Understanding anatomical plasticity of Argan wood features at local geographical scale in ecological and archaeobotanical perspectives

Jérôme Ros,Ahmed S Ettahiri,Mohammed Ater,Sarah Ivorra,Laure Paradis,Bertrand Limier,Abdallah Fili,Jean-Pierre Van Staëvel,Marie-Pierre Ruas,Jean-Frédéric Terral

doi:10.1038/s41598-021-90286-4

Abstract

The emergence of the Argan tree as an agricultural, pastoral, cultural, economic and ecological keystone species in Southern Morocco is considered to be linked to the settlement of agropastoral communities that favored its expansion. Nevertheless, the use and exploitation of Argan tree is documented by both few medieval written sources and archaeobotanical studies, from a single location, Îgîlîz (Toughmart, Morocco), a famous medieval site of the Anti-Atlas Mountains. Therefore, data remain scarce regarding the type of Argan communities exploited at this period. In order to document this question, a quantitative eco-anatomical approach aiming to understand variations of wood characters involved in sap conduction and reserve storage, is developed from modern samples collected in the area of Îgîlîz. Results show that diameter of branches and environmental factors are the major parameters explaining plasticity of wood anatomical characters. Quantitative eco-anatomical features of Argan archaeological charcoal confronted to two statistical models, allow assessing both the diameter of the branches from which it derives and the agro-ecological conditions of tree growth and development. This preliminary study may be considered as a relevant and pioneering work for the understanding of the eco-history of the Argan tree, and of its use and exploitation during the past.

Highlights

The emergence of the Argan tree as an agricultural, pastoral, cultural, economic and ecological keystone species in Southern Morocco is considered to be linked to the settlement of agropastoral communities that favored its expansion
(DVS) and ‘Density of wood fenestrated zones’ (DWF), our study pinpoints the relationship between anatomy and the branch age (Fig. 3)
Young branches and twigs are characterized by a high density of vessels and fenestrated zones that, in an eco-functional perspective, may be interpreted as a higher level of sap conduction security[22]

Summary

Introduction

The emergence of the Argan tree as an agricultural, pastoral, cultural, economic and ecological keystone species in Southern Morocco is considered to be linked to the settlement of agropastoral communities that favored its expansion. Quantitative eco-anatomical features of Argan archaeological charcoal confronted to two statistical models, allow assessing both the diameter of the branches from which it derives and the agro-ecological conditions of tree growth and development. This preliminary study may be considered as a relevant and pioneering work for the understanding of the eco-history of the Argan tree, and of its use and exploitation during the past. The Argan tree is considered to have a Tertiary origin, period during which the coastal areas of the Southwestern Morocco were under tropical to subtropical influence.

Objectives

Methods

Results

Conclusion