A dynamic biomass model of emergent aquatic vegetation under different water levels and salinity

Modeling strategies and data needs for representing coastal wetland vegetation in land surface models

Vegetated coastal ecosystems sequester carbon rapidly relative to terrestrial ecosystems. Coastal wetlands are poorly represented in land surface models, but work is underway to improve process-based, predictive modeling of these ecosystems. Here, we identify guiding questions, potential simulations, and data needs to make progress in improving representation of vegetation in terrestrial-aquatic interfaces, with a focus on coastal and estuarine ecosystems. We synthesize relevant plant traits and environmental controls on vegetation that influence carbon cycling in coastal ecosystems. We propose that models include separate plant functional types (PFTs) for mangroves, graminoid salt marshes, and succulent salt marshes to adequately represent the variation in aboveground and belowground productivity between common coastal wetland vegetation types. We also discuss the drivers and carbon storage consequences of shifts in dominant PFTs. We suggest several potential approaches to represent the diversity in vegetation tolerance and adaptations to fluctuations in salinity and water level, which drive key gradients in coastal wetland ecosystems. Finally, we discuss data needs for parameterizing and evaluating model implementations of coastal wetland vegetation types and function.

A solution for restoration of critical wetlands and waterbird habitats in coastal deltaic systems

Loss of coastal wetland habitats has been directly linked to a decline in waterbird populations including migratory species, leading to calls to reverse this trend in part by restoring these habitats. However, distinct "sediment scarcity" has hindered coastal habitat restoration. Here, taking the Yangtze River Delta, China as an example, we put forward a feasible solution to solve the sediment shortage in habitat restoration so necessary to restore migratory waterbird numbers. Four biological indices including total wetland area, wetland vegetation area and waterbird species richness and abundance, were used to compare and assess the restorative efforts. Three solutions were adopted for the rehabilitation sites, including promoting sediment deposition and settlement through engineering intervention in Chongming Dongtan (CD) and Eastern Nanhui (EN), and using dredged sediments to nourish and create new habitats in Hengsha Eastern Shoal (HES). The mean wetland area increased 19.66 km²/yr in EN, 8.78 km²/yr in HES and 3.83 km²/yr in CD after rehabilitation. Along with the increase of wetlands and habitats, the abundance of waterbirds increased 1.3 times, 121 times and 1.5 times in EN, HES and CD, respectively. In contrast, in the site of Fengxian and Jinshan (FJ) where no any rehabilitation measure was taken after reclamation, the habitats were lost almost completely and the waterbird abundance dropped drastically. The comparison and assessment results demonstrate that proper coastal silting structures and ecological utilization of nearby dredged sediments are the feasible and effective solutions to retain sediments, restore coastal habitats and increase waterbird diversity and abundance.