Response of Plant Species Diversity to Groundwater in Oasis-Desert Zone of the Lower Tarim River, Northwest China

Combining the field investigation and the laboratory analysis, this paper reported the findings of plant diversity responses to groundwater availability in the oasis-desert zones of the lower Tarim River of Northwest China, based on the analysis of the diversity indices including species richness index (R), Shannon-Wiener index (H), Simpson index (D), Pielou evenness index (J_SW), Whittaker index (β_w), and Cody index (β_c). The results indicated: 19 plants were discovered in the oasis-desert zone in the lower reaches of the Tarim River, where the species diversity indices were lower than those of other community types in the same temperate zone. The species diversity was closely related to the depth and TDS of groundwater. The TDS of groundwater mainly restrained the coverage, density and height of plants, but it did not directly induce the death of plant and plant succession. The optimal groundwater depth for the growth of plants with high diversity indices, coverage and density was 3.44m, the stress groundwater depths was 7.99m below which the growth of plants was significantly limited by severe drought at oasis-desert zone in the lower reaches of Tarim River.