| 要旨トップ | 目次 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

一般講演（ポスター発表） P1-565 （Poster presentation）

#### 複数樹種における幹メタン放出と木材腐朽状態の関係【A】【E】
Relationships between stem methane emission and wood decay condition in several tree species【A】【E】

*大竹祐太（京都大学）, 持留匠（京都大学）, 長沢誠（京都大学）, 諏訪錬平（国際農研）, 高木健太郎（北海道大学）, 檀浦正子（京都大学）, Daniel EPRON（Kyoto Univ.）
*Yuuta OHTAKE（Kyoto Univ.）, Takumi MOCHIDOME（Kyoto Univ.）, Makoto NAGASAWA（Kyoto Univ.）, Rempei SUWA（JIRCAS）, Kentaro TAKAGI（Hokkaido univ.）, Masako DANNOURA（Kyoto Univ.）, Daniel EPRON（Kyoto Univ.）

Methane (CH4) is the second most important anthropogenic greenhouse gas, and understanding its global dynamics is crucial for addressing climate change. Stem CH4 flux exhibits spatial and temporal variability, and ongoing studies aim to clarify its controlling factors and production processes. Regarding the relationship between stem CH4 flux and methanogens within stems, previous studies have suggested that methanogen distribution and community size are highly localized. This implies that the “micro-niches” where methanogenesis occurs are spatially heterogeneous, and potentially explains the large intra-individual, inter-individual, and inter-specific variability of stem CH4 flux. In this study, we hypothesized that internal wood decay drives this variability by altering moisture conditions and wood structure, thereby defining the spatial variation of stem CH4 flux.
Field measurements were conducted at the Ashiu Forest Research Station and the Teshio Experimental Forest. Stem CH4 fluxes were calculated from temporal changes in CH4 concentration using a closed-chamber system with a trace gas analyzer (LI-7810). At each site, six individuals were selected from each dominant species (six species at Ashiu and five at Teshio), and five chambers were installed per individual. To assess the progression of decay status while minimizing disturbance, internal wood decay was evaluated non-destructively using acoustic tomography (ArboSonic 3D), which detects differences in sound-wave transmission velocity. Measurements were conducted at four cross-sections for each individual, and three-dimensional decay structures were reconstructed by vertically integrating these data. A chamber-specific decay index was defined based on the mean sound velocity around each chamber.
The results confirmed substantial intra-individual, inter-individual, and inter-specific variability in stem CH4 flux, with these factors explaining most of the observed variance, whereas site effects were negligible. In contrast, decay status exhibited greater inter-site and inter-specific variability than individual-level variation. Overall, stem CH4 flux showed a marginal positive relationship with decay progression (p = 0.091). However, the strength and direction of this relationship differed significantly among species (interaction: p < 0.01), with some species showing strong positive responses to decay, while others exhibited weak, inverse, or no relationships.

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