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

Marzen, Miriam; Kirchhoff, Mario; Marzolff, Irene; Hssaine, Ali Aït; Ries, Johannes B.

doi:10.1002/esp.5002

Cited by 15 publications

(9 citation statements)

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“…In the past, the high fuel value of argan wood resulted in the deforestation of the argan forest for use in the sugarcane industry or for sale as charcoal (Aït Hssaine, 2002;Faouzi, 2013). Although the argan woodlands have been designated a UNESCO biosphere reserve (Charrouf and Guillaume, 2018), afforestation programmes are ongoing and some felled trees have resprouted, the slow growth of Argania spinosa, the high grazing pressure and ongoing illegal firewood harvesting have led to a degradation of the woodlands that is visible in the architecture or growth form (Culmsee, 2005;Kirchhoff et al, 2019a;Marzolff et al, 2020) and the decrease in forest density (up to 44.5 % decline of wooded area between 1970-2007le Polain de Waroux and Lambin, 2012).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of argan tree influence on soil properties in southern Morocco

Kirchhoff

Romes

Marzolff

et al. 2021

SOIL

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Abstract. The endemic argan tree (Argania spinosa) populations in southern 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; however, it is unknown if the trees influence the soil of the intertree areas. Hypothetically, spatial differences in soil parameters of the intertree area should result from the translocation of litter or soil particles (by runoff and erosion or wind drift) from canopy-covered areas to the intertree areas. In total, 385 soil samples were taken around the tree from the trunk along the tree drip line (within and outside the tree area) and the intertree area between two trees in four directions (upslope, downslope and in both directions parallel to the slope) up to 50 m distance from the tree. They were analysed for gravimetric soil water content, pH, electrical conductivity, percolation stability, total nitrogen content (TN), content of soil organic carbon (SOC) and C/N ratio. A total of 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., SOC and TN content decreasing significantly from tree trunk (4.4 % SOC and 0.3 % TN) to tree drip line (2.0 % SOC and 0.2 % TN). However, intertree areas near the tree drip line (1.3 % SOC and 0.2 % TN) differed significantly from intertree areas between two trees (1.0 % SOC and 0.1 % TN) 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 water content 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. This was the case on sites under different land usages (silvopastoral and agricultural), slope gradients or tree densities. 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 water content or TN or SOC content to ensure seedling survival, along with measures to prevent overgrazing.

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Section: Introductionmentioning

confidence: 99%

Spatial distribution of argan tree influence on soil properties in southern Morocco

Kirchhoff

Romes

Marzolff

et al. 2021

SOIL

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“…The parameter Corg shows the most pronounced effects in eastern directions (mostly E, SE) which corresponds to the main wind direction. Marzen et al (2020) found relatively high wind erosion rates under trees using an experimental wind tunnel on one of the here-analysed study sites with the eroded material being mostly tree litter. Sirjani et al (2019) show a negative correlation between Corg content and wind erosion, since higher organic matter often leads to more particle aggregation and more stable aggregates (Tatarko, 2001).…”

Section: Discussionmentioning

confidence: 73%

“…soils in those regions are generally more vulnerable to erosive processes, which are result and cause for degradation and desertification (Ravi et al, 2010;Marzen et al, 2020;Vásquez-Méndez et al, 2011).…”

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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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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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“…Marzen et al ( 2020 ) deployed a portable tunnel wind simulator and dust collectors to explore the susceptibility of different land cover types to erosion by steady‐velocity wind in the Argan woodland of Morocco's Souss basin. They mapped different land cover and surface types on the basis of high‐resolution drone‐based imagery and analysed the corresponding surface and material properties based on field measurements and samples.…”

Section: A Brief Overview Of Special Issue Contributionsmentioning

confidence: 99%

Special issue: German Society for Geomorphology

Heckmann

Meister

Dietze

et al. 2022

Earth Surf Processes Landf

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The German Society for Geomorphology (GSG) (Deutsche Gesellschaft für Geomorphologie: DGGM) evolved out of the German Working Group for Geomorphology in 2021, reflecting the widened scope of relevant topics and involved disciplines, the increasing importance for the professional job market and society in general, as well as the increasing importance of international cooperation and global challenges. In this special issue of the GSG we attempt to visualize the breadth in relevant methods and geomorphological subdisciplines, the wide scope of investigated temporal and spatial scales, but also the diversification in terms of career levels and gender equality. The special issue contains 25 research papers and one commentary, incorporating more than 30 German, Austrian, Swiss and other geomorphology groups, all active in the GSG, with co‐authors from virtually all continents. This editorial provides a short historical overview of the GSG's evolution, short paper summaries, a tabular paper overview and a graphical representation of contributing groups and networking, the career level and gender of all authors, relevant topics, methods, as well as temporal and spatial scales.

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

Cited by 15 publications

References 62 publications

Spatial distribution of argan tree influence on soil properties in southern Morocco

Spatial distribution of argan tree influence on soil properties in southern Morocco

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

Special issue: German Society for Geomorphology

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