Abstract
Sea-level rise and adverse environmental conditions (e.g., drought, herbivory, and altered sedimentation and hydrology) stress coastal salt marsh vegetation, leading to reduced productivity, die-off, and subsequent marsh loss. Potential for loss may vary spatially within a single marsh creek system, as well as at the larger landscape-scale level across creek systems. Spatial patterns of plant stress that may signal future loss could inform management and conservation strategies. To inform predictions of marsh loss, in a field study in 12 Juncus roemerianus marshes on Florida’s Big Bend, we observed spatial patterns of plant stress and potential environmental drivers 1) within individual creek systems and 2) across a region of multiple creek systems. Juncus stress was higher at the creek margin (lower belowground biomass production and higher proline concentrations, K+ and Na+ ion levels, and relative stem water content) where soil salinity was higher and soil nutrients were lower. Patterns were not predicted by elevation alone, and other indicators did not similarly vary within creeks, but differed between creek systems, which often was explained by proximity to large freshwater inputs. Management strategies that account for these observed within- and between-creek patterns of stress, which represent symptoms that likely precede die-off and marsh loss, may best increase marsh persistence. This uniquely comprehensive data set (15 Juncus responses and 8 environmental variables across 12 marshes) highlights the challenge of determining stress patterns across a broad region and the necessary monitoring to generate information needed to spatially prioritize management efforts to ameliorate marsh loss.