针阔混交林凋落物对土壤呼吸的影响

Effect of litter fall on soil respiration in mixed broadleaf-conifer forest

以位于长江三峡库区的重庆缙云山针阔混交林为研究对象,利用美国LI-COR公司生产的LI-8100开路式土壤碳通量测量系统对林地有凋落物和无凋落物两种土壤呼吸速率进行了观测。结果表明:(1)有无凋落物对土壤温度、土壤含水量均无影响;(2)有凋落物和无凋落物土壤呼吸的昼夜变化都呈现为单峰曲线,下午14:00左右达到峰值,并且无凋落物土壤呼吸速率小于有凋落物土壤呼吸速率;(3)有凋落物和无凋落物土壤呼吸季节变化趋势都表现为双峰型,峰值分别出现在7月和9月;(4)针阔混交林通过土壤呼吸释放的CO2量达到24.05 t/hm2,其中由凋落物释放的CO2达到5.09 t/hm2,占总CO2释放量的21.16%,说明凋落物对土壤呼吸影响显著。

In order to evaluate the effect of litter fall on soil respiration under a mixed conifer and broadleaved forest of Jinyun Mountain Natural Reservation in Chongqing, using a field study with litter exclusion and addition in a full factorial design, soil respiration rate were measured by LI-8100 soil respiration carbon dioxide flux measurement system. Results showed that： （ 1 ） Both soil temperature and soil moisture were not affected by litter-fall. （2） Diurnal variation of the rate of soil respiration with litter cover and without litter cover for mixed broadleaf-conifer forest were expressed in a single peak curve, the peak of soil respiration rate appeared around 14 ： 00, and the rate of soil respiration with litter cover was higher than that of without litter cover. （3） Monthly dynamics of the rate of soil respiration with litter cover and without litter cover for mixed broadleaf-eonifer forest showed a bimodal curve, the peak values appeared in July and September re- spectively. （4） During the period from March to December, mixed broadleaf - conifer forest released about 24. 05 t/hm2 of CO2, of which 5.09 t/hm2 was resulted by litter fall, accounting for 21.16% of total CO2 emissions. It was suggested that soil respiration was significantly affected by litter fall.