半干旱黄土丘陵区典型植被土壤养分含量及其分布特征

Content and Distribution Characteristics of Soil Nutrients under Typical Vegetations in Semiarid Hilly Loess Area

以甘肃定西龙滩流域8种典型植被为研究对象,对其3个土层深度的土壤有机质、全氮、全磷、全钾、碱解氮、速效磷、速效钾和pH值进行测定,探讨植被与土壤养分间的关系。结果表明:植被类型主要影响土壤全磷、全钾和速效钾含量及分布,且不同植被间差异显著(p<0.05);土层深度主要影响土壤有机质、全氮、碱解氮和速效钾的含量及分布,而且在不同土层间差异显著(p<0.05)。不同植被间土壤养分分布规律不明显,但不同土层间土壤养分表层聚集效应明显,总体上随土层深度的增加而不断下降。在不同植被和不同土层下土壤养分变异性差异很大,其变异系数由大到小依次为速效磷(>45%)>有机质、全氮、碱解氮(>30%)>速效钾(>15%)>全磷、全钾(<4%)>pH值(<2%)。相关分析表明,pH值与土壤有机质、全氮、碱解氮呈极显著负相关关系(p<0.01),而有机质、全氮、碱解氮相互间呈极显著正相关关系(p<0.01)。在半干旱黄土丘陵区,植被类型和土层深度对土壤pH值和土壤养分含量及分布均有影响,但不同植被对各养分的影响效果并不一样;在今后植被恢复中,应多采用草灌林结合来建人工植被,以使黄土丘陵区复杂多样的土壤生态系统得到健康、持久的发展。

Taking 8 typical vegetation types in the Longtan Basin of Dingxi in Gansu Province as research objects,soil organic matter,total N,total P,total K,alkali hydrolyzed N,available P,available K,and pH values under 3 soil depths were measured to explore the relationship between vegetation and soil nutrients.The results showed that:Vegetation type had a certain influence on soil nutrients mainly for the content and distribution of total P,total K and available K,and the differences were significant among different vegetation types(p<0.05);Soil depth had a great influence on soil nutrients,especially for the content and distribution of organic matter,total N,alkali hydrolyzed N,available K,and there were significant differences among different soil layers(p<0.05).The soil nutrients distribution pattern is not obvious among different vegetation types,but in different soil layers the soil nutrients showed a significant surface aggregation effect,and decreased with the increase of soil depth.The variability of various nutrients under different vegetation and soil layers was very different,and the coefficient of variation from large to small was available P(>45%)>organic matter,total N,alkali hydrolyzed N(>30%)>available K(>15%)>total P,total K(<4%)>pH(<2%).Correlation analysis shows that:pH value showed an extremely significant negative correlation with soil organic matter,total N and alkali-hydrolyzed N(p<0.01),while the organic matter,total N and alkali hydrolyzed N had an extremely significant positive correlation with each other(p<0.01).In semiarid loess hilly region,vegetation type and soil depth have effects on soil pH value and soil nutrient content and distribution,but the effects of different vegetation on each nutrient are not the same;In the future vegetation restoration,a combination of grass,shrub and arbor should be used to build artificial vegetation,in order to promote the healthy and sustainable development of the complex and diverse soil ecosystems in the loess hilly area.