Geographic Patterns and Environmental Determinants of Seed Plants Species Richness in the Loess Plateau

The geographical distribution pattern of species richness and its influencing factors have always been the core issues of macroecology, biogeography and conservation biology. The Loess Plateau is a key ecological fragile area in China, and the biodiversity conservation in the region is suffering a severe degradation situation. Understanding the relationship between species diversity and environmental factors is essential for formulating biodiversity conservation strategies. Here, the distribution pattern of seed plant richness in the Loess Plateau and its main environmental interpretation were discussed based on records of seed plants in the nature reserves, as well as their corresponding climate, habitat heterogeneity, and human disturbance factors. The results show that the diversity of seed plants in the Loess Plateau decreases gradually from southeast to northwest, and the species diversity in mountain nature reserves are the highest. Optimal multivariate linear regression show that precipitation, altitude range, net primary productivity range and human footprint are important factors to determine the distribution pattern of seed plants in the Loess Plateau. Variance decomposition show that climate, habitat heterogeneity and human disturbance can explain 52.0%-53.4% of the variation sources of seed plant density and richness, and the relative contribution of climate and habitat heterogeneity is far greater than that of human disturbance. Nature reserves in the Loess Plateau should be established in the mountainous area with abundant hydrothermal and little human disturbance conditions, which is an optimal strategy to protect seed plants diversity of the Loess Plateau.