Assessing the spatial variability in peak season CO2exchange characteristics across the Arctic tundra using a light response curve parameterization

Biogeosciences

Volumn 11, Issue 17, 2014, Pages 4897-4912

  Mbufong, H N ^a   Lund, M ^a   Aurela, M ^b   Christensen, T R ^a,c   Eugster, W ^d   Friborg, T ^e   Hansen, B U ^e   Humphreys, E R ^f   Jackowicz Korczynski, M ^c   Kutzbach, L ^g   Lafleur, P M ^f   Oechel, W C ^h   Parmentier, F J W ^a,c   Rasse, D P ⁱ   Rocha, A V ^j   Sachs, T ^k   Van Der Molen, M K ^l   Tamstorf, M P ^a  

^a AARHUS UNIVERSITY   (Denmark)

^b FINNISH METEOROLOGICAL INSTITUTE   (Finland)

^c LUND UNIVERSITY   (Sweden)

^d ETH ZURICH   (Switzerland)

^e UNIVERSITY OF COPENHAGEN   (Denmark)

^f TRENT UNIVERSITY   (Canada)

^g UNIVERSITY OF HAMBURG   (Germany)

^h SAN DIEGO STATE UNIVERSITY   (United States)

ⁱ NORWEGIAN INSTITUTE OF BIOECONOMY RESEARCH   (Norway)

^j UNIVERSITY OF NOTRE DAME   (United States)

^k GFZ GERMAN RESEARCH CENTRE FOR GEOSCIENCES   (Germany)

^l WAGENINGEN UNIVERSITY   (Netherlands)

more..

Author keywords

[No Author keywords available]

Indexed keywords

ARCTIC ENVIRONMENT; CLIMATE CHANGE; EDDY COVARIANCE; FLUX MEASUREMENT; GAS EXCHANGE; IRRADIANCE; LIGHT USE EFFICIENCY; MICROMETEOROLOGY; NET ECOSYSTEM EXCHANGE; NUTRIENT AVAILABILITY; PARAMETERIZATION; RESPIRATION; SPATIAL VARIATION; TUNDRA;

ARCTIC; GREENLAND; RUSSIAN FEDERATION;

EID: 84907202565     PISSN: 17264170     EISSN: 17264189     Source Type: Journal    
DOI: 10.5194/bg-11-4897-2014     Document Type: Article

References (78)

