Coarse woody debris (CWD) is an important structural and functional component of forest ecosystems, providing carbon and nutrient storage, substrate for seedling establishment, and habitat for organisms. The uncertain contribution of CWD to forest carbon storage in tropical montane wet forests has major implications in light of global climate change, since pools and fluxes of CWD may vary with warming. The primary objective of this study was to determine the relationship between mean annual temperature (MAT) and CWD biomass in Hawaiian tropical montane wet forests. Because both net primary productivity and decay rates increase with temperature, we predicted that CWD biomass would not vary with MAT. To test this hypothesis, we quantified CWD biomass across a 13-18.2°C MAT gradient. We surveyed three 200 m transects at each of eight different MAT sites in which geologic substrate type and age, species composition, and soil water balance were constant. Simple linear regressions were used to determine the relationship between MAT and CWD biomass.
Results/Conclusions
Results show that CWD biomass does not vary with MAT (P=0.21), which suggests that rising temperature will not affect carbon storage in CWD in wet tropical forests in the absence of changes in recruitment. Mean CWD biomass across the gradient was 89.2 Mg ha-1 and mean surface area was 1,961 m2 ha-1. The majority of CWD biomass (87%) across the MAT gradient was composed of moderately decayed wood (decay class 3), which also did not change with MAT, and may explain why total CWD biomass did not vary with MAT. These results indicate that temperature will not affect the structural and functional roles CWD plays in Hawaiian montane wet forests as warming occurs.