How to realize the sustainable distribution of desert riparian forest?

The purpose of this study is to restore the dominant natural species of the desert riparian forests, that is, Populus euphratica oliv, and clarify the regeneration mechanism. The frequency of P. euphratica euphratica occurrence was investigated, and soil samples were collected every 1 km along the 368-km river to analyse the distribution and influence mechanism of P. euphratica euphratica. The main results show (1) the distribution of soil salt in the lower reaches of the Tarim River showed the phenomenon of high salt content at the head and the tail, whereas the occurrence frequency of P. euphratica was the opposite. (2) Soil salinity had a significant effect on the distribution of P. euphratica (p < 0.001) but had little effect on the distribution of vegetation coverage and species. Soil salinity limits the distribution of P. euphratica seeds by limiting their germination. When the concentration of NaCl solution reached 0.3 mol/L, the germination rate of P. euphratica seeds began to decrease significantly, and when the concentration reached 0.6 mol/L, the germination rate decreased, with almost no germination. P. euphratica had the lowest saline-alkali resistance among the main tree species in desert riparian forests. (3) In order to promote the regeneration of forest land, the moderate flooding disturbance should be adopted. Flooding regimes were a pre-condition of P. euphratica regeneration, which provided conditions for seed germination and seeding growth.