帽峰山森林土壤碳氮随雨季月及土壤深度的时空变化特征

Temporal and spatial variation of soil carbon and nitrogen in forest ecosystem of Maofeng Mountain

采用森林生态系统定位观测及对比试验方法,对广州帽峰山常绿阔叶林和杉木人工林（16年）土壤（0~90 cm）有机碳、无机碳、总氮及有机氮的雨季月（5—10月）含量动态、垂直梯度变化特征及土壤湿度影响进行了对比观测研究。结果表明：常绿阔叶林及杉木林土壤有机碳、无机碳雨季月的剖面权均含量变化趋势均为倒S型,常绿阔叶林土壤有机碳剖面权均质量分数较相应杉木林大0.14%、土壤无机碳则小0.12%。常绿阔叶林土壤表层0~10、10~30 cm有机碳雨季月含量变差较杉木林分别高出1.83%、0.61%,土壤30~90 cm雨季月含量变差相对较小;常绿阔叶林土壤70~90 cm无机碳含量在5—8月份较高、杉木林则以土壤30~50 cm在5、6及10月含量较高;常绿阔叶林群落土壤0~20 cm的总氮雨季月含量均大于相应杉木林,植被吸收作用影响使土壤20 cm以下层的雨季各月总氮相对较低;常绿阔叶林土壤剖面雨季月无机氮含量随土层深度递减变化显著,即表层0~30 cm受矿化作用影响较大、深层30~90 cm则受植被吸收作用影响较大;而杉木林土壤剖面层无机氮含量则随雨季的月变化显著,5—7月份含量相对较小、8—10月份含量相对较大。常绿阔叶林土壤有机碳、总氮含量随土壤深度的增加均呈幂函数规律的递减,而杉木人工林土壤有机碳随土壤深度的增加呈对数函数规律的递减、土壤总氮含量则随土壤深度的增加呈二次函数规律的递减。在0~10 cm处,土壤有机碳和有机氮含量与土壤湿度呈负相关。

The monthly and vertical variation of Broad-leaved Evergreen Forest（BEF） and Chinese Fir Plantation（CFP） were studied by using positional observation and contrast experiment in soil of 0-90 cm depth at MaoFeng Mountain,Guangzhou.Results shows organic and inorganic carbon in both types of forest changes was from ＂S＂ parallel to a horizontal line.Organic carbon was 0.15% higher in Broad-leaved Evergreen Forest than in Chinese Pine Plantation,while inorganic carbon was 0.12% lower in former one than in latter one.In soil of 0-10 cm and 10-30 cm layers,organic carbon were higher in BEF than in CFP,with value of 1.83% and 0.61% each,the variation was not significant in layers between 30-90 cm.In BEF with depth from 70-90 cm,the value of inorganic carbon was higher from the month of May to August.In CFP with depth from 30-50 cm,the value of inorganic carbon was higher in the months of May,June and October.Total N content in soil depth from 0-20 cm of BEF was greater than the corresponding CFP,and the TN content below 20 cm of soil layer was relatively low with impact of absorption in the rainy season months.The inorganic N content of soil in BEF has a significantly decrease with soil depth and showed that soil surface（0-30 cm） has major effect by mineralization and soil deep layer（30-90 cm） has a greater impact by vegetation absorbing in the rainy season months.While the inorganic N content of soil profile CFP is significantly over by months of the rainy season,the content is relatively small from 5 to 7 month and relatively large from 8 to 10 month.Soil organic carbon,inorganic carbon and total nitrogen in both types of forest decreases with depth of soil.There was negative correlation between organic carbon and nitrogen with soil moisture above 0-10 cm in soil layer.