作 者 ：崔海, 张亚红
期 刊 ：核农学报 2016年 30卷 8期 页码：1614-1624
Keywords:arid region, soil respiration rate, different weather conditions, diurnal variation, desert steppe,
摘 要 ：为探讨干旱区不同天气条件下荒漠草原土壤呼吸作用日变化特征及影响因子,在生长季连续观测禁牧封育(简称Ec)荒漠草原和放牧未封育(简称Gz)荒漠草原土壤呼吸速率及环境因子。结果表明,不同天气Ec和Gz荒漠草原土壤呼吸速率日变化均呈单峰曲线变化趋势,在日尺度上,土壤呼吸速率均表现为晴天>阴天,8月>6月>10月,且Ec>Gz。不同天气Ec和Gz荒漠草原土壤呼吸速率与空气、土壤温度均呈显著指数相关(P<0.05),且随着土层深度增加相关性逐渐变小;温度敏感性系数Q10表现为阴天(2.743)>晴天(1.712),且晴天Q10为Ec(1.508)<Gz(1.915),阴天Q10为Ec(3.145)>Gz(2.340)。不同天气Ec和Gz荒漠草原土壤呼吸速率与土壤湿度一元二次模型达到极显著水平,与光照强度和风速呈显著线性正相关,与空气CO2浓度呈极显著线性负相关。主成分分析表明,0~20 cm土壤水热状况是不同天气荒漠草原土壤呼吸的主要驱动因子。综上,阴天增加了温度敏感性系数,晴天增加了土壤呼吸作用,禁牧封育亦增加土壤呼吸作用。本研究为当地及中国北方干旱半干旱地区荒漠草原不同天气碳排放提供了理论依据,同时也为荒漠草原生态系统碳汇功能提供了科学参考。
Abstract:The fenced measures could improve the ecological environment of degraded grassland, and it’s a main measure for restoration of degraded grassland vegetation in China. Soil respiration (Rs) is an important component of an ecosystem’s carbon cycle and the main pathway for carbon moving from the ecosystem to the atmosphere. In order to explore soil respiration’s diurnal variation characteristics and influencing factors in dry desert steppe in different weather conditions, we continuously observed Rs rate and environmental factors in growing season of enclosed (Ec) and grazing (Gz) desert steppe in Ningxia. The results showed that: Both sunny and cloudy variation of Rs rate showed a single asymmetric peak changing in Ec and Gz desert steppe. On the day time scale, Rs rate in growing season of Ec and Gz desert steppe both followed the order of sunny>cloudy, and Ec>Gz. And the Rs rate of the growing season in different weather conditions was in the order of August>June>October. According to statistical analysis, it indicated that Rs rate had a significant exponential positive relationship with air and soil temperature in different weather conditions of Ec and Gz desert steppe (P<0.05). And with the increase of soil depth, the correlation of Rs rate and temperature gradually become smaller. The temperature sensitivity coefficient Q10 was 2.743 forcloudy and 1.712 for sunny, and in sunny day Q10 was 1.508 for and 1.915 for Gz, in cloudy day was presented as Ec (3.145) and Gz (2.340). The temperature sensitivity coefficient was increased in cloudy weather conditions. A extremely significant quadratic model was observed for the relationship between Rs rate and soil moisture content of Ec and Gz desert steppe in different weather conditions (P<0.01). Rs rate had a significant linear positive correlation with wind speed and light intensity (P<0.05), Rs rate had a significant linear negative correlation with air carbon dioxide concentration (P<0.01). The results of principal component analysis showed that 0 to 20 cm soil temperature and moisture were the main influencing factors of soil respiration of arid desert steppe in different weather conditions. In conclusion, it indicated that the cloudy day enhances the temperature sensitivity coefficient Q10, and the sunny day enhances the soil respiration, and the enclosure and grazing prohibition enhances the soil respiration. The present study provides a theoretical basis to understand the role of different weather conditions play in carbon emission of desert grassland of Ningxia and other arid and semiarid areas of northern China,meanwhile, it also provides a scientific reference of carbon sink function in desert steppe ecosystem.