Abstract: Moisture and salinity are the basic characteristics of soil in coastal wetlands, and are the key factors affecting the growth of Suaeda salsa. The study selected Yancheng Coastal Wetland of Jiangsu Province as research area. The diagnosis of Suaeda salsa degradation state was determined by analyzing the relationship between soil moisture, salinity and Suaeda salsa. The results show that:(1) Soil moisture and salinity were closely related to the growth of Suaeda salsa, and were the key factors determining plant individual morphology. (2) Soil moisture and salinity of Suaeda salsa was between 18.61%-32.18% and 2.53-20.33 mS·cm^-1, respectively, in the normal state. During the maturity period, the average plant density was 44 plants·m^-2, and plant height and root length were between 14-23 and 12-20 cm, respectively, with many branches and high single plant coverage. The ecological index range was between 0.8 and 1. The soil moisture of Suaeda salsa was between 8.03% and 35.45% and the soil salinity was between 0.69 and 34.25 mS·cm^-1, in slightly degraded and moderately to severely degraded states, showing a large fluctuation and low stability. During the maturity period, the average plant density can reach to 1 516 plants·m^-2, and the plant height and root length were between 17-56 cm and 5-19 cm, respectively, with few branches and low single plant coverage, and the ecological index ranges were[0.6,0.8] and[0, 0.6), respectively. The results of the study could provide scientific basis for ecological degradation diagnosis and restoration effect evaluation of coastal Suaeda salsa.

Key words: coastal wetlands, Suaeda salsa, soil moisture and salinity, ecological degradation, entropy weight-grey relation analysis