A Novel Index System for Assessing Ecological Risk under Water Stress in the Yellow River Delta Wetland

Abstract

The Yellow River Delta Wetland (YRDW) is one of the youngest wetlands, and also the most complete, extensive wetlands in warm temperate areas in China. However, since zero flow of the Yellow River from 1972, the degeneration area is over 3 × 104 hm2. To assess the risk caused by water shortage, a new risk assessment index system is imperative. Hence, a two-year experiment on soil and plants is performed to acquire the data for the assessment. We have set up 13 sample fields along both side of the Yellow River, which are all 30m × 30m and spaced evenly. And about 10 soil samples and 10 plant samples are collected from each of the sample field in three seasons including spring, summer and autumn. According to the results of the experiments, we have discovered the rules that the soil moisture affects the community of wetland and three representative species including Phragmites australis, Suaeda salsa., Tamarix chinensis. And the rules are the foundation of the novel ecological risk assessment index system which encompasses three scales including community, single plant and microscopic, and five indices including biodiversity, biomass and absorptivity of elements nitrogen, phosphorus and potassium. Based on the risk assessment index system and GIS, we present a two-level ERA result YRDW in different seasons of each index.