The Diversity of Understory Vegetation Species in the Loess Plateau Forests and Its Influencing Factors
This study focuses on different densities of Robinia pseudoacacia forests in the Loess Plateau.By investigating the ter-rain and soil physicochemical properties of sample plots,and utilizing methods such as analysis of variance,linear fitting,and redundancy analysis,we analyzed the characteristics of understory vegetation species diversity and explored the factors influencing it.The results showed that there are significant differences in understory vegetation species diversity among R.pseudoacacia forests with varying stand densities(P<0.05).The Margalef richness index of shrubs beneath R.pseudoaca-cia decreases with increasing slope direction,while the Margalef richness index of herbaceous plants decreases with in-creasing slope gradient.The main influencing factors of shrub species diversity in R.pseudoacacia forests are density,slope direction,soil total nitrogen mass fraction,and soil ammonium nitrogen mass fraction.The primary influencing factor for herbaceous plant species diversity is the soil available phosphorus mass fraction.