This data set contains one data file (.csv format) that quantifies net primary productivity (NPP) as a function of rainfall in mesic to wet montane rainforests on the island of Maui, Hawaii, U.S.A. The NPP data were collected at six mature forests stands that comprise the Maui Moisture Gradient, a sequence of sites located on Maui where mean annual precipitation ranges from 2,200 mm to 5,050 mm while temperature and all other state factors (parent material, substrate age, organisms, and topography) that control NPP remain relatively constant.

Estimates are given for above-ground and below-ground productivity, and total NPP based on measurements made in 1996 and 1997. These data are part of a larger study that focused on the dynamics of carbon cycling and storage in everwet rainforest as a function of changes in rainfall regime.

The Hawaiian Islands flora and fauna are relatively species-poor, thus a few species and genera occupy a broad range of environmental conditions. As a result, the forest canopy at all sites was consistently dominated by the native evergreen tree Metrosideros polymorpha (Myrtaceae) which comprises 80% to 100% of basal area in these forests. The understory vegetation was dominated by a variety of ferns and other herbaceous species at all sites, but the dominance of particular understory species shifted among sites. This watershed area has never been cleared by humans.