College of Resources and Environment Science, Xinjiang University, Urumqi, 830046, China.
Key Laboratory of Oasis Ecology, Ministry of Education, Urumqi, 830046, China.
Sci Rep. 2020 Nov 11;10(1):19556. doi: 10.1038/s41598-020-76368-9.
Seasonal snowfall, a sensitive climate factor and the main form of precipitation in arid areas, is important for forest material circulation and surface processes and profoundly impacts litter decomposition and element turnover. However, how the thickness and duration of snow cover affect litter decomposition and element release remain unclear. Thus, to understand the effects of snow on litter decomposition, fiber degradation and their relationships with soil properties, a field litterbag experiment was conducted under no, thin, medium, and thick snow cover in a Schrenk spruce (Picea schrenkiana) forest gap in the Tianshan Mountains. The snow cover period exhibited markedly lower rates of decomposition than the snow-free period. The litter lignin, cellulose and N concentrations in the pregrowing season and middle growing season were significantly higher than those in the deep-freeze period, and the litter C and P concentrations were significantly higher during the onset of the freeze-thaw period, deep-freeze period and thaw period than in the late growing season. The litter cellulose, C and N concentrations were significantly higher under thick snow cover than under no snow cover in most stages. Moreover, the correlations among litter mass, cellulose, lignin/cellulose and soil bulk density varied with snow cover depth. The temporal variations and snow cover depth affected the decomposition process significantly. The former affected lignin, cellulose and P, and the latter affected cellulose, C and N and changed the litter-soil properties relationship. These differences provide references for understanding how winter conditions affect material cycling and other ecological processes under climate change.
季节性降雪是一种敏感的气候因素，也是干旱地区的主要降水形式，它对森林物质循环和地表过程非常重要，深刻影响着凋落物分解和元素周转。然而，积雪的厚度和持续时间如何影响凋落物分解和元素释放仍不清楚。因此，为了了解雪对凋落物分解、纤维降解及其与土壤性质关系的影响，在天山山间断陷谷云杉（Picea schrenkiana）林隙中开展了无雪、薄雪、中雪和厚雪覆盖条件下的野外凋落袋实验。结果表明，雪覆盖期的分解速率明显低于无雪期。在预生长季和中生长季，凋落物木质素、纤维素和 N 浓度显著高于深冻期，在冻融期、深冻期和解冻期，凋落物 C 和 P 浓度显著高于晚生长季。在大多数阶段，厚雪覆盖下凋落物纤维素、C 和 N 浓度显著高于无雪覆盖。此外，凋落物质量、纤维素、木质素/纤维素与土壤容重之间的相关性随积雪深度而变化。时间变化和积雪深度对分解过程有显著影响。前者影响木质素、纤维素和 P，后者影响纤维素、C 和 N，并改变凋落物-土壤性质关系。这些差异为了解冬季条件如何在气候变化下影响物质循环和其他生态过程提供了参考。
