CONCLUSIONS
Crab burrowing is an important type of bioturbation,which can effectively mix surface and subsurface soil through burrow trapping and crab excavating processes. These processes could stimulate ecosystem C and N cycling. Plants (P. australis and S. alterniflora) enhanced soil nutrient concentrations,but obstructed the vertical movement of materials driven by crab burrowing, limiting nutrient cycling and reuse. Therefore, crabs directly and indirectly affect ecosystem processes and
functioning of the salt marshes, and their roles in the conservation and restoration of coastal wetlands need to be considered..