Seasonal effects of snow cover on soil soluble carbon and nitrogen content and microbial activity
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摘要: 全球气候变暖问题日益严峻, 复杂的气候变化导致全球积雪格局发生明显变化。基于此, 本研究于2020年11月—2022年5月采用人工控制积雪深度的方法, 将试验区样地分为3个处理组, 分别为增雪组(TS)、除雪组(TR)和对照组(C), 通过测定土壤环境因子、有效碳氮含量、微生物量、脲酶活性以及蔗糖酶活性, 分析各指标的季节性动态变化过程。田间野外试验表明, 除雪处理会导致土壤温湿度显著降低。此外, 除雪处理在冬季早期显著增加了土壤无机氮含量, 加雪处理与之相反。从深雪期开始, 除雪处理在一定程度上造成了土壤无机氮的流失, 但增加了可溶性有机碳和可溶性有机氮含量。除雪处理使土壤微生物活性在冬季大部分时间保持较高水平, 但进入作物生长早期后, 除雪处理的土壤微生物活性明显降低。积雪的减少显著降低了土壤脲酶和蔗糖酶的活性, 积雪的加深与之相反。本研究证明了未来积雪变化将导致土壤有效碳氮及微生物活性的动态变化特征发生转变。研究结果为进一步探究气候变暖背景下中国东北黑土区的陆地生态系统的物质循环过程提供了一定理论基础和科学依据。Abstract: Global warming is becoming increasingly serious, and the complicated climate change situation has led to obvious changes in global snow cover patterns. Therefore, we explored the effects of future climate warming on the physical and chemical properties of black soil in Northeast China. This study adopted the method of artificial snow depth control from November 2020 to May 2022 and divided the plots in the test area into three treatment groups: snow increase (TS), snow removal (TR), and control (C). Soil environmental factors, available carbon and nitrogen contents, microbial biomass, urease activity, and sucrase activity were determined. The seasonal dynamic change process of each index was analyzed. Long-term field experiments shown that snow removal significantly reduced soil temperature and humidity. In addition, lower soil temperature and humidity accelerated the release of soil nutrients, and significantly increased the contents of soil nitrate nitrogen and ammonium nitrogen in early winter, while the opposite was true with snow increase treatment. However, from the beginning of the deep snow period, the snow-removal treatment caused a loss of soil inorganic nitrogen to a certain extent while increased contents of soluble organic carbon and nitrogen. The snow removal treatment maintained soil microbial activity at a high level for most of the winter. However, at the end of winter, owing to the rapid release of soluble organic matter under snow treatment, soil microorganisms under snow treatment absorbed a large amount of nutrients and exist in a more suitable soil environment, which significantly increases the soil microbial activity under the snow treatment. However, owing to the loss of heat insulation from snow cover, a large number of microorganisms decomposed and died at this time, which significantly reduced soil microbial activity. Before and after the test period, snow treatment significantly increased the soil microbial activity by 23.07 mg∙kg−1, and snow removal treatment significantly increased the soil microbial activity by 11.92 mg∙kg−1, with a difference of 93.5%. The decrease in snow cover significantly decreased the activities of soil urease and sucrase during most of the winter, and the activities of soil urease and sucrase were significantly increased by snow treatment. These results show that the activities of these two enzymes increased significantly by more than 10.5%. In summary, this study demonstrated that changes in snow cover in the future will lead to changes in the dynamic change characteristics of soil available carbon and nitrogen and microbial activity, and the influence of snow cover change on soil enzyme activity will also indirectly affect the soil nutrient cycling process and physical and chemical properties of soil. The results of this study provide a theoretical foundation and scientific basis for further research on the material cycle of terrestrial ecosystems in the black soil region of northeast China in the context of climate warming.
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图 2 不同处理下土壤有效碳氮含量变化特征
C: 正常积雪对照; TS: 积雪加深处理; TR: 除雪处理; BSC: 积雪形成前; ESC: 早雪期; DSC: 深雪期; SCM: 融雪期; EGS: 作物生长早期。不同小写字母表示不同处理在P<0.05水平差异显著。C: normal snow cover control; TS: snow deepening treatment; TR: snow removal treatment; BSC: before snow formation; ESC: early snow period; DSC: deep snow period; SCM: snowmelt period; EGS: early stage of crop growth. Different lowercase letters indicate significant differences at P<0.05 levels among different treatments.
Figure 2. Variation characteristics of soil available carbon and nitrogen under different treatments
图 3 不同处理下土壤微生物量碳氮含量变化特征
C: 正常积雪对照; TS: 积雪加深处理; TR: 除雪处理; BSC: 积雪形成前; ESC: 早雪期; DSC: 深雪期; SCM: 融雪期; EGS: 作物生长早期。不同小写字母表示不同处理在P<0.05水平差异显著。C: normal snow cover control; TS: snow deepening treatment TR: snow removal treatment; BSC: before snow formation; ESC: early snow period; DSC: deep snow period; SCM: snowmelt period; EGS: early stage of crop growth. Different lowercase letters indicate significant differences at P<0.05 levels among different treatments.
Figure 3. Changes of soil microbial biomass carbon and nitrogen contents under different treatments
图 4 不同处理下土壤酶活性变化特征
C: 正常积雪对照; TS: 积雪加深处理; TR: 除雪处理; BSC: 积雪形成前; ESC: 早雪期; DSC: 深雪期; SCM: 融雪期; EGS: 作物生长早期。不同小写字母表示不同处理在P<0.05水平差异显著。C: normal snow cover control; TS: snow deepening treatment; TR: snow removal treatment; BSC: before snow formation; ESC: early snow period; DSC: deep snow period; SCM: snowmelt period; EGS: early stage of crop growth. Different lowercase letters indicate significant differences at P<0.05 levels among different treatments.
Figure 4. Changes of soil enzymes activities under different treatments
表 1 试验区不同土层的物理性质
Table 1. Physical properties of different soil layers of the test area
土壤深度
Soil depth (cm)干容重
Dry bulk density (g∙cm−3)饱和含水率
Saturated moisture content (%)砂粒
Sand (%)黏粒
Clay (%)粉粒
Silt (%)0~20 1.46 43.30 46.4 37.5 16.1 20~40 1.50 42.50 45.0 40.6 14.4 40~60 1.52 40.11 47.3 38.7 14.0 60~100 1.57 40.85 42.2 40.9 16.9 100~140 1.60 40.23 36.5 48.5 15.0 140~180 1.61 40.02 42.5 43.8 13.7 -
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