Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 11, 763-778, 2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
07 Feb 2014
Phenology as a strategy for carbon optimality: a global model
S. Caldararu1,*, D. W. Purves2, and P. I. Palmer1 1School of GeoSciences, University of Edinburgh, Edinburgh, UK
2Microsoft Research, Cambridge, UK
*now at: Microsoft Research, Cambridge, UK
Abstract. Phenology is essential to our understanding of biogeochemical cycles and the climate system. We develop a global mechanistic model of leaf phenology based on the hypothesis that phenology is a strategy for optimal carbon gain at the canopy level so that trees adjust leaf gains and losses in response to environmental factors such as light, temperature and soil moisture, to achieve maximum carbon assimilation. We fit this model to five years of satellite observations of leaf area index (LAI) using a Bayesian fitting algorithm. We show that our model is able to reproduce phenological patterns for all vegetation types and use it to explore variations in growing season length and the climate factors that limit leaf growth for different biomes. Phenology in wet tropical areas is limited by leaf age physiological constraints while at higher latitude leaf seasonality is limited by low temperature and light availability. Leaf growth in grassland regions is limited by water availability but often in combination with other factors. This model will advance the current understanding of phenology for ecosystem carbon models and our ability to predict future phenological behaviour.

Citation: Caldararu, S., Purves, D. W., and Palmer, P. I.: Phenology as a strategy for carbon optimality: a global model, Biogeosciences, 11, 763-778, doi:10.5194/bg-11-763-2014, 2014.
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