桂林毛村不同土地利用方式下土壤呼吸空间变异特征

Spatial Variability in Soil Respiration Under Different Land Use Patterns in Maocun Village,Guilin

为了研究岩溶非岩溶交错区不同土地利用方式下土壤呼吸的空间变异特征及其影响因素,在桂林毛村进行野外观测试验,测定了土壤呼吸速率、δ^(13)C-CO_2值及相应的环境、土壤、植被因子,分析了土壤呼吸的空间变异性及与这些因子之间的关系.结果表明,土壤呼吸速率变化范围为1. 39～5. 31μmol·(m2·s)-1,最高值约为最低值的3. 8倍.毛村不同岩性区下土地利用方式的变化对土壤呼吸具有重要影响,相同岩性区土地利用方式改变前G2点松树林的土壤呼吸速率约为半坡毁林后G1点沙糖桔园的2. 3倍.土壤呼吸导致大气中CO_2浓度增高及δ^(13)C-CO_2值降低,并且两者之间的统计关系可以用反比例函数来描述.结果还发现,在水热条件与全年均值较接近的4月中旬,土地利用方式对土壤呼吸的影响要大于土壤温度、土壤湿度等环境因子.土地利用方式造成的土壤有机碳含量不同是影响土壤呼吸空间变异性的关键因子.在所有观测的生态系统中,土壤呼吸与有机碳含量和全氮含量之间的关系可以用二元线性回归方程描述,并能解释土壤呼吸92. 5%的空间变异性.

To investigate the factors influencing the spatial variability in soil respiration among different land use patterns in a karst non-karst interactive distribution area,field experiments were conducted in Maocun Village,Guilin. Soil respiration,δ13C-CO2 value,and relevant environment,vegetation,and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were examined. The results indicated that soil respiration rates ranged from 1. 39μmol·( m2·s)-1 to 5. 31 μmol·( m2·s)-1,with the highest value being approximately 3. 8 times the minimum. Soil respiration varied significantly among different land use patterns under different lithology zones. The soil respiration rate of the G2 pines in the same lithology area was 2. 3 times higher than that in the orchard G1 point after the destruction of the forest. The soil respiration caused an increase in CO2 concentration in the atmosphere and a decrease in the δ13C-CO2 value;the relationship between the two could be described by an inverse proportional function. The study found that in mid-April,the average water heat condition was close to that of the entire year. The difference in soil organic carbon content caused by land use was a driving factor of the spatial variability in soil respiration. In all ecosystems studied,the relationship between soil respiration and soil organic carbon content and total nitrogen content could be described by a two-element linear regression equation and explained 92. 8% of the spatial variability in soil respiration.