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

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

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。

In order to disclose the interaction between forest and the grassland ecosystems with atmosphere in Kanas National Nature Reserve in Xinjiang and the spatial and temporal variation of soil respiration rate （SRR） as well as the influential factors, LI - 8150 soil carbon flux measurement system was used to continuously and automatically monitor daily soil respiration rates under the two vegetation ecosystems in the growing season. The results showed that the diurnal variation of SRR under both forest and grassland ecosystems in the growing season presented obvious unimodal type curve, the monthly maxima of SRR both appeared in July, maximum of SRR under forest ecosystem （2.43 μmol/（m2·s）） was significantly higher than that under grass ecosystem （1.55 μmol/（m2·s））. Monthly SRR under forest ecosystem was obviously higher than that under grass ecosystem. The peak and bottom of SRRs occurred at 17：00-18：00 and at 9：00-10：00, respectively. Minimum of SRRs occurred in June under grass ecosystem （0.35 μmol/（m2·s）） and in May under forest ecosystem （0.71 μmol/（m2·s））. SRR was higher during the day than in the evening. COa was the main exhalant ingredient throughout the day. SRRs of woodland and grassland ecosystems had similar change trend and significant positive correlation with soil temperature in the growing season, but not with soil moisture content.