Traits of plant species were measured from April to November 2013 as part of the CHAMBASA (Challenging Attempt to Measure Biotic Attributes along the Slopes of the Andes) project. A detailed description of field sampling techniques is provided elsewhere (22), but here, we provide an overview. One hundred eighty tree species were sampled, which accounted for 80% of total basal area per site. For each species, five individual trees in upland sites and three individual trees in lowland sites were sampled. Collection of leaf samples was conducted using tree climbing techniques to cut branches at the top of the canopy. Two branches of ≥1 cm diameter were sampled for each tree, with a total of 1025 branches sampled from 620 trees. Fully expanded leaves were randomly selected for determination of leaf LMA and leaf water concentration (Water), NSC, and leaf content of Chl following standard protocols (19, 36). We selected these four traits because they can be remotely sensed and have shown variation across the elevation gradient (22).