The influence of water conveyance embankments on the Populus euphratica’s communities and populations in the middle reaches of Tarim River Niche characteristics of plants on four environmental gradients in middle reaches of Tarim River Response of the Species Diversity of Desert Riparian Forest to the Changes of Groundwater Depth in Middle Reaches of Tarim River Drought Resistance Mechanism of Three Plant Species in the Middle Reaches of Tarim River,China The distribution pattern dynamics of Populus euphratica are influenced by hydrology in the middle reaches of Tarim River