Can traces of hydrophobic Euphorbia polymers be found on sand particles from inside the fairy circles of Namibia?
EMSL Project ID
49674
Abstract
There is currently no generally accepted hypothesis on the cause and maintenance of the hundreds of thousands of fairy circles (barren patches) found mainly in the Namibian pro-desert. Several theories have been proposed but none has been generally accepted. We propose that these fairy circles are caused by an allelopathic effect from Euphorbia species growing in the environment. We found the ‘footprints’ of the latex producing Euphorbia gummifera in the fairy circles of the Garub region (southern Namibian) by showing with GCMS analysis that euphol, a characteristic triterpenoid of the Euphorbia genus, is present in 19 out of 20 soil samples from inside fairy circles in the Garub region. Only trace amounts of euphol could be found in 3 of 20 samples from outside the fairy circles. This implies that E. gummifera grew in the places where there are now fairy circles. We could however, not detect euphol in the hexane extracts of the fairy circle sand samples from the northern parts of Namibia. We are not sure why, but propose that these circles from the northern parts were formed longer ago and the triterpenoids of Euphorbia species might have broken down in the harsh desert conditions. Our recent unpublished results showed strong hydrophobicity in fairy circle sand and also in sand collected underneath dead Euphorbia plants. Possibly indicating the adsorption of lipids/gummy resin/rubber from the latex on the sand particles (E. damarana is used by the local people for its rubber production).We request to utilize EMSL’s ultra-high resolution mass spectrometry capabilities (FTICR, LESA FTICR and laser ablation) to determine the molecular composition of desert sand from 1) inside fairy circles, 2) outside fairy circles and 3) sand collected underneath dead Euphorbia plants. We hypothesize that the results will show strongly bound polymers from Euphorbia species on sand particles from inside fairy circles corresponding to samples from sand collected underneath dead Euphorbia, but not to samples from outside fairy circles where mainly the grass species, Stipagrostis, grows.
Project Details
Project type
Limited Scope
Start Date
2017-02-20
End Date
2017-04-22
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)