Spatial patterns of argan-tree influence on soil quality of intertree areas in open woodlands of South Morocco

  • The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to overbrowsing, illegal firewood extraction and the expansion of intensive agriculture. Bare areas between the isolated trees increase due to limited regrowth, but show lower soil quality than their neighbouring tree areas. Hypothetically, spatial differences of soil quality of the intertree area should result from translocation of litter or soil particles (by runoff and erosion or wind drift) from canopy-covered areas to the intertree areas. 385 soil samples were taken around the tree from the trunk along the tree drip line (within and outside the tree area) as well as the intertree area between two trees in four directions (upslope, downslope and in both directions parallel to the slope) and analysed for soil moisture, pH, electrical conductivity, percolation stability, total nitrogen content, content of soil organic carbon and C/N ratio. 74 tension-disc infiltrometer experiments were performed near the tree drip line, within and outside the tree area, to measure the unsaturated hydraulic conductivity. We found that the tree influence on its surrounding intertree area is limited, with e.g., Corg- & N-content decreasing significantly from tree trunk to tree drip line. However, intertree areas near the tree drip line differed significantly from intertree areas between two trees, yet only with a small effect. Trends for spatial patterns could be found in eastern and downslope directions due to wind drift and slope wash. Soil moisture was highest in the north due to shade from the midday sun, the influence extended to the intertree areas. The unsaturated hydraulic conductivity also showed significant differences between areas within and outside the tree area near the tree drip line. Although only limited influence of the tree on its intertree area was found, the spatial pattern around the tree suggests that reforestation measures should be aimed around tree shelters in northern or eastern directions with higher soil moistures, N- or Corg-content to ensure seedling survival.

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Author:Mario KirchhoffORCiDGND, Tobias RomesGND, Irene MarzolffORCiDGND, Manuel SeegerORCiDGND, Ali Aït Hssaine, Johannes B. RiesGND
URN:urn:nbn:de:hebis:30:3-627555
DOI:https://doi.org/10.5194/soil-2021-32
ISSN:2199-3998
Parent Title (English):Soil discussions
Publisher:Copernicus Publ.
Place of publication:Göttingen
Document Type:Article
Language:English
Date of Publication (online):2021/04/19
Date of first Publication:2021/04/19
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/07/11
Volume:7
Page Number:26
First Page:1
Last Page:26
Note:
This research was funded by Deutsche Forschungsgemeinschaft (DFG), grant numbers RI 835/24-1 & MA 2549/6-1. We hereby acknowledge the support of the laboratories of Goethe University Frankfurt am Main, Trier University as well as of
the Université Ibn Zohr Agadir.
Note:
Begutachteter Artikel erschienen in: Soil, 7.2021, Nr. 2, S. 511–524, doi: 10.5194/soil-7-511-2021
HeBIS-PPN:502474653
Institutes:Geowissenschaften / Geographie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0