Rainfall partitioning varies across a forest age chronosequence in the southern A ppalachian M ountains

Evaporation of precipitation from plant surfaces, or interception, is a major component of the global water budget. Interception has been measured and/or modelled across a wide variety of forest types; however, most studies have focused on mature, second‐growth forests, and few studies have examined interception processes across forest age classes. We present data on two components of interception, total canopy interception ( E i ) and litter interception—that is, O i + O e horizon layers—( E ff ), across a forest age chronosequence, from 2 years since harvest to old growth. We used precipitation, throughfall, and stemflow collectors to measure total rainfall ( P ) and estimate E i ; and collected litter biomass and modelled litter wetting and drying to estimate evaporative loss from litter. Canopy E i , P minus throughfall, increased rapidly with forest age and then levelled off to a maximum of 21% of P in an old‐growth site. Stemflow also varied across stands, with the highest stemflow (~8% of P ) observed in a 12‐year‐old stand with high stem density. Modelled E ff was 4–6% of P and did not vary across sites. Total stand‐level interception losses ( E i + E ff ) were best predicted by stand age ( R 2 = 0.77) rather than structural parameters such as basal area ( R 2 = 0.49) or leaf area ( R 2