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., C_org- & 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 C_org-content to ensure seedling survival.

中文翻译：

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摩洛哥南部空旷林地中乔木树的空间格局对树间地区土壤质量的影响

摘要。地方性的摩洛哥坚果树（Argania spinosa）由于过度浏览，非法砍伐柴火和集约化农业的扩张，南摩洛哥的人口高度退化。孤立的树木之间的裸露区域由于有限的再生而增加，但土壤质量却比其邻近的树木区域低。假设地，树间地区土壤质量的空间差异应归因于凋落物或土壤颗粒（由于径流，侵蚀或风漂移）从树冠覆盖区域向树间地区的迁移。从树干周围沿着树木滴水线（树木内部和外部）以及沿两个方向（上坡，下坡以及平行于坡度的两个方向）的两棵树之间的树间区域采集了385个土壤样品。分析土壤湿度，pH，电导率，渗透稳定性，总氮含量，土壤有机碳含量和碳/氮比。在树木区域内外的树木滴水线附近进行了74次张力盘式渗透仪实验，以测量非饱和导水率。我们发现树对周围树间区域的影响是有限的，例如，C_组织-＆N含量从树干到滴灌线显着下降。但是，树木滴水线附近的树间区域与两棵树之间的树间区域有显着差异，但影响很小。由于风的漂移和斜坡的冲刷，可以在东部和下坡方向发现空间格局的趋势。由于正午的阳光遮阴，北部的土壤水分最高，其影响延伸至树间地区。树木滴水线附近的树木区域内外的区域之间的非饱和导水率也显示出显着差异。尽管只发现了树木对其树间区域的影响有限，但树木周围的空间格局表明，造林措施应针对土壤湿度，N或C较高的北部或东部方向的树木遮蔽处_组织含量确保幼苗存活。