Current position:observation site > Sites > Grassland Ecosystem > Ansai


Ansai Loess Plateau temperate shrub-grass flux observation site (36°51′30″N, 109°19′23″E, and elevation 1260 m) is located in the middle of Loess Plateau in Ansai Shaanxi province, which belongs to Ansai national ecological experiment station and Chinese Ecosystem Research Network (CERN). The observation site of flux is in a north facing hillside of the station with a slope from 18°-20°, and the observation area is 120m×80m.


Ansai station is in the semi-arid temperate climate zone with an annual mean temperature of 8.8℃,the maximum and minimum monthly temperature are -6.9℃ (Jaunary) and 22.6℃ (July), respectively. The annual mean precipitation amount is 540 mm, and the precipitation mainly concentrated during July-September.

Vegetation and soil

The vegetation type of this area belongs to transition zone of temperate deciduous broad-leaved forest to temperate grassland. The original forests at this site were clearance cut and destroyed since 19th century,which also caused the serious water soil and loss. The flux observation area is dominated by natural secondary grassland, occupied by Bothriochloa ischaemum, Stipa bungeana, Artemisia gmelinii and Artemisia giraldii. Meanwhile, some natural secondary shrub species such as Hippopha Rhamnoides were also observed. The soil type is dominated by loessial soil and silt loam, with highly calcareous (pH 8.4), thick soil layer (50–80 m), and low organic carbon.

Observation system

(1) Flux observation system:An eddy covariance system, observed water and carbon fluxes, was mounted at 4 m on a tower. It consisted of a LI-7500 open-path CO2/H2O analyzer (LI-7500, Li-cor , USA) and a three-dimensional sonic anemometer (CSAT3, Campbell , USA). In addition, soil heat flux was measured by two HFP01 (Campbell, USA) heat flux plate, and were mounted at heights of 0.05m below the ground.

(2) Meteorological observation: Net radiation and quantum sensor of photosynthetically active radiation were mounted at height of 1.5m, through a four-component radiometer (Model CNR-1, Kipp & Zonen Inc., The Netherlands) and a photosynthetically active radiatiometer (Model LI190SB, Licor Inc.), respectively. Air temperature and relative humidity sensors (Model HMP45C, Campbell Scientific Inc., USA) and wind speed/direction sensors (A100R, Vector Inc.) were mounted at heights of 1, 2, 3, 5m, above the ground. A wind speed and direction sensor was also mounted at height of 6m above the ground. Precipitation was monitored with a rain gauge (Model 52203, RM Young Inc., USA).

(3) Soil temperatures were made at depths of 2, 5, 20, 50 and 100 cm with thermocouples (109SS, Campbell Scientific Inc., USA), meanwhile soil volumetric water contents were recorded at depths of 5, 20 and 50 cm using three TDR probes (Model CS616-L, Campbell Scientific Inc., USA).

(4) The flux data were sampled at 10 Hz with 30 min averages collected by CR3000 dataloggers (Model CR3000, Campbell Scientific Inc., USA), and  meteorological data were sampled at 1 Hz with 30 min averages collected by CR1000 dataloggers (Model CR1000, Campbell Scientific Inc., USA).

Principal Investigator

 Yunming Chen


Station director

Yunming Chen          Professor


Guobin Liu              Professor                  Yinli Liang          Professor

Zongsuo Liang        Professor                  Jijun Wang         Professor

 Fuli Xu                     Professor                  Ruilian Han        Professor

 Xuexuan Xu             Professor                  Gangshuan Bai    Professor

 Guanghui Zhang       Professor





The coupling relationship of stoichiometry characteristics between forest-litter-soil as well as its response to abiotic environmental factors in Loess Hilly forest .          (Yunming Chen    2014-2017)

The drought effect to distribution and content of non-structural carbon, nitrogen and phosphorus in Loess Plateau plantation .            (Yang Chao    2013-2015)

The water consumption research of Quercus wutaishanica in forest-forest grass transition zone in Loess Plateau .         (Sheng Du     2012-2015)

Affecting degree and scaling effect of environmental variability to soil water content in Loess Plateau hilly region.         (Feng Jiao     2012-2016)

Resistance mechanism of revert slop farmland and warping dam to slop-ditch system erosion in Loess Plateau.        (Juying Jiao    2011-2015)

The research of vegetation structure simulation based on species library- A case study in
Loess Plateau.          (Guoqing Li      2014-2016)

Rhizosphere carbon precess and microbial function analysis of vegetation succession in Loess Plateau hilly region .          (Sha Xu    2014-2016)

Affecting effect and mechanism of soil available Nitrogen to fine root decomposition processes of Chinese pine .          (Guoliang Wang      2014-2017)

The inhibition mechanism of grass root to soil erosion in abandoned farmland in Loess Plateau.The inhibit effect of plant root to soil erosion in Loess Plateau.       (Bing Wang     2014-2016)

The response of dominant natural grass to rainfall pluses in Loess Plateau hilly region.       (Bingcheng Xu    2014-2018)


Construction of the northwestern ground-remote sensing data information platform.         (Yunming Chen    2014-2015)

The soil nutrient balance and productive maintains in Loess Plateau plantation.      (Yang Chao    2013-2015)  

The carbon sequestration rate and potential in project of Forest (grass) Rehabilitation from Slope Agriculture.      (Guobin Liu     2011-2015)


The carbon sequestration ability, rate and potential research of temperate deciduous broad-leaved forest in Shaanxi province.       (Yunming Chen    2011-2015)

The carbon sequestration ability, rate and potential research of temperate forest in Midwest China.       (Sheng Du    2011-2015)

The integration and demonstration to key technology of efficient agricultural production in hilly region .      (Yinli Liang      2011-2015)



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