The Swiss Canopy Crane Project (SCC)

Important Publication

Klein T, Siegwolf RTW, Körner C (2016) Belowground carbon trade among tall trees in a temperate forest. Science Magazine 352:342-344 (14. April 2016) DOI 10.1126/science.aad6188
In March 1999 a ca. 45 m tall crane was installed in a highly diverse, mature temperate forest at Hofstetten near Basel, 550 m above sea level.
This research tool enabled canopy research in both adult conifers and deciduous trees typical for European forests. With a new type of Free Air CO₂ Enrichment, called webFACE, part of this forest is exposed to 530 ppm CO₂ since October 2000 (see Pepin and Koerner 2002). Tree genera include: Fagus, Quercus, Carpinus, Acer, Tilia, Prunus, Abies, Picea, Pinus, Larix.
Swiss Canopy Crane
The forest has by 2016 an age of 120 years and dominant trees vary between 32 m and 40 m in height. Except for Larix and Picea (which were introduced from slightly higher elevations) all species occur naturally. With the broad leaved evergreen Ilex aquifolium and Hedera helix in the understory the spectrum is ideal for a an assessment of functional aspects of forest biodiversity.
Research was strictly comparative in order to capitalize on this unique species richness. Topics attended by our team include canopy architecture and fuctional leaf attributes, reproductive dynamics and storage reserves in whole tree canopy CO₂-enrichment, sapflow and stable isotopes.
After 4 years, we found an immediate and sustained enhancement of carbon flux, but there was no overall stimulation in stem growth and leaf litter production (Koerner et al. 2005).
We cooperated with partners from other Swiss institutions (WSL, PSI and others) and colleagues from Germany and Austria. Internationally this project lined up with currently operative crane projects in Panama, Venezuela, Oregon, NE-Australia, and Japan, providing a global network which also includes animal sciences. With its sole emphasis on experimental and analytical work in the top of a mature forest, this is the first crane project in Europe, and one out of three globally in a temperate deciduous/mixed forest (the others are in Japan and in Germany). The SCC project first of all seeked to contribute to biodiversity research in forests.


