Browsed Betula pubescens trees are not carbon‐limited

Abstract

Summary 1Slower growth after repetitive browsing of young trees has been attributed to a carbon (C) limitation, but data from long-term studies are lacking. To determine if repeated summer browsing causes a C (source) limitation in trees in the long-term, we analysed the non-structural carbohydrate (NSC) and nitrogen (N) concentrations and pools of Betula pubescens saplings subjected to different clipping treatments (unclipped, 33% and 66% shoot removal) for 7 years. 2The short-term effect of browsing on C allocation was assessed by clipping trees with different browsing histories and analyzing their C and N responses within the same growing season. 3Long-term repetitive summer browsing significantly decreased sapling growth and soluble sugar (SS) concentrations in fine roots. However, trees subjected to different browsing histories did not change their C partitioning into starch. Although trees with a different browsing history showed differences in the NSC concentrations and pools of leaves, these differences were not maintained through time. 4Simulated browsing had no significant short-term effect on root C and N pools of birch trees, but it decreased all C pools in leaves, 1-year and current-year stems and the starch and total NSC pools in main stems. 5We conclude that although browsing may cause a temporary decrease in C pools, B. pubescens trees are able to compensate for such losses and hence are not C-limited in the long-term.