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Background <p>Xylogenesis is synchronous among trees in regions with a distinct growing season, leading to a forest-wide time lag between growth and carbon uptake. In contrast, little is known about interspecific or even intraspecific variability of xylogenesis in tropical forests. Yet an understanding of xylogenesis patterns is key to successfully combine bottom-up (e.g., from permanent forest inventory plots) and top-down (e.g., from eddy covariance flux towers) carbon flux estimates.</p> Methods <p>Here, we monitor xylogenesis development of 18 trees belonging to 6 abundant species during 8&#xa0;weeks at the onset of the rainy season from March to April 2022 in a semideciduous rainforest in the Yangambi reserve (central Democratic Republic of the Congo). For each tree, the weekly cambial state (dormant or active) was determined by epifluorescence microscopy.</p> Results <p>We find interspecific variability in the cambial phenology, with two species showing predominant cambial dormancy and two species showing predominant cambial activity during the monitoring period. We also find intraspecific variability in two species where individuals either display cambial dormancy or cambial activity. All trees kept &gt; 60% of their leaves throughout the dry season and the monitoring period, suggesting a weak relationship between the phenology of the cambial and foliar. Our results suggest that individual trees in Yangambi asynchronously activate their cambial growth throughout the year, regardless of leaf phenology or seasonal rainfall.</p> Conclusion <p>These results are consistent with global analysis of gross primary productivity estimates from eddy covariance flux towers, showing that tropical biomes lack a synchronous dormant period. However, a longer-term monitoring experiment, including more species, is necessary to confirm this for the Congo Basin. As Yangambi is equipped with facilities for microscopic wood analysis, a network of inventory plots and a flux tower, further research in this site will reveal how xylogenesis patterns drive annual variability in carbon fluxes and how ground-based and top-down measurements can be combined for robust upscaling analysis of Congo basin carbon budgets.</p>

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Asynchronous xylogenesis among and within tree species in the central Congo Basin

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年3月12日

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  • Pauline Hicter,
  • Hans Beeckman,
  • Basile Luse Belanganayi,
  • Tom De Mil,
  • Jan Van den Bulcke,
  • Peter Kitin,
  • Marijn Bauters,
  • Kévin Lievens,
  • Donatien Musepena,
  • José Mbifo Ndiapo,
  • Nestor K. Luambua,
  • Félix Laurent,
  • Bhély Angoboy Ilondea,
  • Wannes Hubau

摘要

Background

Xylogenesis is synchronous among trees in regions with a distinct growing season, leading to a forest-wide time lag between growth and carbon uptake. In contrast, little is known about interspecific or even intraspecific variability of xylogenesis in tropical forests. Yet an understanding of xylogenesis patterns is key to successfully combine bottom-up (e.g., from permanent forest inventory plots) and top-down (e.g., from eddy covariance flux towers) carbon flux estimates.

Methods

Here, we monitor xylogenesis development of 18 trees belonging to 6 abundant species during 8 weeks at the onset of the rainy season from March to April 2022 in a semideciduous rainforest in the Yangambi reserve (central Democratic Republic of the Congo). For each tree, the weekly cambial state (dormant or active) was determined by epifluorescence microscopy.

Results

We find interspecific variability in the cambial phenology, with two species showing predominant cambial dormancy and two species showing predominant cambial activity during the monitoring period. We also find intraspecific variability in two species where individuals either display cambial dormancy or cambial activity. All trees kept > 60% of their leaves throughout the dry season and the monitoring period, suggesting a weak relationship between the phenology of the cambial and foliar. Our results suggest that individual trees in Yangambi asynchronously activate their cambial growth throughout the year, regardless of leaf phenology or seasonal rainfall.

Conclusion

These results are consistent with global analysis of gross primary productivity estimates from eddy covariance flux towers, showing that tropical biomes lack a synchronous dormant period. However, a longer-term monitoring experiment, including more species, is necessary to confirm this for the Congo Basin. As Yangambi is equipped with facilities for microscopic wood analysis, a network of inventory plots and a flux tower, further research in this site will reveal how xylogenesis patterns drive annual variability in carbon fluxes and how ground-based and top-down measurements can be combined for robust upscaling analysis of Congo basin carbon budgets.