Data from: Early stages of sea-level rise lead to decreased salt marsh plant diversity through stronger competition in Mediterranean-climate marshes

Climate change shuffles species ranges and creates novel interactions that
may either buffer communities against climate change or exacerbate its
effect. For instance, facilitation can become more prevalent in salt
marshes under stressful conditions while competition is stronger in benign
environments. Sea-level rise (SLR) is a consequence of climate change that
affects the distribution of stress from inundation and salinity. To
determine how interactions early in SLR are affected by changes in these
two stressors in Mediterranean-climate marshes, we transplanted marsh
turfs to lower elevations to simulate SLR and manipulated cover of the
dominant plant species, Salicornia pacifica (formerly Salicornia
virginica). We found that both S. pacifica and the subordinate species
were affected by inundation treatments, and that subordinate species cover
and diversity were lower at low elevations in the presence of S. pacifica
than when it was removed. These results suggest that the competitive
effect of S. pacifica on other plants is stronger at lower tidal
elevations where we also found that salinity is reduced. As sea levels
rise, stronger competition by the dominant plant will likely reduce
diversity and cover of subordinate species, suggesting that stronger
species interactions will exacerbate the effects of climate change on the
plant community.