摘要
以极端干旱区(敦煌)泡泡刺群落为研究对象,采用动态气室法(Li-8100,USA)于2010年5月至9月测定分析了生长季内增雨对泡泡刺群落土壤碳排放量的影响。结果表明:裸地和灌丛在09:00—11:00的碳排放量与全天碳排放量具有线性正相关关系(裸地R2=0.31—0.76,P<0.001;灌丛R2=0.85—0.96,P<0.001)。增雨50%(4 mm)—300%(24 mm)能够加速裸地和灌丛土壤的碳排放,每增雨1 mm,裸地和灌丛土壤的碳排放分别增加0.27和1.12 g/m2。当泡泡刺群落盖度一定时,与对照相比,每增加1 mm降雨,泡泡刺群落土壤碳排放量增加0.69 g/m2。在未来中国西北干旱地区降雨增加背景下,这一研究数据将为进一步估算该区域群落或生态系统碳收支提供可靠的参考数据。
Our previous research showed an increasing trend of rainfall in a temperate arid region of China. In this study, to address potential effects of additional rain on carbon emissions of an arid ecosystem, we conducted a field manipulative experiment with five simulated rain addition treatments （four rain addition treatments and one for comparison ）. Each treatment included four repetitive plots, each with an area of approximately 113 m^2, in Dun Huang, Gansu. The design simulated rain increases of 0% （CK）, 50%, 100%, 200% and 300% of the long-term （1978--2008） average annual precipitation （40 mm） at the study site. We used the Li-8100 automated soil CO2 flux system in a Nitraria sphaerocarpa community during the growing season, from May to September 2010. Our results showed a linear positive correlation in soil carbon emissions between 09：00--11：00 and 24：00 hours for vegetated and bare soil （bare soil R^2 = 0. 31--0. 76, P〈 0. 001; vegetated soil R^2 =0.85--0.96, P〈0. 001 ）. The rain increases accelerated vegetated and bare soil respiration in the plots. Compared with the g/m^2 ,and the emissions of v control group, soil carbon emissions of bare soil increased by 8.83, 11.03, 26.64, 31.69 egetated soil increased by 30.02, 45.34, 98.08, 133.90 g/m^2 with the 0% （CK）, 50%, 100% , 200% and 300% treatments, respectively. Soil carbon emissions of vegetated soil were three times greater than those of bare soil during the growing season, which was statistically significant. There was a significant linear correlation between soil carbon emissions and precipitation during the growing season, in both bare soil and vegetated soil. With a 1 mm increase in rainfall, soil carbon emissions in vegetated and bare soils increased 1. 12 g/m^2 and 0.27 g/m^2, respectively. With a given community cover, every 1 mm rainfall increase produced an additional 0.69 g/m^2 of soil carbon emission, relative to the control treatment.
We developed a multiple linear regression model for community coverage, precipitation and soil carbon emissions of a community of Nitraria sphaerocarpa, and found that soil carbon emissions of the control group were 2.97--6.55 kg from May to September. During the growing season, when community coverage waa eight percent, soil carbon emissions of the community increased by 0.62, 2.18, 5.30 and 8.42 kg with the 0% （CK）, 50% , 100% , 200% and 300% treatments, respectively. With community coverage at nineteen percent, the emissions respectively increased by 1.56, 3.12, 6.24 and 9.36 kg for those same treatments. For community coverage of thirty-eight percent, the respective emission increases were 2.50, 4, 06, 7.18 and 10.30 kg. This study is important for estimating the ecosystem carbon budget in the arid region of Northwest China with future rainfall increases.
出处
《生态学报》
CAS
CSCD
北大核心
2012年第17期5396-5404,共9页
Acta Ecologica Sinica
基金
林业公益性行业科研专项(201104077)
中央级公益性科研院所基本科研业务费专项资金重点项目(CAFYBB2007008)资助
关键词
人工模拟增雨
极端干旱区
土壤碳排放量
泡泡刺
rain addition
hyperarid region
soll carbon emissions
Nitraria sphaerocarpa