1. ACIA: Arctic Climate Impact Assessment-Scientific Report, 1st edn., New York, 2005.
2. AMAP: AMAP Assessment Report: Arctic Pollution Issues, Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway, 859 pp., 1998.
3. Aubinet, M., Grelle, A., Ibrom, A., Rannik, U., Moncrieff, J., Foken, T., Kowalski, A S., Martin, P H., Berbigier, P., Bernhofer, C., Clement, R., Elbers, J., Granier, A., Grunwald, T., Morgenstern, K., Pilegaard, K., Rebmann, C., Snijders, W., Valentini, R., and Vesala, T.: Estimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology, Adv. Ecol. Res., 30, 113-175, 2000.
4. Aurela, M., Laurila, T., and Tuovinen, J P.: Seasonal CO2 balances of a subarctic mire, J. Geophys. Res.-Atmos., 106, 1623-1637, 2001.
5. Aurela, M., Laurila, T., and Tuovinen, J P.: The timing of snow melt controls the annual CO2 balance in a subarctic fen, Geophys. Res. Lett., 31, L16119, doi10.1029/2004GL020315, 2004.
6. Baldocchi, D.: Breathing of the terrestrial biosphere: lessons learned from a global network of carbon dioxide flux measurement systems, Aust. J. Bot., 56, 1-26, 2008.
7. 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.
8. Baldocchi, D D., Falge, E., Gu, L H., Olson, R., Hollinger, D., Running, S., Anthoni, P., Bernhofer, C., Davis, K., Evans, R., Fuentes, J., Goldstein, A., Katul, G., Law, B., Lee, X H., Malhi, Y., Meyers, T., Munger, W., Oechel, W., U, K T P., Pilegaard, K., Schmid, H P., Valentini, R., Verma, S., Vesala, T., Wilson, K., and Wofsy, S.: FLUXNET: a new tool to study the temporal and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities, B. Am. Meteorol. Soc., 82, 2415-2434, 2001.
9. Bigger, C M. and Oechel, W C.: Nutrient effect on maximum photosynthesis in Arctic plants, Holarctic Ecol., 5, 158-163, 1982.
10. Bjorkman, O., Boardman, N K., Anderson, J M., Thorne, S W., Goodchild, D J., and Pyliotis, N A.: Effect of light intensity during growth of Atriplex patula on the capacity of photosynthetic reactions, chloroplast components and structure, Carnegie I. Wash., 115-135, 1972.
11. Burba, G G., McDermitt, D K., Grelle, A., Anderson, D J., and Xu, L K.: Addressing the influence of instrument surface heat exchange on the measurements of CO2 flux from open-path gas analyzers, Glob. Change Biol., 14, 1854-1876, 2008.
12. Centritto, M., Brilli, F., Fodale, R., and Loreto, F.: Different sensitivity of isoprene emission, respiration and photosynthesis to high growth temperature coupled with drought stress in black poplar (Populus nigra) saplings, Tree Physiol., 31, 275-286, 2011.
13. Chapin, F S. and Shaver, G R.: Physiological and growth responses of arctic plants to a field experiment simulating climatic change, Ecology, 77, 822-840, 1996.
14. Chapin, F S., Eugster, W., McFadden, J P., Lynch, A H., and Walker, D A.: Summer differences among Arctic ecosystems in regional climate forcing, J. Climate, 13, 2002-2010, 2000.
15. Christensen, T R., Jackowicz-Korczynski, M., Aurela, M., Crill, P., Heliasz, M., Mastepanov, M., and Friborg, T.: Monitoring the multi-year carbon balance of a subarctic palsa mire with micrometeorological techniques, Ambio, 41, 207-217, 2012.
16. Eugster, W., McFadden, J P., and Chapin, F S.: Differences in surface roughness, energy, and CO2 fluxes in two moist tundra vegetation types, Kuparuk watershed, Alaska, USA, Arct. Antarct. Alp. Res., 37, 61-67, 2005.
17. Fahnestock, J T., Jones, M H., and Welker, J M.: Wintertime CO2 efflux from arctic soils: implications for annual carbon budgets, Global Biogeochem. Cy., 13, 775-779, 1999.
