CO2 FLUXES OF ARTIFICIAL GRASSLAND IN THE SOURCE REGION OF THE THREE RIVERS ON THE QINGHAI-TIBETAN PLATEAU, CHINA

doi:10.3773/j.issn.1005-264x.2008.03.003

Abstract

Abstract:

Aims It is important to the study of the carbon cycle and ecological issues to understand seasonal variation in CO₂ flux and the influence of environmental factors on the artificial grassland in the source region of the three rivers on the Qinghai-Tibetan Plateau.

Methods We utilized the eddy covariance method to observe net ecosystem CO₂ exchange (NEE) and biological and environmental factors and their variation at the Elymus nutans artificial grassland from September 1, 2005 to August 31, 2006.

Important findings The daily maximum uptake of CO₂ was 2.38 g C·m^-2·d^-1 on July 30. The ratio of daily uptake and emission in August were observed, -6.82 and 2.95 μmol CO ₂·m^-2·s^-1, respectively. In the growing seasons, daily NEE was dominated by the variation of photosynthetically active radiation (PAR). At the same time, daily NEE combined with leaf area and community diversity to control photosynthetic rate and photosynthetic efficiency. Maximum photosynthetic rate was 2.46-10.39 μmol CO ₂·m^-2·s^-1, and the apparent quantum yield (denoting the maximum efficiency of light utilization in photosynthesis) was 0.013-0.070 μmol CO ₂·μmol^-1 PAR. The influence of temperature, Q₁₀ (1.8) in the growing season was less than in the non-growing season. The respiration of the ecosystem was mainly dominated by temperature and leaf area. Carbon absorption was not dominated by the larger temperature difference of the day and night in the growing season. Our study proved that the artificial grassland ecosystem was a carbon sink with a carbon absorption of -49.35 g C·m^-2·a^-1. Our study also proved that the source and sink function of carbon was influenced by the amount, intensity and seasonal allocation of annual precipitation, as well as by plant community diversity.

Key words: artificial grassland ecosystem, CO₂ fluxes, temperature difference of day and night

ZHAO Liang, GU Song, ZHOU Hua-Kun, XU Shi-Xiao, ZHAO Xin-Quan, LI Ying-Nian. CO₂ FLUXES OF ARTIFICIAL GRASSLAND IN THE SOURCE REGION OF THE THREE RIVERS ON THE QINGHAI-TIBETAN PLATEAU, CHINA[J]. Chin J Plant Ecol, 2008, 32(3): 544-554.

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.plant-ecology.com/EN/10.3773/j.issn.1005-264x.2008.03.003

https://www.plant-ecology.com/EN/Y2008/V32/I3/544

Figures/Tables 10

Table 1 Meteorological parameters and instruments used

观察要素 Meteorological parameters	仪器介绍 Instruments or sensor	设置高度 Location (cm)
CO₂ 和H₂O 浓度 CO₂ and H₂O concentrations	Li-7500, Li-Cor, USA	300
三维风速和空气 Vertical wind and air temperature	CSAT3, CSI,USA	300
净辐射Net radiation	CNR-1, Kipp and Zonen, Netherlands	150
光量子通量Photosynthetic photon flux density	Li-190SB, Li-Cor, USA	150
风速和风向Wind speed and direction	014A and 034A-L, CSI,USA	110, 300
空气温度和湿度Air temperature and humidity	HUMP45C, CSI, USA	110, 300
地表面温度Soil surface temperature	107,CSI,USA	0
土壤热通量Soil heat flux	HFT-3, CSI, USA	-2
土壤温度Soil temperature	105T,CSI,USA	-3, -10, -20, -30, -40, -50, -60, -70
土壤含水量Soil water content	TDR,CS615, CSI, USA	-3, -20, -50
降雨量Precipitation	TE525MM, CSI, USA	50

Fig.1 Seasonal variability of photosynthetically active radiation (PAR), average daily air temperature (Ta), soil temperature at a 5 cm depth (Ts), vapor pressure deficit (VPD), and daily total precipitation (PPT) and daily average volumetric soil moisture (SWC)

