Land use in the Souss region, South Morocco and its influence on wadi dynamics

Kirchhoff, Mario; Peter, Klaus Daniel; Hssaine, Ali Aït; Ries, Johannes B.

doi:10.1127/zfg_suppl/2019/0525

Cited by 9 publications

(10 citation statements)

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“…well as soil loss. Other studies have already shown that there are strong erosive processes in the Souss valley [27]. Usage on the sites is not only limited to the area between the trees.…”

Section: Study Areamentioning

confidence: 89%

“…While various studies have investigated the degradation of argan trees [3,22,25,26], there is a lack of knowledge regarding the connection between vegetation degradation and soil degradation as While various studies have investigated the degradation of argan trees [3,22,25,26], there is a lack of knowledge regarding the connection between vegetation degradation and soil degradation as well as soil loss. Other studies have already shown that there are strong erosive processes in the Souss valley [27]. Usage on the sites is not only limited to the area between the trees.…”

Section: Introductionmentioning

confidence: 89%

“…Precipitation varies unevenly in between years with the most chance of rainfall in the late autumn to early spring. Kirchhoff et al showed precipitation data from 2011-2014 for the study site of Taroudant with varying rainfall [27]. To ensure comparability across the three study areas in spite of the differences in altitude, climate conditions, and soil types, land-use/environmental characteristics were included as classification parameters for grouping the test sites (see Figure 3; Table 1).…”

Section: Study Areamentioning

confidence: 99%

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Geomorphodynamics in Argan Woodlands, South Morocco

Kirchhoff

Engelmann

Zimmermann

et al. 2019

Water

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The endemic argan tree (Argania spinosa) populations in South Morocco are highly degraded due to their use as a biomass resource in dry years and illegal firewood extraction. The intensification and expansion of agricultural land lead to a retreat of the wooded area, while the remaining argan open woodlands are often overgrazed. Thus, canopy-covered areas decrease while areas without vegetation cover between the argan trees increase. In total, 36 rainfall simulation experiments as well as 60 infiltration measurements were conducted to investigate the potential difference between tree-covered areas and bare intertree areas. In addition, 60 soil samples were taken under the trees and in the intertree areas parallel to the contour lines. Significant differences using a t-test were found between tree and intertree areas for the studied parameters Ksat, Kh, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content, and Mg-content. Surface runoff and soil losses were not as conclusive but showed similar trends. The results showed that argan trees influence the soil underneath significantly, while the soil in intertree areas is less protected and more degraded. It is therefore reasonable to assume further degradation of the soil when intertree areas extend further due to lack of rejuvenation of argan trees.

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“…well as soil loss. Other studies have already shown that there are strong erosive processes in the Souss valley [27]. Usage on the sites is not only limited to the area between the trees.…”

Section: Study Areamentioning

confidence: 89%

Section: Introductionmentioning

confidence: 89%

Section: Study Areamentioning

confidence: 99%

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Geomorphodynamics in Argan Woodlands, South Morocco

Kirchhoff

Engelmann

Zimmermann

et al. 2019

Water

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“…The 100m × 100m test site IRG1c is part of a larger research area situated on an alluvial fan, formed by Wadi Irguitène originating from the High Atlas in the north (Kirchhoff et al, 2019a;Kirchhoff et al, 2019b). It belongs to the remaining natural habitat of the argan tree Argania spinosa, which can be assumed to be a paramount keystone species in this environment.…”

Section: Location and Test Sitementioning

confidence: 99%

Relative quantification of wind erosion in argan woodlands in the Souss Basin, Morocco

Marzen

Kirchhoff

Marzolff

et al. 2020

Earth Surf Processes Landf

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The endemic argan woodlands cover large parts of South Morocco and create a characteristic landscape with areas of sparsely vegetated and bare soil surfaces between single trees. This unique ecosystem has been under extensive agrosilvopastoral management for centuries and is now at risk of degradation caused by overgrazing and increasing scarcity and variability of rainfall. To investigate susceptibility to wind erosion, we conducted an experimental–empirical study including wind tunnel tests and a drone‐generated digital elevation model and quantified wind‐erodible material on five different associated surface types by means of sediment catchers. The highest emission flux was measured on freshly ploughed surfaces (1875 g m–2 h–1), while older ploughed areas with a re‐established crust produced a much lower emission flux (795 g m–2 h–1). Extensive tillage may have been a sustainable practice for generations, but increasing drought and uncertainty of rainfall now lead to an acute risk of severe soil erosion and dust production. The typical crusted surfaces characterized by residual rock fragment accumulation and wash processes produced the second highest emission flux (1,354 g m–2 h–1). Material collected from tree‐shaded areas (933 g m–2 h–1) was revealed to be a considerable source of organic material, possibly affecting substrate conditions positively on a larger regional scale. The lowest flux was measured on rock fragment‐covered surfaces (301 g m–2 h–1). The data show that open argan woodland may be a considerable source for wind erosion and dust production, depending on surface characteristics strongly related to management. An adapted management must include the conservation of argan trees to offer a promising approach to prevent severe wind erosion and dust production and mitigate possible impacts of land‐use change and climate change related shifts in wind and rainfall patterns. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

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“…While the differences between tree or shrub vegetation and their corresponding intertree/intershrub areas have been investigated before, especially in 'fertile island '-research (e.g., Pérez, 2019;Qu et al, 2018;de Boever et al, 2015;Boettcher and Kalisz, 1990;Belsky et al, 1993), the spatial pattern of influence around trees (Zinke, 1962) has been less well researched and not at all for argan trees. In South Morocco, where the geomorphologic processes are highly dynamic (Peter et al, 2014;Kirchhoff et al, 2019b;Aït Hssaine, 2002;Marzen et al, 2020), it is likely that litter and soil particles are dislocated to the intertree areas. The knowledge about this possible dislocation and improvement of soil quality in the intertree areas could enable a better regrowth in these areas (Defaa et al, 2015;Boulmane et al, 2017).…”

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confidence: 99%

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

Kirchhoff¹,

Romes²,

Marzolff³

et al. 2021

Preprint

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Abstract. 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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Land use in the Souss region, South Morocco and its influence on wadi dynamics

Cited by 9 publications

References 0 publications

Geomorphodynamics in Argan Woodlands, South Morocco

Geomorphodynamics in Argan Woodlands, South Morocco

Relative quantification of wind erosion in argan woodlands in the Souss Basin, Morocco

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

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