Abstract: Based on the investigation from 30 plant sampling plots on 5 sections and the corresponding groundwater data in the lower reaches of Tarim River in 2014, the relationship between groundwater depth and the aboveground ecological characteristics of herbaceous plants was analyzed. The results showed that: (1) With the increase of distance from river channel, the groundwater depth increased while the biodiversity and the vegetation coverage declined and the structure of plant community became simple. Herbaceous plants were rare when the groundwater depth was 6-7 m. (2) A significant correlation between groundwater depth and aboveground biomass showed that, as the groundwater depth increased, the aboveground biomass and the moisture content decreased, whereas the relationship between groundwater depth and net primary productivity was inconspicuous. (3) The groundwater level rose obviously nearby the river due to the project of ecological water conveyance and the expansion of the influenced region of ecological water conveyance; the response of vegetation was remarkable, i.e. the growth vigor improved, and the biodiversity and coverage increased obviously.

Key words: soil organic carbon pool, fertilizer application mode, cotton, residue management