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研究地形和土地利用对深层土壤有机碳(soil organic carbon,SOC)的影响,对准确评估土壤固碳潜力和土壤碳循环具有重要意义.以3种地形(峁顶、峁坡、沟底)和7种土地利用类型(农田、果园、天然草地、人工与天然灌木林、人工与天然乔木林)为对象,在黄土丘陵沟壑区燕沟流域采集53个0～1m土壤剖面中6个层次,898个土壤样品,研究了地形和土地利用方式对黄土丘陵沟壑区小流域深层SOC含量和分布影响.结果表明,地形、土地利用方式、土层深度及其两两交互作用对流域深层SOC空间分布有极显著影响(p<0.01).深层(10～100cm)与表层(0～10cm)SOC在3种地形的分布不同.对于表层土壤(0～10cm),峁坡SOC含量(10.7g·kg-1)最高,其次是沟底(8.9g·kg-1),峁顶最低(4.4g·kg-1);对深层土壤有机碳,沟底最高(5.6g·kg-1),峁坡次之(4.5g·kg-1),峁顶最低(3.2g·kg-1).深层SOC空间分布因土地利用方式存在显著差异.与农田相比,果园0～40cm土层SOC含量降低21%,但80～100cm土层SOC含量提高13%;天然灌木林40～100cm平均含量(5.3g·kg-1)较农田高66%(p<0.05);但天然乔木林40～100cm与其它土地利用方式差异较小.沟底深层(20～100cm)SOC储量(5.04kg·m-2)最大,占1m剖面SOC储量的71.4%;峁坡占63.6%;峁顶占72.3%.深层(20～100cm)SOC储量天然灌木林最高,为6.01kg·m-2,占1m剖面SOC储量的64.7%,天然乔木林深层相对储量最小,仅占49.7%;农田和果园深层相对储量均达到70%以上.
To study the effects of topography and land use on soil organic carbon (SOC) is of great significance for accurate assessment of soil carbon sequestration potential and soil carbon cycle.Taking three kinds of topography (top, bottom and bottom) and Seven kinds of land use types (farmland, orchard, natural grassland, artificial and natural shrub forest, artificial and natural trees) were selected to collect sixty-six soil layers in 0 ~ 1m soil profile in Yanougou watershed of Loess Hilly and Gully Region, 898 Soil samples were used to study the effects of topography and land use on deep SOC content and distribution in the small watershed in the hilly and gully regions of the Loess Plateau.The results showed that topography and land use patterns, (0 ~ 10cm), the SOC of deep layer (10 ~ 100cm) and surface layer (0 ~ 10cm) 1), followed by the bottom of the ditch (8.9 g · kg -1) and the lowest (4.4 g · kg -1) of the top of the ditch, and the highest soil organic carbon (5.6 g · kg -1) (4.5g · kg-1) and lowest (3.2g · kg-1) in the top of the soil.The spatial distribution of deep SOC was significantly different due to land use patterns Compared with farmland, the SOC content of 0-40cm soil layer in orchard decreased by 21%, but the SOC content increased by 13% in 80-100cm soil layer. The average content of 40-100cm in natural shrub forest (5.3g · kg-1) was 66% (P <0.05), but the difference of 40-100 cm of natural tree forest was less than that of other land use types.The SOC (5.04 kg · m-2) in the deep ditch (20-100 cm) was the largest, accounting for 71.4% (63.6%) of the slope and 72.3% of the top of the natural shrub (SOC) in the deep (20-100 cm) SOC.It is the highest in the natural shrub forest with 6.01 kg · m-2, accounting for 64.7% Only 49.7%; deep relative reserves of farmland and orchard reached more than 70%.