城乡梯度森林土壤原易位N矿化

Soil Nitrogen Mineralization of in situ and Exchange-location Incubation in Forest along an Urban-to-Rural Gradient

以位于南昌市城乡生态界面的湿地松(Pinus elliottii)人工林为研究对象,开展城区、郊区、乡村3个不同梯度土壤N原位、易位培养试验。结果表明:培养土壤来源对土壤的氨化、硝化速率影响差异极显著(P<0.001),对净矿化速率影响差异显著(P<0.05);氨化速率表现为乡村土壤来源(0.11 mg.kg-1.30 d-1)>郊区土壤来源(-0.92 mg.kg-1.30d-1)>城区土壤来源(-2.02 mg.kg-1.30 d-1);硝化速率表现为乡村土壤来源(0.44 mg.kg-1.30 d-1)较低,城区(3.18 mg.kg-1.30 d-1)和郊区土壤来源(3.35 mg.kg-1.30 d-1)较高;净矿化速率表现为乡村土壤来源(0.54 mg.kg-1.30 d-1)<城区土壤来源(1.16 mg.kg-1.30 d-1)<郊区土壤来源(2.43 mg.kg-1.30 d-1)。培养位置对氨化速率影响差异不显著(P>0.05),对硝化速率、净矿化速率影响差异极显著(P<0.001);硝化速率和净矿化速率均表现为乡村(0.68 mg.kg-1.30 d-1和-0.29 mg.kg-1.30 d-1)和郊区(1.78 mg.kg-1.30 d-1和1.06 mg.kg-1.30 d-1)较低,城区(4.51 mg.kg-1.30 d-1和3.36 mg.kg-1.30 d-1)较高。总体来看,土壤N的矿化过程既与土壤理化特性有关,又明显受到城市化的影响。

Soil nitrogen mineralization of in situ and exchange-location incubation was studied in Pinus elliottii. plantations along a 30 km urban-suburban-rural transect in Nanchang City. The results showed that the effects of incubation soil source on the rates of ammonification, nitrification and net mineralization were significant at the levels of P 〈0.001 and P 〈0.05, respectively. The ammonifieation rate for different incubation soil sources showed an increase tendency with further away from the urban, they were - 2.02 mg ·kg^-1·30d^-1, - 0.92 mg ·kg^-1·30d^-1, and 0.11 mg ·kg^-1·30d^-1 respectively in urban, suburban and rural soils. However, the rate of nitrification in rural source soil （0.44 mg ·kg^-1·30d^-1） showed much lower than that in suburban source soil （3.18 mg ·kg^-1·30d^-1 ）and urban source soil （3.35 mg ·kg^-1·30d^-1）. The net mineralization rate showed contrary tendency, 0.54 mg ·kg^-1·30d^-1, 1. 16 mg ·kg^-1·30d^-1, 2.43 mg ·kg^-1·30d^-1 showed in urban, suburban, rural soil. The effects of soil incubation location on the rates of nitrification and net mineralization was significant at the level of P 〈 0. 001, while the effect on ammonification rate was no significant （ P 〈 0.05 ）. Both of the rates of nitrification and net mineralization for different soil incubation locations showed the lower rates in rural source soil（0.68 mg ·kg^-1·30d^-1 and -0.29 mg ·kg^-1·30d^-1）and suburban source soil（ 1.78 mg ·kg^-1·30d^-1 and 1.06 mg ·kg^-1·30d^-1）, but the rates are much higher in urban source soil （4.51 mg ·kg^-1·30d^-1and 3.36 mg ·kg^-1·30d^-1）. In conclusion, soil nitrogen mineralization process was influenced by soil characteristics as well as urbanization process.