Forest–Water–Atmosphere Theory: A Multiscale Framework for Management-Induced Coupling in Forested Landscapes

Eva Verena Müller 

Recent advances in ecohydrology, land–atmosphere coupling and Earth System Science increasingly recognize the importance of forests for coupled water, energy and climate dynamics. However, the explicit integration of forest management, multiscale hydrological pathways and atmospheric feedbacks remains limited, despite increasing recognition of forests as active biophysical regulators within Earth-system frameworks. This paper proposes the Forest–Water–Atmosphere Theory (FWAT) as a management-relevant conceptual framework that synthesizes these perspectives and provides a basis for developing testable hypotheses regarding the effects of forest management on coupled forest–water–atmosphere systems. FWAT does not propose new process physics, but a new way of integrating existing knowledge by explicitly conceptualizing forest management as an intervention in coupled forest–water–atmosphere systems operating across scales. Within this framework, evapotranspiration is hypothesized as a key candidate coupling variable linking hydrological, physiological and atmospheric processes across scales, while its relative importance and atmospheric relevance remain context-dependent empirical questions.