Conclusion
The results of this study suggested that the annual ephemeral species adapt to the common effects of environmental filtration and interspecific competition through convergence or divergence of root system architecture traits. Additionally, the divergence of plasticity of traits related to resource acquisition (e.g. SRL, SRA) and the convergence of soil space exploration methods (e.g. TI) play an important role in the process of adapting to highly heterogeneous desert habitats. The evolutionary history of species significantly affects the development of MRD in annual ephemerals. The LMF reflects the water demand of plants, while the RMF is the foundation for root exploration of soil space. Although root trait variation patterns and biomass allocation are important ecological indicators reflecting root adaptation to the environment, the impact of phylogenetic relationships is equally important.