Key nitrogen cycling processes in pine plantations along a short urban-rural gradient in Nanchang, China

作者：Chen, Fu-sheng^*; Fahey, Timothy J.; Yu, Ming-yuan; Gan, Lu

来源：Forest Ecology and Management, 2010, 259(3): 477-486.

DOI：10.1016/j.foreco.2009.11.003

• Ion exchange resin bag method
• Mid-subtropical region
• China
• Nitrification
• Nutrient resorption
• Soil extracellular enzymes
• Soil microbial biomass
• Soil nitrogen mineralization
• Urbanization

We used pine (Pinus elliottii Engelm.) forests located along a short urban-rural gradient in Nanchang, China to study nitrogen (N) cycling responses to urbanization. Annual average rates of nitrification and net N-mineralization in soils (0-15 cm depth) measured from February 2007 to January 2009 increased from rural (8 and 37 kg ha(-1) year(-1)) to suburban (69 and 79 kg ha-1 year(-1)) and urban sites (114 and 116 kg ha(-1) year(-1)) (P < 0.05). Soil nitrate and mineral IN pools exhibited the same spatial patterns in response to urban location. In comparison to rural sites, urban and suburban sites experienced soil microbial biomass N that increased by 98% and 38%, sucrase activity that increased by 40% and 26%, and urease activity that decreased by 35% and 25%, respectively. Soil microbial biomass C:N and free amino acids varied little along the urban-rural gradient. Foliar N concentrations and N resorption proficiencies were higher in urban (12.3 and 4.8 g kg(-1)) and suburban (12.3 and 6.2 g kg(-1)) than in rural (9.9 and 3.6 g kg(-1)) sites, while N resorption efficiencies (from 58% to 72%) were not statistically different. These results indicate that forests in suburban and especially in urban areas are moving rapidly towards a state of "N saturation" and increased potential N loss most likely attributable to higher N deposition to these sites.

• 出版日期2010-1-25
• 单位南昌大学; 江西科技师范大学