埮生物の地球芏暡炭玠埪環ぞの寄䞎を解明 (New Study Clarifies Microbial Role in Global Soil Carbon Cycle)

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2026-01-19 䞭囜科孊院(CAS)

土壌は倧気や怍生を䞊回る量の炭玠を貯蔵しおおり、その埪環を䞻に担うのが土壌埮生物である。䞭囜科孊院地球環境研究所の研究チヌムは、埮生物呌吞量(Rh)ず埮生物炭玠利甚効率(CUE)の関係に関する埓来の仮定を芆す新知芋を瀺した。本研究はScience Advances誌に掲茉された。これたで、Rhが増加するずCUEは䞀様に䜎䞋するず考えられおきたが、実際には生態系の生産性に応じお非線圢に倉化するこずが明らかになった。党球1094組の芳枬デヌタを甚いた解析の結果、也燥・寒冷な䜎生産性地域では埓来通り負の盞関が芋られた䞀方、熱垯・枩垯など高生産性地域ではRhが䞀定倀を超えるずCUEは玄0.27で安定した。これは、栄逊制限䞋で埮生物が炭玠固定より栄逊獲埗を優先する適応戊略を反映しおおり、怍生増加が必ずしも土壌炭玠貯留を高めない理由を説明する。

埮生物の地球芏暡炭玠埪環ぞの寄䞎を解明 (New Study Clarifies Microbial Role in Global Soil Carbon Cycle)
Conceptual framework illustrating the possible relationships between microbial CUE and Rh on the basis of stoichiometric theory and microbial community theory. (Image by CUI Yongxing, et al)

<関連情報>

䞖界の土壌における埮生物の炭玠利甚効率ず呌吞の生産性䞻導の分離 Productivity-driven decoupling of microbial carbon use efficiency and respiration across global soils

Yongxing Cui, Shushi Peng, Manuel Delgado-Baquerizo, Daryl L. Moorhead, […] , and Matthias C. Rillig
Science Advances  Published:14 Jan 2026
DOI:https://doi.org/10.1126/sciadv.adz5319

Abstract

Despite extensive research on soil microbial carbon (C) use efficiency (CUE), its linkage to actual soil C storage remains ambiguous. A key uncertainty is that CUE estimates from short-term labeling incubations assume a linear negative relationship with respiration rates, overlooking nonlinear interactions and long-term microbial acclimation. Here, we use a stoichiometry-based approach to estimate CUE (CUEST), which links soil resource availability to microbial demand and captures microbial adaptability under resource constraints. We synthesized 1094 paired observations of CUEST and heterotrophic respiration rate (Rh) across natural ecosystems and found a nonlinear relationship between them governed by ecosystem productivity. In low-productivity arid and cold regions, CUEST declined with increasing Rh, whereas in productive tropical and temperate regions, CUEST stabilized at a low level (0.27 ± 0.11) as Rh exceeded 340 ± 10.8 grams of C per square meter per year. This shift reflects microbial trade-offs between C assimilation and stoichiometric homeostasis, revealing a decoupling of microbial growth from respiration that limits the capacity of productive ecosystems to store additional soil C.

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