[This dataset is embargoed until January 16, 2027]. This dataset compiles leaf-level functional traits collected at a tropical elevational gradient in the Albertine Rift in Rwanda at two experimental sites across two common garden plantations with contrasting mean annual temperatures (15.2°C and 20.0°C). Sampling included species from eight native tropical Afromontane and transitional rainforest. The dataset includes leaf structural traits (leaf area, thickness, and leaf mass per area (LMA)), leaf optical properties (reflectance, transmittance, and absorptance) and leaf angle measurements (pitch, roll, azimuth, and vertical angle). Measurement campaigns were conducted between January and February 2025. Together, these data provide a comprehensive characterization of leaf functional and thermoregulation 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/10.5285/37c4c87a-de90-4b35-96d8-32e077c5dab2
