广州市常绿阔叶林土壤有机碳组分特征分析

Characteristics of soil organic carbon fractions in the evergreen broad-leaved forests in Guangzhou,China

选取广州市(龙眼洞、天鹿湖、大夫山、龙头山、滴水岩、王子山、石门)的7个常绿阔叶林为样地,分析城市化对广州森林土壤有机碳组分的影响。研究发现:(1)7个森林土壤总有机碳、易氧化有机碳和不易氧化有机碳含量的差异显著(p<0.05),均呈随样地距市中心距离增加而增加;(2)森林土壤的碳库活度和活度指数距离市中心越近数值越高,碳库指数和碳库管理指数距离市中心越近数值越低;(3)土壤总有机碳与易氧化有机碳、不易氧化有机碳、碳库指数、碳库管理指数、全氮、C:N和样地距城中心距离均呈显著正相关。结果表明城市化改变了常绿阔叶林土壤的有机碳组分,使土壤有机碳的稳定性下降。

This study was conducted to reveal differences in the SOC fractions of seven evergreen broad-leaved forests along the urban-rural gradient of Guangzhou,China,including Longyandong,Tianluhu,Dafushan,Maofengshan,Longtoushan,Dishuiyan,Wangzishan,and Shimen forests.The results showed that the contents of total organic carbon(TOC),readily oxidizable organic carbon(ROC)and non-readily oxidizable organic carbon(NROC)in the surface soil were significantly different among sites(p<0.05).In particular,the soils had significantly lower TOC,ROC and NROC contents in these forests(e.g.,Longyandong and Tianluhu forests)near the center of the city than in those(e.g.,Wangzishan and Shimen forests)far away from the city center.The carbon pool activity and activity index were significantly higher in the forests near the city center than in those forests outside the city(p<0.05).Furthermore,the soil carbon pool index(CPI)and carbon pool management index(CPMI)showed a contrasting trend,with the CPI and CPMI indexes being significantly higher in the suburban forests than in the urban forests(p<0.05).Moreover,the content of TOC was significantly positively related to the contents of ROC and NROC,CPI,CPMI,the nitrogen content,C:N,and the distance from the sample plots to the city center.Our results suggest that urbanization changes the organic carbon fractions of soil in evergreen broad-leaved forests,which may be adverse to the SOC accumulation and stabilization in the subtropical forests.