References

Biogeosciences

1726-4189

Copernicus Publications

Göttingen, Germany

10.5194/bg-11-4679-2014

Biophysical controls on net ecosystem CO2 exchange over a semiarid shrubland in northwest China

Jia

² ¹ Zha

T. S.

² ¹ Wu

¹ ² Zhang

Y. Q.

² ¹ Gong

J. N.

³ Qin

S. G.

² ¹ Chen

G. P.

⁴ Qian

² ¹ Kellomäki

³ Peltola

Yanchi Research Station, College of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China

Key Laboratory of soil and Water Conservation and Desertification Combating, Ministry of Education, Beijing Forestry University, Beijing 100083, China

School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland

Institute of Forest Sciences, Bailongjiang Forestry Management Bureau, Wudu, Gansu 746010, China

08 09 2014

11 17 4679 4693

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://bg.copernicus.org/articles/11/4679/2014/bg-11-4679-2014.html

The full text article is available as a PDF file from https://bg.copernicus.org/articles/11/4679/2014/bg-11-4679-2014.pdf

The carbon (C) cycling in semiarid and arid areas remains largely unexplored, despite the wide distribution of drylands globally. Rehabilitation practices have been carried out in many desertified areas, but information on the C sequestration capacity of recovering vegetation is still largely lacking. Using the eddy-covariance technique, we measured the net ecosystem CO2 exchange (NEE) over a recovering shrub ecosystem in northwest China throughout 2012 in order to (1) quantify NEE and its components and to (2) examine the dependence of C fluxes on biophysical factors at multiple timescales. The annual budget showed a gross ecosystem productivity (GEP) of 456 g C m−2 yr−1 (with a 90% prediction interval of 449–463 g C m−2 yr−1) and an ecosystem respiration (Re) of 379 g C m−2 yr−1 (with a 90% prediction interval of 370–389 g C m−2 yr−1), resulting in a net C sink of 77 g C m−2 yr−1 (with a 90% prediction interval of 68–87 g C m−2 yr−1). The maximum daily NEE, GEP and Re were −4.7, 6.8 and 3.3 g C m−2 day−1, respectively. Both the maximum C assimilation rate (i.e., at the optimum light intensity) and the quantum yield varied over the growing season, being higher in summer and lower in spring and autumn. At the half-hourly scale, water deficit exerted a major control over daytime NEE, and interacted with other stresses (e.g., heat and photoinhibition) in constraining C fixation by the vegetation. Low soil moisture also reduced the temperature sensitivity of Re (Q10). At the synoptic scale, rain events triggered immediate pulses of C release from the ecosystem, followed by peaks of CO2 uptake 1–2 days later. Over the entire growing season, leaf area index accounted for 45 and 65% of the seasonal variation in NEE and GEP, respectively. There was a linear dependence of daily Re on GEP, with a slope of 0.34. These results highlight the role of abiotic stresses and their alleviation in regulating C cycling in the face of an increasing frequency and intensity of extreme climatic events.

References 1

Aires, L. M. I., Pio, C. A., and Pereira, J. S.: Carbon dioxide exchange above a Mediterranean C3/C4 grassland during two climatologically contrasting years, Glob. Change Biol., 14, 539–555, 2008.

Asner, G. P., Archer, S., Hughes, R. F., Ansley, R. J., and Wessman, C. A.: Net changes in regional woody vegetation cover and carbon storage in Texas drylands, 1937–1999, Glob. Change Biol., 9, 316–335, 2003.

Baldocchi, D. D.: Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future, Glob. Change Biol., 9, 479–492, 2003.

Burba, G. and Anderson, D.: A Brief Practical Guide to Eddy Covariance Flux Measurements: Principles and Workflow Examples for Scientific and Industrial Applications, LI-COR Biosciences, 2010.

Chen, X. and Duan, Z.: Changes in soil physical and chemical properties during reversal of desertification in Yanchi County of Ningxia Hui autonomous regions, China, Environ. Geol., 57, 975–985, 2009.

Chen, S., Lin, G., Huang, J., and Jenerette, D.: Dependence of carbon sequestration on the differential responses of ecosystem photosynthesis and respiration to rain pulses in a semiarid steppe, Glob. Change Biol., 15, 2450-2461, 2009.

Dragoni, D., Schmid, H. P., Grimmond, C. S. B., and Loescher, H. W.: Uncertainty of annual net ecosystem productivity estimated using eddy covariance flux measurements, J. Geophys. Res., 112, D17102, <a href="http://dx.doi.org/10.1029/2006JD008149">https://doi.org/10.1029/2006JD008149</a>, 2007.

