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Evapotranspiration (ET) plays a pivotal role in the water budget of Bottomland Hardwood Forests (BHF), influenced by an intricate interplay of meteorological variables. Eddy covariance water and heat flux data obtained from 2013 to 2018 collected at the US-ULM flux tower (37.30m) were used to characterize diurnal, seasonal, and inter-annual fluxes. We used a structural equation modeling approach to dissect the drivers of ET across varying timescales and seasons. The latent heat flux exhibited a distinct diurnal pattern from March to September, peaking at 146 w/m2 around solar noon. Notably, latent heat (LE) flux surpassed sensible heat (H) flux during late spring and summer, showcasing values of 127 w/m2 and 145 w/m2, respectively. In contrast, H flux (36 w/m2) exceeded LE flux (28 w/m2) during winter-spring transitions when temperature fluctuations were maximal (-5 to 20°C). Daily ET values ranged from 0.52 mm/day in winter to 5.2 mm/day in summer. Factor analysis unveiled shared variance among drivers, while path analysis quantified individual drivers' independent contributions. Results highlighted the coherence between ET and net radiation (Rn) variability, particularly with Vapor Pressure Deficit (VPD) and temperature during Spring, Summer, and Autumn. However, Winter exhibited disparate patterns. Path analysis underscored Rn as the primary driver of ET variations through direct and indirect pathways. Windspeed and precipitation made significant, albeit smaller, contributions to ET variability. Overall, an average daily ET of 3.4 mm/day was predominantly driven by net radiation across all seasons. The study suggests that in deciduous forests like BHFs, ET is primarily energy-dependent during the growing season and early non-growing season, transitioning to temperature-dependence after leaf senescence in winter [ABSTRACT FROM AUTHOR] more...