Ecological response and hydrological mechanism of desert riparian forest in inland river, northwest of China

The interactive relationships of ecological and hydrological processes on individual plant growth and development as well as community succession have been a main focus of research in plant ecohydrology. In this paper, we firstly explore the spatial difference of the desert riparian ecosystems as distance to the river in the arid inland Tarim River Basin and then investigate the response of vegetation communities to emergent ecological water conveyances. Results showed that the decreasing groundwater table is the main driving force for vegetation degradation. Herbs exhibit degradation when the groundwater table is 4–6 m below the surface, whereas trees do not exhibit degradation until the groundwater table exceeds 6 m from the soil surface, in the lower reaches of the Tarim River. In addition, the structure of the plant community is controlled by the depth of the groundwater table. The mixed trees/shrubs/herbs structure is distributed in areas where the groundwater table is between 2 and 4 m in depth, the trees/shrubs structure is distributed in areas where the groundwater depth is 4–8 m and the simple structure of degraded Populus euphratica/Tamarix chinensis dominates the areas where the groundwater depth is >8 m. After ecological water conveyance, the Phraginites communis leaf weight, length and width decrease with the increasing distance from the river channel. The length of current-year twigs and average number of leaves of P. euphratica are significantly greater in the upstream section of the lower reach than in the downstream section of the lower reach. We concluded that the ecologically suitable groundwater depth for P. euphratica and T. chinensis is 2–4 m and the critical groundwater depth for drought stress is about 9 m. Copyright © 2013 John Wiley & Sons, Ltd.