Location

 Eddy covariance measurement is conducted on the southern margin of Gurbantonggut Desert (44°12′–44°21′ N, 87°50′–87°54′ E, 450 m above sea level). The site is in the vicinity of the Fu-kang Station of Desert Ecology, Chinese Academy of Sciences. The topography is characterized by alternating sand dunes and wide, flat interspaces between the dunes. The longitudinally parallel sand dunes are generally 2–5 km in length, with a relative height ranging from 20 to 30 m. The interspaces between sand dunes are usually between 200 and 500 m wide. The Gurbantunggute Desert has a typical temperate continental climate with a dry hot summer and cold winter, the air temperature ranges from a minimum of −42.2 °C in winter to a maximum of 44.2 °C in summer, and annual mean temperature is 6.6 °C; annual mean precipitation is 70–180 mm, of which 25 % is generally snowfall; and annual pan evaporation is about 2000 mm. Typically, this area has an average snow cover period of about 120 d from mid- November to mid-March of the following year. The depth of snow cover is about 20–30 cm, and melts in early April.

Climatic

Vegetation and soil

 H. ammodendron and H. persicum are the dominant species in the Gurbantonggut Desert, with H. ammodendron mainly growing at inter-dunes, and H. persicum mainly at dune crests – the mean densities of adult plants were 700 and 120 plants ha−1 in their respective habitats. The dominant ephemeral plants including: E. oxyrrhynchum, M. scorpioides, A. linifolium, and accounting for more than 60 % and 85 % of the community coverage and biomass, respectively. The dominant annuals including: S. subcrassa, C. arenarius, A. squarrosum.

Soil physical and hydraulic properties differ in inter-dune and dune crest habitats. Particle sizes of inter-dune soil were 26.34 % medium (0.500–0.250 mm), 39.08 % fine (0.250–0.125 mm), 30.16 % extremely fine (0.125–0.063 mm) and 4.42 % silt (<0.063 mm); and corresponding values for dune crest 55.28, 41.28, 3.26 and 0.18 %.

Observation system

 The system consist of a 3-D ultrasonic anemometer-thermometer (CSAT 3D, Campbell Scientific, Logan, UT, USA) and an open path infrared gas (CO₂/H₂O) analyzer (LI-7500, Licor Inc., Lincoln, NE, USA). Additional meteorological instruments measured air temperature, soil temperature, soil moisture, air humidity, and incoming and outgoing total radiation, photosynthetic active radiation and soil heat flux. All data are logged with a CR23X data-logger (Campbell Scientific, Logan, Utah, USA).

Principal Investigator

YanLi

E-mail: liyan@ms.xjb.ac.cn