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Impact of Cloud on net ecosystem co2 exchange of Alpine Meadow in Tibetan Plateau

Chinese Journal of Population,Resources and Environment 2010年第4期8卷 69-75页

作者： Fan Yuzhi Zhang Xianzhou Shi Peili Wu Jianshuang Institute of Geographic Sciences and Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Meteorological elements and co2 fluxes over alpine meadow ecosystem were observed continuously from 2004 to 2005 in Damxung Alpine Meadow Flux Station, China Flux network. Based on the eddy covariance co2 fluxes and meteorological data obtained, the relationships among the co2 fluxes, the cloud amount, and the meteorological factors in alpine meadow ecosystem were explored and analyzed. Some conclusions can be drawn from the discussion with previous researches as following：（1） the cloud amount can affect the net ecosystem co2 exchange （NEE） of alpine meadow on Tibetan Plateau; （2） the soil temperature sensitive to the cloud amount, is a major environmental controlling factor for NEE, and closely relates to the maximum of NEE. In the moming period with large cloud amount, the NEE reaches its maximum when the clearness index ranges from 0.5 to 0.7; yet in the afternoon it comes to the maximum with the index from 0.2 to 0.35. The span of soil temperature covers from 12 to 15℃ as the NEE at its highest; （3） the scatterplots between NEE and photosynthetic available radiation （PAR） was a significant inverse triangle in the clear day, two different kinds of concave curves in the cloudy day, and strongly convergent rectangular hyperbola in the overcast day. These differences were controlled by the changes of light radiation and soil temperature.

关键词： net ecosystem co2 exchange cloud amount clearness index alpine meadow ecosystem Tibetan Plateau

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Effect of solar radiation on net ecosystem co_2 exchange of alpine meadow on the Tibetan Plateau

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Journal of Geographical Sciences 2011年第4期21卷 666-676页

作者： FAN Yuzhi ZHANG Xianzhou WANG Jingsheng SHI Peili Key Laboratory of ecosystem network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

On the Tibetan Plateau, the alpine meadow is the most widespread vegetation type. The alpine meadow has a low biological productivity and low vegetation coverage in the growing season. The daytime NEE between the atmosphere and the alpine meadow ecosystem was influenced by solar radiation. To analyze the characteristics of change in NEE and to calculate the parameters related to photosynthesis and respiration in different solar radiation environments, the NEE measurements were taken in Damxung from July to August in 2003, 2004, 2005 and 2006 using the eddy covariance technique. Solar radiation was grouped into three levels according to the net radiation, which was more than 155 W m-2 d-1 on clear days, 144±5 W m-2 d-1 on partly cloudy days and less than 134 W m-2 d-1 on cloudy days. The diurnal relationships between NEE and PAR varied with differences in solar radiation, which was a rectangular hyperbola form on clear days, two different concave curves on partly cloudy days and an irregular triangle form on cloudy days. The mean co2 absorption rate showed a decreasing trend with increasing solar radiation. The daytime absorption maximum occurred around 10：00 on clear days with an average of slightly less –0.2 mg m-2 d-1, around 11：00 on partly cloudy days with an average of about –0.2 mg m-2 d-1, and around 12：00 on cloudy days with an average of about –0.25 mg m-2 d-1. As solar radiation increased, the Amax and the Q10 decreased. However, the R10 increased and the maximum of the α occurred on partly cloudy days. The optimum net solar radiation was about 134–155 W m-2 d-1, which induced a PAR of about 1800-2000 μmol m-2 s-1 and soil temperature at a depth of 5 cm of about 14℃. Therefore, on the Tibetan Plateau, the alpine meadow ecosystem will have a higher carbon absorption potential while solar radiation decreases in the future.

关键词： Tibetan Plateau alpine meadow net ecosystem co2 exchange solar radiation

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comparative study of the net exchange of co2 in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau

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Science Bulletin 2005年第16期 97-104页

作者： ZHAO Liang1, LI Yingnian1, ZHAO Xinquan1, XU Shixiao1, TANG Yanhong2, YU Guirui3, GU Song1, DU Mingyuan4 & WANG Qinxue3 1. Northwest Plateau Institute of Biology, the Chinese Academy of Sci-ences, Xining 810001, China 2. National Institute for Environmental Studies, Tsukuba, Ibaraki3050053, Japan 3. Institute of Geographic Sciences and Natural Resources Research,Beijing 100101, China 4. National Institute for Agro-Environmental Science, Tsukuba, Ibaraki3058604, Japan

Using the eddy covariance method,from 1 July2003 to 30 June 2004, we conducted the observation andanalysis of ecosystem co2 flux in 3 types of alpine meadowvegetation (Kobresia humilis, Potentilla fruticosa shrub andKobresia tibetica swamp meadows) on the Qinghai-TibetanPlateau. The results show that the Kobresia humilis meadow,the shrub meadow and the swamp meadow’s highest co2uptake rates are 16.78, 10.42 and 16.57 μmol·m?2·s?1respectively, while their highest co2 release rates are 8.22,7.73 and 18.67 μmol·m?2·s?1 respectively. The Kobresiahumilis meadow and shrub meadow’s annual atmosphericuptakes are 282 g co2/m2 and 53 g co2/m2, respectively,while swamp meadow’s annual atmospheric release is 478 gco2/m2. This proves that the Kobresia humilis meadow andthe shrub meadow on the Qinghai-Tibetan Plateau haverelatively low potential for co2 uptake and release comparedto C4 grasslands, a number of lowland grasslands, andforests. Moreover, swamp meadow has relatively high releasepotential. This, in turn, reveals clear differences in carbonsource/sink between different types of vegetation in theQinghai-Tibetan Plateau alpine meadow ecosystem. Thesedifferences are mainly brought by differences in thevegetations’ photosynthetic capacity and soil respiration.

关键词： Qinghai-Tibetan Plateau net ecosystem co2 exchange eddy covariance method.

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net ecosystem co2 Flux and Effect Factors in Peatland ecosystem of Central China

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Journal of Geoscience and Environment Protection 2020年第8期8卷 95-106页

作者： Ihab Alfadhel Jiwen Ge Sakinatu Issaka School of Environmental Studies China University of Geosciences Wuhan China

Peatland ecosystems play an important role in the global carbon cycle because they act as a pool or sink for the carbon cycle. However, the relationship between seasonality effect factors and net ecosystem co2 exchange (NEE) remains to be clarified, particularly for the non-growing season. Here, based on the eddy covariance technique, NEE in the peatland ecosystem of Central China was examined to measure two years’ (2016 and 2017) accumulation of carbon dioxide emissions with contrasting seasonal distribution of environmental factors. Our results demonstrate the cumulative net ecosystem co2 emissions during the study period was in the first non-growing season 2.94 ± 4.83 μmolco2 m-2.s-1 with the lowest values in the same year in first growing season was -2.79 ± 4.92 μmolco2 m-2.s-1. The results indicate the effect of seasonal variations of NEE can be directly reflected in daily and seasonal variations in growth and respiration of peatland ecosystem by environmental parameters over different growing stages.

关键词： Dajiuhu Peatland ecosystem Respiration Eddy covariance Gross Primary Product net ecosystem co2 exchange

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