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Université catholique de Louvain (2019)

Anatomical characterization of the cambial growth of Balanites aegyptiaca (L.) Del. in the Sahelian part of Senegal, the Ferlo

Laurent, Félix

Titre : Anatomical characterization of the cambial growth of Balanites aegyptiaca (L.) Del. in the Sahelian part of Senegal, the Ferlo.

Auteur : Laurent, Félix

Université de soutenance : Université catholique de Louvain

Grade : Master : bioingénieur en gestion des forêts et des espaces naturels 2019

Résumé
The Sahel is a biogeographic zone characterized by an arid to semiarid tropical climate. It is delimited by the 100 mm and 600 mm isohyets of annual precipitations, which are concentrated during a short rainy season. Two main strati constitute the Sahelian vegetation : the grass layer dominated by annual herbaceous grasses and the top layer composed of shrubs and trees. The water and vegetal biomass are two fundamental resources that support agropastoralism, the main activity sustaining the 60 million inhabitants of the Sahel. This study takes place in the Sahelian part of Senegal, the Ferlo. The evergreen tree Balanites aegyptiaca (L.) Del. provides goods and services and is characterized by its high tolerance toward environmental stresses, making it a dominant species in arid woodlands and an asset in the context of the climate change. The dominant status and resilient capacity of Balanites make it a prime candidate for dendrochronological studies. Its use is however prevented due to the lack of references detailing the tree-growth phenology and its relation with the cambial dynamics. Observations were conducted on Balanites samples in order to improve the knowledge relative to its cambial growth anatomical characterization in the prospect of paving the way for dendrochronological studies. Hypotheses were tested regarding the detection of growth markers on different sample types : microscopic cross sections, macroscopic cross sections, and microdensity profiles. Radial growth rates were calculated as well to test the periodicity of the data gathered with the samples. The comparative study of microscopic and macroscopic cross sections allowed us to characterize different types of cambial growth markers and to assess the unreliability of the marker detection method at the macroscopic scale. The raw microdensity data could not be used to identify markers but served to highlight prospects for future research. The growth rates allowed for a better grasp of the cambial growth periodicity. Nonetheless, substantial uncertainties suggest that these rates should be considered carefully and that more studies should be dedicated to assessing reliable growth rates for Balanites.

Mots clés : Balanites aegyptiaca, Ferlo, Climate change

Présentation

Page publiée le 14 janvier 2020