亚热带天然阔叶林转换为杉木人工林对土壤呼吸的影响

Effects of conversion of natural broad-leaved forest to Chinese fir plantation on soil respiration in subtropical China

采用静态箱-气相色谱法对浙江省临安市玲珑山风景区天然阔叶林和由天然阔叶林改造的杉木人工林的土壤呼吸进行1年的定位监测.结果表明：天然阔叶林和杉木人工林土壤CO2排放速率均呈现一致的季节性变化规律即夏秋季高、冬春季低;天然阔叶林和杉木人工林土壤CO2排放速率分别为20.0-111.3和4.1-118.6 mg C·m-2·h-1;天然阔叶林土壤CO2年累积排放通量（16.46 t CO2·hm-2·a-1）显著高于杉木人工林（11.99 t CO2·hm-2·a-1）.天然阔叶林和杉木人工林土壤CO2排放速率与土壤含水量均没有显著相关性,而与5cm处土壤温度呈显著指数相关,Q10值分别为1.44和2.97;天然阔叶林土壤CO2排放速率与土壤水溶性碳（WSOC）含量无显著相关性,杉木人工林土壤CO2排放速率与WSOC含量呈显著相关.天然阔叶林转换为杉木人工林显著降低了土壤CO2排放,提高了土壤呼吸对环境因子的敏感性.

Soil CO2 effluxes in natural broad-leaved forest and the conversed Chinese fir plantation in Linglong Mountains Scenic of Zhejiang Province were evaluated by using static closed chamber and gas chromatography method. The results showed that soil CO2 efflux showed consistent seasonal dynamics in natural broad-leaved forest and Chinese fir plantation,with the maximums observed in summer and autumn,the minimums in winter and spring. Soil CO2 effluxes were 20. 0- 111. 3 and4. 1- 118. 6 mg C·m- 2·h- 1in natural broad-leaved forest and Chinese fir plantation,respectively. The cumulative soil CO2 emission of natural broad-leaved forest（ 16. 46 t CO2·hm- 2·a- 1）was significantly higher than that of Chinese fir plantation（ 11. 99 t CO2·hm- 2·a- 1）. Soil moisture did not affect soil CO2 efflux. There was a significant relationship between soil CO2 efflux and soil temperature at 5 cm depth. There was no significant relationship between soil CO2 efflux of natural broad-leaved forest and water soluble organic carbon content,while water soluble organic carbon content affected significantly soil CO2 efflux in Chinese fir plantation. Converting the natural broadleaved forest to Chinese fir plantation reduced soil CO2 efflux significantly but improved the sensitivity of soil respiration to environmental factors.