Effects of Snow Cover on Carbon Dioxide Emissions and Their δ13C Values of Temperate Forest Soils with and without Litter
Effects of Snow Cover on Carbon Dioxide Emissions and Their δ13C Values of Temperate Forest Soils with and without Litter
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DOI：
10.3390/f14071384
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发表时间：
2023-07
期刊：
影响因子：
2.9
通讯作者：
Xingkai Xu;H. Wu;Jin Yue;Shuirong Tang;W. Cheng
中科院分区：
文献类型：
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作者：
Xingkai Xu;H. Wu;Jin Yue;Shuirong Tang;W. Cheng
凋落物和冬季积雪的存在会影响森林土壤有机质的分解和土壤呼吸CO2的δ 13 C值的变化。然而，有限的信息是从森林土壤的CO2排放量和δ 13 C值的响应，积雪和凋落物增加了一年。利用中国东北两个典型温带森林的原状土柱，研究了人工雪覆盖对土壤异养呼吸及其δ 13 C值的影响。根据研究区森林表层土壤一年四季的平均温度，在实验室条件下依次模拟了秋季冻融、冬季冻融、春季冻融和生长季。采用一套新型的分析系统，包括自动化箱设备和激光光谱分析，并结合高频测量CO2浓度和CO2中13 C/12 C同位素比值，研究了人工积雪和凋落物对土壤异养呼吸及其δ 13 C值的影响。在秋季冻融模拟过程中，大雪覆盖下土壤CO2排放量和负δ 13 C值均大于小雪覆盖下，表明冬季冻融前积雪覆盖的增加会增加温带森林下土壤有机C的分解。各处理土壤呼吸CO2的δ 13 C值随着模拟春季冻融的进行，平均负值减小，这与模拟秋季冻融过程中δ 13 C的变化相反。春季冻融模拟的土壤异养呼吸和δ 13 C值均表现为大雪覆盖时小于小雪覆盖时，与秋季冻融模拟和生长季模拟的结果不同。研究结果表明，积雪对温带森林土壤异养呼吸及其δ 13 C值的影响可能因季节和凋落物的存在而异。
The presence of litter and winter snow cover can affect the decomposition of organic matter in forest soils and changes in δ13C values of soil-respired carbon dioxide (CO2). However, limited information is available on the responses of CO2 emissions from forest soils and their δ13C values to snow cover and litter addition over the year. We experimentally manipulated snow cover to study the impacts of light and heavy artificial snow cover on soil heterotrophic respiration and its δ13C values, using undisturbed large soil columns collected from two typical temperate forests in Northeastern China. Based on the average temperatures of surface forest soils in four seasons of the year in this study region, the simulations of autumn freeze–thaw, winter freeze, spring freeze–thaw, and the growing season were sequentially carried out under laboratory conditions. A set of novel analysis systems, including automated chamber equipment and laser spectroscopy analysis with high-frequency measurements for CO2 concentrations and the 13C/12C isotopic ratios in CO2, was used to study the effects of artificial snow cover and the presence of litter on soil heterotrophic respiration and its δ13C values. During the autumn freeze–thaw simulation, there were larger CO2 emissions and less negative δ13C values of soil-respired CO2 upon heavy snow cover than upon light snow cover, indicating that the presence of increased snow cover prior to winter freeze can increase the decomposition of organic C in subsurface soils under temperate forests. The δ13C values of soil-respired CO2 in all treatments were, on average, less negative as the simulated spring freeze–thaw proceeded, which was contrary to the variations of the δ13C during the autumn freeze–thaw simulation. Soil heterotrophic respiration and its δ13C values during the spring freeze–thaw simulation were, on average smaller upon heavy snow cover than upon light snow cover, which differed from those during the autumn freeze–thaw and growing season simulations, respectively. Taken together, the results highlight that the effects of snow cover on soil heterotrophic respiration and its δ13C values under temperate forests may vary with different seasons of the year and the presence of litter.