2016Bader MKF, Mildner M, Baumann C, Leuzinger S, Körner C (2016) Photosynthetic enhancement and diurnal stem and soil carbon fluxes in a mature Norway spruce stand under elevated CO₂. Environ Exp Bot 124:110-119
Klein T, Bader MKF, Leuzinger S, Mildner M, Schleppi P, Siegwolf RTW, Körner C (2016) Growth and carbon relations of mature Picea abies trees under 5years of free-air CO₂ enrichment. J Ecol 104:1720-1733
Klein T, Siegwolf RTW, Körner C (2016) Belowground carbon trade among tall trees in a temperate forest. Science Magazine 352:342-344 (14. April 2016) DOI 10.1126/science.aad6188
2015Mildner M, Bader MKF, Baumann C, Körner C (2015) Respiratory fluxes and fine root responses in mature Picea abies trees exposed to elevated atmospheric CO₂ concentrations. Biogeochemistry 124:95-111
2014Mildner M, Bader MKF, Leuzinger S, Siegwolf RTW, Körner C (2014) Long-term C-13 labeling provides evidence for temporal and spatial carbon allocation patterns in mature Picea abies. Oecologia 175:747-762
2013Bader MFK, Leuzinger S, Keel SG, Siegwolf RTW, Hagedorn F, Schleppi P, Körner C 2013: Central European hardwood trees in a high CO₂ future: synthesis of an 8‐year forest canopy CO₂ enrichment project. J Ecol DOI: 10.1111/1365-2745.12149
Körner C 2013: A mature forest canopy in a CO₂-rich future: An experiment at the Swiss Canopy Crane Research Site In M. Lowman et al. (eds.), Treetops at Risk: Challenges of Global Canopy Ecology and Conservation, Springer NY. pp 141-145
2012Schleppi P, Bucher-Wallin I, Hagedorn F, Körner C (2012) Increased nitrate availability in the soil of a mixed mature temperate forest subjected to elevated CO₂ concentration (canopy FACE). Glob Change Biol 18:757-768
2011Han Q, Kabeya D, Körner Ch, Hoch G 2011: Leaf traits, shoot growth and seed production in mature Fagus sylvatica trees after eight years’ CO₂ enrichment. Annals of Botany 107:1405-1411
Leuzinger S, Hartmann A, Körner Ch 2011: Water relations of climbing ivy in a temperate forest. Planta doi 10.1007/s00425-011-1363-6
2010Bader MKF, Körner Ch 2010: No overall stimulation of soil respiration under mature deciduous forest trees after 7 years of CO₂ enrichment.
Bader MKF, Siegwolf R, Körner CH 2010: Sustained enhancement of photosynthesis in mature deciduous forest trees after 8 years of free air CO₂ enrichment. Planta 232:1115-1125
Körner C, Bader M (2010) Der Wald in einer CO₂-reichen Welt. Lehrmittelverlag Kanton Solothurn, Solothurn
Leuzinger S, Körner Ch 2010: Rainfall distribution is the main driver of runoff under future CO₂-concentration in a temperate deciduous forest Global Change Biology 16:246-254
Leuzinger S, Vogt R, Körner Ch 2010: Tree surface temperature in an urban environment. Agricultural and Forest Meteorology 150:56-62
2009Bader M, Hiltbrunner E, Körner Ch 2009: Fine root responses of mature deciduous forest trees to free air carbon dioxide enrichment (FACE). Functional Ecology doi: 10.1111/j.1365-2435.2009.01574.x
Schädel C, Blöchl A, Richter A, Hoch G 2009: Short-term dynamics of non-structural carbohydrates and hemicelluloses in young branches of temperate forest trees during bud break. Tree Physiology 29:901-911
2008Asshoff R, Keel SG, Siegwolf RTW, Körner Ch 2008: Tracing arthropod movement in a deciduous forest canopy using stable isotopes. In: Floren A, Schmidl J (eds) Canopy arthropod research in Europe, Bioform, Nürnberg, pp 327-338
2007Keel SG, Pepin S, Leuzinger S, Körner Ch 2007. Stomatal conductance in mature deciduous forest trees exposed to elevated CO₂. Trees 21:151-159
Keel SG, Siegwolf RTW, Jäggi M, Körner Ch 2007. Rapid mixing between old and new C pools in the canopy of mature forest trees. Plant Cell Environ 30:963-972
Leuzinger S, Körner Ch 2007. Tree species diversity affects canopy leaf temperatures in a mature temperate forest. Agric For Meteorol 146:29-37
Leuzinger S, Körner Ch 2007. Water savings in mature deciduous forest trees under elevated CO₂. Glob Change Biol 13:1-11
2006Asshoff R, Zotz G, Körner Ch 2005. Growth and phenology of mature temperate forest trees in elevated CO₂. Global Change Biol 12:848-861
Hoch G, Keel SG 2006: ¹³C labelling reveals different contributions of photoassimilates from infructescences for fruiting in two temperate forest tree species. Plant Biology 8:606-614
Keel SG, Siegwolf RTW, Körner Ch 2006. Canopy CO₂ enrichment permits tracing the fate of recently assimilated carbon in a mature deciduous forest. New Phytol 172:319-329
Körner Ch 2006. Forests, biodiversity and CO₂: surprises are certain. Biologist 53:82-90
Körner Ch 2005. CO₂-Anreicherung in der Luft – Sind Wald- und Holzwirtschaft mit betroffen? Wald und Holz 6/06:51-53
2005Hoch G 2005: Fruit bearing branchlets are carbon autonomous in mature broad-leaved temperate forest trees. Plant Cell and Environment 28:651-659
Hoch G 2005: Grenzen ausloten. UNINOVA 100:15-17
Körner Ch, Asshoff R, Bignucolo O, Hättenschwiler S, Keel SG, Peláez-Riedl S, Pepin S, Siegwolf RTW, Zotz G 2005: Carbon Flux and Growth in Mature Deciduous Forest Trees Exposed to Elevated CO₂. Science 309:1360-1362 (26 August 2005)
Körner Ch 2005: Wald, Biodiversität und CO₂ - Überraschungen sind sicher. Naturwissenschaftliche Rundschau 58:61-69
Pennisi E 2005: Sky-High Experiments. Science 309:1314-1315 (26 August 2005)
Zotz G, Pepin S, Körner C. 2005. No down-regulation of leaf photosynthesis in mature forest trees after long-term exposure to elevated CO₂. Plant Biology 7:369-374.
2004Hättenschwiler S, Schafellner C 2004: Gypsy moth feeding in the canopy of a CO₂-enriched mature forest. Global Change Biology 10:1899-1908
Körner Ch 2004: Through enhanced tree dynamics carbon dioxide enrichment may cause tropical forests to lose carbon. Phil Trans R Soc Lond Ser B-Biol Sci 359:493-498
Steinmann K, Siegwolf RTW, Saurer M, Körner Ch 2004: Carbon fluxes to the soil in a mature temperate forest assessed by 13C isotope tracing. Oecologia 141:489-501
2003Altermatt F 2003: Potential negative effects of atmospheric CO₂-enrichment on insect communities in the canopy of a mature deciduous forest in Switzerland. Mitt Schweiz Entomol Ges 76:191-199
Cech PG, Pepin S, Körner Ch 2003: Elevated CO₂ reduces sap flux in mature deciduous forest trees. Oecologia 137:258-268
Hoch G, Richter A, Körner Ch 2003: Non-structural carbon compounds in temperate forest trees. Plant Cell Environ 26:1067-1081
Körner Ch 2003: Carbon limitation in trees. J Ecol 91:4-17
Körner Ch 2003: Ecological impacts of atmospheric CO2 enrichment on terrestrial ecosystems. Phil Trans R Soc Lond A 361:2023-2041
Körner Ch, Zotz G 2003: Cranes in temperate forests; Basel, Switzerland. In: Y Basset, V Horlyck, SJ Wright (eds) Studying forest canopies from above: The International Canopy Crane Network. Smithsonian Tropical Research Institute and UNEP, Panama. pp 67-70
2002Körner Ch 2002: Basel canopy crane, Switzerland. In: Mitchell AW, Secoy K, Jackson T (eds) Global canopy handbook. Global Canopy Foundation, Oxford, pp 42-46
Pepin S, Körner Ch 2002: Web-FACE: a new canopy free air CO₂ enrichment system for tall forest trees in mature forests. Oecologia, 133:1-9


Global Canopy Programme - a world wide network of scientific studies of forest canopies.
Canopy Crane Access System



Dr. Günter Hoch (Postdoc), Dr. Tamir Klein (Postdoc), Manuel Mildner (PhD)


Paul Scherrer Institut, Villigen (Dr. R. Siegwolf)
Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf (I. Bucher, F. Hagedorn, P. Schlaeppi)


Erwin Amstutz, Georges Grun