Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China.
Institut de Recherche en Horticulture et Semences, Université d'Angers, 42 rue Georges Morel, Beaucouzé, 49070, France.
New Phytol. 2024 Dec;244(6):2225-2238. doi: 10.1111/nph.20170. Epub 2024 Oct 3.
Carbon isotope discrimination (∆) in leaf biomass (∆) and tree rings (∆) provides important proxies for plant responses to climate change, specifically in terms of intrinsic water-use efficiency (iWUE). However, the nonphotosynthetic C/C fractionation in plant tissues has rarely been quantified and its influence on iWUE estimation remains uncertain. We derived a comprehensive, ∆ based iWUE model (iWUE) which includes nonphotosynthetic fractionations (d) and characterized tissue-specific d-values based on global compilations of data of ∆, ∆ and real-time ∆ in leaf photosynthesis (∆). iWUE was further validated with independent datasets. ∆ was larger than ∆ by 2.53‰, while ∆ and ∆ showed a mean offset of 2.76‰, indicating that ∆ is quantitatively very similar to ∆. Applying the tissue-specific d-values (d = 2.5‰, d = 0‰), iWUE estimated from ∆ aligned well with those estimated from ∆ or gas exchange. ∆ and ∆ showed a consistent iWUE trend with an average CO sensitivity of 0.15 ppm ppm during 1975-2015. Accounting for nonphotosynthetic fractionations improves the estimation of iWUE based on isotope records in leaf biomass and tree rings, which is ultimate for inferring changes in carbon and water cycles under historical and future climate.
叶片生物量 (∆) 和树木年轮 (∆) 的碳同位素分馏 (∆) 为研究植物对气候变化的响应提供了重要的替代指标，尤其是在内在水分利用效率 (iWUE) 方面。然而，植物组织中非光合作用的 C/C 分馏作用很少被量化，其对 iWUE 估算的影响仍然不确定。我们推导出了一个综合的、基于 ∆ 的 iWUE 模型 (iWUE)，其中包括非光合作用分馏 (d)，并基于叶片光合作用 (∆) 中 ∆、∆ 和实时 ∆ 的全球数据汇编，确定了组织特异性的 d 值。进一步用独立数据集验证了 iWUE。∆ 比 ∆ 大 2.53‰，而 ∆ 和 ∆ 的平均偏移为 2.76‰，这表明 ∆ 在数量上非常类似于 ∆。应用组织特异性的 d 值 (d = 2.5‰，d = 0‰)，从 ∆ 估算的 iWUE 与从 ∆ 或气体交换估算的 iWUE 非常吻合。∆ 和 ∆ 与 CO 平均敏感性为 0.15 ppm ppm 一致，显示出一致的 iWUE 趋势，在 1975-2015 年间。考虑非光合作用分馏作用可以提高基于叶片生物量和树木年轮同位素记录估算 iWUE 的准确性，这对于推断历史和未来气候下碳和水循环的变化至关重要。
