Temperature‐Dependent and Temperature‐Independent Changes in Photosynthetic Traits Across the Day in the Tropical Tree Calophyllum inophyllum
熱帯樹木Calophyllum inophyllumにおける光合成特性の日変動：温度依存性と非依存性の変化 (AI 翻訳)
Juan C. Mejía‐Medina, Roxana Alveo, M. Slot
🤖 gxceed AI 要約
日本語
熱帯樹木の光合成能力が午後には午前よりも最大29%低下することを発見。この低下は生化学的ダウンレギュレーションによるもので、熱耐性は変化しない。将来の気候下での炭素吸収量推定には日変動を考慮する必要がある。
English
Photosynthetic capacity in tropical tree Calophyllum inophyllum declines up to 29% in the afternoon due to biochemical downregulation, while heat tolerance remains stable. This diurnal variation must be accounted for in carbon uptake models under future climate scenarios.
Unofficial AI-generated summary based on the public title and abstract. Not an official translation.
📝 gxceed 編集解説 — Why this matters
日本のGX文脈において
日本の森林は温帯が中心だが、熱帯林の炭素循環モデリングは全球の気候予測に直結する。日本の気候変動適応策やGX政策において、森林炭素吸収源の正確な評価に間接的に寄与しうる。
In the global GX context
This study highlights the risk of overestimating tropical forest carbon uptake if diurnal photosynthetic decline is ignored. Relevant for global carbon cycle models used in IPCC assessments and nature-based climate solutions.
👥 読者別の含意
🔬研究者:Climate modelers should incorporate diurnal variation in photosynthetic capacity to avoid overestimating future carbon sinks.
📄 Abstract（原文）
Tropical forests play a crucial role in global carbon cycling but face increasing stress from rising temperatures and atmospheric drought (vapor pressure deficit, VPD). While most studies assess photosynthetic performance at fixed time points, short‐term diurnal variation in photosynthetic parameters remains underexplored. We examined how the optimum temperature of photosynthesis, photosynthetic capacity, electron transport rate, and thermal tolerance vary throughout the day in tropical tree species Calophyllum inophyllum . Morning and afternoon measurements were conducted using gas exchange ( FAsTeR and Dynamic A‐Ci methods) and chlorophyll fluorescence. Photosynthetic capacity declined significantly in the afternoon, with lower light‐saturated photosynthesis rates, A max (−29%), maximum carboxylation rate, Vc max (−32%), and triose‐phosphate utilization rate, TPU (−21%) than in the morning, despite consistent measurement conditions. These declines were not driven by stomatal or mesophyll conductance, suggesting biochemical downregulation. In contrast, thermal tolerance metrics ( T 50 and T crit ) remained stable between morning and afternoon, indicating decoupling between heat tolerance and metabolic performance. Our findings support a physiological strategy in C. inophyllum that prioritizes morning carbon gain and modulates photosynthetic efficiency throughout the day without compromising heat tolerance. This dynamic regulation underscores the need to account for diurnal variation and temperature‐sensitive constraints into models of tropical forest function. Relying on photosynthetic capacity estimated under favorable morning conditions risks overestimating carbon uptake under future climate scenarios.
🔗 Provenance — このレコードを発見したソース
- semanticscholar https://doi.org/10.1111/btp.70202first seen 2026-06-29 09:08:29
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