18. Falge, E., Baldocchi, D., Olson, R., Anthoni, P., Aubinet, M., Bernhofer, C., Burba, G., Ceulemans, R., Clement, R., Dolman, H., Granier, A., Gross, P., Grunwald, T., Hollinger, D., Jensen, N O., Katul, G., Keronen, P., Kowalski, A., Lai, C T., Law, B E., Meyers, T., Moncrieff, H., Moors, E., Munger, J W., Pilegaard, K., Rannik, U., Rebmann, C., Suyker, A., Tenhunen, J., Tu, K., Verma, S., Vesala, T., Wilson, K., and Wofsy, S.: Gap filling strategies for defensible annual sums of net ecosystem exchange, Agr. Forest Meteorol., 107, 43-69, 2001.
19. Frolking, S E., Bubier, J L., Moore, T R., Ball, T., Bellisario, L M., Bhardwaj, A., Carroll, P., Crill, P M., Lafleur, P M., McCaughey, J H., Roulet, N T., Suyker, A E., Verma, S B., Waddington, J M., and Whiting, G J.: Relationship between ecosystem productivity and photosynthetically active radiation for northern peatlands, Global Biogeochem. Cy., 12, 115-126, 1998.
20. Gilmanov, T G., Verma, S B., Sims, P L., Meyers, T P., Bradford, J A., Burba, G G., and Suyker, A E.: Gross primary production and light response parameters of four Southern Plains ecosystems estimated using long-term CO2-flux tower measurements, Global Biogeochem. Cy., 17, 1071, doi10.1029/2002GB002023, 2003.
21. Givnish, T J.: Adaptation to sun and shade-a whole-plant perspective, Aust. J. Plant Physiol., 15, 63-92, 1988.
22. Givnish, T. J., Montgomery, R. A., Goldstein, G.: Adaptive radiation of photosynthetic physiology in the Hawaiian lobeliads: Light regimes, static light responses, and whole-plant compensation points, Am. J. Botany, 91, 228-246, 2004.
23. Griffis, T. J., Rouse, W. R., Waddington, J. M.: Interannual variability of net ecosystem CO2 exchange at a subarcticfen, Glob. Biogeo. Cy., 14, 1109-1121, 2000.
24. Groendahl, L., Friborg, T., and Soegaard, H.: Temperature and snow-melt controls on interannual variability in carbon exchange in the high Arctic, Theo. Appl. Climatol., 88, 111-125, 2007.
25. Hugelius, G., Bockheim, J G., Camill, P., Elberling, B., Grosse, G., Harden, J W., Johnson, K., Jorgenson, T., Koven, C D., Kuhry, P., Michaelson, G., Mishra, U., Palmtag, J., Ping, C.-L., O'Donnell, J., Schirrmeister, L., Schuur, E A G., Sheng, Y., Smith, L C., Strauss, J., and Yu, Z.: A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region, Earth Syst. Sci. Data, 5, 393-402, doi10.5194/essd-5-393-2013, 2013.
26. Humphreys, E R., Lafleur, P M., Flanagan, L B., Hedstrom, N., Syed, K H., Glenn, A J., and Granger, R.: Summer carbon dioxide and water vapor fluxes across a range of northern peatlands, J. Geophys. Res.-Biogeo., 111, G04011, doi10.1029/2005JG000111, 2006.
27. IPCC: Summary for policymakers, in: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Stocker, T F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P M., Cambridge, 1-29, 2013.
28. Jacovides, C P., Tymvios, F S., Asimakopoulos, D N., Theofilou, K M., and Pashiardes, S.: Global photosynthetically active radiation and its relationship with global solar radiation in the Eastern Mediterranean basin, Theor. Appl. Climatol., 74, 227-233, 2003.
29. Jones, M H., Fahnestock, J T., and Welker, J M.: Early and late winter CO2 efflux from arctic tundra in the Kuparuk River watershed, Alaska, USA, Arct. Antarct. Alp. Res., 31, 187-190, 1999.
30. Kiepe, I., Friborg, T., Herbst, M., Johansson, T., and Soegaard, H.: Modeling Canopy CO2 Exchange in the European Russian Arctic, Arc. Antarc. Alp. Res., 45, 50-63, 2013.
31. Kuhry, P., Ping, C L., Schuur, E A G., Tarnocai, C., and Zimov, S.: Report from the International Permafrost Association: carbon pools in permafrost regions, Permafrost Periglac., 20, 229-234, 2009.
32. Kutzbach, L., Wille, C., and Pfeiffer, E.-M.: The exchange of carbon dioxide between wet arctic tundra and the atmosphere at the Lena River Delta, Northern Siberia, Biogeosciences, 4, 869-890, doi10.5194/bg-4-869-2007, 2007.
33. Kwon, H J., Oechel, W C., Zulueta, R C., and Hastings, S J.: Effects of climate variability on carbon sequestration among adjacent wet sedge tundra and moist tussock tundra ecosystems, J. Geophys. Res.-Biogeo., 111, G03014, doi10.1029/2005JG000036, 2006.
