針葉樹リターが長期的な土壌炭素安定化を促進する仕組みを解明(Researchers Uncover How Coniferous Litter Enhances Long-Term Soil Carbon Stabilization)

2026-03-17 中国科学院(CAS)

中国科学院華南植物園の研究は、亜熱帯森林における土壌炭素安定化の新たな仕組みを解明した。従来は高品質リター(落葉)が炭素蓄積に有利とされたが、栄養価が低く分解の遅い針葉樹リターの方が効率的に土壌有機炭素を増加させることが示された。360日間の分解実験と炭素同位体解析により、針葉樹リターは分解が18~32%遅い一方、炭素蓄積量は1.4~2.1倍高いことが判明。特に鉱物結合有機炭素(MAOC)の形成を促進し、長期安定化に寄与する。高いC/N比による微生物の窒素制限や鉱物表面への結合が主要因であり、森林再生や炭素固定戦略への応用が期待される。

針葉樹リターが長期的な土壌炭素安定化を促進する仕組みを解明(Researchers Uncover How Coniferous Litter Enhances Long-Term Soil Carbon Stabilization)
Conceptual diagram illustrating how litter decomposition from different plant growth forms drives the formation and stabilization of soil organic carbon. (Image by LIU Zhanfeng et al.)

<関連情報>

実験室での培養実験により、針葉樹の落葉は広葉樹の落葉よりも分解速度が遅いにもかかわらず、土壌炭素の安定化効果が高いことが明らかになった Laboratory incubation reveals greater soil carbon stabilization by coniferous leaf litter than by broadleaf leaf litter despite slower decomposition

Panpan Wu ,Ting Wu ,Yun Zhang ,Yidong Ding ,Zhanfeng Liu ,Rong Mao
Journal of Plant Ecology  Published:14 March 2026
DOI:https://doi.org/10.1093/jpe/rtag040

Abstract

Plant growth forms influence soil organic carbon (SOC) turnover through litter quality, yet their impacts on SOC formation pathways (particulate [POC] vs. mineral-associated [MAOC]) remain poorly understood in forest ecosystems. Here, leaf litter of deciduous broadleaf (4 species), evergreen broadleaf (5 species), and evergreen coniferous trees (3 species) was collected in a subtropical forest. Using natural δ13C abundance, we traced litter-derived carbon flows into POC and MAOC pools during a 360-day laboratory incubation. Despite 18–32% lower mass loss, coniferous litter contributed 1.4- to 2.1-fold more to net SOC accumulation than broadleaf litter. This resulted from the higher SOC, MAOC, and POC formation efficiencies (coniferous: 28–32%; broadleaf: 11–19%). Litter C:N ratio was the primary driver of net SOC and POC balance. In contrast, net MAOC balance was co-regulated by litter-derived dissolved organic C production and biodegradation. Our results suggest that evergreen coniferous litter, despite its lower substrate quality and slower decomposition rate, may promote greater SOC accrual and stabilization than both deciduous and evergreen broadleaf litter. This counterintuitive finding underscores that recalcitrant coniferous litter enhances long-term soil C sequestration efficiency, and imply that afforestation with coniferous species may benefit SOC sequestration by promoting MAOC formation in subtropical forests.

1901環境保全計画
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