AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar.

Adrian Patrut,Pascal Danthu,Jean-Michel Leong Pock-Tsy,Laszlo Rakosy,Karl F Von Reden,Daniel A Lowy,Roxana T Patrut

doi:10.1371/journal.pone.0146977

Abstract

The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old.

Highlights

The genus Adansonia belonging to the Bombacoideae, a subfamily of Malvaceae, consists of nine species
This research is based on our new approach, which enables the dating of standing and live specimens by AMS radiocarbon investigation of small wood samples collected from their inner cavities and/or from different areas of their trunk/stems
For the longest cavity sample AZA-3, ages increase from the cavity walls up to a certain distance into the wood, after which the values decrease toward the outer part, see Table 1

Summary

Introduction

The genus Adansonia belonging to the Bombacoideae, a subfamily of Malvaceae, consists of nine species. Six species are endemic to Madagascar and have a natural distribution only on this island [1,2,3,4]. In 2005, we started in-depth research for elucidating several controversial or less understood aspects concerning the African baobab (Adansonia digitata L.). This research is based on our new approach, which enables the dating of standing and live specimens by AMS radiocarbon investigation of small wood samples collected from their inner cavities and/or from different areas of their trunk/stems. Due to the peculiar ability of baobabs to produce stems periodically.

Methods

Results

Discussion

Conclusion