Fig.2 Averages of aboveground biomass and leaf area index (LAI) for the artificial grassland in the source region of the three rivers

Fig.3 Relationships between net daily CO2 exchange (NEE) and day/night temperature (Tad-Tan) in each month (a) and whole growing season (b)

Fig.4 Response of ecosystem respiration (Reco) to change in soil temperature at the depth of 5 cm(Ts) during growth season

Fig.5 Response of ecosystem respiration (Reco) to change in soil temperature at the depth of 5 cm (Ts) during non-growing season

Fig.6 Relationship between photosynthetically active radiation (PAR) and the net CO2 exchange (NEE) measured in each month over a growth season

Fig.7 Linear regression of daytime net carbon exchange rate (NEE) on incident photosynthetically active radiation

Fig.8 Average monthly diurnal trends in net ecosystem CO2 exchange (NEE)

Fig.9 Fig. 1

References 25

[1]	Andrew ES, Shashi BV (2001). Year-round observations of the net ecosystem exchange of carbon dioxide in a native tall grass prairie. Global Change Biology, 7,279-289.
[2]	Cheng GD (1999). Glaciology and geocryology of china during the past 40 years: progress and prospects. Journal of Glaciolgy and Geocryology, 21,289-309.
[3]	Dugas WA, Heuer ML, Mayeux HS (1999). Carbon dioxide fluxes over bermudagrass, native prairie, and sorghum. Agricultural and Forest Meteorology, 93,121-139.
[4]	Flanagan LB, Wever LA, Carson PJ (2002). Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland. Global Change Biology, 8,599-615.
[5]	Gu S, Tang YH, Du MY, Kato T, Li YN, Cui XY, Zhao XQ (2003). Short-term variation of CO ₂ flux in relation to environmental controls in an alpine meadow on the Qinghai-Tibetan Plateau . Journal of Geophysical Research, 108,4670-4679.
[6]	Kato T, Tang YH, Gu S, Cui XY, Hirota M, Du MY, Li YN, Zhao XQ, Oikawa T (2004). Carbon dioxide exchange between the atmosphere and an alpine meadow ecosystem on the Qinghai-Tibetan Plateau, China. Agricultural and Forest Meteorology, 124,121-134.
[7]	Kato T, Tang YH, Gu S, Hirota M, Du MY, Li YN, Zhao XQ (2006). Temperature and biomass influences on interannual changes in CO ₂ exchange in an alpine meadow on the Qinghai-Tibetan Plateau . Global Change Biology, 12,1285-1298.
[8]	Kim J, Verma SB (1990). Carbon dioxide exchange in a temperate grassland ecosystem. Boundary-Layer Meteorology, 52,135-149.
[9]	Ham JM, Knapp AK (1998). Fluxes of CO₂, water vapor, and energy from a prairie ecosystem during the seasonal transition from carbon sink to carbon source . Agricultural and Forest Meteorology, 89,1-14.
[10]	Hollinger DY, Kelliher FM, Byers JN, Hunt JE, McSeveny TM, Weir PL (1994). Carbon dioxide exchange between an undisturbed old-growth temperate forest and the atmosphere. Ecology, 75,134-150.
[11]	Hollinger DY, Goltz SM, Davidson EA, Lee JT, Tu K, Valentine HT (1999). Seasonal patterns and environmental control of carbon dioxide and water vapor exchange in an ecotonal boreal forest. Global Change Biology, 5,891-902.
[12]	Hunt JE, Kelliher FM, McSeveny TM, Byers JN (2002). Evaporation and carbon dioxide exchange between the atmosphere and a tussock grassland during a summer drought. Agricultural and Forest Meteorology, 111,65-82.
