Soil Respiration In Typical Plant Communities In The Wetland Surrounding High-salinity Ebinur Lake

The Ebinur Lake is the largest saltwater lake in Xinjiang Uygur Autonomous Region of China,which is affected by high salt,water shortage,desertificationand gale leads to serious degradation of soil and vegetation in this area.Its ecological security and stability directly not only threaten the sustainable development of the economic belt of the northern slope of Xinjiang Tianshan Mountains,but also rebuild an indispensable part of the economic belt of the Silk Road.Soil respiration is an important link in the global carbon cycle.In recent years,soil carbon cycling has been paid more and more attention,but the research on soil carbon cycle in arid highsalinity lake wetland has lagged far behind in other areas.In this study,a longitudinal transect of 4 km from the south of the lake was set up at the Bird Island Station in Ebinur Lake,and the typical plant community of reed(Phragmites australis)and tamarisk(Tamarix ramosissima)were selected as the research object and the bare soil was the control group.The soil respiration rate of Phragmites australis,Tamarix and bare soil was monitored for 24 hours in the middle and late month of the month from April to November 2015-2016,and the carbon flux monitor LI-840A(Li-cor Company,USA)and record and measure environmental factors.The diurnal variation of soil respiration rate and the seasonal variation of soil respiration rate were studied,and the factors influencing the soil respiration rate of typical plant communities in Ebinur Lake wetland were discussed in order to provide basic experimental data and basis for scientific evaluation of soil carbon cycle in arid and semi arid areas.The results are as follows:(1)The diurnal variation of soil respiration rate in different growth stages of reed,tamarisk and bare soils showed irregular diurnal curves;The average daily of soil respiration rate during the germination period,rapid growth period,mid-growth period and thriving period were in the order of reed> tamarisk > bare land,while withering period and wintering period were tamarisk > reed> bare land.In the wintering period of the reed,the germination period and the rapid growth period and the overwintering period of tamarisk,all the growth period of tamarisk were negative values at night,indicating that the soil under the reed,tamarisk and bare soil absorbed CO2 from air in some way in the monitoring period.(2)The soil respiration rate of reed,tamarisk and bare soils showed a seasonal variation of irregular diurnal curves.The soil respiration rate of reed> tamarisk > bare soils,reed and tamarisk showed carbon emission process,and bare soils was carbon uptake process.(3)There was a significant positive correlation between air temperature and soil respiration rate of reed,tamarisk and bare soil,and significant negative correlation between air relative humidity and soil respiration rate(except the wintering period of reed,tamarisk and baresoil);significant positive correlation with soil temperature.The Q10 value of reed is greater than tamarisk and bare soil;and the soil water content was not fixed;it was negatively correlated with the salt content of tamarisk and bare soil,while the reed was positively correlated.It was was negatively correlated with soil p H,it were positively correlated with soil organic carbon,total phosphorus and ammonium nitrogen;it was negatively correlated with the nitrate nitrogen of reed and tamarisk,while the bare soil was positively correlated.It were significantly or not significantly positive correlation between soil urease,phosphatase,catalase and soil respiration rate.(4)The air temperature of Reed,Tamarix and bare soil in the range of 22~35,23~30,24~34?,soil temperature in the range of 21~33,21~29,23~36,soil water content in the range of 3.8~14.9,2.2~24.9,0.2~10.9%,organic carbon content in the range of 12.8~26.8,26.3~40.6,1.4~8 g/kg,Urease reached 0.18,0.14,0.1 mg/kg or more,Phosphatase reached 0.33,0.75,0.03 mg/kg or more,Catalase were 2.05,5.59,2.57mg/kg or more will promote the production of soil respiration rate.And when the relative humidity of air at the range of 42~69,52~75,33~80%,salinity reached 24.7,22.5 and 7.6 g/kg,pH above 7.4 will inhibit the production of soil respiration rate.(5)The reed of diurnal variation of soil respiration rate were affected by soil temperature,soil water content and air temperature at different growth stages.The tamarisk of diurnal variation of soil respiration were affected by soil temperature,air relative humidity and soil water content.The bare soilof diurnal variation of soil respiration were affected by the soil temperature and air temperature and humidity.The environmental factors influencing the seasonal of respiration rate of reed soil were air temperature and air relative humidity.Tamarix was the air temperature,soil temperature and ammonium nitrogen.The bare soil was dominated by soil temperature,nitrate nitrogen and catalase.(6)The growth season of high-salinity Ebinur Lake wetland show the carbon emission process(except the bare soil in this study).The GWPs of reed,tamarisk and bare soil in the growing season were 650.58,412.22 and-3.97 kg CO2 / hm2,respectively,which were smaller than those in other study areas and had less ability to enhance greenhouse effect.