34. Lafleur, P M. and Humphreys, E R.: Spring warming and carbon dioxide exchange over low Arctic tundra in central Canada, Glob. Change Biol., 14, 740-756, 2008.
35. Lafleur, P M., Humphreys, E R., St Louis, V L., Myklebust, M C., Papakyriakou, T., Poissant, L., Barker, J D., Pilote, M., and Swystun, K A.: Variation in peak growing season net ecosystem production across the Canadian Arctic, Environ. Sci. Technol., 46, 7971-7977, 2012.
36. Laurila, T., Soegaard, H., Lloyd, C R., Aurela, M., Tuovinen, J P., and Nordstroem, C.: Seasonal variations of net CO2 exchange in European Arctic ecosystems, Theor. Appl. Climatol., 70, 183-201, 2001.
37. Lindroth, A., Lund, M., Nilsson, M., Aurela, M., Christensen, T R., Laurila, T., Rinne, J., Riutta, T., Sagerfors, J., Strom, L., Tuovinen, J P., and Vesala, T.: Environmental controls on the CO2 exchange in north European mires, Tellus B, 59, 812-825, 2007.
38. Loranty, M M., Goetz, S J., Rastetter, E B., Rocha, A V., Shaver, G R., Humphreys, E R., and Lafleur, P M.: Scaling an instantaneous model of Tundra NEE to the Arctic landscape, Ecosystems, 14, 76-93, 2011.
39. Lund, M., Falk, J M., Friborg, T., Mbufong, H N., Sigsgaard, C., Soegaard, H., and Tamstorf, M P.: Trends in CO2 exchange in a high Arctic tundra heath, 2000-2010, J. Geophys. Res.-Biogeo., 117, G02001, doi10.1029/2011JG001901, 2012.
40. Lund, M., Lafleur, P M., Roulet, N T., Lindroth, A., Christensen, T R., Aurela, M., Chojnicki, B H., Flanagan, L B., Humphreys, E R., Laurila, T., Oechel, W C., Olejnik, J., Rinne, J., Schubert, P., and Nilsson, M B.: Variability in exchange of CO2 across 12 northern peatland and tundra sites, Glob. Change Biol., 16, 2436-2448, 2010.
41. Marushchak, M E., Pitkamaki, A., Koponen, H., Biasi, C., Seppala, M., and Martikainen, P J.: Hot spots for nitrous oxide emissions found in different types of permafrost peatlands, Glob. Change Biol., 17, 2601-2614, 2011.
42. Marushchak, M E., Kiepe, I., Biasi, C., Elsakov, V., Friborg, T., Johansson, T., Soegaard, H., Virtanen, T., and Martikainen, P J.: Carbon dioxide balance of subarctic tundra from plot to regional scales, Biogeosciences, 10, 437-452, doi10.5194/bg-10-437-2013, 2013.
43. McGuire, A D., Anderson, L G., Christensen, T R., Dallimore, S., Guo, L D., Hayes, D J., Heimann, M., Lorenson, T D., Macdonald, R W., and Roulet, N.: Sensitivity of the carbon cycle in the Arctic to climate change, Ecol. Monogr., 79, 523-555, 2009.
44. McGuire, A D., Christensen, T R., Hayes, D., Heroult, A., Euskirchen, E., Kimball, J S., Koven, C., Lafleur, P., Miller, P A., Oechel, W., Peylin, P., Williams, M., and Yi, Y.: An assessment of the carbon balance of Arctic tundra: comparisons among observations, process models, and atmospheric inversions, Biogeosciences, 9, 3185-3204, doi10.5194/bg-9-3185-2012, 2012.
45. Mooney, H A., Bjorkman, O., and Collatz, G J.: Photosynthetic acclimation to temperature in desert shrub, larrea-divaricata, 1. Carbon-dioxide exchange characteristics of intact leaves, Plant Physiol., 61, 406-410, 1978.
46. New, M., Lister, D., Hulme, M., and Makin, I.: A high-resolution data set of surface climate over global land areas, Clim. Res., 21, 1-25, 2002.
47. Niu, S L., Li, Z X., Xia, J Y., Han, Y., Wu, M Y., and Wan, S.: Climatic warming changes plant photosynthesis and its temperature dependence in a temperate steppe of northern China, Environ. Exp. Bot., 63, 91-101, 2008.
