Soil respiration rates of tropical peatlands in Micronesia and Hawaii

Abstract

There are very few published reports of soil respiration rates from tropical peatlands, despite their importance to global carbon cycling. This study quantified in situ soil respiration rates in a suite of tropical peatlands in Micronesia and Hawaii using a soil CO2 flux chamber connected to a LI-COR 6400 Portable Photosynthesis Infrared Gas Analyzer. Soil respiration rates were higher in the warmer Micronesian peatlands (2.15–2.54 umol m−2 s−1) than in the cooler Hawaiian montane peatlands (0.83–1.81 umol m−2 s−1). The lone exception was the taro-cultivated peatland in Micronesia that had low soil respiration rates likely due to low amount of litterfall, root biomass, and root production. Deep standing water decreased soil respiration rates, while lowered water levels had mixed effects on soil respiration rates. Surprisingly, measured soil respiration rates were lower than rates measured in temperate and boreal peatlands in the summer. However, soil respiration rates in tropical peatlands are not limited by large diurnal or seasonal changes and can continue respiring at the same rates, resulting in higher annual CO2 flux rates compared to other nontropical peatlands.