wAbstract
@To understand spatial and temporal variations of nitrous oxide
(N2O) fluxes, we chose to measure N2O emissions from three plant stands (Kobresia
tibetica, Carex muliensis, and Eleocharis valleculosa
stands) in an open fen on the northeastern Qinghai-Tibetan plateau
during the growing seasons from 2005 to 2007. The overall mean
N2O emission rate was about 0.018}0.056 mgN
m-2 h-1 during the growing seasons from
2005 to 2007, with highly spatiotemporal variations. The hummock
(K. tibetica stand) emitted N2O at
the highest rate about 0.025}0.051 mgN m-2 h-1,
followed by the hollow stands: the E. valleculosa stand
about 0.012}0.046 mgN m-2 h-1 and the C.
muliensis stand about 0.017}0.068 mgN m-2 h-1.
Within each stand, we also noted significant variations of N2O emission. We also observed the significant
seasonal and inter-annual variation of N2O
fluxes during the study period. The highest N2O
emission rate was all recorded in July or August in each year
from 2005 to 2007. Compared with the mean value of 2005, we found
the drought of 2006 significantly increased N2O
emissions by 104 times in the E. valleculosa stand, 45
times in K. tibetica stand, and 18 times in the C. muliensis
stand. Though there was no significant relation between standing
water depths and N2O emissions, we still
considered it related to the spatiotemporal dynamics of soil water
regime under climate change.
Keywords: Inter-annual variations; Global change; Extreme climate
events; Greenhouse gases; Biogeochemistryx
1. Introduction
2. Materials and methods
@2.1. Site description
@2.2. Soil physical-chemical characteristics
@2.3. Growth of vegetation
@2.4. Sampling plots establishment and N2O
flux measurement
@2.5. Statistical analysis
3. Results
@3.1. N2O fluxes from the three stands
@3.2. Seasonal and inter-annual variations of N2O
fluxes
@3.3. Key factors controlling N2O emissions
4. Discussion
5. Conclusions
Acknowledgments
References