不同坡度坡位下滇中烤烟地土壤呼吸的变化特征

Characteristics of soil respiration in flue-cured tobacco fields under different slope gradients in Central Yunnan

以云南省玉溪市典型烤烟农田生态系统为研究对象,采用动态密闭气室红外CO2分析仪(LI-6400-09)对平地、15°上坡位、15°中坡位、15°下坡位、30°上坡位、30°中坡位、30°下坡位7种处理的烤烟地生长季的土壤呼吸速率及其影响因子进行了测定和分析.结果表明:(1)烤烟农田土壤呼吸具有明显的时间变化,呈双峰型变化趋势;坡度的增加显著降低了平均土壤呼吸速率(降低6.4μmol·m^(-2)·s^(-1)),且减缓了移栽后烤烟伸根期的土壤呼吸速率;(2)不同坡位的土壤湿度差异显著,坡位的升高显著降低了平均土壤呼吸速率(降低2.6~3.5μmol·m^(-2)·s^(-1));(3)土壤温度是引起土壤呼吸变化的关键因素,土壤呼吸温度敏感系数Q10在1.01~1.39之间,且随着坡度的升高而增大,坡度的升高还会导致土壤温度对土壤呼吸的高相关性由中、下坡位转变为上坡位;(4)在该研究区内土壤湿度对于土壤呼吸的作用大于土壤温度,下坡位土壤呼吸对湿度的敏感性大于中坡位和上坡位.综上,坡面类型的变化能显著改变土壤温度与水分状况,进而影响烤烟地土壤呼吸作用.

Taking the ecological system of typical flue-cured tobacco field in Yuxi city of Yunnan as the research object,the flue-cured tobacco was treated by using the dynamic closed air chamber infrared CO2 analyzer（ LI-6400-09） for the treatment of flat ground,15° upper slope position,15° middle slope position,15° lower slope position,30° upper slope position,30° middle slope position and 30° lower slope position. Soil respiration rate and its influencing factors in the growing season were measured and analyzed. The results were as follows：（ 1） the soil respiration of flue-cured tobacco had a significant time change,which showed a trend of change in Shuangfeng type. The increase of gradient significantly reduced the average soil respiration rate（ reduce 6.4 μmol·m^-2·s^-1）,and slowed down the soil respiration rate of the extension root of flue-cured tobacco after transplanting.（ 2） Soil moisture at different slope positions was significantly different. The increase of slope position significantly reduced the average soil respiration rate（ reduce 2.6～ 3.5 μmol·m^-2·s^-1）;（ 3） Soil temperature was the key factor causing soil respiration. The temperature sensitivity coefficient Q10 of soil respiration was 1.01～（-1）.39 and increased with the increase of slope. The increase of slope would also lead to a high correlation between soil temperature and soil respiration from the middle and the lower to the upper slope.（ 4） In the study area,soil humidity had greater effect on soil respiration than soil temperature,and the sensitivity of downslope soil respiration to humidity was greater than that of middle slope and uphill slope. In summary,changes in slope types can significantly change soil temperature and water conditions,and then affect soil respiration in flue-cured tobacco fields.