| 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（口頭発表） M03-02 （Oral presentation）

#### Depth-dependent energetic properties of organic matter: linking chemical composition to energy release feasibility and quality in mountain soils【E】【発表取消/Cancelled】

*Wenting FENG（Beijing Forestry University）, Dengchun XING（Chinese Academy of Agri Sci）, Xiaofang JI（Beijing Forestry University, Lanzhou University）, Yugang WANG（Xinjiang Inst Ecol Geogr）, Shikui DONG（Beijing Forestry University）, Xin JING（Lanzhou University）

The decomposition of soil organic matter (SOM) is influenced by its energy content, chemical composition, and the energy required to overcome intrinsic barrier. This study addresses a critical knowledge gap by quantifying the relationship between SOM’s chemical composition and its energetic properties. We assessed energy content by energy density and characterized the energetic barrier using activation energy and the differential scanning calorimetry temperature at which 50% of SOM-stored energy releases (DSC-T50). The return-on-investment (ROI), defined as the ratio of energy density to activation energy, served as a proxy for energy quality. Measurements were taken at various soil depths (0-5, 5-15, 15-30, and 30-50 cm) in mountain ecosystems located in arid regions, with elevations ranging from 1500 m to 3035 m. Our findings reveal that the energetic parameters—energy density, activation energy, DSC-T50, and ROI—were positively correlated with the relative abundance of recalcitrant compounds (aliphatic-C1 and aromatic-C) and the fraction of OC with an Ea of >150 kJ mol-1 and negatively correlated with labile compounds (polysaccharide-C) and the fraction of OC with an Ea of <150 kJ mol-1. Notably, chemical composition significantly influenced energy content and ROI only in subsoil layers (15-30 cm and 30-50 cm), with the impact on activation energy and DSC-T50 increasing with depth. These results suggest that a higher proportion of recalcitrant SOM enhances energy content, energetic barrier, and overall energy quality of SOM, particularly in deeper soil layers. Across all soil layers, the ROI ratio consistently increased with energy density but not with activation energy, indicating that energy content was a strong determinant of energy quality than activation energy. Our study highlights the importance of considering the decoupling between chemical composition and energetic properties in future research, emphasizing the distinct role of energy content and energetic barriers in shaping energy quality.

日本生態学会