48. Niu, S L., Luo, Y Q., Fei, S F., Yuan, W P., Schimel, D., Law, B E., Ammann, C., Arain, M A., Arneth, A., Aubinet, M., Barr, A., Beringer, J., Bernhofer, C., Black, T A., Buchmann, N., Cescatti, A., Chen, J Q., Davis, K J., Dellwik, E., Desai, A R., Etzold, S., Francois, L., Gianelle, D., Gielen, B., Goldstein, A., Groenendijk, M., Gu, L H., Hanan, N., Helfter, C., Hirano, T., Hollinger, D Y., Jones, M B., Kiely, G., Kolb, T E., Kutsch, W L., Lafleur, P., Lawrence, D M., Li, L H., Lindroth, A., Litvak, M., Loustau, D., Lund, M., Marek, M., Martin, T A., Matteucci, G., Migliavacca, M., Montagnani, L., Moors, E., Munger, J W., Noormets, A., Oechel, W., Olejnik, J., Kyaw, T P U., Pilegaard, K., Rambal, S., Raschi, A., Scott, R L., Seufert, G., Spano, D., Stoy, P., Sutton, M A., Varlagin, A., Vesala, T., Weng, E S., Wohlfahrt, G., Yang, B., Zhang, Z D., and Zhou, X H.: Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms, New Phytol., 194, 775-783, 2012.
49. Oberbauer, S F. and Oechel, W C.: Maximum CO2-assimilation rates of vascular plants on an Alaskan Arctic Tundra slope, Holarctic Ecol., 12, 312-316, 1989.
50. Oberbauer, S F., Starr, G., and Pop, E W.: Effects of extended growing season and soil warming on carbon dioxide and methane exchange of tussock tundra in Alaska, J. Geophys. Res.-Atmos., 103, 29075-29082, 1998.
51. Oechel, W C., Vourlitis, G L., Hastings, S J., Zulueta, R C., Hinzman, L., and Kane, D.: Acclimation of ecosystem CO2 exchange in the Alaskan Arctic in response to decadal climate warming, Nature, 406, 978-981, 2000.
52. Ow, L F., Griffin, K L., Whitehead, D., Walcroft, A S., and Turnbull, M H.: Thermal acclimation of leaf respiration but not photosynthesis in Populus deltoides x nigra, New Phytol., 178, 123-134, 2008a.
53. Ow, L F., Whitehead, D., Walcroft, A S., and Turnbull, M H.: Thermal acclimation of respiration but not photosynthesis in Pinus radiata, Funct. Plant Biol., 35, 448-461, 2008b.
54. Parmentier, F J W., van der Molen, M K., van Huissteden, J., Karsanaev, S A., Kononov, A V., Suzdalov, D A., Maximov, T C., and Dolman, A J.: Longer growing seasons do not increase net carbon uptake in the northeastern Siberian tundra, J. Geophys. Res.-Biogeo., 116, G04013, doi10.1029/2011JG001653, 2011.
55. Robinson, C H., Michelsen, A., Lee, J A., Whitehead, S J., Callaghan, T V., Press, M C., and Jonasson, S.: Elevated atmospheric CO2 affects decomposition of Festuca vivipara (L) Sm litter and roots in experiments simulating environmental change in two contrasting arctic ecosystems, Glob. Change Biol., 3, 37-49, 1997.
56. Rocha, A V. and Shaver, G R.: Burn severity influences postfire CO2 exchange in arctic tundra, Ecol. Appl., 21, 477-489, 2011.
57. Ross, J.: The Radiation Regime and Architecture of Plant Stands, Tasks for Vegetation Sciences, The Hague, Boston, London, 391 pp., 1981.
58. Ruimy, A., Jarvis, P G., Baldocchi, D D., and Saugier, B.: CO2 fluxes over plant canopies and solar radiation: a review, Adv. Ecol. Res., 26, 1-68, 1995.
59. Runkle, B R K., Sachs, T., Wille, C., Pfeiffer, E.-M., and Kutzbach, L.: Bulk partitioning the growing season net ecosystem exchange of CO2 in Siberian tundra reveals the seasonality of its carbon sequestration strength, Biogeosciences, 10, 1337-1349, doi10.5194/bg-10-1337-2013, 2013.
60. Schuur, E A G., Bockheim, J., Canadell, J G., Euskirchen, E., Field, C B., Goryachkin, S V., Hagemann, S., Kuhry, P., Lafleur, P M., Lee, H., Mazhitova, G., Nelson, F E., Rinke, A., Romanovsky, V E., Shiklomanov, N., Tarnocai, C., Venevsky, S., Vogel, J G., and Zimov, S A.: Vulnerability of permafrost carbon to climate change: implications for the global carbon cycle, Bioscience, 58, 701-714, 2008.
61. Shaver, G R., Billings, W D., Chapin, F S., Giblin, A E., Nadelhoffer, K J., Oechel, W C., and Rastetter, E B.: Global change and the carbon balance of Arctic ecosystems, Bioscience, 42, 433-441, 1992.
62. Shaver, G R., Rastetter, E B., Salmon, V., Street, L E., van de Weg, M J., Rocha, A., van Wijk, M T., and Williams, M.: Pan-Arctic modelling of net ecosystem exchange of CO2, Philos. T. R. Soc. B, 368, 20120485. doi10.1098/rstb.2012.0485, 2013.
