EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Soil Degradation in Argan Woodlands, South Morocco

Mario Kirchhoff1, Lars Engelmann1, Lutz Leroy Zimmermann1, Irene Marzolff2, Manuel Seeger1, Ali Aït Hssaine3, and Johannes B. Ries1
Mario Kirchhoff et al.
  • 1Trier University, Department of Physical Geography, Trier, Germany (
  • 2Goethe University Frankfurt am Main, Department of Physical Geography, Frankfurt am Main, Germany
  • 3Université Ibn Zohr, Department of Geography, Agadir, Morocco

The argan tree (Argania spinosa) populations, endemic to South Morocco, have been highly degraded. Although the argan tree is the source of the valuable argan oil and is protected by law, overbrowsing and -grazing as well as the intensification and expansion of agricultural land lead to tree and soil degradation. Young stands cannot establish themselves; undergrowth is scarce due to the semiarid/arid climate and thus, goats, sheep and dromedaries continually browse the trees. Canopy-covered areas decrease and are degraded while areas without vegetation cover between the argan trees increase.

On 30 test sites, 60 soil samples of tree and intertree areas were studied on their soil physical and chemical properties. 36 rainfall simulations and 60 single-ring infiltration measurements were conducted to measure potential differences between tree/intertree areas in their runoff/erosion and infiltration properties. Significant differences using a t-test were found for the studied parameters saturated hydraulic conductivity, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content and Mg-content. Surface runoff and soil erosion were not statistically significant, but showed similar trends due to the higher complexity of runoff formation. The soil covered by argan trees generally showed less signs of degradation than intertree areas. With ever-expanding intertree areas due to the lack of rejuvenation of argan trees a further degradation of the soil can be assumed.

How to cite: Kirchhoff, M., Engelmann, L., Zimmermann, L. L., Marzolff, I., Seeger, M., Aït Hssaine, A., and Ries, J. B.: Soil Degradation in Argan Woodlands, South Morocco, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11249,, 2020

Display materials

Display file