Leaf water-use efficiency of dominant trees across successional stages and seasons in a tropical forest, Khao Yai National Park, Thailand

This dataset supports the study "Leaf water-use efficiency varies by season and successional stage in tropical forests of Thailand." It contains leaf-level gas-exchange measurements and associated leaf functional traits for nine dominant tree species sampled in an old-growth forest (>200 years) and a young secondary forest (~10 years) in Khao Yai National Park, Thailand, during the dry and wet seasons of 2025.

Each of the 300 leaf-level records includes net photosynthetic rate (Anet), transpiration rate (E), stomatal conductance (gs), instantaneous water-use efficiency (WUE = Anet/E), specific leaf area (SLA), leaf chlorophyll content (Chl), and the leaf-to-air vapor pressure deficit (VPD) at the time of measurement. The data were used to examine how leaf gas-exchange rates and water-use efficiency respond to VPD and vary with season and forest successional stage.