Plant community, soil, litter decomposition, and environmental data for Acacia koa stands on Hawaiʻi Island, 2019

This data publication contains data obtained from March through August 2019 on tree basal area, grass biomass, soil moisture, nitrogen and carbon pools and fluxes, light levels, as well as litter quantity, quality, and decomposition rates under Acacia koa stands of varying density in multiple mid-elevation old pasture sites on Hawaiʻi Island.
These data were collected in an attempt to better understand where, and by what mechanisms, Acacia koa (a native N-fixing tree) is able to lower invasive grass biomass in old pasture sites that have been restoration sites across Hawaiʻi Island that vary in climate. Nitrogen-fixing trees are often planted in tropical reforestation work because of their fast growth rates and ability to enrich soil nutrients. However, nitrogen (N) contributed to the soil from N-fixing trees can also facilitate growth of competitive exotic grasses. The balance between grass suppression versus facilitation may depend upon tree density and site conditions. Using planted stands of a native N-fixer, Acacia koa (koa), on Hawaiʻi Island, we evaluated the efficacy of invasive grass suppression by koa and what mechanisms (e.g, variation in litter decomposition rates or total standing pools of litter, light levels in stands, soil N levels, etc.) might be responsible. We identified a range of tree densities and sites spanning the island.
For more information about these data and this study, see Esch and Yelenik (in review).