River-groundwater interaction affected species composition and diversity perpendicular to a regulated river in an arid riparian zone

Abstract

In regulated rivers, many studies have found that ecological water conveyance was conducive to protection and restoration of riparian plants. However, most of the studies about the influence of water conveyance on plants did not consider river-groundwater relationship in regional scale. In this study, field investigation, dynamic observation, Canonical Correspondence Analysis and ANOSIM analysis were mainly used to explore the lateral zonation of plant composition and diversity among different river-groundwater relationship types and reveal its reasons. The obtained results showed that: Spatio-temporal change of river-groundwater relationship controlled the difference of lateral zonation of species composition and diversity. Within the groundwater fluctuation zone, the water-table depth and salinity decreased during flood season. The proportion of hygrophyte herb and mesophyte shrub species is large with the highest diversity. If the river was gaining river during dry season, the riparian water table depth was less than 4–5 m, the strong evaporation-crystallization process lead to Cl-, Na+, and SO42- enriched. The total dissolved solids (TDS) was more than 6–10 g/L and the plants degenerated to halophyte herbs and shrubs with low diversity outside the groundwater fluctuation zone. If the river dry out during dry season, the riparian water table depth was more than 6–10 m. Plants were under water stress and degenerated to xerophyte herbs and mesophyte and xerophyte shrubs with low diversity outside the groundwater fluctuation zone. The study can enrich the understanding of riparian plant distribution pattern and provide guidance for making appropriate water conveyance scheme.

Keywords

• Manasi River riparian zone
• Riparian species composition and diversity
• River-groundwater interaction
• Riparian zone protection
• Lateral dimension