Research press release


Nature Climate Change

Increased leaf litter boosts soil carbon release

落葉が増加すると熱帯森林土壌からの炭素放出を加速し、予測されている森林の炭素貯蔵と一部が相殺するとの研究成果が、Nature Climate Change(電子版)に報告される。


E Sayerらはパナマで森林土壌に落葉を付加し、6年間にわたって監視することで落葉の増加が土壌の炭素貯蔵に及ぼす影響を調べた。同位体測定を用いて異なった炭素発生源を区別することにより、彼らは落葉が加わることで、土壌の微生物が容易に分解できる有機物が付加され刺激を受ける「プライミング」として知られる過程によって、土壌有機炭素からの二酸化炭素放出が顕著に増加することを見つけた。


Increased leaf-litter input may boost carbon release from tropical forest soils, partially offsetting predicted gains in forest carbon storage, according to research published online this week in Nature Climate Change.

Enhanced tropical forest productivity stimulated by increasing carbon dioxide concentrations could act as a substantial carbon sink, potentially slowing down the rate of global warming. However, feedbacks between increased productivity and soil carbon dynamics remain unexplored, limiting our ability to predict future changes in carbon storage.

Emma Sayer and colleagues added leaf litter to forest soils in Panama and monitored them for six years to investigate the effects of enhanced litterfall on carbon storage in the soil. Using isotope measurements to distinguish between carbon sources, they found that litter addition significantly increases the release of carbon dioxide from soil organic carbon through a process known as ‘priming’, where soil microbes are stimulated by the addition of easily decomposable organic matter.

The researchers estimate that a 30% increase in litterfall could release about 0.6 tonnes of carbon per hectare from lowland tropical forest soils each year. This amount of carbon is greater than estimates of the climate-induced increase in forest biomass in Amazonia over recent decades.

doi: 10.1038/nclimate1190


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