海口城市草坪绿地土壤CO2通量时间变化及其环境解释——以海南师范大学南校区为例

利用LI-8100A土壤碳通量测量系统对热带城市草地土壤CO_2通量进行定点系统监测,阐明土壤CO_2通量时间变化特征及其对环境因子响应。结果表明,1)草坪绿地土壤CO_2通量日变化呈单峰曲线,最高值一般出现在09:00-16:00,不同月份、不同天气条件有所差异;土壤CO_2通量的日平均值6月份最大,为4.27μmol·(m~2·s)~(-1),12月份最小,为0.86μmol·(m~2·s)~(-1),年内变化趋势总体呈单峰曲线;2)草坪绿地土壤CO_2通量变化与气温、土壤温度呈显著的正相关关系(P0.05),而与土壤体积含水量之间的关系较为复杂,相关性不显著(P0.05)。3)较小强度降水对土壤CO_2通量变化影响较小,而强降雨对土壤CO_2通量变化产生明显的挤出作用。一次大的降水过程初期,随着降水量增加,土壤呼吸速率持续增大;而当土壤水分含量较高时,降雨则对土壤呼吸产生抑制作用。

Analysis on the temporal variation of soil CO2 flux and its response to the environmental factors in Haikou urban lawn-A case study of the south campus of Hainan Normal University

To explore the change characteristics of soil CO2 flux and its response to air temperatures,soil temperatures,soil moistures and other environmental factors,the soil respiration rates of tropical urban lawn ecosystems were measured by using the LI-8100A Soil CO2 Flux System,and meanwhile air temperatures,soil temperatures at 5 cm and soil moisture 0-10 cm in depth were monitored from November of 2013 to October of 2014.The results showed that: 1) Daily variation of soil respiration was single peak curve.The peaks usually occurred at 09:00-16:00,and the time when peak values generally appeared were different in different months and weather conditions.Yearly variation of soil respiration was also a single peak curve.The mean daily soil respiration rate was 0.86 to 4.27 μmol·(m2·s)-1,with the maximum in June,and the minimum in December.2) There was a significant positive correlation between soil respiration rate and air temperature and soil temperature.However,the relationship between the CO2 flux and soil volumetric water content was more complex,and the correlation was not significant.3) Rainfalls had complicated effects on soil respiration.A light rain didn't significantly change soil respiration,but a heavy rainfall could have an obvious extrusion effect on soil CO2 flux.At the early stage of a heavy rainfall process,soil respiration rate increased with the increase of rainfall,however,continuous rainfall could increase the soil moisture,and rainfall became an important factor limiting soil respiration.