模拟增温对高寒地区农田土壤呼吸日动态特征的影响

Effect of simulated warming on diurnal dynamic characteristics of soil respiration in altitude cold farmland

【目的】研究高原高寒农田生态系统土壤呼吸的温度、体积含水量响应特征,为科学评估西藏农田生态系统土壤碳周转和全球气候变暖背景下研究青藏高原高寒农田生态系统土壤呼吸提供理论支持。【方法】以西藏农牧学院试验农场幼苗期青稞农田为研究对象,设置增温(2.0±0.5)℃和对照两个处理,采用LI-8100土壤呼吸监测系统,于2017年5月6日、5月8日-5月13日对农田土壤呼吸速率进行实时监测,分析土壤温度和土壤体积含水量对幼苗期青稞农田昼、夜间土壤呼吸速率特征动态变化的影响以及土壤呼吸作用对增温的响应特征。【结果】(1)增温处理和对照的土壤温度、体积含水量及土壤呼吸速率均表现为单峰型日变化特征。就土壤温度而言,增温处理最高值出现在12:00-14:00,对照最高值出现在14:00-16:00;两者最低值均出现在00:00-07:00。就土壤体积含水量而言,增温处理和对照日最大值均出现在02:00-09:00;最小值出现时间存在差异,增温处理出现在14:00-17:00,对照出现在14:00-19:00。增温处理和对照的土壤呼吸速率日峰值分别出现在14:00-16:00和15:00-17:00;最小值均出现在07:00-09:00。(2)17:00-07:00两个处理土壤呼吸速率与土壤温度、体积含水量呈极显著线性关系,08:00-16:00两个处理速率变化滞后效应表现不同。(3)通过双变量回归模型拟合土壤呼吸与温度、体积含水量的复合关系可知,土壤温度、体积含水量的协同影响更能反映实际情况。【结论】增温能在短期内显著改变土壤水热条件,促进有机碳分解,加大土壤CO 2排放速率。

【Objective】The response characteristics of soil respiration to temperature and volume water content in Alpine farmland ecosystem were studied to provide support for scientific assessment of soil carbon turnover and global warming in Alpine farmland ecosystem.【Method】The highland barley field in the experimental farm of Tibet Agriculture&Animal Husbandry was selected,two treatments of increasing temperature(2.0±0.5)℃and control were set up,and LI-8100 soil respiration monitoring system was used to monitor the soil respiration in real time during May 06,08-13,2017.The effects of soil temperature and soil volume water content on dynamic changes of soil respiration characteristics and responses to temperature increase of highland barley field in the seedling stage were then analyzed.【Result】(1)The soil temperature,volume water content and soil respiration rate of the warming treatment and the control showed a single peak diurnal variation.The highest temperature of the warming treatment occurred at 12:00-14:00,the highest temperature of the control occurred at 14:00-16:00,and the lowest temperature of both occurred at 00:00-07:00.The maximum soil volume water content of the warming treatment and the control appeared at 02:00-09:00,and the minimum value appeared at 14:00-17:00 or 14:00-19:00.The daily peak values of soil respiration rate of warming treatment and control appeared at 14:00-16:00 and 15:00-17:00,respectively,while the minimum values appeared at 07:00-09:00.(2)The stage of 17:00-07:00 showed very significant linear relationship,and at 08:00-16:00 the change of soil respiration lagged behind the change of soil temperature.(3)It can be concluded that the synergistic effect of soil temperature and volume water content on soil respiration rate can better reflect the actual situation.【Conclusion】Increasing temperature can significantly change soil water and heat conditions in short time,promote decomposition of organic carbon,and increase soil CO 2 emission.