the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Measurement report: Age-dependent BVOC emissions in Eucalyptus urophylla: a comparison of leaf cuvette and branch chamber measurements
Abstract. Biogenic volatile organic compound (BVOC) emission factors (Es) underpin air quality and climate models, yet current databases intermingle data from both seedlings and mature trees and from two enclosure techniques, leaf cuvettes and dynamic branch chambers, whose comparability has rarely been rigorously tested. Here we quantified BVOC emissions from Eucalyptus urophylla by pairing the two methods on a statistically representative number of 2-month-old seedlings in the laboratory and 2-year-old trees measured at a managed plantations in subtropical China. Leaf-cuvette and branch-chamber determination of isoprene Es matched within 5 % for both age classes, demonstrating method equivalence. In contrast, tree age exerted a significant impact on both the magnitude and speciation of emissions. Seedlings emitted ~50 % more isoprene and were enriched in cyclic monoterpenes like α-pinene and 1,8-cineole, whereas field-grown trees shifted toward highly reactive acyclic monoterpenes, with β-ocimenes accounted for over 85 % of the terpene flux. These ontogenetic shifts imply that one-third of the entries in global Es compilations, which are derived from seedling studies, likely overestimate local isoprene fluxes while under-representing the atmospheric reactivity of mature canopies. Our results validate the use of either chamber type for measuring isoprene Es, highlight the need for improved analytical sensitivity before extending this equivalence to terpenes, and call for systematic, large-sample, branch-level measurements of adult trees to produce representative Es values. Incorporating age-resolved emission factors into models will refine estimates of ozone and secondary organic aerosol formation in fast-growing subtropical plantations and other managed forests worldwide.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-3226', Anonymous Referee #1, 30 Jul 2025
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AC1: 'Reply on RC1', Xinming Wang, 18 Sep 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-3226/egusphere-2025-3226-AC1-supplement.pdf
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AC1: 'Reply on RC1', Xinming Wang, 18 Sep 2025
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RC2: 'Comment on egusphere-2025-3226', Anonymous Referee #2, 04 Sep 2025
Dear Authors-
As handling editor of this manuscript, I am passing on an anonymous review submitted via email. The two specific comments were as follows:
1. Were the genotypes of the seedlings and saplings the same? Croteau (Mentha) and Lorio (Pinus) showed more than 30 years ago that genotype has a huge impact on the particular monoterpenes emitted, even from the same species of plant.
2. Were the light, temperature, and nitrogen conditions similar for the seedling and sapling leaf development? This is NOT a question about light and temperature during measurement but during the growth of the leaf. Fall, Funk, Guenther, Harley, Monson, and several others have shown the importance of growth environment, especially for isoprene emission.Building on these comments, though you describe ontogenetic effects, which does suggest some attention to environment, the major conclusions of the paper (outside sampling strategy) focus on on age-dependent emissions, with no controls for environmental conditions. It is not clear how these two can be differentiated, or what the implications are for the results and conclusions.
Paraphrasing a final author comment: If the authors did not control for genotype (not just species), AND if they did not control for the growth conditions, then I suggest rejection.
Citation: https://doi.org/10.5194/egusphere-2025-3226-RC2 -
AC2: 'Reply on RC2', Xinming Wang, 18 Sep 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-3226/egusphere-2025-3226-AC2-supplement.pdf
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AC2: 'Reply on RC2', Xinming Wang, 18 Sep 2025
Data sets
Measurement report: Age‑dependent BVOC emissions in Eucalyptus urophylla: a comparison of leaf‑cuvette and branch‑chamber measurements Jianqiang Zeng https://doi.org/10.17632/jw8g8gkm5t.1
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This research is a fundamental study in the field of BVOCs, highlighting the previously overlooked emission factors and potential variations in the composition of BVOCs with tree age in previous studies. It also clarifies to a certain extent issues such as the comparability of different sampling methods. Overall, the research has good innovation, especially for model users and developers, it has very good enlightenment and guidance significance. However, the manuscript still requires some revision to enhance its reliability, make the manuscript's logic more complete, and enrich the content to reach the publication standard.