Journal Article

Characteristics of soil CO₂ efflux variability in an aseasonal tropical rainforest in Borneo Island

Ohashi, Mizue, Kumagai, Tomo'omi, Suzuki, Masakazu, Kume, Tomonori, Saitoh, Taku M, Gyokusen, Koichiro

2008

Overview

Although soil carbon dioxide (CO₂) efflux from tropical forests may play an important role in global carbon (C) balance, our knowledge of the fluctuations and factors controlling soil CO₂ efflux in the Asian tropics is still poor. This study characterizes the temporal and spatial variability in soil CO₂ efflux in relation to temperature/moisture content and estimates annual efflux from the forest floor in an aseasonal intact tropical rainforest in Sarawak, Malaysia. Soil CO₂ efflux varied widely in space; the range of variation averaged 17.4 μmol m⁻² s⁻¹ in total. While most CO₂ flux rates were under 10 μmol m⁻² s⁻¹, exceptionally high fluxes were observed sporadically at several sampling points. Semivariogram analysis revealed little spatial dependence in soil CO₂ efflux. Temperature explained nearly half of the spatial heterogeneity, but the effect varied with time. Seasonal variation in CO₂ efflux had no fixed pattern, but was significantly correlated with soil moisture content. The correlation coefficient with soil moisture content (SMC) at 30 and 60 cm depth was higher than at 10 cm depths. The annual soil CO₂ efflux, estimated from the relationship between CO₂ efflux and SMC at 30 cm depth, was 165 mol m⁻² year⁻¹ (1,986 g C m⁻² year⁻¹). As this area is known to suffer severe drought every 4-5 years caused by the El Nino-Southern Oscillation, the results suggest that an unpredictable dry period might affect soil CO₂ efflux, leading an annual variation in soil C balance.

• Publisher: Dordrecht : Springer Netherlands,Springer,Springer Netherlands,Springer Nature B.V
• Subject: Agricultural soils / Animal and plant ecology / Animal, plant and microbial ecology / Annual variations / Biogeosciences / Biological and medical sciences / Borneo / carbon / Carbon dioxide / correlation / Correlation coefficient / Correlation coefficients / Depth / Drought / Earth and Environmental Science / Earth Sciences / Earth, ocean, space / Ecosystems / Efflux / El Nino / El Nino phenomena / Engineering and environment geology. Geothermics / Environmental Chemistry / Exact sciences and technology / Forest floor / forest litter / Forest soils / Fundamental and applied biological sciences. Psychology / Geochemistry / Heterogeneity / Life Sciences / Malaysia / Moisture content / Patchiness / Pollution, environment geology / Rainforests / seasonal variation / Seasonal variations / Soil / Soil ecology / soil heterogeneity / Soil moisture / Soil respiration / Soil temperature / Soil temperature regimes / Soil water / soil water content / Soils / Southern Oscillation / Spatial analysis / Spatial dependencies / Spatial heterogeneity / Spatial variability / Spatial variations / Surficial geology / Synecology / Temperature / Temporal variability / Terrestrial ecosystems / Tropical environments / Tropical forests / Tropical rain forests / Tropical soils / tropics / Water content