This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/GCB.14949 This article is protected by copyright. All rights reserved MR. PATRICK MÖHL (Orcid ID : 0000-0002-5058-8135) DR. CHRISTIAN KOERNER (Orcid ID : 0000-0001-7768-7638) Article type : Primary Research Articles Halving sunlight reveals no carbon limitation of aboveground biomass production in alpine grassland Patrick Möhl, Erika Hiltbrunner, Christian Körner Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, CH-4056 Basel, Switzerland Corresponding author: Patrick Möhl, p.moehl@unibas.ch Abstract In temperate alpine environments, the short growing season, low temperature and a slow nutrient cycle may restrict plant growth more than carbon (C) assimilation does. To test the C-limitation hypothesis, we applied a shade gradient ranging from ambient light to 44% (maximum shade) of incident photon flux density (PFD) in late successional, Carex curvula dominated alpine grassland at 2580 m elevation in the Swiss central Alps for three years (2014–2016). Total aboveground biomass did not significantly decrease under reduced PFD, with a confidence interval reaching from +4% to -15% biomass in maximum shade. Belowground biomass, consisting to more than 80% of fine roots, was significantly reduced by a mean of 17.9 ± 4.6% (± SE), corresponding to 228 g m -2 , in maximum shade in 2015 and 2016. This suggests reduced investments into water and nutrient acquisition according to the functional equilibrium concept. Specific leaf area (SLA) and maximum leaf lengths of the most abundant species increased with decreasing PFD. Foliar concentration of non-structural carbohydrates (NSC) was reduced by 12.5 ± 4.3% under maximum Accepted Article