Data from: Carbon allocation to root exudates is maintained in mature temperate tree species under drought

Abstract

Please cite as: Benjamin D Hafner, Melanie Brunn, Marie J Zwetsloot, Fabian Weikl, Karin Pritsch, Kyohsuke Hikino, Nadine K Ruehr, Emma J Sayer, Taryn L Bauerle. (2022) Data from: Carbon allocation to root exudates is maintained in mature temperate tree species under drought. [dataset] Cornell University eCommons Repository. https://doi.org/10.7298/6r80-8a15Data in support of the following research: Carbon (C) exuded via roots is proposed to increase under drought and facilitate important ecosystem functions. However, it is unknown how exudate quantities relate to the total C budget of a drought-stressed tree, i.e. how much of net-C assimilation is allocated to exudation at the tree level. We calculated the proportion of daily C assimilation allocated to root exudation during early summer by collecting root exudates from mature Fagus sylvatica L. and Picea abies (L.) Karst. exposed to experimental drought, and combining above- and belowground C fluxes with leaf, stem, and fine-root surface area. Exudation from individual roots increased exponentially with decreasing soil moisture, with the highest increase at the wilting point. Despite ~50 % reduced C assimilation under drought, exudation from fine-root systems was maintained and trees exuded 1.0 % (F. sylvatica) to 2.5 % (P. abies) of net C into the rhizosphere, increasing the proportion of C allocation to exudates two- to threefold. Water-limited P. abies released two-thirds of its exudate-C into the surface soil, whereas it was only one-third in droughted F. sylvatica. Across the entire root system, droughted trees maintained exudation similar to controls, suggesting drought-imposed belowground C investment, which could be beneficial for ecosystem resilience.German Research Foundation (DFG), grant numbers: PR555/2-1, PR292/22-1, GR 1881/5-1, MA1763/7-1, MA1763/10-1 Bavarian State Ministry for Nutrition, Agriculture and Forestry and Bavarian State Ministry for Environment and Consumer Protection, grant number: W047/Kroof II