土地利用方式对土壤有机碳和碳库管理指数的影响

Effects of Land Uses on Soil Organic Carbon and Carbon Pool Management Index

土壤碳库管理指数反映土壤管理的科学性。对比研究了干热河谷新银合欢林、苏门答腊金合欢林、大叶相思林、印楝林、荒地和旱耕地土壤有机碳(SOC)、易氧化有机碳(ROC)含量和土壤碳库管理指数。结果表明:6种土地利用方式下SOC和ROC含量范围分别为4.22 5.92 g.kg-1和1.34 2.33 g.kg-1。各利用方式之间SOC含量差异不显著,但4类人工林ROC含量均显著(P<0.05)高于旱耕地和荒地。SOC与ROC含量存在极显著(P<0.001)线性相关关系(R2为66.3%)。以荒地作为参照,4类人工林土壤碳库管理指数变化范围为1.77至2.36,旱耕地为0.99。研究揭示:植被凋落量和管理措施是不同利用类型ROC含量变异的主要原因。在干热河谷生态脆弱地区,封禁管理有助于人工林土壤碳库的提高,而旱耕地土壤碳库处于不良管理状况。

Carbon management index（ICM） is used to evaluate the scientificity of soil management.Soil organic carbon（SOC） and readily oxidized carbon（ROC） contents under Leucaena leucocephala stand,Acacia glauca stand,Acacia auriculiformis stand,Azadirachta indica stand,wasteland and dry cropland were determined and their ICM were calculated.The results showed that the SOC and ROC contents under the 6 land use types were 4.22—5.92 g·kg-1 and 1.34—2.33 g·kg-1,respectively.No significant differences in SOC contents among these land uses were observed.The ROC contents under the 4 types of woodland,however,were significantly higher than these under dry cropland or wasteland（P0.05）.The ROC were high significantly（P0.001） correlated（R2 is 66.3%） with SOC.Compared with wasteland,the ICM ranged from 1.77 to 2.36 under these woodlands,and 0.99 under dry cropland.It is revealed that the litter quantity and land management under these land uses may be the key factors resulting in the variation of ROC.At ecological fragile region of Dry-hot Valley,closure management is useful to sequestrate C in woodland soils.However,the management systems for soil carbon pool under dry cropland are not in a sound way.