Hydrological connectivity: One of the driving factors of plant communities in the Yellow River Delta
Jiakai Liu, Bernard A. Engel, Guifang Zhang, Yu Wang, Yanan Wu, Mingxiang Zhang, Zhenming Zhang
Abstract
Coastal wetlands play an important role in regional and even continental sustainable development because of their valuable ecosystem services. The coupling mechanism among hydrology, edaphic factors, and vegetation is the key to coastal wetland management. The current study conducted in the Yellow River Delta used an improved-comprehensive hydrological connectivity structure index, Topographic Over Field Capacity Index (TOFCI), based on both soil water conditions (SWC) and topography to highlight the role of hydrological connectivity on intertidal flat (IF), tidal marsh (TM), semi-artificial pond (AP) and riverside intermittent flooded (RS) wetland classes among other environmental variables. The results showed plant community distributions and structures among wetland classes differed from each other significantly, and hydrological connectivity structure is one of the driving factors. The results provided three pieces of evidence for this inference: 1) according to PCA results, the contribution of TOFCI is the highest among all environmental variables; 2) TOFCI values show significant difference among different plant communities; 3) TOFCI is also significantly correlated to species composition and distribution according to the CCA and RDA results. TOFCI values are positively linearly correlated to the plant coverage and biomass in intertidal flat wetlands according to linear regression analysis. Furthermore, salinity, soil total nitrogen and soil total phosphorus also influence plant community distribution and species composition. Finally, simple parameters for soil water conditions or topographic characteristics do not show significant explanatory power to hydrology-vegetation interaction. The results of the current study provide a new perspective for coastal wetland conservation and restoration.