This study evaluates the impact of land use and topographic features (slope and aspect) on soil organic carbon (SOC) within the Wadi Beja watershed in north-western Tunisia. A soil spectral library was set up to assess the variation in the SOC for 1440 soil samples from four land use types (field crops, permanent crops, forest, and grazing land), three slope categories (flat, moderate, and steep) and two aspects (north- and south-facing). For field crops, only one factor – slope – significantly affected SOC, with SOC content in north-facing areas appearing to be higher in flat areas (0.75 %) than in hilly areas (0.51 %). However, in south-facing areas, SOC content was also higher in flat areas (0.74 %) than in hilly areas (0.50 %). For permanent crops, which were inter-planted with field crops, the slope significantly affected SOC content, which improved to 0.97 % in flat north-facing and 0.96 % in flat south-facing areas, scoring higher than hilly south- and north-facing areas (0.79 %). In the grazing land use system, both of the investigated factors – aspect and slope – significantly affected the SOC content, which was significantly higher in flat areas (north-facing: 0.84 %, south-facing: 0.77 %) than in hilly areas (north-facing: 0.61 %, south-facing: 0.56 %). For the forest, none of the factors had a significant effect on SOC content, which was higher in flat areas (north-facing: 1.15 %, south-facing: 1.14 %) than in steep areas (1.09 % in north-facing areas and 1.07 % in south-facing areas). This study highlights the ability of visible and near-infrared (VNIR) spectroscopy to quantify C in diverse soils collected over a large diverse geographic area in order to indicate that calibrations are feasible, and therefore, assessing the variation of SOC content under land use and topographic features (slope and aspect) will result in better sustainable land management planning.

中文翻译：

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土地利用和地形对地中海景观中土壤有机碳的影响（西北突尼斯）

这项研究评估了西北突尼斯Wadi Beja流域内土地利用和地形特征（坡度和坡向）对土壤有机碳（SOC）的影响。建立了一个土壤光谱库，以评估来自四种土地利用类型（田间作物，永久作物，森林和牧场），三种坡度类别（平坦，中度和陡峭）的1440种土壤样品的SOC变化方面（朝北和朝南）。对于大田作物，只有一个因素-坡度-严重影响了SOC，而朝北地区的SOC含量在平坦地区（0.75％）似乎比丘陵地区（0.51％）高。但是，在朝南地区，平坦地区的SOC含量（0.74％）也高于丘陵地区（0.50％）。对于与大田作物一起种植的永久性作物，坡度会显着影响SOC含量，在平坦的北向地区中提高到0.97％，在平坦的南向地区中提高到0.96％，得分高于丘陵的南部和北部地区（0.79％）。在放牧土地利用系统中，调查的因素（长宽比和坡度）均显着影响SOC含量，平坦地区（北向：0.84％，南向：0.77％）显着高于丘陵地区（朝北：0.61％，朝南：0.56％）。对于森林，没有一个因素对SOC含量有显着影响，在平坦地区（朝北：1.15％，朝南：1.14％）要比陡峭地区（朝北地区为1.09％）高。朝南地区为1.07％）。