期刊
BIOGEOCHEMISTRY
卷 144, 期 2, 页码 197-214出版社
SPRINGER
DOI: 10.1007/s10533-019-00580-7
关键词
Soil organic carbon; Carbon cycle; Nitrogen cycle; SOM model; Precipitation
资金
- SREI2020 EnviroSphere research program of the University of Sydney
- Mid Career Research Award of the University of Sydney
- Sydney Research Accelerator Fellowship (SOAR) of the University of Sydney
- Office of Science, Office of Biological and Environmental Research of the U.S. Department of Energy under LBNL TES Belowground Biogeochemistry Scientific Focus Area [DE-AC02-05CH11231]
Climate change is expected to alter hourly and daily rainfall regimes and, in turn, the dynamics of ecosystem processes controlling greenhouse gas emissions that affect climate. Here, we investigate the effects of expected twenty-first century changes in hourly and daily rainfall on soil carbon and nitrogen emissions, soil organic matter (SOM) stocks, and leaching using a coupled mechanistic carbon and nitrogen soil biogeochemical model (BAMS2). The model represents various abiotic and biotic processes involving 11 SOM pools. These processes include fungal depolymerization, heterotrophic bacterial mineralization, nitrification, denitrification, microbial mortality, necromass decomposition, microbial response to water stress, protection, aqueous advection and diffusion, aqueous complexation, and gaseous dissolution. Multi-decadal modeling with varying rainfall patterns was conducted on nine Australian grasslands in tropical, temperate, and semi-arid regions. Our results show thatannual CO2 emissions in the semi-arid grasslands increase by more than 20% with a 20% increase in annual rainfall (with no changes in the rainfall timing), but the tropical grasslands have opposite trends. A 20% increase in annual rainfall also increasesannual N2O and NO emissions in the semi-arid grasslands by more than 10% but decreases emissions by at least 25% in the temperate grasslands. When subjected to low frequency and high magnitude daily rainfall events with unchanged annual totals, the semi-arid grasslands are the most sensitive, but changes inannual CO2 emissions and SOM stocks are less than 5%. Intensification of hourly rainfall did not significantly alter CO2 emissions and SOM stocks but changedannual NH3 emissions in the tropical grasslands by more than 300%.
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