黄土丘陵区不同植被类型根际土壤微团聚体及颗粒分形特征

 【目的】研究黄土丘陵区坡耕地退耕后不同植被根际土壤微团聚体及颗粒的分形特征,为该地区植被恢复中土壤质量评价和生态恢复的持续健康发展提供科学依据。【方法】通过室内分析,运用分形理论,研究黄土丘陵区墩山小流域天然草地、人工草地和人工灌木等6种植被根际土壤微团聚体以及颗粒组成的分形特征。【结果】黄土丘陵区坡耕地退耕后,不同植被对土壤微团聚体以及颗粒组成影响不同。无论是根际还是非根际,天然草地0.25—0.05 mm、0.05—0.01 mm微团聚体含量以及土壤团聚状况、团聚度均高于人工灌木和人工草地,而0.25—0.05 mm、0.05—0.01 mm土壤颗粒含量以及分散系数、分散率低于人工灌木和人工草地,根际微团聚体分形维数和颗粒分形维数高于人工灌木和人工草地。除柳枝稷外,根际土壤团聚状况和团聚度高于非根际,分散系数和分散率低于非根际;不同植被根际微团聚体分形维数和颗粒分形维数均低于非根际土。相关性分析表明,与非根际相比,根际土壤微团聚体及颗粒分形维数与土壤基本理化性质相关性更显著。【结论】黄土丘陵区坡耕地退耕后,天然草地对于土壤微团聚体的改善作用优于人工灌木和人工草地。与非根际相比,根际土壤具有更好团聚结构,而且根际土壤分形特征能更好反映土壤性质的变化规律,因此可作为该地区植被恢复过程中土壤质量评价的指标。

Fractal Features of Rhizosphere Soil Microaggregate and Particle-Size Distribution Under Different Vegetation Types in the Hilly-Gully Region of Loess Plateau

【Objective】The research was made to provide scientific guidance for the sustainable development of ecological restoration and the evaluation of soil quality by studying fractal features of rhizosphere soil microaggregate and particle-size distribution under different vegetation types on abandoned slope cropland in the hilly-gully region of Loess Plateau. 【Method】In this paper, the fractal theory was applied to analyze the fractal features of rhizosphere soil microaggregate and particle-size distribution under natural grassland, artificial grassland and artificial shrubland in Dunshan watershed through experimental analysis. 【Result】The results showed that the effect of different plants on the soil microaggregate and particles was different after slope cropland was abandoned. Whatever in rhizosphere or non-rhizosphere soil, 0.25-0.05 mm, 0.05-0.01 mm class size microaggregate, aggregate state and aggregate degree in natural grassland was higher than that in artificial shrubland and artificial grassland, the content of 0.25-0.05 mm, 0.05-0.01 mm particle, dispersion coefficient and dispersion rate was lower than that in artificial shrubland and artificial grassland. With the exception of Panicum virgatum, a higher aggregate state and aggregate degree was found in rhizosphere compared with non-rhizosphere soil where the dispersion coefficient and dispersion rate was observed. Microaggregate and particle fractal dimension in rhizosphere was lower than that in non-rhizosphere soil. Correlation analysis indicated a more significant correlation between rhizosphere microaggregate, particle fractal dimension and soil physico-chemical properties than non-rhizosphere soil.【Conclusion】In the hilly-gully region of Loess Plateau, the improvement of natural grassland of soil microaggregate is more significant than artificial shrubland and artificial grassland after slope cropland was abandoned. Compared to the non-rhizosphere soil, the aggregate structure in rhizosphere is more favorable and the fractal feature can better reflect the change of soil properties, thus it can be used for evaluating the soil quality during the revegetation in this region.