喀纳斯自然保护区林地和草地土壤呼吸速率差异及影响因素

为了研究新疆喀纳斯国家自然保护区森林生态和草地生态系统与大气的相互作用,分析土壤呼吸速率的时空变异特征及与影响因子的关系,2012年及2013年5月上旬至9月上旬利用土壤碳通量测量系统LI-8150对林地和草地两种植被类型土壤的呼吸速率日动态进行了全天连续自动监测,研究了两类土壤呼吸速率在生长季各月日的变化规律。结果表明:林地和草地生态系统土壤呼吸速率在植被生长季内均呈现较明显的单峰曲线型日变化,其月最大值均出现在7月,林地土壤呼吸速率的最大值(2.43μmol/(m~2·s))显著高于草地土壤呼吸速率最大值(1.55μmol/(m~2·s)),且各月林地生态系统的土壤呼吸速率均明显高于草地,波峰出现在北京时间17:00—18:00,波谷出现在北京时间9:00—10:00,草地最小值出现在6月(0.35μmol/(m~2·s)),而林地最小值出现在5月,其呼吸速率仅0.71μmol/(m~2·s),且整个生长季白天大于晚上,全天以呼出CO_2为主。植被生长季内林地和草地土壤呼吸速率与土壤温度的变化趋势相似,具有显著的正相关性,但与土壤含水量的变化没有这样的趋势。

Differences in Soil Respiration Between Forestland and Grassland Ecosystems and Influential Factors in Kanas Nature Reserve

In order to study the interaction of forest and the grassland ecosystem and atmosphere in Kanas national nature reserve in Xinjiang, and analysis of spatial and temporal variation of soil respiration rate and the relationship with the impact factor, we used LI - 8150 soil carbon flux measurement system to monitor soil respiration rate dynamic throughout the continuous automatic monitoring, and analyzed the change rule of soil respiration rate for two types of soil in the growing season. The result showed that the soil respiration rate of forest and grassland ecosystem in the growing season were presented obvious unimodal type curve of diurnal variation with the maximumSmonthly average in July, while the soil respiration rate of forest ecological system were significantly greater than that of grass ecological system with the peak at 17:00-18:00 and the vale at 9:00-10:00, and the value during the day was larger than in the evening. CO2 was the main exhalant ingredient throughout the day. The soil underlying surface soil respiration rate and soil temperature of woodland and grassland are of a similar change trend in the growing season, with a significant positive correlation, but soil moisture content has no such trend.