biostudies-literatureJoseph JSwiss National Science FoundationSino Swiss Science and Technology Cooperation24885-24892https://www.ebi.ac.uk/biostudies/studies/S-EPMC7547207biostudies-literatureUnknown117(40)Drought alters carbon (C) allocation within trees, thereby impairing tree growth. Recovery of root and leaf functioning and prioritized C supply to sink tissues after drought may compensate for drought-induced reduction of assimilation and growth. It remains unclear if C allocation to sink tissues during and following drought is controlled by altered sink metabolic activities or by the availability of new assimilates. Understanding such mechanisms is required to predict forests' resilience to a changing climate. We investigated the impact of drought and drought release on C allocation in a 100-y-old Scots pine forest. We applied ¹³CO₂ pulse labeling to naturally dry control and long-term irrigated trees and tracked the fate of the label in above- and belowground C pooProceedings of the National Academy of Sciences of the United States of AmericaRhizosphere activity in an old-growth forest reacts rapidly to changes in soil moisture and shapes whole-tree carbon allocation.PMC7547207159866310030_18910931003A_159866189109EG 09-122016310030Luster JGessler APeter MLehmann MMSchonbeck LBrunner IThomas FMGao DWerner RAHug CPoll CRuehr NKHoch GKahmen ABackes BHaeni MHagedorn FLi MHRigling AHartmann HWerner WRissanen KAJoseph JSchaub MGleixner GWohlgemuth TBloch CSaurer MStern BfalseRhizosphere activity in an old-growth forest reacts rapidly to changes in soil moisture and shapes whole-tree carbon allocation.Drought alters carbon (C) allocation within trees, thereby impairing tree growth. Recovery of root and leaf functioning and prioritized C supply to sink tissues after drought may compensate for drought-induced reduction of assimilation and growth. It remains unclear if C allocation to sink tissues during and following drought is controlled by altered sink metabolic activities or by the availability of new assimilates. Understanding such mechanisms is required to predict forests' resilience to a changing climate. We investigated the impact of drought and drought release on C allocation in a 100-y-old Scots pine forest. We applied ¹³CO₂ pulse labeling to naturally dry control and long-term irrigated trees and tracked the fate of the label in above- and belowground C poo2020-01-01T00:00:00Z2020 Oct2025-04-04T11:54:20.194Z2025-04-04T11:54:20.194ZS-EPMC75472073295866210.1073/pnas.2014084117