Hélène Morel

Tél. : (+594) 5 94 32 09 60

email : Helene.Morel at EcoFoG.gf

PhD defended on may, 21st 2013.

Study of the intra-annual tree growth of tropical rain forest in French Guiana

Dendrochronology, which studies tree growth rings, allows to date trees and to determine its growth rhythm. Widely used in temperate and boreal forests, dendrochronology is less used in the tropics, because of lack of winter season, which makes it difficult to produce growth ring (Stahle, 1999).So, the main objective of this PhD is the understanding of the determinism involved in the secondary growth of trees (i.e. radial growth) from French Guyana tropical rainforest and to set up dendrochronological methods, allowing us to date trees and reconstruct their passed growth even without reliable growth ring. Our research is based on three main axes.
In the first axis, we will confront various approaches (anatomic, micro-densitometric, chemical and isotopic) to bring out markers of the radial growth rhythmicity.

The second axis will aim to confirm or not the annual nature of secondary growth rhythmicity. We will study the dynamic of the seasonal cambial activity of trees and we will try to understand which environmental and/or intrinsic factors are involved in this dynamic. In this purpose, microcores of the cambial zone will be taken twice a month. The dynamic of secondary growth will be compared with the dynamic of primary growth (i.e. growth in height).

The first principle in dendrochronology, needed to establish reliable chronological series, require the identification of a common pattern in a group of individuals. By the way it is not trivial to know if individuals belonging to the same species and growing in the same environment react in the same way to inter-annual climatic variations, or if each individual has a different inter-annual growth pattern. We will try, in this third axis, to characterize individual growth synchronism of few model species on a sampling realized on many individuals.

PhD Directors

  • FSE Guyane {PNG}Union Européenne {PNG}

Cette thèse a été cofinancée par l’Union Européenne.

View online : Download the Thesis

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