Plant distribution and diversity in relation to environmental factors across saline-alkali lands in the Hexi Corridor’s desert-oasis ecotone

We investigated the distribution patterns of plant communities in saline-alkali lands within the desert-oasis ecotone in the Hexi Corridor as well as the environmental factors influencing such distribution by using the importance value of each species as an indicator. To explore the relationship between plant diversity and environmental factors, plant communities in the Hexi Corridor region were classified and ordinated using two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA), and canonical correspondence analysis (CCA). Based on the results of TWINSPAN, plants from 113 sampling sites were classified into 11 distinct types of plant communities. Among them, Association VII had the lowest diversity index, Association XI had the lowest richness index, and Associations II and III had the highest similarity index. Redundancy analysis revealed that elevation, soil water content, and soil electrical conductivity were positively correlated with the Shannon-Wiener diversity index, Margalef richness index, Simpson index, and Pielou evenness index, whereas pH was negatively correlated with these indices. Ordination analysis of the sampling sites via CCA indicated that elevation, precipitation, and total salt content explained 4.6%, 2.8%, and 1.5% of the community distribution, with contribution rates of 33.3%, 20.2%, and 11.2%, respectively. In conclusion, the most significant environmental factors affecting the distribution of plant communities in the saline-alkali lands of the Hexi Corridor desert-oasis ecotone are elevation, precipitation, and total salt content, in this order. Different plant communities exhibit specific distribution patterns along the elevation gradient. This study provides a scientific basis for understanding the distribution and diversity of plant communities in the saline-alkali lands in the Hexi Corridor and may significantly contribute to the protection and restoration of plant ecosystems in these areas.