Effects of plant traits and ecosystem properties on wave attenuation and soil carbon content

Understanding the relationships among the environment, species traits and
ecosystem properties is important for developing management measures that
optimize the delivery of ecosystem services (ESs). Here, we identify the
most important relationships responsible for the delivery of two key ESs
provided by tidal marshes: (1) nature-based shoreline protection through
wave attenuation and (2) mitigation of climate change through soil carbon
storage. In two tidal zones below and above the mean high water (MHW, Elbe
Estuary, Germany) level, we measured environmental parameters, such as
soil salinity and inundation, as well as plant traits representing
adaptations to hydrodynamic stress and strongly influencing decomposition
rates. Multiple linear regression results showed that wave attenuation
rates were positively related to aboveground community biomass and stem
bending resistance, and soil organic carbon was positively related to
stem-specific density (below the MHW level). In the tidal zone above the
MHW level, soil carbon density was governed by inundation duration and
decomposition rates. Our study highlights that (1) ES delivery is not
equally spread across tidal marshes and (2) ecosystem management should
stimulate the development and persistence of habitat diversity (here, low
and high marsh zones) to maximize ES delivery potential. Securing the
delivery of the two studied ESs under climate change will depend on
providing suitable (landward) space to sustain the functioning of the two
marsh zones. In the studied marshes, these services are highly dependent
on a few species (i.e., wave attenuation on Schoenoplectus tabernaemontani
and Bolboschoenus maritimus and carbon storage on Phragmites australis),
and as such, current and future ESs strongly depend on specific species’
responses to changing environmental conditions.