长白山高山苔原季节性雪斑土壤呼吸对温度响应的模拟研究

利用LI-8100土壤呼吸测定系统, 在室内控制温度条件下测定了长白山高山苔原季节性雪斑大白花地榆(Sanguisorba sitchensis (=S. stipulata))群落土壤呼吸对温度的响应过程, 并根据野外连续测定的全年温度, 估算了雪斑群落土壤呼吸的季节变化, 同时模拟气温升高对土壤呼吸的影响。雪斑土壤温度全年大部分时间维持在0 ℃以上, 极端温度变动幅度不超过20 ℃。模拟计算了10 cm深土壤的呼吸强度, 海拔2 036 m处为307.1 g C·m^-2·a^-1, 海拔2 260 m处的呼吸量为270.9 g C·m^-2·a^-1。由于积雪时间长, 冬季呼吸占很大比例, 而且随着海拔的升高比例加大。从海拔2 036 m到2 260 m, 积雪期土壤呼吸分别占全年的42.5% (125.4 g C·m^-2·a^-1)和49.7% (128.7 g C·m^-2·a^-1)。模拟气温升高1 ℃并假设积雪时间减少20天, 冬天的呼吸量减少8%左右, 但全年总呼吸量增加8%左右。升温后, 平均增加的呼吸量为0.25 g C·kg^-1·a^-1 (或22.65 g C·m^-2·a^-1), 冬季呼吸量减少0.118 g C·kg^-1·season^-1 (或10.81 g C·m^-2·season^-1)。

Simulation of soil respiration in response to temperature under snowpacks in the Changbai Mountain, China

Aims The objective was to investigate the respiration rate of snowpack soil in relation to temperature in the al-pine tundra community of Sanguisorba sitchensis (= S. stipulata) in the Changbai Mountain, northeastern China. Methods Soil respiration under different temperatures was measured with an LI-8100 automated CO_2 flux sys-tem in the laboratory, and annual respiration was estimated based on current and presumed temperature scenarios. Important findings Soil temperature under snowpack most of the year was around or over 0 ℃, and the varia-tion was less than 20 ℃. Estimated respiration rates within 10 cm depth were 307.1 g C·m~(-2)·a~(-1) at 2 036 m elevation and 270.9 g C·m~(-2)·a~(-1) at 2 260 m. Because the snow cover was present for a long period, the length of which increased with elevation, winter respiration accounted for 42.5% at 2 036 m and 49.7% at 2 260 m. Under the sce-nario that the snow period decreases if annual temperature rises 1 ℃, annual respiration would increase by 8% or 0.25 g C·kg~(-1)·a~(-1) (22.65 g C·m~(-2)·a~(-1)), but winter respiration would decrease by 0.118 g C·kg~(-l)·a~(-1) (10.81 g C·m~(-2)·a~(-1)).