Seasonal response of Suaeda salsa to hydrological connectivity in intertidal salt marshes through changing trait networks

Abstract

Hydrological connectivity could greatly influence wetland plant traits and spatial patterns. However, it remains poorly understood how the whole plant or community responds to the changes in hydrological connectivity through plant traits at different stages of plant growth. Here we constructed the hydrological connectivity index (HCIs) and plant trait network (PTNs) in three seasons to identify the relationships between HCIs and PTNs in the intertidal salt marshes. The results showed that the relationships between plant traits were enhanced from spring to fall and PTNs were becoming tighter and more complex, and the characteristics of “tight inside and loose outside” of PTNs gradually eased. In the same season, PTNs became tighter and more complex from low to high tidal flats. Results of evaluating plant traits by their node parameters showed that the branch number of the total PTN in spring got the highest score, followed by the branch number node of the PTN in the high tidal flat in fall and the density node of the PTN in the high tidal flat in spring. Generally, a nonlinear relationship between HCIs and PTN parameters was observed; the middle tidal flat with moderate hydrological connectivity was the most suitable place for Suaeda salsa to grow with branch number as a central regulating trait of Suaeda salsa, while Suaeda salsa would develop adaptive strategies by forming different trait modules in the areas with low or high hydrological connectivity. Understanding the relationships between PTN and hydrological connectivity can guide us in choosing an appropriate site to begin plant rehabilitation and make wetland restoration more efficient.