Easterling, D. R., Meehl, G. A., Parmesan, C., Changnon, S. A., Karl, T. R., and Mearns, L. O.: Climate extremes: observations, modeling, and impacts, Science, 289, 2068–2074, 2000.

Feng, W., Zhang, Y., Wu, B., Zha, T., Jia, X., Qin, S., Shao, C., Liu, J., Lai, Z., and Fa, K.: Influence of disturbance on soil respiration in biologically crusted soil during the dry season, Sci. World J., 2013, 408560, <a href="http://dx.doi.org/10.1155/2013/408560">https://doi.org/10.1155/2013/408560</a>, 2013.

Flanagan, L. B. and Johnson, B. G.: Interacting effects of temperature, soil moisture and plant biomass production on ecosystem respiration in a northern temperate grassland, Agr. Forest Meteorol., 130, 237–253, 2005.

Flanagan, L. B., Wever, L. A., and Carlson, P. J.: Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland, Glob. Change Biol., 8, 599–615, 2002.

Fu, Y. L., Yu, G. R., Sun, X. M., Li, Y. N., Wen, X. F., Zhang, L. M., Li, Z. Q., Zhao, L., and Hao, Y. B.: Depression of net ecosystem CO2 exchange in semi-arid Leymus chinensis steppe and alpine shrub, Agr. Forest Meteorol., 137, 234–244, 2006.

Gao, Y., Li, X., Liu, L., Jia, R., Yang, H., Li, G., and Wei, Y.: Seasonal variation of carbon exchange from a revegetation area in a Chinese desert, Agr. Forest Meteorol., 156, 134–142, 2012.

Hagen, S. C., Braswell, B. H., Linder, E., Frolking, S., Richardson, A. D., and Hollinger, D. Y.: Statistical uncertainty of eddy flux-based estimates of gross ecosystem carbon exchange at Howland Forest, Maine, J. Geophys. Res., 111, D08S03, <a href="http://dx.doi.org/10.1029/2005JD006154">https://doi.org/10.1029/2005JD006154</a>, 2006.

Hollinger, D. Y. and Richardson, A. D.: Uncertainty in eddy covariance measurements and its application to physiological models, Tree Physiol., 25, 873–885, 2005.

Jarvis, P., Rey, A., Petsikos, C., Wingate, L., Reyment, M., Pereira, J., Banza, J., David, J., Miglietta, F., Borghetti, M., Manca, G., and Valentini, R.: Drying and wetting of Mediterranean soils stimulates decomposition and carbon dioxide emission: the "Birch effect", Tree Physiol., 27, 929–940, 2007.

Lal, R.: Carbon sequestration in dryland ecosystems, Environ. Manage., 33, 528–544, 2004.

Lee, X., Wu, H. J., Sigler, J., Oishi, C., and Siccama, T.: Rapid and transient response of soil respiration to rain, Glob. Change Biol., 10, 1017–1026, 2004.

Li, S. G., Asanuma, J., Eugster, W., Kotani, A., Liu, J. J., Urano, T., Oikawa, T., Davaa, G., Oyunbaatar, D., and Sugita, M.: Net ecosystem carbon dioxide exchange over grazed steppe in central Mongolia, Glob. Change Biol., 11, 1941–1955, 2005.

Li, X. R., Ma, F. Y., Xiao, H. L., Wang, X. P., and Kim, K. C.: Long-term effects of revegetation on soil water content of san dunes in arid regions of Northern China, J. Arid Environ., 57, 1–16, 2004.

Liu, R., Li, Y., and Wang, Q. X.: variations in water and CO2 fluxes over a saline desert in western China, Hydrol. Process., 26, 513–522, 2011.

Liu, R., Pan, L. P., Jenerette, G. D., Wang, Q. X., Cieraad, E., and Li, Y.: High efficiency in water use and carbon gain in a wet year for a desert halophyte community, Agr. Forest Meteorol., 162–163, 127–135, 2012.

McCarthy, J., Canziani, O., Leary, N., Dokken, D. J., and White, K. S.: Climate Change 2001: Impacts, Adaptation, and Vulnerability, Cambridge University Press, New York, 2001.

