Pedosphere 15(1): 52--58, 2005
ISSN 1002-0160/CN 32-1315/P
©2005 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Soil N pools and transformation rates under different land uses in a subalpine forest-grassland ecotone |
SUN Geng , WU Ning and LUO Peng |
| Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041 (China). E-mail: sungeng@cib.ac.cn |
| ABSTRACT |
| 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 better indicator of soil nitrification. |
| Key Words: denitrification, gross nitrification, land use, subalpine forest-grassland ecotone, Tibetan Plateau |
| Citation: Sun, G., Wu, N. and Luo, P. 2005. Soil N pools and transformation rates under different land uses in a subalpine forest-grassland ecotone. Pedosphere. 15(1): 52-58. |
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