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Pan-tropical analysis of climate effects on seasonal tree growth

Wagner F., Rossi V., Aubry-Kientz M., Bonal D., Dalitz H., Gliniars R., Stahl C., Trabucco A., Hérault B.. 2014. PloS One, 9 (3) : 15 p..

Climate models predict a range of changes in tropical forest regions, including increased average temperatures, decreased total precipitation, reduced soil moisture and alterations in seasonal climate variations. These changes are directly related to the increase in anthropogenic greenhouse gas concentrations, primarily CO2. Assessing seasonal forest growth responses to climate is of utmost importance because woody tissues, produced by photosynthesis from atmospheric CO2, water and light, constitute the main component of carbon sequestration in the forest ecosystem. In this paper, we combine intraannual tree growth measurements from published tree growth data and the corresponding monthly climate data for 25 pan-tropical forest sites. This meta-analysis is designed to find the shared climate drivers of tree growth and their relative importance across pan-tropical forests in order to improve carbon uptake models in a global change context. Tree growth reveals significant intra-annual seasonality at seasonally dry sites or in wet tropical forests. Of the overall variation in tree growth, 28.7% was explained by the site effect, i.e. the tree growth average per site. The best predictive model included four climate variables: precipitation, solar radiation (estimated with extrasolar radiation reaching the atmosphere), temperature amplitude and relative soil water content. This model explained more than 50% of the tree growth variations across tropical forests. Precipitation and solar radiation are the main seasonal drivers of tree growth, causing 19.8% and 16.3% of the tree growth variations. Both have a significant positive association with tree growth. These findings suggest that forest productivity due to tropical tree growth will be reduced in the future if climate extremes, such as droughts, become more frequent. (Résumé d'auteur)

Mots-clés : séquestration du carbone; zone tropicale; sécheresse; température; précipitation; teneur en eau du sol; Énergie solaire; stockage; carbone; adsorption; variation saisonnière; changement climatique; facteur climatique; modèle mathématique; modèle de simulation; croissance; arbre; forêt tropicale humide; forêt tropicale; monde

Thématique : Foresterie - Considérations générales; Physiologie et biochimie végétales; Météorologie et climatologie; Méthodes mathématiques et statistiques

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