Carbon balance of a tropical savanna of northern Australia

Abstract

Through estimations of above- and below-ground standing biomass, annual biomass increment, fine root production and turnover, litterfall, canopy respiration and total soil CO(2) efflux, a carbon balance on seasonal and yearly time-scales is developed for a Eucalypt open-forest savanna in northern Australia. This carbon balance is compared to estimates of carbon fluxes derived from eddy covariance measurements conducted at the same site. The total carbon (C) stock of the savanna was 204+/-53 ton C ha(-1), with approximately 84% below-ground and 16% above-ground. Soil organic carbon content (0-1 m) was 151+/-33 ton C ha(-1), accounting for about 74% of the total carbon content in the ecosystem. Vegetation biomass was 53+/-20 ton C ha(-1), 39% of which was found in the root component and 61% in above-ground components (trees, shrubs, grasses). Annual gross primary production was 20.8 ton C ha(-1), of which 27% occurred in above-ground components and 73% below-ground components. Net primary production was 11 ton C ha(-1) year(-1), of which 8.0 ton C ha(-1) (73%) was contributed by below-ground net primary production and 3.0 ton C ha(-1) (27%) by above-ground net primary production. Annual soil carbon efflux was 14.3 ton C ha(-1) year(-1). Approximately three-quarters of the carbon flux (above-ground, below-ground and total ecosystem) occur during the 5-6 months of the wet season. This savanna site is a carbon sink during the wet season, but becomes a weak source during the dry season. Annual net ecosystem production was 3.8 ton C ha(-1) year(-1).

Soil respiration and carbon balance in a Moso bamboo (Phyllostachys heterocycla (Carr.) Mitford cv. Pubescens) forest in subtropical China

“…However, such estimate was higher than that obtained for a similar forest in the Hunan province (3.96 t C ha -1 y -1 -Xiao et al 2010), as well as for an open eucalypt savanna in northern Australia (3.8 t C ha -1 y -1 - Chen et al 2003). Contrastingly, annual NEP estimated in this study was lower than that reported for a European temperate deciduous forest (5.9 t C ha -1 y -1 - Malhi et al 1999) and a natural evergreen forest of Castanopsis kawakamii (7.5 t C ha -1 y -1…”

Local-Scale Mapping of Biomass in Tropical Lowland Pine Savannas Using ALOS PALSAR

“…) [64], while in South and Central America, the highest biomass values recorded have been observed in Brazilian cerrado vegetation (~31.8 tha −1 ) [65]. This leads to the suggestion that the pantropical carbon maps may be overestimating AGWB in savanna areas, and this suggestion will need to be explored more rigorously as more field-based estimates of biomass are collated from other savanna woodlands.…”

The Nature of Northern Australia: its natural values, ecological processes and future prospects

“…Chen et al 2003;Williams et al 2004Williams et al , 2005 suggest that for the Eucalyptus miniata-tetrodonta savannas, which are very extensive in the higher rainfall areas of Northern Australia, more carbon is sequestered than lost back to the atmosphere, with this amount increasing when fires are less frequent, intense or extensive. That is, these savannas are carbon sinks.…”