| 摘要: |
| 目的 通过2019—2021年对松嫩平原盐碱地土壤呼吸的监测，探究盐碱土是否存在净碳吸收过程，明确盐碱土碳吸收在区域碳循环中的作用和地位。方法 文章基于纯盐碱地原位土壤呼吸的3年连续监测，探究盐碱地土壤CO2通量动态变化及其环境响应。结果 （1）松嫩平原盐碱地除碳释放外存在阶段性碳吸收，不同年份盐碱土发生碳吸收的时间和强度不一致。（2）2019年和2021年土壤碳吸收主要发生在夜间，两次间歇性碳吸收分别发生于生长季初期和末期，其强度与土壤温、湿度显著相关，是由水分参与下的NaCO3转化为NaHCO3的化学性吸碳。（3）松嫩平原盐碱土在水淹期间存在连续性碳吸收，水淹状态下的吸碳来源于温度梯度驱动的大气CO2形成水合二氧化碳的物理性吸碳。结论 （1）生长季的不同时期，松嫩平原盐碱土有着不同的碳吸收模式和强度。（2）土壤水分是影响盐碱土夜间间歇性吸碳的关键因素，温差是影响水淹吸碳的重要驱动力，随着温差加大，土壤碳吸收加强。（3）2019年和2021年夜间土壤碳吸收的最大值分别为-0.31 μmol CO2 m-2 s-1和-0.75 μmol CO2 m-2 s-1；2020年和2021年淹水期间碳吸收最大强度为-1.51 μmol CO2 m-2 s-1和-1.27 μmol CO2 m-2 s-1。（4）松嫩平原盐碱土的规律性固碳可为生态系统年净碳吸收贡献15%。不考虑土壤碳吸收的空间异质性，其每年的碳吸收潜力预计可达0.37 Tg C a-1。 |
| 关键词: 盐碱土 土壤呼吸 夜间吸碳 水淹 松嫩平原 |
| DOI：10.7621/cjarrp.1005-9121.20240112 |
| 分类号:S181 |
| 基金项目:国家自然科学基金重大项目“不同管理措施下草原生产力和碳汇功能的协同与调控机制”（32192464） |
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| PROCESS AND MECHANISM OF SALINE-ALKALI SOIL CARBON UPTAKE POTENTIAL IN THE SONGNEN PLAIN OF CHINA |
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Wang Yixuan1, Wang Ke2, Qu Luping3, Jiang Shicheng4, Shao Changliang1
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1.Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China;2.School of Life Science, Shanxi University, Taiyuan 030006, Shanxi, China;3.Forest College, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China;4.School of Life Sciences, Northeast Normal University, Changchun 130024, Jilin, China
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| Abstract: |
| The monitoring of soil respiration in the saline-alkali soil of the Songnen Plain from 2019 to 2021 was used to investigate whether there exists a net carbon uptake process for the saline-alkali soil and clarify the role and function in the regional carbon cycle. Based on the 3-years continuous monitoring of in-situ soil respiration for the pure saline-alkali soil in the Songnen Plain during 2019-2021, the CO2 flux dynamics and environment response of saline-alkali soil was explored. The results were showed as follows. (1) Besides the carbon release, the periodic carbon uptake existed in the saline-alkali soil of the Songnen Plain, and the time and intensity of soil carbon uptake in different years were inconsistent. (2) In 2019 and 2021, the saline-alkali soil carbon uptake intermittently occurred at night at the beginning and/or end of the growing season respectively. The intensity was significantly correlated with soil temperature and moisture and the uptake was a chemical carbon absorption via NaHCO3-NaCO3 transformation dominated by soil water. (3) The saline-alkali soil had continuous carbon uptake during the flooding period induced by the heavy rainfalls. The inorganic carbon uptake was derived from the physical carbon absorption of atmospheric CO2 driven by temperature gradient to form hydrated carbon dioxide. The conclusion are listed as follows. (1) In different periods of growing season, inorganic carbon uptake in the saline-alkali soil of the Songnen Plain has the different pattern and intensity. (2) Soil moisture is the key factor affecting the intermittent carbon uptake of saline-alkali soil at night. Temperature difference is an important driving force affecting carbon uptake by flooding, with the increase of soil-atmosphere temperature difference, saline-alkali soil carbon uptake is enhanced. (3) The maximum nighttime soil carbon uptake in 2019 and 2021 was -0.312 μmol CO2 m-2 s-1 and -0.753 μmol CO2 m-2 s-1, respectively; the maximum intensity of carbon uptake during flooding in 2020 and 2021 was -1.507 μmol CO2 m-2 s-1 and -1.27 μmol CO2 m-2 s-1, respectively. (4) The regular pattern of carbon uptake by saline-alkali soil in the Songnen Plain can contribute 15% to the annual net CO2 ecosystem exchange (NEE). Regardless of the spatial heterogeneity of soil carbon uptake, the annual saline-alkali soil carbon uptake potential is estimated to be 0.37 Tg C a-1. |
| Key words: saline-alkali soil soil respiration nocturnal carbon uptake waterlogging Songnen Plain |
