Location

  Haibei alpine meadow ecosystem flux observation station (Haibei station) located in the southeast of Lenglong ridge, north branch of Qilian mountain, northeastern of the Tibetan plateau.
Geographical coordinates is 37°37′N, 101°19′E, at an altitude of 3190m, belonging to Northwest Institute of Plateau Biological, Chinese Academy of Sciences. There are three flux tower in the station, kobresia humilis meadow（37°36.766′ N，101°18.768′E，at an altitude of 3216 m）、Potentilla froticosa shrub meadow（37°39.912′N，101°19.870′E，at an altitude of 3358 m）and  kobresia tibetica swamp meadow（37°36.505′N，101°19.640′ E，at an altitude of 3357 m）. This station represents a typical alpine meadow ecosystem type in the northeast of Tibetan plateau.

Climatic

 Haibei station, located in the hinterland of Asian continent, has plateau continental climate. Due to high altitude, the temperature is very low. There are only two seasons (warm season and cold season) here. The ean annual temperature is -1.2 ℃ and the mean temperatures of the hottest and coldest month is 10.4 ℃ and -14.4℃ respectively. The extreme maximum and minimum temperature is 27.6 ℃ and -37.1℃.  The ≥0 ℃ accumulated temperature is 1104.4 ℃ and frostless period are 20 days. Average annual precipitation is 535.2mm. In the plant growing season (May to September), precipitation is 437.5mm account for 82% of annual precipitation. Annual sunshine hours are 2451.7 h, and the percentage is 55%.The global solar radiation is 6348.5 MJ/m2.

Vegetation and soil

 Kobresia humilis meaodw mainly distributed in the gentle beach and semi-sunny slope mountain where the soil moisture is moderate. The dominant and companion species are Elymus nutans, Stipaaliena, Gen tiana straminea, Oxytropis kansuensis, Poa crmophila, and Poa praten. The vegetation coverage can reach to 98% at the end of growing season. Canopy height is 25 cm. The NPP is between 330-467 g/m2 and the average value is 393.2 g/m2. The soil is subalpine meadow soil. Content of organic matter and nitrogen of the soil in 0-40cm is 5.85% and 0.33% respectively.
Potentilla froticosa shrub meadow mainly distributed in the shady slope of the mountain and valley where the soil moisture is relatively high. Besides the constructive specie Potentilla fruticosa,, the dominant species and accompanying species are  Kobresia humilis、Festuca ovina、 Stipa aliena Keng、Festuca rubra、Elymus nutans 、Gentiana straminea、Kobresia capillifolia、Anemone、Lancea tibetica、Pedicularis、Grass Family,etc. The vegetation coverage can reach 85% at the end of growing season. The crown surface height of the upper canopy of Potentilla fruticosa can reach 60 cm. The average height of lower herbs is about 18 cm. The NPP is in the range of 223 to 378 g/m2 and the average NPP is 284.4 g/m2. The soil is alpine shrub meadow soil. Content of organic matter and nitrogen of the soil in 0-40 cm is 11.94% and 0.62% respectively.
Kobresia tibetica swamp meadow mainly distributed in the valley where the drainage is impeded and the soil humidity is very high. Accompanying species include Blysmus sinocompressus、Carex atrofusca 、Carex moorgropt、Gentianopsis paludosa、Pedicularis longiflora subsp. tubiformis、Primula nutans Georgi、Saussurca stilla,etc. The vegetation coverage can reach to 88% at the end of growing season. Average height is 25 cm, the NPP is between 229-347 g/m2 and the average NPP is 300.1 g/m2. Content of organic matter and nitrogen of the soil in 0-40 cm is 28.08% and 1.27% respectively.
Plants are low and the community structure is simple, in all the three types of meadows with low primary product.

Observation system

 The equipment of flux observation system include ultrasonic anemometer (CSAT3, Campbell,USA）and CO2/H2O gas analyzer（Li-7500, Li-cor, USA. The height of the flux tower in kobresia humilis meadow is 220 cm and in Potentilla froticosa bush meadow and swamp meadow is both 250cm. The height of air temperature and humidity probe is 110 cm and 220 cm. Radiometer height is 150 cm. Depth of soil temperature probe is -2, -5, -10, -20, -30, -40, -50, -60 and -70 cm. Soil moisture probe is -5，-20 and -50 cm. Data sampling frequency is 10 Hz. Average flux is collected every 30 minutes.
Observation of kobresia humilis meadow started in August 2001 and observation of Potentilla froticosa shrub meadow and Kobresia tibetica swamp meadow started in September 2002.

Principal Investigator

Yingnian Li

E-mail: ynli@nwipb.ac.cn