Deep roots mitigate drought impacts on tropical trees despite limited quantitative contribution to transpiration

• DOI: 10.1016/j.scitotenv.2023.164763
• Publication Date: 2023-06-10T23:12:48Z
• Authors: Kathrin Kühnhammer; Joost van Haren; Angelika Kübert; Kinzie Bailey; Maren Dubbert; Jia Hu; S. Nemiah Ladd; Laura K. Meredith; Christiane Werner; Matthias Beyer
• Keywords: Water use; Tropical rain forest

Deep rooting is considered a central drought-mitigation trait with vast impact on ecosystem water cycling. Despite its importance, little known about the overall quantitative use via deep roots and dynamic shifts of uptake depths changing ambient conditions. Knowledge especially sparse for tropical trees. Therefore, we conducted drought, soil labeling re-wetting experiment at Biosphere 2 Tropical Rainforest. We used in situ methods to determine stable isotope values tree high temporal resolution. Complemented by stem content sap flow measurements determined percentages quantities deep-water total root dynamics different species. All canopy trees had access (max. depth 3.3 m), contributions transpiration ranging between 21 % 90 during when surface availability was limited. Our results suggest that an essential source delays potentially detrimental drops plant potentials limited could hence mitigate impacts increasing drought occurrence intensity as consequence climate change. Quantitatively, however, amount low due trees' reduction drought. Total largely followed switched back their dynamically, from shallow soils, following rainfall. fluxes were driven precipitation input.