黄土丘陵沟壑区退耕地人工柠条林土壤养分特征及其空间变异

应用时空互代方法,以柠条林为例,对黄土丘陵沟壑区不同利用年限人工林土壤养分特征、空间变异及其演变进行了系统的研究。结果表明,该区人工林土壤肥力处于较低水平;人工林表层土壤养分中速效磷和速效钾的空间变异性较大;各环境因子对土壤养分有一定的影响,海拔、坡度和坡向等环境因子与人工林地土壤养分间呈负相关关系,坡位和地形与人工林地土壤养分间呈正相关关系。随着利用年限的增加,人工林土壤养分各指标含量均增加,与利用年限有显著的相关性。有机质、全氮、有效氮和速效磷的增加量不明显,全磷含量保持相对稳定的水平,速效钾经过多年积累有明显的增加。从土壤养分指数模型可以算出该区的人工林土壤有机质、全氮、有效氮约需35a能达到中上等养分水平,速效钾则约需27a才能达到中上等养分水平。

Characteristics,Spatial Variability and Evolution of Soil Nutrients on Abandoned Artificial Forest(Caragana korshinskii)Lands in the Loess Hilly Region

The characteristics, spatial variability and evolution of soil nutrients in artificial forest lands (Caragana korshinskii) with different ages in the loess hilly and gully region are systematically studied through the approach of substituting the temporal serial for the spatial serial. Results show that soil nutrient contents on artificial forest lands are in a low level. Spatial variability of soil available phosphorus(AP) and spatial variability of available potassium(AK) are greater than those of other nutrients in top soils. The environment of factors affects soil nutrients to some extent. Correlation of soil nutrients with elevation, gradient and aspect is negative, while correlation of soil nutrients with position of slope and relief is positive. The soil nutrient contents increase with the increase in landuse year. Significant correlation is found between soil nutrient contents and landuse year. No significant increases in organic matter(OM), total nitrogen(TN), available nitrogen(AN) and available phosphorus(AP) are found with the increase in landuse year. Total phosphorus(TP)keeps a relatively stable content in different landuse years. However, AK increases significantly after the community of many years. From the formula of soil nutrient index(SNI), we can know that OM, TN, AN can reach the middle nutrient level after 35 years, and AK can reach the middle nutrient level after 27 years on artificial forest land in the loess hilly and gully region.