Soil Respiration Characteristics and Its Relationship with Environmental Factors of Different Vegetation Types during Growing Season in Dongting Lake

摘要

In order to ascertain the soil carbon flux characteristics of poplar plantations and crop communities in the Dongting Lake area during the growing season and their correlation with hydrothermal conditions,soil respiration rate was monitored at fixed sites and time points with an LI-8100A automated soil flux system.Meanwhile,the surface temperature and soil temperature and humidity were measured.The soil respiration variation in the two different vegetation types and its correlation with environmental factors were analyzed.The results showed that in the growing season,the diurnal variation curves of soil respiration rate in the two different vegetation types showed a single peak variation,but there was certain difference in the appearance time of the peak.The peak of the crop appeared around 11:00 am,while the peak of soil respiration in the poplar appeared around 13:00.The soil respiration rate of the poplar was also significantly higher than that of the crop,and the average difference of soil respiration rate between the two was 3.09 and 3.55μmol/(m 2·s)in April and August,respectively.Temperature and soil moisture were the main factors affecting soil respiration of the poplar plantation and crop community.Temperature had a greater effect on the soil respiration of the crop community,and soil humidity had a greater impact on soil respiration in the poplar plantation,showing a correlation coefficient reaching 0.952.