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Aim : Erythrophleum species and gene pools, despite being morphologically similar, oc-
cupy contrasted habitats. The aim of this work is to determine if Erythrophleum species
and gene pools respond differently to shade and drought, to understand the underlying
mechanisms that explain these differences by measuring traits on control seedlings, and
finally to understand if these differences can explain their distribution patterns.
Location : Industrial site of Pallisco-CIFM in Mindourou, Cameroon, and two zones
in southern (Dja-and-Lobo department) and central Cameroon (Mba-and-Kim depart-
ment).
Methods : The work consisted of an in situ and a drought and shade experiment. Dur-
ing the in situ experiment, two zones where species or gene pools are coexisting were
sampled. During the drought/shade experiment, two modalities of drought (watered or
non watered) and two modality of light (low light and hight light) were tested on 190
seedlings from two species and six gene pools to compare their response to stress. At the
end of the experiment, functional traits were measured on 56 control seedlings.
Results : Allometric models have been calculated and phenophases compared for field
individuals sampled in the field of two gene pools. Differences of phenophases and crown
shape have been highlighted. No clear difference between species and gene pools were
observed experimentally in seedling survival and response to drought and shade. Differ-
ences of functional traits have been found between species and gene pools, suaW having
more drought-adapted traits than any other pool.
Main conclusions : Dry forests gene pools had more drought tolerant traits than pools
found in wetter forests, but did not show more resistance to drought or more sensitivity
to shade in the drought/shade experiment. A difference exist but is thin because of
the morphological proximity of the pools and species, supporting the ecological gradient
hypothesis.

Tropical forests, Central Africa, Cameroon, Erythrophleum, ecological specialisation, trade-offs, gene pools, functional traits, allometry, diversification, stress tolerance --- Sciences du vivant > Sciences de l'environnement & écologie