Variability in tree water uptake determined with stable water isotopes in an African tropical montane forest

Ecohydrological processes in tropical rainforests are insufficiently understood, and existing studies yield contradictory results. We investigated relative contributions of different soil depths to tree water uptake 83 trees possible species-specific differences a 50 × m forest plot at four dates montane Kenya using stable isotopes the Bayesian mixing model framework MixSIAR. found distinct individual (e.g. Drypetes gerrardii taking 75% its from <0.5 m, or rather large shift patterns based on climatic conditions, that is fourth sampling date), but no consistent small-scale spatiotemporal depth contributions. Soil δ18O showed lateral variation up 6‰, which was accounted for by spatial interpolation enabled us improve allocations sources trees. Our results show ignoring variability isotope signatures soils complicates applicability this context might be widespread constraint reducing validity comparability Further research underlying fluxes ecosystems urgently needed we point out need considering isotopic composition despite homogeneous characteristics.