Moffat, A. M., Papale, D., Reichstein, M., Hollinger, D. Y., Richardson, A. D., Barr, A. G., Beckstein, C., Braswell, B. H., Churkina, G., Desai, A. R., Falge, E., Gove, J. H., Heimann, M., Hui, D., Jarvis, A. J., Kattge, J., Noormets, A., and Stauch, V. J.: Comprehensive comparison of gap-filling techniques for eddy covariance net carbon fluxes, Agr. Forest Meteorol., 147, 209–232, 2007.

Papale, D., Reichstein, M., Aubinet, M., Canfora, E., Bernhofer, C., Kutsch, W., Longdoz, B., Rambal, S., Valentini, R., Vesala, T., and Yakir, D.: Towards a standardized processing of Net Ecosystem Exchange measured with eddy covariance technique: algorithms and uncertainty estimation, Biogeosciences, 3, 571–583, <a href="http://dx.doi.org/10.5194/bg-3-571-2006">https://doi.org/10.5194/bg-3-571-2006</a>, 2006.

Poulter, B., Frank, D., Ciais, P., Myneni, R. B., Andela, N., Bi, J., Broquet, G., Canadell, J. G., Chevallier, F., Liu, Y. Y., Running, S. W., Sitch, S., and van der Werf, G. R.: Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle, Nature, 509, 600–603, 2014.

Schmid, H. P.: Experimental design for flux measurements: matching scales of observations and fluxes, Agr. Forest Meteorol., 87, 179–200, 1997.

Suyker, A. E. and Verma, S. B.: Year-round observations of the net ecosystem exchange of carbon dioxide in a native tallgrass prairie, Glob. Change Biol., 7, 279–289, 2001.

Tappeiner, U. and Cernusca, A.: Model simulation of spatial distribution of photosynthesis in structural differing plant communities in the Central Caucasus, Ecol. Model., 113, 201–223, 1998.

Wang, Y., Zhou, G., and Wang, Y.: Environmental effects on net ecosystem CO2 exchange at half-hour and month scales over Stipa krylovii steppe in northern China, Agr. Forest Meteorol., 148, 714-722, 2008.

Wan, S. and Luo, Y.: Substrate regulation of soil respiration in tallgrass prairie: results of a clipping and shading experiment, Global Biogeochem. Cy., 17, 1054, <a href="http://dx.doi.org/10.1029/2002GB001971">https://doi.org/10.1029/2002GB001971</a>, 2003.

Wang, B., Zha, T. S., Jia, X., Wu, B., Zhang, Y. Q., and Qin, S. G.: Soil moisture modifies the response of soil respiration to temperature in a desert shrub ecosystem, Biogeosciences, 11, 259–268, <a href="http://dx.doi.org/10.5194/bg-11-259-2014">https://doi.org/10.5194/bg-11-259-2014</a>, 2014.

Whittaker, R. H.: Communities and Ecosystems, MacMillan publishing Co., New York, 1975.

Xu, L. and Baldocchi, D. D.: Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California, Agr. Forest Meteorol., 123, 79–96, 2004.

Yang, X., Zhang, K., Jia, B., and Ci, L.: Desertification assessment in China: An overview, J. Arid Environ., 63, 517–531, 2005.

Yang, F., Zhou, G., Hunt, J. E., and Zhang, F.: Biophysical regulation of net ecosystem carbon dioxide exchange over a temperate desert steppe in Inner Mongolia, China, Agr. Forest Meteorol., 142, 318–328, 2011.

Ye, Z. P.: A new model for relationship between irradiance and the rate of photosynthesis in Oryza sativa, Photosynthetica, 45, 637–640, 2007.

Zha, T., Kellomäki, S., Wang, K., and Rouvinen, I.: Carbon sequestration and ecosystem respiration for 4 <abbr>years</abbr> in a scots pine forest, Glob. Change Biol., 10, 1492–1503, 2004.

Zhang, W. L., Chen, S. P., Chen, J., Wei, L., Han, X. G., and Lin, G. H.: Biophysical regulations of carbon fluxes of a steppe and a cultivated cropland in semiarid Inner Mongolia, Agr. Forest Meteorol., 146, 216–229, 2007.

Zhu, Z., Sun, X., Wen, X., Zhou, Y., Tian, J., and Yuan, G.: Study on the processing method of nighttime CO2 eddy covariance flux data in ChinaFLUX, Sci. China Ser. D, 49, supp. II, 36–46, 2006.

Zhou, J., Zhang, Z., Sun, G., Fang, X., Zha, T., McNulty, S., Chen, J., Jin, Y., and Noormets, A.: Response of ecosystem carbon fluxes to drought events in a poplar plantation in Northern China, Forest Ecol. Manag., 300, 33–42, 2013.