63. Shaver, G R., Street, L E., Rastetter, E B., Van Wijk, M T., and Williams, M.: Functional convergence in regulation of net CO2 flux in heterogeneous tundra landscapes in Alaska and Sweden, J. Ecol., 95, 802-817, 2007.
64. Shurpali, N J., Verma, S B., Kim, J., and Arkebauer, T J.: Carbon-dioxide exchange in a peatland ecosystem, J. Geophys. Res.-Atmos., 100, 14319-14326, 1995.
65. Skre, O. and Oechel, W C.: Moss functioning in different Taiga ecosystems in Interior Alaska, 1. Seasonal, phenotypic, and drought effects on photosynthesis and response patterns, Oecologia, 48, 50-59, 1981.
66. Sorensen, P L., Jonasson, S., and Michelsen, A.: Nitrogen fixation, denitrification, and ecosystem nitrogen pools in relation to vegetation development in the subarctic, Arct. Antarct. Alp. Res., 38, 263-272, 2006.
67. Street, L E., Shaver, G R., Williams, M., Van and Wijk, M T.: What is the relationship between changes in canopy leaf area and changes in photosynthetic CO2 flux in arctic ecosystems?, J. Ecol., 95, 139-150, 2007.
68. Street, L E., Stoy, P C., Sommerkorn, M., Fletcher, B J., Sloan, V L., Hill, T C., and Williams, M.: Seasonal bryophyte productivity in the sub-Arctic: a comparison with vascular plants, Funct. Ecol., 26, 365-378, 2012.
69. SWIPA: Snow, Water, Ice, Permafrost in the Arctic, available at: http://www.amap.no/swipa/, 2011.
70. Ueyama, M., Iwata, H., Harazono, Y., Euskirchen, E. S., Oechel, W. C., and Zona, D.: Growing season and spatial variations of carbon fluxes of Arctic and boreal ecosystems in Alaska (USA), Ecol. Appl., 23, 1798-1816, 2013.
71. van der Molen, M K., van Huissteden, J., Parmentier, F J W., Petrescu, A M R., Dolman, A J., Maximov, T C., Kononov, A V., Karsanaev, S V., and Suzdalov, D A.: The growing season greenhouse gas balance of a continental tundra site in the Indigirka lowlands, NE Siberia, Biogeosciences, 4, 985-1003, doi10.5194/bg-4-985-2007, 2007.
72. Vourlitis, G L. and Oechel, W C.: Landscape-scale CO2, H2O vapour and energy flux of moist-wet coastal tundra ecosystems over two growing seasons, J. Ecol., 85, 575-590, 1997.
73. Vourlitis, G L. and Oechel, W C.: Eddy covariance measurements of CO2 and energy fluxes of an Alaskan tussock tundra ecosystem, Ecology, 80, 686-701, 1999. hack
74. Walker, D A., Jia, G J., Epstein, H E., Raynolds, M K., Chapin, F S., Copass, C., Hinzman, L D., Knudson, J A., Maier, H A., Michaelson, G J., Nelson, F., Ping, C L., Romanovsky, V E., and Shiklomanov, N.: Vegetation-soil-thaw-depth relationships along a Low-Arctic bioclimate gradient, Alaska: synthesis of information from the ATLAS studies, Permafrost Periglac., 14, 103-123, 2003.
75. Walker, D A., Raynolds, M K., Daniels, F J A., Einarsson, E., Elvebakk, A., Gould, W A., Katenin, A E., Kholod, S S., Markon, C J., Melnikov, E S., Moskalenko, N G., Talbot, S S., Yurtsev, B A., and Team, C.: The Circumpolar Arctic vegetation map, J. Veg. Sci., 16, 267-282, 2005.
76. Westergaard-Nielsen, A., Lund, M., Hansen, B U., and Tamstorf, M P.: Camera derived vegetation greenness index as proxy for gross primary production in a low Arctic wetland area, ISPRS J. Photogramm., 83, 89-99, 2013.
77. Williams, M., Street, L E., van Wijk, M T., and Shaver, G R.: Identifying differences in carbon exchange among arctic ecosystem types, Ecosystems, 9, 288-304, 2006.
78. Yuan, W., Luo, Y., Liang, S., Yu, G., Niu, S., Stoy, P., Chen, J., Desai, A R., Lindroth, A., Gough, C M., Ceulemans, R., Arain, A., Bernhofer, C., Cook, B., Cook, D R., Dragoni, D., Gielen, B., Janssens, I A., Longdoz, B., Liu, H., Lund, M., Matteucci, G., Moors, E., Scott, R L., Seufert, G., and Varner, R.: Thermal adaptation of net ecosystem exchange, Biogeosciences, 8, 1453-1463, doi10.5194/bg-8-1453-2011, 2011.