Abstract
AbstractClimate greatly influences the structure and functioning of tidal saline wetland ecosystems. However, there is a need to better quantify the effects of climatic drivers on ecosystem properties, particularly near climate‐sensitive ecological transition zones. Here, we used climate‐ and literature‐derived ecological data from tidal saline wetlands to test hypotheses regarding the influence of climatic drivers (i.e., temperature and precipitation regimes) on the following six ecosystem properties: canopy height, biomass, productivity, decomposition, soil carbon density, and soil carbon accumulation. Our analyses quantify and elucidate linear and nonlinear effects of climatic drivers. We quantified positive linear relationships between temperature and above‐ground productivity and strong positive nonlinear (sigmoidal) relationships between (1) temperature and above‐ground biomass and canopy height and (2) precipitation and canopy height. Near temperature‐controlled mangrove range limits, small changes in temperature are expected to trigger comparatively large changes in biomass and canopy height, as mangrove forests grow, expand, and, in some cases, replace salt marshes. However, within these same transition zones, temperature‐induced changes in productivity are expected to be comparatively small. Interestingly, despite the significant above‐ground height, biomass, and productivity relationships across the tropical–temperate mangrove–marsh transition zone, the relationships between temperature and soil carbon density or soil carbon accumulation were not significant. Our literature review identifies several ecosystem properties and many regions of the world for which there are insufficient data to fully evaluate the influence of climatic drivers, and the identified data gaps can be used by scientists to guide future research. Our analyses indicate that near precipitation‐controlled transition zones, small changes in precipitation are expected to trigger comparatively large changes in canopy height. However, there are scant data to evaluate the influence of precipitation on other ecosystem properties. There is a need for more decomposition data across climatic gradients, and to advance understanding of the influence of changes in precipitation and freshwater availability, additional ecological data are needed from tidal saline wetlands in arid climates. Collectively, our results can help scientists and managers better anticipate the linear and nonlinear ecological consequences of climate change for coastal wetlands.
Highlights
Across the globe, climatic drivers greatly influence the structure and functioning of ecosystems (Jenny 1941, Holdridge 1967, Whittaker 1970, Woodward 1987, Jobbagy and Jackson 2000, Chapin et al 2011)
There were no significant relationships between mean annual air temperature and soil carbon density (Fig. 3m) or soil carbon accumulation (Fig. 3p) in eastern North America (Appendix S7: Tables S1 and S2)
We found canopy height data distributed across a precipitation gradient, we could not find sufficient ecological data to test our hypotheses regarding the influence of precipitation upon above-ground biomass, productivity, decomposition, soil carbon density, or soil carbon accumulation
Summary
Climatic drivers (i.e., temperature and precipitation regimes) greatly influence the structure and functioning of ecosystems (Jenny 1941, Holdridge 1967, Whittaker 1970, Woodward 1987, Jobbagy and Jackson 2000, Chapin et al 2011). Nonlinear relationships, and climate-sensitive ecosystem properties can be useful for predicting where and when small changes in temperature or precipitation regimes may trigger comparatively large and abrupt changes in ecosystem structure and function (i.e., regime shifts sensu Scheffer et al 2001). We used a combination of climate- and literature-derived ecological data to investigate the influence of temperature and precipitation regimes upon ecosystem structure and function in tidal saline wetlands. All three of these ecosystem types occupy similar hydrogeomorphic positions within the landscape (i.e., sheltered tidally inundated saline wetland habitats). The conservation and maintenance of these systems in the face of climate change are a high priority for coastal environmental managers (Alongi 2008, McKee et al 2012, Kirwan and Megonigal 2013)
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