Application of Stable Isotopes in Water Transport Processes of the Soil–Plant–Atmosphere Continuum in Eucalyptus Plantations: A Review

Abstract

The water cycle in forest ecosystems is a core component of ecosystem services, and it is crucial for revealing terrestrial hydrological processes and regulation mechanisms. Investigating water migration across interfaces of the soil–plant–atmosphere continuum (SPAC) has long been a hotspot in ecohydrological research. Eucalyptus stands are among the world’s major commercial timber species, and their hydrological effects have attracted growing public attention. Naturally occurring hydrogen and oxygen stable isotopes can effectively differentiate water sources, serving as powerful tracers widely applied in hydrological research. Nevertheless, comprehensive systematic reviews on SPAC water dynamics of Eucalyptus plantations using stable isotope quantification are still lacking. This study systematically reviews the application of hydrogen and oxygen stable isotopes in analyzing water transport and transformation processes at multiple interfaces of Eucalyptus plantation SPAC, covering atmospheric precipitation sources, soil and plant water migration, plant transpiration and groundwater exchange. Future research should strengthen in-situ continuous monitoring of isotopic signatures in diverse water bodies, facilitate the popularization of isotope-based models, and advance quantitative partitioning of evapotranspiration in Eucalyptus ecosystems. This review provides theoretical and technical support for exploring hydrological processes and mechanisms in forest ecosystems, and offers scientific references for improving forest water use efficiency and optimizing regional water resource allocation.