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Qin L.,Xinjiang Key Laboratory of Oasis Ecology | Qin L.,Xinjiang University | Lv G.,Xinjiang Key Laboratory of Oasis Ecology | Lv G.,Xinjiang University | And 11 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013

As an special process for soils in the regions of high altitude, the freeze-thaw process directly or indirectly influences the physical, chemical and biological properties of soils. Under the background of the global warming, increasing attention has been paid to the effect of soil freezing-thawing alternation on carbon cycles. By measuring the changes of depth of seasonal frozen soil, of soil properties and soil respiration, our main objective was to provide insight into the responses of soil properties and soil respiration to changes in depth of seasonal frozen soil in arid area, and to further elaborate the effect of global warming on seasonal frozen soil and the resulted carbon release. Soil respiration rate (Rs) of Ebinur Lake area was measured from January to April in 2010 in the field using an automated CO2efflux system (LI-8100). Meanwhile, temperature (air temperature), atmospheric relative humidity and wind speed were measured 150 cm above the ground. Temperature, atmospheric relative humidity and wind speed were also measured at 10 cm above the ground, with a handheld weather instrument. Soil temperatures were measured at 5 cm, 10 cm, 15 cm, 20 cm and 25 cm below soil surface with two geo-thermometers. The results showed that: during the frozen period, soil temperature is the most important factor determining the depth of frozen soil, while during thawing period, the depth of frozen soil was not influenced by temperature (P > 0.05). There was significant positive correlation between soil respiration rate and depth of frozen soil during most of the freezing period (R2=0.782, P < 0.05), this correlation did not apply to the initial stage of freezing period (P > 0.05). There was no significant difference in soil respiration rate between the freezing period and the initial stage of freezing period, but soil respiration rate significantly increased with the temperature during thawing period until the soil was unfrozen completely (the changes was 0.14-0.37μmol•m-2•s-1), indicating that permafrost melting significantly increased soil carbon emissions. Climate change impact on seasonal frozen soil depth, on the duration of frozen period, will change the seasonal crop production in permafrost regions. The natural vegetation biomass, spatial distribution pattern of vegetation and ranges of natural native plants distribution will also be changed. Even the plant community succession direction and patterns may also be altered by the changes in duration and depth of frozen soil. All those will affect the ecosystem carbon cycling process. The difference in soil respiration rate of different periods was influenced by soil organic content, snow-melt recharging to soil water and other factors, which may have a collectively effect on carbon cycle of the local ecosystem. Our preliminary findings in the current study revealed the impacts of seasonal frozen-thawing process on soil respiration in Ebinur Lake area, and provided theoretical basis for revealing carbon release mechanism during frozen-thawing processes under the background of global warming.


Yang X.-D.,East China Normal University | Yang X.-D.,Tiantong National Forest Ecosystem Observations and Research Station | Zhang X.-N.,Xinjiang University | Zhang X.-N.,Xinjiang Key Laboratory of Oasis Ecology | And 4 more authors.
PLoS ONE | Year: 2014

The hydraulic redistribution (HR) of deep-rooted plants significantly improves the survival of shallow-rooted shrubs and herbs in arid deserts, which subsequently maintain species diversity. This study was conducted in the Ebinur desert located in the western margin of the Gurbantonggut Desert. Isotope tracing, community investigation and comparison analysis were employed to validate the HR of Populus euphratica and to explore its effects on species richness and abundance. The results showed that, P. euphratica has HR. Shrubs and herbs that grew under the P. euphratica canopy (under community: UC) showed better growth than the ones growing outside (Outside community: OC), exhibiting significantly higher species richness and abundance in UC than OC (p<0.05) along the plant growing season. Species richness and abundance were significantly logarithmically correlated with the P. euphratica crown area in UC (R2 = 0.51 and 0.84, p<0.001). In conclusion, P. euphratica HR significantly ameliorates the water conditions of the shallow soil, which then influences the diversity assembly in arid desert communities. © 2014 Yang et al.


Qin L.,Xinjiang Key Laboratory of Oasis Ecology | Qin L.,Xinjiang University | Qin L.,Xinjiang Academy of Environmental Protection Science | Lv G.H.,Xinjiang Key Laboratory of Oasis Ecology | And 11 more authors.
Eurasian Soil Science | Year: 2015

