However, little information is available on how alterations in snow-depth influence the degradation of foliar litter lignin and cellulose, and there is still a gap in exploring C dynamics in forest ecosystems under the scenarios of climate change.
To assess effects of snow-depth on the degradation of foliar litter lignin and cellulose, a snow-depth manipulation experiment including treatments of control, snow-addition and snow-removal was conducted in Northeast China. Foliar litter of Pinus koraiensis and Quercus mongolica were placed on top of the ground in each treatment and sampled for six times from November 2014 to October 2015.
Results/Conclusions
Lignin and cellulose degradation rates decreased with the reduction of snow-depth during the snow-covered season because of the insulating effect provided by snowpack; this relationship was reversed during the snow-free season due to more labile carbon remaining after the snowmelt. During the snow-covered season, lignin and cellulose degradation rates were positively correlated to the sum of degree days above 0 oC. Additionally, lignin degradation rate was also negatively correlated to the litter initial C/N ratio during the snow-covered season. In contrast, lignin and cellulose degradation rates were positively correlated with litter microbial biomass carbon during the snow-free season.
The alterations in snow-depth play an important role in determining the degradation of foliar litter lignin and cellulose, but the directions and drivers were determined by depth and season, suggesting that the reduced or increased snow-depth resulting from climate change could limit or promote lignin and cellulose degradation rates, respectively. Therefore, we need to improve our understanding on the biogeochemical cycle experiencing significant seasonal snowpack under climate change scenarios. It is conducive to enhancing our mechanistic understanding of plant-soil interactions.