[13]	Ma YS (马玉寿), Lang BN (郎百宁), Wang QJ (王启基) (1999). Review and prospect of the study on `black soil type' deteriorated grassland. Pratacultural Science (草业科学), 16(2),5-8. (in Chinese with English abstract)
[14]	Ruimy A, Jarvis PG, Baldocchi DD, Saugier B (1995). CO₂ fluxes over plant canopies and solar radiation: a review . Advances in Ecological Research, 26,1-68.
[15]	Shi PL (石培礼), Sun XM (孙晓敏), Xu LL (徐玲玲), Zhang XZ (张宪洲), He YT (何永涛), Zhang DQ (张东秋), Yu GR (于贵瑞) (2006). Experimental study on net ecosystem CO ₂ exchange in the alpine grassland ecosystem on Tibetan Plateau . Science in China (Series D) (中国科学 (D辑)), 26 (Suppl. Ⅰ),194-203. (in Chinese)
[16]	Valentini R, Gamon JA, Field CB (1995). Ecosystem gas exchange in a California grassland: seasonal patterns and implications for scaling. Ecology, 76,1940-1952.
[17]	Verma SB, Kim J, Clement R (1992). Momentum, water vapor, and carbon dioxide exchange at a centrally located prairie site during FIFE. Journal of Geophysics Research, 97,18629-18639.
[18]	Wang QJ (王启基), Lai DZ (来德珍), Jing ZC (景增春), Li SX (李世雄), Shi HL (史惠兰) (2005). The present of resource, ecological environment and sustainable development in the source region of yangtze, yellow and yalu tsangpo rivers. Journal of Lanzhou University (Natural Sciences Edition) (兰州大学学报(自然科学版)), 41(4),1-7. (in Chinese with English abstract)
[19]	Webb EK, Pearman GI, Leuning R (1980). Correction of flux measurements for density effects due to heat and water vapor transport. Quarterly Journal of the Royal Meteorological Society, 106,85-100.
[20]	Wilson K, Goldstein A, Falge E, Aubinet M, Baldocchi D, Berbigier P, Bernhofer C, Ceulemans R, Dolman H, Field C, Grelle A, Ibrom A, Law BE, Kowalski A, Meyers T, Moncrieff J, Monson R, Oechel W, Tenhunen J, Valentini R, Verma S (2002). Energy balance closure at FLUXNET sites. Agricultural and Forest Meteorology, 113,223-243.
[21]	Zhao L, Li YN, Zhao XQ, Xu SX, Tang YH, Yu GR, Gu S, Du MY, Wang QX (2005a). Comparative study of the net exchange of CO ₂ in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau . Chinese Science Bulletin, 50,1767-1774.
[22]	Zhao L, Li YN, Gu S, Zhao XQ, Xu SX, Ru GR (2005b). Carbon dioxide exchange between the atmosphere and an alpine shrubland meadow during the growing season on the Qinghai-Tibetan Plateau. Journal of Integrative Plant Biology, 47,271-282.
[23]	Zhao L (赵亮), Xu SX (徐世晓), Li YN (李英年), Tang YH (唐艳鸿), Zhao XQ (赵新全), Gu S (古松), Du MY (杜明远), Yu GR (于贵瑞) (2006). Relations between carbon dioxide fluxes and environmental factors of Kobresia humilis meadows and Potentilla fruticosa meadows on the Qinghai-Tibetan Plateau . Acta Botanica Boreali-Occidentalia Sinica (西北植物学报), 26,133-142. (in Chinese with English abstract)
[24]	Zhao L, Li YN, Xu SX, Zhou HK, Gu S, Yu GR, Zhao XQ (2006). Diurnal, seasonal and annual variation in net ecosystem CO ₂ exchange of an alpine shrubland on the Qinghai-Tibetan Plateau . Global Change Biology, 12,1940-1953.
[25]	Zhou XM (周兴民) (2001). The Kobresia Meadow of China (中国嵩草草甸). Science Press, Beijing. (in Chinese)

CO₂ FLUXES OF ARTIFICIAL GRASSLAND IN THE SOURCE REGION OF THE THREE RIVERS ON THE QINGHAI-TIBETAN PLATEAU, CHINA

FullText

PDF (PC)

Knowledge

Abstract

Cite this article

share this article

Figures/Tables 10

References 25

Related Articles 1

Recommended Articles

Metrics

Comments