Arid and semiarid areas account for about one-third of the total land surface, and which play an important role in the global carbon cycle and climate system. However, up to now, compare with plenty knowledge information on winter soil efflux of forest ecosystems in mid-latitude ecosystems, winter soil efflux of arid areas at mid-latitude ecosystems is scare, Ebinur Lake Area, which is the study area of the present study, is located in arid regions of Northern China, with a vulnerable ecological environment suffering from extreme weather and climate. The objectives of this study were: (1) measure the winter soil respiration rate in our study area and determine its major environmental factors; (2) determine the winter soil CO2 efflux and its contribution to annual soil CO2 efflux in different ecosystems; and (3) discuss the estimated method of soil respiration that is most suitable to arid areas. We measured winter soil CO2 efflux and the associated environment factors in a farmland ecosystem (50a and 9a cotton fields), an abandoned land ecosystem (7a and 3a abandoned lands) and desert ecosystem (Populus euphratica, Phragmites australis communities and sandy desert) in Ebinur Lake Area, China. The average winter soil respiration rate in the arid areas in the mid-latitude was 0.063 μmol m−2 s−1 to 0.730 μmol m−2 s−1. Specifically, the average winter soil respiration rate in the farmland ecosystems, abandoned land ecosystems and desert ecosystems were 0.686 μmol m−2 s−1, 0.443 μmol m−2 s−1 and 0.276 μmol m−2 s−1, respectively. Range of annual Q10 (known as the increase in soil respiration rate per 10°C increase in temperature) in the three ecosystems were 0.989 to 4.962, 1.971 to 2.096 and 0.947 to 5.173, respectively. The relatively higher Q10 values in the different ecosystems were all obtained in winter. We found that water (in the form of soil moisture or atmospheric humidity) was the primary factor that affected the change of soil respiration rate in the winter. Winter soil CO2 efflux were 9 g C m−2 to 132 g C m−2 and 19 g C m−2 to 130 g C m−2 by the observed and modelled method for soil respiration, respectively. The average winter soil CO2 efflux were 79.4 and 78.7 g C m−2, reLspectively. The contributions of winter soil CO2 efflux to annual one were 4% to 31% and 4% to 30%. In the study area, the model using the observed ecosystem-specific response equations between soil respiration and water-temperature simulated the soil respiration rate was the most suitable ones. © 2015, Pleiades Publishing, Ltd.


He X.M.,Xinjiang Key Laboratory of Oasis Ecology | He X.M.,Xinjiang University | Lu G.H.,Xinjiang Key Laboratory of Oasis Ecology | Lu G.H.,Xinjiang University | And 8 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

With the global climate change and the resulting frequent regional natural disasters becoming increasingly real, CO2, H2O, and energy transport and transformation processes of the surface atmosphere are becoming important concerns for the international community. Carbon flux in the non-growing season (Jan. 15 to Mar. 15, Nov. 1 to Dec. 14 in 2012; Nov. 1 to 16 in 2013) was measured in the Ebinur Lake Wetland National Nature Reserve of Xinjiang using the eddy covariance technique. Then, research was conducted on the carbon flux data processing method after consulting the flux data processing standards in China, and the data were further analyzed to understand the carbon flux data characteristics in the non-growing season, and to attempt to reveal the controlling factors and change law. The results indicated that there were a large number of “wild” non-growing season carbon flux observation data in the study area, which accounted for 37.39% of the total. The effective carbon flux was in the range from -0.197 mg m-2 s-1 to 0.283 mg m-2 s-1, and the average atmospheric CO2 concentration and carbon flux were 766.905 mg/m3 and 0.018 mg m-2 s-1 respectively, which showed weak carbon sources. Axis-rotation correction results showed TR < DR < PF, and the planer fit (PF) correction showed better accuracy (R2 = 0.9349, P < 0.01). The frequency-response correction increased carbon flux by 7.55%, but the carbon flux was less affected by the hydrothermal correction. The energy closure throughout the non-growing season in the study area was 0.62, indicating that 38% of the energy is not closed in the non-growing season. The proportion of IST classification results of carbon flux data in the desert wetland in quality levels 1—6 was 92.03%, indicating that the distribution in different quality grades of carbon flux data in the desert-wetland ecosystem was relatively uniform. The percentage of ITC classification results in the five quality levels was 91.65%, illustrating that the development of atmospheric turbulence was at a middle level of adequacy in this period. When the friction velocity was 0—0.15, 0.15—0.30, and more than 0.30 m/s, respectively, the carbon flux showed grade variation characteristics; therefore, frictional wind speed at night can be divided into the three levels, and data within the 0 m/s and 0.30 m/s can be selectively weeded out. The proportions of data eliminated through the methods of sensor abnormal state, check analysis, and threshold analysis were 26.34%, 2.48%, and 8.57%, respectively, and the vast majority showed intermittent loss characteristics. There were no significant correlations between carbon flux and solar radiation or 5 cm soil temperature. Use of the linear interpolation and average daily variation methods could realize interpolation of missing data, but these could not reflect the true flux variations in a better manner. Conducting research on carbon flux in the non-growing season in a unique ecosystem in a desert-wetland environment surrounded by arid land and probing the carbon flux data characteristics and peculiarities could help provide the needed carbon flux research data and also a basis for improving research on carbon flux in China. © 2014, Science Press. All rights reserved.

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