Seasonal variations in phenological traits: leaf shedding and cambial activity in Parkia nitida Miq. and Parkia velutina Benoist (Fabaceae) in tropical rainforest

Hélène Morel (1) , Thomas Mangenet (2) , Jacques Beauchêne (1) , Julien Ruelle (3) , Eric Nicolini (2) , Patrick Heuret (1) , Bernard Thibaut (4, 5)

1 UMR ECOFOG - Ecologie des forêts de Guyane
2 UMR AMAP - Botanique et Modélisation de l'Architecture des Plantes et des Végétations
3 LERFoB - Laboratoire d'Etudes des Ressources Forêt-Bois
4 LMGC - Laboratoire de Mécanique et Génie Civil
5 BOIS - Bois

Studies on the periodicity of wood formation provide essential data on tree age and factors related to the control of tree growth. The aim of this work was to investigate the cambial phenology and its relation with leaf phenology and climatic seasonality in two tropical rainforest species belonging to the genus Parkia known for having a contrasted leaf phenology. From wood samples collected at 15 day intervals from April 2009 to February 2012 in five trees of both species, we quantified cambial activity by counting layers of cells in cambial zone, enlarging cells zone and wall thickening cells zone from wood prepared anatomical micro sections. In the same time, we observed leaf shedding behaviors in the crown of the studied trees. In both species, cambial activity was significantly reduced during leafless period. However, the cambial activity of P. velutina was not affected by seasonality while in P. nitida, we found a significant positive effect of the dry season on cambial activity. This diminution of activity associated to leaf shedding occurred annually during the dry season in P. nitida whereas the trees were not synchronous in time for P. velutina. On the contrary that is often admitted, the rest cambial period can be independent of environmental restriction such as dry season. Leaf phenology remains the best proxy to estimate cambial activity.

Mots clés: tropical rain forest; leaf shedding pattern; climate; cambial activity; French Guiana

Domaines: Botanique; Ecosystèmes

Hélène Morel, Thomas Mangenet, Jacques Beauchêne, Julien Ruelle, Eric Nicolini, et al.. Seasonal variations in phenological traits: leaf shedding and cambial activity in Parkia nitida Miq. and Parkia velutina Benoist (Fabaceae) in tropical rainforest. Trees - Structure and Function, 2015, 29 (4), pp.973-984. ⟨10.1007/s00468-015-1177-4⟩. ⟨hal-01135166⟩