祁连山放牧草原土壤呼吸及影响因子分析

Soil Respiration and Its Influencial Factors in Grazing Steppe of Qilian Mountain

在海拔2 500,2 700,2 850,3 000 m的草原上利用Li-6400-09土壤呼吸叶室测定仪测定一个生长季节祁连山排露沟流域放牧草原土壤呼吸速率,分析不同环境条件下土壤CO2释放速率对气候和土地利用的反馈作用。辅助测定地面温度(0 cm、最低温度和最高温度)、地下温度(5,10,15,20 cm)、空气温度、土壤含水量。通过2003-2006年的观测结果表明:(1)土壤呼吸速率有明显日变化规律,7:00-14:00逐渐升高,14:00达到最大值,其值为8.92μmol/(m2.s);之后开始逐渐下降,5:00-6:00达最小值,其值为0.37μmol/(m2.s);(2)土壤呼吸速率有显著的季节变化趋势,呈单峰曲线,与温度的季节动态相吻合,出现"低-高-低"变化趋势。(3)放牧直接影响土壤含水量,放牧程度与土壤含水量呈负相关,土壤含水量与土壤呼吸速率呈正相关。重度放牧区土壤含水量>过度放牧区土壤含水量>极度放牧区土壤含水量,且重度放牧区土壤呼吸速率>过度放牧区土壤呼吸速率>极度放牧区土壤呼吸速率。(4)温度是影响土壤呼吸的主要因子,温度与土壤呼吸速率呈正相关,呼吸速率最大值出现在一年温度最高月6-7月,值为8.92μmol/(m2.s);最小值出现在5月,值为0.37μmol/(m2.s),继续降温呼吸速率基本停止。

The soil respiration rate of Grazing grasslands was measured by the soil respiration detector of LI- 6400-09 in different altitude （2 500, 2 700, 2 850,3 000 m） in Pailugou valley of Qilian mountain in a growing season. The impacts of soil CO2 releasing rate on climate and landuse at different environment condition were analyzed, the land surface temperature （0 cm,maximum temperature and minimum temperature）,temperature underground（5,10,15,20 cm）, air temperature, soil water content（0- 5 cm, 5 -- 10 cm） were also measured. Observation from 2003 to 2006 shows that： （1）soil respiration rate has a obvious diurnal law, it assanding from 7：00--14：00 and reach the maximum value 92 μmol/（m^2· s） at 14：00;then desanding and reach the minimum value 0. 37 μmol/（m^2 · s） at 5：00-6：001（2） soil respiration rate also has a obvious seasonal change law, it shows the Single-peak curve and consistent with temperature seasonal dynamics, the changing trend is ＂low-high-low＂ . （3）grazing directly impact on soil water content, It is negative correlation between grazing and soil water content, and positive correlation between soil water content and soil respira- tion, severe grazing areas soil water content 〉overgrazing areas areas soil water contentextremely grazing areas soil water content, and severe grazing areas soil respiration rate 〉overgrazing areas areas soil respiration rate〉 extremely grazing areas soil respiration rate. （4）the temperature is the major factor which impacts the soil respiration, it is positive correlation between temperature and soil respiration, the maximum soil respiration rate 8.92μmol/（m^2 · s） is reached from June and July during which the temperature is highest in a year. The minimum value 0.37 μmol/（m^2· s） is reached in May, respiration will stop if temperature lower.