天然灌木林改造成板栗林对土壤碳库和氮库的影响

Effects of the conversion from native shrub forest to Chinese chestnut plantation on soil carbon and nitrogen pools

在浙江省安吉县采集了相邻的天然灌木林和板栗林土壤,分析土壤水溶性碳(WSOC)、微生物生物量碳(MBC)、易氧化碳(ROC)、水溶性有机氮(WSON)和微生物生物量氮(MBN),并利用核磁共振方法分析土壤总有机碳的波谱特征,研究天然灌木林改造成板栗林对土壤碳库和氮库的影响.结果表明:天然灌木林改造成板栗林后,土壤中的碱解氮、有效磷和速效钾显著增加,而WSOC、MBC、ROC、WSON和MBN显著下降.天然灌木林和板栗林土壤有机碳以烷基碳和烷氧碳为主.天然灌木林改造成板栗林后,土壤有机碳中的烷氧碳和羰基碳比例显著下降,而烷基碳和芳香碳比例以及A/O-A值和芳香度均显著增加.天然灌木林改造成板栗林并长期集约经营后,土壤活性碳库和氮库含量均显著下降,而土壤碳库的稳定性显著增加.

To investigate the effects of the conversion from native shrub forest（NF） to Chinese chestnut plantation（CP） on the soil carbon（C） and nitrogen（N） pools,soil samples were collected from the adjacent NF and CP in Anji County of Zhejiang Province,with their water-soluble organic C（WSOC）,microbial biomass C（MBC）,readily oxidizable C（ROC）,water-soluble organic N（WSON）,and microbial biomass N（MBN） determined.The spectral characteristics of soil organic C were also determined by using nuclear magnetic resonance（NMR） technique.After the conversion from NF to CP,the soil alkalyzable N,available phosphorus,and available potassium contents increased significantly,while the soil WSOC,MBC,ROC,WSON,and MBN were in adverse.The soil organic C in both NF and CP was dominated by alkyl C and O-alkyl C,but the proportions of O-alkyl C and carbonyl C in soil organic C decreased while the proportions of alkyl C and aromatic C as well as the alkyl C / O-alkyl C ratio and the aromaticity of soil organic C all increased significantly after the conversion from NF to CP,indicating that this conversion increased the stability of soil organic C pool significantly.In conclusion,the conversion from NF to CP and the intensive management of CP decreased the contents of soil labile C and soil N but increased the stability of soil C pool significantly.