Impact of ecosystem engineers on intertidal edaphic environment in coastal wetland: mechanisms involved

Under the background of climate change, human activities aggravate the degradation process of salt marsh in the Yellow River delta. Then understanding the natural ecosystem, especially the ecosystem engineers shaping the environment, is really important to carry out ecological restoration based on the key process of ecosystem. Field investigation and field control experimentsin the Yellow River delta were done to explore the influencing mechanism of ecosystem engineers crabs burrowing activity on intertidal geomorphological processes and edaphic environment in the coastal wetland. Our results show that the crabs burrowing activity is one of the key factors for the concave-convex microtopography and the geomorphology spatial heterogeneity. Comparing to the flat microtopography without crab burrows, the soil hardness and the soil salinity in the crabs burrowing concave-convex microtopography are significantly lower, and the soil moisture content in the concave-convex microtopography is significantly higher. Combining with the field simulation experiment, we can find that the changing of the microtopography and the physicochemical indicators made by crabs burrowing can make positive feedback effect for the crabs burrowing activity. This study shows that the artificial simulating ecosystem engineer process can also change the geomorphological features of tidal flats, and then improving the edaphic environment for crabs to live, consequently making the scientific and effective guidance for the restoration of coastal salt marsh.