This dataset compiles leaf-level functional trait measurements collected along a tropical elevational gradient in the Colombian Andes across three common garden plantations with contrasting mean annual temperatures (MAT) (13.7 °C, 22.1 °C, and 25.5 °C). Experimental sites have been named after their MAT. Sampling included 15 dominant tree species at the 13.7 °C site, 10 species at the 22.1 °C site, and 4 species at the 25.5 °C site. Sampling at the 25.5°C site was done only for a limited type of measurements. The dataset includes: High-resolution leaf thermocouple measurements and leaf level PAR data (1-minute resolution). Leaf temperature, relative humidity and air temperature (10-minute resolution). Leaf angle measurements (pitch, roll, azimuth, and vertical angle). Leaf optical properties (reflectance, transmittance, and absorptance). Minimum leaf conductance (gmin) and leaf area. Leaf thermotolerance traits, including T50, maximum fluorescence (Fm), variable fluorescence (Fv), and PSII efficiency metrics (Fv/Fm and Fv/F₀). Measurement campaigns were conducted between January-February 2024 and April 2025.Together, these data provide a comprehensive characterization of leaf thermoregulation and tolerance traits across contrasting tropical montane environments, supporting research on plant ecophysiology, climate adaptation, and ecosystem responses to environmental stress. Full details about this dataset can be found at https://doi.org/10.5285/23a59d77-6f2c-4c48-ac13-77ee7b21fcee