Soil N Pools and Transformation Rates Under Different Land Uses in a Subalpine Forest-Grassland Ecotone

作     者：SUNGeng WUNing LUOPeng SUN Geng, WU Ning and LUO PengChengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041 (China).

作者机构：ChengduInstituteofBiologyChineseAcademyofSciencesChengdu610041China 

出 版 物：《Pedosphere》 (土壤圈（英文版）)

年 卷 期：2005年第15卷第1期

页      面：52-58页

核心收录：

学科分类：0818[工学-地质资源与地质工程] 09[农学] 0903[农学-农业资源与环境] 0901[农学-作物学] 090301[农学-土壤学] 

基　　金：ProjectsupportedbytheKnowledgeInnovationProjectofChineseAcademicofSciences(No.KSCX1-07)theImportantOrientationProject(No.KSCX2-01-09)theNational"TenthFive-YearPlan"KeyProject(No.2001BA606A-05)theYouthScienceandTechnologyFoundationofSichuanProvince(No.03ZQ026-043) 

主　　题：denitrification gross nitrification land use subalpine forest-grassland ecotone Tibetan Plateau 

摘      要：Soil nitrogen pools (NP), denitrification (DN), gross nitrification (GN), N2O and CO2 flux rates with their responses to temperature increases were determined under five different land uses and managements in a subalpine forest-grassland ecotone of the eastern Tibetan Plateau. Land uses consisted of 1) sparse woodland, 2) shrub-land, 3) natural pasture, 4)fenced pasture, and 5) tilled pasture mimicking a gradient degenerating ecosystem under grazing impacts. The NO3--N content was higher than the NH4+-N content. Comparing tilled pasture with fenced pasture showed that higher intensive management (tillage) led to a significant decrease of soil organic matter (SOM) (P 0.05) in the soils, which was in contrast to the significant increases (P 0.05) of DN, GN, N2O and CO2 flux rates. GN (excluding tilled pasture) and CO2 flux rates increased with a temperature rise, but DN and N2O flux rates normally reached their maximum values at 12-14 ℃ with tilled pasture (the highest management intensity) being very sensitive to temperature increases. There was a difference between net nitrification and GN, with GN being a betterindicator of soil nitrification.