温度对武夷山不同海拔土壤有机碳矿化的影响

采用碱吸收法测定武夷山不同海拔土壤分别在15℃、25℃、35℃下培养35d时土壤有机碳矿化速率及矿化量的变化．结果表明，土壤有机碳矿化速率随培养时间延长而逐渐降低，尤以培养3d～7d时下降最为明显．各海拔土壤累积矿化量均随培养温度升高而逐渐增加．培养35d时15℃和35℃下土壤累积矿化量随海拔升高而增加，但25℃下黄红壤的累积矿化量高于红壤和黄壤而低于山地草甸土．各培养温度下，土壤有机碳平均矿化速率均以山地草甸土最高，红壤最低．而对于各海拔土壤，不同温度下土壤有机碳平均矿化速率大小顺序为：15℃〈25℃〈35℃．培养3d时温度为15℃／25℃黄壤的Q10值显著高于其他海拔土壤（P〈0．05），但培养35d时15℃／25℃下的土壤Q10值以黄红壤的最高．培养3d和35d时，25℃／35℃下不同海拔土壤Q10值差异均不显著（P〉0．05）．根据土壤平均矿化速率计算的Q10值在温度范围为15℃／25℃时以黄壤的最高，但25℃／35℃时红壤的Q10值最大．

Effect of Temperature on Soil Organic Carbon Mineralization Along an Elevation Gradient in the Wuyi Mountains

Soil samples from surface soil （0 -20 cm） along an elevation gradient in the Wuyishan National Nature Reserve of Fujian province in the Southeast of China were incubated for 35 days at tem- peratures of 15 ℃, 25 ℃ and 35 ℃ in laboratory. The soil mineralization rates were measured using the alkali absorption method at the incubation time of 3, 7, 14, 21, 28 and 35 days. Results showed that soil organic carbon （SOC） mineralization rate decreased gradually with incubation time. The most obvious decrease occurred from the 3rd to 7th day of incubation. The cumulative amount of SOC miner- alization increased with incubation temperature. At the end of incubation, cumulative mineralized C at 15 ℃ and 35 ℃ increased with increasing elevations, but at 25 ℃, cumulative mineralized C of yellow-red soil was higher than those of red and yellow soils while lower than that of mountain meadow soil. Average mineralization rate of SOC of mountain meadow soil at three temperatures was highest and red soil was lowest. Also, mean mineralization rate was highest at 35 ℃, followed by those at 25 ℃ and 15 ℃. At the temperature range of 15 - 25 ℃, Ql0 values of yellow soil on the 3rd day and yellow-red soil on the 35th day were significantly higher than those of other soils respectively （P 〈 0. 05 ）. However, at 25 - 35 ℃, there were no significant differences in Q10 values among different soils on the 3rd and 35th day of incubation. In addition, the highest Q10 value for the average mineralization rate at 15 -25 ℃ was found for yellow soil, while mean Q10 value at 25 -35 ℃ was maximum for red soil.