| 增温和增雨对黄土丘陵区撂荒草地土壤呼吸的影响 |
| 摘要点击 1921 全文点击 534 投稿时间：2021-06-11 修订日期：2021-08-03 |
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| 中文关键词 气候变化 撂荒草地 活性有机碳 土壤呼吸速率 呼吸温度敏感性 |
| 英文关键词 climate change abandoned grassland labile organic carbon soil respiration rate temperature sensitivity of soil respiration |
| 作者 | 单位 | E-mail | | 王兴 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | wangxing1996@nwafu.edu.cn | | 钟泽坤 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | | | 朱玉帆 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | | | 王佳懿 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | | | 杨改河 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | | | 任成杰 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | | | 韩新辉 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100 | hanxinhui@nwsuaf.edu.cn |
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| 中文摘要 |
| 明确气候变化背景下脆弱生境地区生态系统土壤呼吸的变化趋势及驱动因素，对理解区域碳循环以及生态系统碳源汇功能转换具有重要意义.以陕北黄土丘陵区自然撂荒恢复12 a的草地为研究对象，采用人工气候箱（OTC）和人工增加自然降雨的方式模拟了气候变暖、降水增加及其交互作用.通过结合野外监测与室内分析，探究了土壤水热、养分和土壤呼吸速率对增温增雨的响应特征，并进一步分析了影响土壤呼吸改变的关键因素.结果表明：①增温显著提高了5 cm土壤温度，在整个取样年平均增加1.34℃，而增雨显著降低了5 cm土壤温度，在整个取样年平均降低了0.88℃，同时增加了土壤水分含量，2018年和2019年增雨处理土壤水分含量分别高出对照13.12%和16.45%.此外，与对照相比，增温增雨的交互作用既增加了土壤温度，也提高了土壤水分，增温和增雨在影响土壤温度和水分含量上起到了相互拮抗的作用.②增雨显著增加了土壤有机碳、可溶性有机碳和活性有机碳含量，改变了土壤元素计量比以及活性-惰性碳组分的分配特征，而增温对有机碳的影响不显著.此外，土壤全氮全磷以及速效氮磷养分在不同处理间差异不显著.③增雨显著增加了土壤呼吸速率，而增温对土壤呼吸速率的影响主要取决于降水量和季节温度，表现为冬季和降雨充沛季节增温对土壤呼吸速率具有显著促进作用.土壤呼吸速率和5 cm土壤温度的指数拟合发现，增雨处理下土壤呼吸温度敏感性（Q10）最高，达到1.68，而增温处理下Q10最低（1.50）.④线性回归显示土壤有机碳、可溶性有机碳和活性有机碳均与土壤呼吸速率显著正相关.方差分解分析表明，土壤水热和养分特性共同可解释64.43%的土壤呼吸速率的变异，其中土壤水热因子是土壤呼吸速率变化的主控因子，解释度为31.16%.相关性分析也表明，土壤水热与土壤呼吸速率、土壤有机碳、可溶性有机碳、活性有机碳、碳氮比和碳磷比存在显著相关关系.综上所述，黄土丘陵区撂荒草地趋于暖湿的气候预测会显著影响区域水热环境和养分特征，改变土壤活性和惰性碳的分配比例，同时促进了区域土壤碳排放，分析结果表明驱动黄土丘陵区撂荒草地土壤呼吸速率改变的关键因素是土壤水热特征. |
| 英文摘要 |
| Clarifying the changing trends and driving factors of soil respiration in fragile habitats under the background of climate change is of great significance for understanding the regional carbon cycle and the conversion of ecosystem carbon source and sink functions. This research focused on grasslands that had been naturally abandoned and restored for 12 years in the loess hilly region of northern Shaanxi, using an open top chamber (OTC) and artificially increased natural rainfall to simulate climate warming and precipitation increase and their interaction. Furthermore, we used a combination of field monitoring and indoor analysis to explore soil water content, temperature, and nutrient characteristics and the response characteristics of soil respiration rate to warming and increased precipitation and further analyzed the key factors driving changes in soil respiration. The results showed that:① warming (W) significantly increased the 5 cm soil temperature, with an average increase of 1.34℃ throughout the sampling year, whereas the increased precipitation (P50%) treatment significantly reduced the 5 cm soil temperature, reducing the average 5 cm soil temperature during the entire sampling year by 0.88℃ and increasing the soil water content (SWC) at the same time. The SWC was 13.12% and 16.45% higher than that in the control (CK), respectively. In addition, compared with that in the CK, the treatment of warming and increased precipitation (WP50%) not only increased soil temperature but also increased SWC; in general, the increase in temperature and precipitation played an antagonistic effect on the influence of soil temperature and humidity. ② P50% significantly increased the content of soil organic carbon, dissolved organic carbon, and labile organic carbon, causing changes in the soil stoichiometric ratio and the distribution characteristics of labile-recalcitrant carbon components, whereas W did not have a significant impact on organic carbon. In addition, soil total nitrogen and phosphorus and available nitrogen and phosphorus nutrients were not significantly different between treatments. ③ P50% significantly increased the Rs rate, and the effect of W on the soil respiration rate mainly depended on the seasonal precipitation and temperature. It was demonstrated that warming in winter and seasons with abundant rainfall had a significant promotion effect on the soil respiration rate. The exponential fitting of soil respiration rate and 5 cm soil temperature found that the soil respiration temperature sensitivity (Q10) was the highest under the precipitation treatment, reaching 1.68, whereas the Q10 was the lowest under the warming treatment (1.50). ④ Linear regression analysis showed that soil organic carbon, dissolved organic carbon, and labile organic carbon were all significantly positively correlated with soil respiration rate. Variation partitioning analysis showed that soil temperature, SWC, and nutrient characteristics explained 64.43% of the variation in soil respiration rate. The soil temperature and SWC were the main controlling factors of the change in soil respiration rate, with an explanation degree of 31.16%. Correlation analysis also showed that there was a significant correlation between SWC, soil temperature and respiration rate, soil organic carbon, dissolved organic carbon, labile organic carbon, C:N, and C:P. In summary, the climate prediction of abandoned grassland tending toward warm temperatures and high humidity in the loess hilly region will significantly affect the regional hydrothermal environment and nutrient characteristics, change the distribution ratio of soil labile and recalcitrant carbon, and promote regional soil carbon emissions. The analysis results showed that the key factor driving the change in soil respiration rate of abandoned grassland in the loess hilly region was soil temperature and SWC characteristics. |
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