杉木纯林与常绿阔叶林土壤活性有机碳库的比较

Comparison of active soil organic carbon pool between Chinese fir plantations and evergreen broadleaved forests.

森林土壤有机碳库占全球土壤有机碳库的70％，其贮量的微小变化，都可显著地引起大气CO2浓度的改变．为了解森林类型转换对土壤活性有机碳库的影响，作者于2005年5月在中国科学院会同森林生态实验站采样分析了杉木纯林和常绿阔叶林0～10cm和10～20cm土层内土壤活性有机碳含量．结果表明，杉木纯林土壤微生物量碳、可溶性有机碳、自由态和闭锁态轻组有机碳含量均显著低于阔叶林土壤（P〈0．05）．但各活性有机碳组分占土壤有机碳的比率没有规律；两种林分土壤的自由态、闭锁态轻组有机碳和重组有机碳含量与土壤有机碳总量均呈极显著的正相关（P〈0．01），而土壤微生物量碳、可溶性有机碳仅在常绿阔叶林下与土壤有机碳总量呈显著正相关；杉木纯林土壤各有机碳组分与土壤养分的相关性低于常绿阔叶林，且与全磷的相关性低于有效磷，这说明磷的有效性影响杉木纯林的土壤肥力．

Forest soil contains more than 70% organic carbon pool of the earth. So small changes in forest soil organic carbon （SOC） pool can remarkably cause the variance in CO2 density of atmosphere. At Huitong Experimental Station of Forest Ecology, CAS, Hu＇nan Province in May 2005, the authors analyzed the active SOC under Chinese fir plantations and evergreen broadleaved forests in the depth of 0-10 cm and 10-20 cm to assess the effects of forest conversion on active SOC pool. Results showed that the contents of soil microbial biomass carbon（MBC）, dissolved organic carbon （DOC）, free （FLOC） and occluded （OLOC） light fraction organic carbon under Chinese fir plantations were significantly lower than that of evergreen broadleaved forests. However, the rules of percentages of different active SOC to total SOC under two forest soils were not found. The significant correlations were observed between FLOC and SOC, OLOC and SOC, as well as between heavy fraction organic carbon （HOC） and SOC under the two forests. The close relationships between MBC and SOC along with DOC and SOC were only found under evergreen broadleaved forests. It was also found that the correlation coefficients between active fraction organic carbon and soil nutrients under Chinese fir plantations were lower than that of evergreen broadleaved forests, and their relationships with available phosphor were higher than total phosphor. This indicated that phosphor availability affected soil fertility of Chinese fir plantations.