Variations in soil nutrients and salinity caused by tamarisk in the coastal wetland of the Laizhou Bay, China

The nature of resource islands created by patchy distribution of plants remains controversial in arid, semi-arid, and even some coastal ecosystems. This study explores these effects of isolated and clustered tamarisk (Tamarix chinensis Lour.) in coastal wetland of the Laizhou Bay. Soil samples were collected and analyzed from 0 to 30 cm depth near the trunks of isolated tamarisk plants, in clustered tamarisk communities, and in open land. The results showed that available nitrogen (AN), available phosphorus (AP), and soluble aqueous sodium (Na) concentrations of soil under the isolated and clustered tamarisk canopies were significantly higher than those from open land. The Na and electrical conductivity (EC) values of intra-canopy in clustered tamarisk were higher than those in the inter-canopy space, while Na and EC of intra-and inter-canopy space were significantly lower than those under the isolated tamarisk. Soil nutrients under isolated and clustered tamarisk canopies in the coastal zone of the Laizhou Bay exhibited significant resource island effects. However, the size of this resource island effect was significantly lower under clustered tamarisk than that of isolated tamarisk, indicating that this effect will weaken following the vegetation restoration or the succession of plant community in the studied area.