干湿交替对东北温带次生林与落叶松人工林土壤有机碳矿化的影响

Effects of Rewetting on Soil Organic Carbon Mineralization in Temperate Secondary Forest and Larix olgensis Plantation of Northeast China

在中温带的黑龙江省帽儿山地区,采集次生林和落叶松人工林表层(0-10cm)土壤,进行室内有机碳矿化培养。先在不同温度(5,15,25,35℃)下干土培养3d,然后进行不同水平的增湿处理(土壤含水率为25%,50%,75%,100%)继续培养11d。结果表明:加水增湿后两林分土壤有机碳矿化速率均被激发并在短时间(1～4d)内达到最大值,不同处理次生林土壤有机碳矿化速率最大值变化范围为15.94～212.65μg CO2-C/(g.d),落叶松人工林土壤为16.75～110.85μg CO2-C/(g.d)。两林分土壤有机碳矿化速率和矿化量随处理湿度的增加而增大,但落叶松人工林100%湿度处理在培养温度超过5℃时,土壤有机碳矿化速率和矿化量却低于75%湿度处理。高温(≥25℃)和高湿(50%～100%)条件下次生林土壤有机碳矿化的激发效应明显大于落叶松人工林土壤,而且次生林土壤有机碳矿化的湿度敏感性系数(k)和温度敏感性系数(Q10)均大于落叶松人工林土壤。这表明随着温度的升高,干湿交替可导致次生林土壤较落叶松人工林土壤损失更多的碳。

With incubation test,this paper studied the responses of mineralization rate and cumulative mineralized amount of surface soil （0-10 cm） organic carbon to temperature （5,15,25,35℃） and soil rewetting with different moisture （water content： 25%,50%,75%,100%） from secondary forest and Larix olgensis plantation in Maoershan mountain of Heilongjiang province.The results showed that soil organic carbon mineralization （SOCM） rates excited rapidly and reached the maximum in few days （1~4 d） following rewetting treatment.The highest SOCM ates changed from 15.94μg CO2-C/（g·d） to 212.65 μg CO2-C/（g·d） in secondary forest,and from 16.75μg CO2-C/（g·d） to 110.85 μg CO2-C/（g·d） in Larix olgensis plantation.With the increase of water addition,SOCM rates increased,both of secondary forest and Larix olgensis plantation.But when temperature exceeded 5℃,SOCM rates of 100% water treatment were less than 75% water treatment in Larix olgensis plantation.At high temperature （≥ 25℃） and big moisture （50% to 100%） conditions,the rates of SOCM increased in secondary forest were significantly larger than Larix olgensis plantation.In addition,moisture sensitivity coefficients （k） and temperature sensitivity coefficients （Q10） of SOCM in secondary forest were greater than Larix olgensis plantation.This suggested that with the temperature rising,rewetting may lead more organic carbon lost in secondary forest soil than Larix olgensis plantation.