In the BlueGreen Labs’ Kearsley et al. (2023) paper we described how tropical leaf phenology in the central Congo basin was strongly influenced by a solar radiation. This study was based upon in-situ data and provided a bottom up analysis using both (historical) species specific phenology responses and detailed inventories of species composition as gathered through field assessments.
A recent paper by Liu et al. (2024) in the Journal of Advances in Modeling Earth Systems (JAMES), to which BlueGreen Labs contributed as co-authors, takes a top-down modelling approach and explores if including a radiation component into a common land-surface model (i.e. ORCHIDEE) would provide a more accurate representation of the African tropical forest phenological response in this model - taking a lead from our previously published work.
Liu et al. (2024) used short-wave incoming radiation as a phenological driver behind leaf shedding and (partial) canopy rejuvenation. Including these processes increased the correlation between the modelled leaf area index (LAI) and the observed Enhanced Vegetation Index (EVI) to 27%, where a correlation was previously absent. Although this improvement seems limited, both the direction and magnitude of this number should not be understated.
Phenology is a first order control productivity as the presence or cycling of leaves is directly related to photosynthesis. Even small improvements in the representation of phenological processes are important for the accurate model representation tropical forest growth. It must also be noted that tropical forests are highly diverse. As mentioned in both Kearsley et al. (2023) this diversity can create heterogeneity in the phenological responses throughout a landscape, where at times these responses can be dominated by very large tree individuals (Bastin et al. 2015). Combining both this bottom-up and top-down knowledge provides a clear path forward to further improve model representation.
References
- Kearsley, E., Verbeeck, H., Stoffelen, P., Janssens, S. B., Yakusu, E. K., Kosmala, M., De Mil, T., Bauters, M., Kitima, E. R., Ndiapo, J. M., Chuda, A. L., Richardson, A. D., Wingate, L., Ilondea, B. A., Beeckman, H., van den Bulcke, J., Boeckx, P., & Hufkens, K. (2024). Historical tree phenology data reveal the seasonal rhythms of the Congo Basin rainforest. Plant-Environment Interactions, 5, e10136. https://doi.org/10.1002/pei3.10136
- Liu, Liyang, Philippe Ciais, Fabienne Maignan, Yuan Zhang, Nicolas Viovy, Marc Peaucelle, Elizabeth Kearsley, et al. “Solar Radiation Triggers the Bimodal Leaf Phenology of Central African Evergreen Broadleaved Forests.” Journal of Advances in Modeling Earth Systems 16, no. 7 (July 2024): e2023MS004014. https://doi.org/10.1029/2023MS004014.
- Bastin, J.-F., N. Barbier, M. Réjou-Méchain, a. Fayolle, S. Gourlet-Fleury, D. Maniatis, T. de Haulleville, et al. “Seeing Central African Forests through Their Largest Trees.” Scientific Reports 5 (2015): 13156. https://doi.org/10.1038/srep13156.
[preview image by Liu et al. 2024]
