Location
The eddy covariance tower was established at an experimental site (41°46'41"N, 111°53'50" E, 1438 m a.s.l) fenced from 2007 at the Siziwang Station (41°47'17"N, 111°53'46" E, 1456 m a.s.l), which is administrated by the Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, located in the south central area of Siziwang Banner, Ulanqab City, Inner Mongolia. The vegetation type belongs to desert steppes.
Climatic
The study area is mid-temperate zone, continental climate. The mean annual temperature is 3.6℃, ranging from -39℃ to 37℃, and annual precipitation is 313.6mm. The mean annual relative humidity is 52%, annual sunshine hour is 3117.7 hours and the average frost-free period is 108 days.
Vegetation and soil
The native vegetation belongs to desert steppes, dominated by Stipa breviflora, Cleistogenes songorica and Artemisia frigid. Major companion species includes Convolvulus ammannii, Neopallasia pectinate, Kochi prostrate, Allium tenuissimum, Caragana stenophylla, Leymus chinensis, and Caragana microphylla.
The eddy covariance tower located at a fenced (since 2007) steppe community dominated by Stipa breviflora, Cleistogenes songorica and Artemisia frigida, and the height of vegetations is about 10-20cm.
The soil is light chestnut soil (FAO classification) with 1m depth, and there is a calcic horizon at 50-60 cm layer. Topsoil organic carbon and total nitrogen (0-10 cm) are 14g kg-1 and 1.7g kg-1, respectively. The soil particles are composed of largest amount of sand and less silt and clay.
Observation system
The eddy covariance tower was set up in May 2005. The height of tower is 3 m. An open-path eddy covariance system consists of an infrared gas analyzer (LI-7500, LICOR) and a three-dimensional sonic anemometer (CSAT3, CSI) (2 m above ground) were installed for flux measurement. The data of wind speed and gas concentration were sampled at 10 Hz. Continuous high frequency data were recorded and the covariance was calculated at 30 min intervals. Net radiation and photosynthetically active radiation were measured at 2 m above ground using a four-component net radiometer (CNR-1, Kipp & Zonen) and a quantum sensor (LI190SB, LICOR). Air temperature and relative humidity were measured at two levels (1 m and 2 m) with HMP45C (CSI). Rainfall was recorded continuously by a tipping bucket rain gauge (TE-525, CSI) 2 m above the ground. The top of 10 cm volumetric soil water content was measured by a TDR sensor (CS616, CSI). Soil temperature was measured with temperature probes (107, CSI) at three soil layers (5, 10 and 20 cm). Soil heat flux was determined with soil heat transducers (HFT-3, CSI) at 2 cm below the soil surface with three replicates. All micrometeorological data was stored every 30 min.
Principal Investigator
Shiping Chen
E-mail: spchen@ibcas.ac.cn