新疆焉耆盆地绿洲区农田土壤有机碳储量动态模拟

以焉耆盆地绿洲区丝路重镇——焉耆回族自治县长期定位监测的数据为基础,实地采集800个土样进行土壤有机碳(SOC)实验室测试,进行点位模拟校验模型,并拓展到区域模拟,采用BCCC-CSM1.1气候模式,研究农田土壤有机碳密度分布特征及有机碳储量空间分布格局,为气候变化条件下,绿洲区耕地SOC储量和SOC密度变化提供数据支持。结果表明:(1) DNDC模型能够较好地模拟研究区农田的SOC及其动态变化,相关系数大于0.96,模拟值与观测值的均方根误差(RMSE)在0.48%—13.08%之间,模拟值与实测值显著相关。(2)点位模拟不同处理间SOC变化显示,不同土壤质地土壤有机碳含量差异明显,5年来SOC增长趋势表现为粉砂质壤土壤土砂质壤土。(3) 2017年焉耆县农田表层土壤有机碳总储量为0.44 Tg C,在未来30年里,在相应农业措施下,研究区农田0—20 cm土层SOC密度和储量呈显著增加趋势,单位面积碳增量增幅为-7%—29%;新增固碳量3.708×10~8—1.978×10~9 t,增幅为-5%—48%,呈现出"碳汇"趋势,这对恢复农田SOC的平衡和绿洲农业的可持续发展至关重要。

Dynamic simulation of soil organic carbon storage in farmland of the Yanqi Basin Oasis area, in Xinjiang Province

Based on the long-term monitoring data of Yanqi Basin, which is an important county along the Silk Road, 800 soil samples were collected during our study from the selected area to conduct soil organic carbon (SOC) determinations in the laboratory. By using the BCCC-CSM1.1 climate model from the Coupled Model Intercom parison Project Phase 5 (CMIP5), we expanded our work to research the change in the spatial distribution of the soil organic carbon density and organic carbon storage in the oasis area under climate change conditions. The results showed that:(1) The DNDC model better simulated the SOC content and dynamic change in the study area, the correlation coefficient was greater than 0.96, and the root mean square error (RMSE) between simulated and observed values was between 0.48% and 13.08%. The analog value was significantly correlated with the measured value. (2) The SOC content among different soils was significantly different. The growth trend of SOC content over the past five years was in the order silty loam > loam > sandy loam. (3) In 2017, the total SOC storage in the farmland of Yanqi County was 0.44 Tg C. In simulations of 30 years in the future, under the corresponding agricultural measures, the SOC density in the 0-20 cm soil layer in the study area exhibited a significant increasing trend. The SOC content per unit area was increased by -7%-29% and the new carbon fixation amount was 3.708×10⁸ t-1.978×10⁹ t, which could obtain an increase of -5%-48%. The unified management of farmland in the oasis areas will have an important impact on the effects of SOC fixation.