Linear and nonlinear effects of temperature and precipitation on ecosystem properties in tidal saline wetlands

Macroclimatic drivers, such as temperature and rainfall regimes, greatly influence ecosystem structure and function in tidal saline wetlands. Understanding the ecological influence of macroclimatic drivers is important because it provides a foundation for anticipating the effects of climate change. Tidal saline wetlands include mangrove forests, salt marshes, and salt flats, which occupy similar geomorphic settings but different climatic regimes. However, most global- or regional-scale analyses have treated these wetlands as independent systems. Here we used climate and literature-derived ecological data from all three systems, collected across targeted regional-scale macroclimatic gradients, to test hypotheses regarding macroclimatic controls of tidal saline wetland ecosystem properties, specifically canopy height, above-ground biomass, productivity, decomposition, soil carbon density, and soil carbon accumulation. We quantified region-specific climate based ecological thresholds for three data-rich transition zones including eastern North America, eastern Australia, and western Gulf of Mexico. The results of our analyses suggest that small macroclimatic changes might have large ecological implications near climatic thresholds. Our results also demonstrate that relationships between macroclimatic drivers and the ecosystem attributes of tidal saline wetlands are likely to be region-specific. The ecosystem-climate linkages revealed by our analysis should help to characterize important climatic thresholds for ecological regime shifts and could also be used to identify and target for conservation critical transition areas that may be especially sensitive to climate change.