不同林龄木荷-青冈栎混交林幼林土壤活性有机碳库研究

以中国北亚热带地区退化灌木林补植改造7 a和11 a后形成的木荷-青冈栎混交林为研究对象，以保留的灌木林为对照，分析了造林初期林龄对林分土壤活性有机碳含量的影响。结果表明：(1) 7 a和11 a生木荷-青冈栎林0～50 cm各土层土壤总有机碳含量比灌木林分别增加了22.79%~43.34%和52.33%~96.13%，易氧化碳含量增加了11.11%~25.18%和57.89%~100.90%，轻组有机质含量增加了18.18%~85.20%和74.50%~93.75%，水溶性有机碳含量7 a生木荷-青冈栎林比灌木林降低了4.10%~9.53%(10~20 cm除外)，而11 a生林分比灌木林增加了0.71%~5.37%。(2) 3种林分土壤活性有机碳在总有机碳中所占的比率大小顺序、水溶性有机碳/土壤总有机碳均为灌木林>7 a生木荷-青冈栎林>11 a生木荷-青冈栎林，易氧化碳/土壤总有机碳为11 a生木荷-青冈栎林>灌木林>7 a生木荷-青冈栎林。（3）3种林分各活性有机碳组分与土壤总有机碳的相关性均达到极显著水平，而水溶性有机碳与总有机碳的相关系数相对较低；各林分土壤总有机碳、易氧化碳、轻组有机质与土壤养分的相关性均达到极显著水平，而灌木林水溶性有机碳与土壤水解氮、速效钾相关性不显著。研究认为，灌木林改造为常绿阔叶人工林，林分土壤有机碳在幼林期已有显著变化，随着林龄增长，人工林有机碳的积累还有待进一步研究。

Analyse of Soil Labile Organic Carbon Pools in Mixed Schima superba-Cyclobalanpsis glauca Young Plantations at Different Stand Ages

Taking 7- and 11-year-old mixed Schima superba - Cyclobalanpsis glauca plantations(SC)(plantations were transformed from degraded shrub forest) and the reserved shrub forest(SF) in north subtropical areas of China as test objects,we analyzed the effects of stand age on the soil labile organic carbon content.(1)As compared with SF,the soil total organic carbon content(TOC),easily-oxidized carbon content(EOC) and light fraction organic matter content(LFOM) in both 7- and 11-year-old SC stands were increased by 22.79%-43.34% and 52.33%-96.13%,11.11%-25.18% and 57.89%-100.90%,18.18%-85.20% and 74.50%-93.75%,respectively.The water-soluble organic carbon content(WSOC) in 7-year-old SC were decreased by 4.10%-9.53%(except in 10-20 cm soil layer) and in 11-year-old SC increased by 0.71%-5.37% compared with SF.(2)The ratios of WSOC/TOC in the soils followed the order of SF>7-year-old SC>11-year-old SC,whereas the EOC/TOC in the soils followed the order of 11-year-old SC>SF>7-year-old SC.(3)In the three stands,soil WSOC,EOC,and LFOC had extremely significant correlations with soil TOC(P<0.01),and the correlation coefficients between WSOC and TOC were lower than others.The soil TOC,EOC,and LFOC in the three stands were extremely significantly correlated with soil nutrients,but the soil WSOC in SF had no significant correlations with soil hydrolysable N and available K.The soil organic carbon of evergreen broad-leaved young plantations transformed from shrub forest has changed significantly,and the long-term effect of stand age on the soil organic carbon accumulation need to be further studied.