Aboveground productivity and soil respiration in three Hawaiian rain forests

Abstract

I measured aboveground productivity and soil respiration in three Hawaiian rain forests to compare carbon allocation patterns among natural forests varying in climatic, soil and vegetational characteristics. I hypothesized that total carbon allocation to roots (i.e., root production plus respiration) would increase with increasing aboveground detritus production, but that proportional allocation to roots would decline with increasing productivity. The three forests studied comprised a gradient, along which aboveground production and nutrient fluxes in litter production increased. Rates of fine litter production ranged from 492–614 g m −2 yr −1, tree growth ranged from 90–468 g m −2 yr −1, and aboveground net productivity (ANPP) ranged from 583–1082 g m −2 yr −1. Soil respiration ranged from 650–890 g m −2 yr −1 of CO 2–C and increased with increasing aboveground production. In the three forests studied, estimated belowground C allocation increased with increasing rates of aboveground production, but the relative amount of C allocated belowground declined with increasing ANPP. A larger proportion of production was allocated to wood in the more productive sites.