Salt Marshes as Potential Indicators of Global Climate Change

Abstract

Coastal scientists postulate that salt marshes are significantly affected by dynamics of global climate. However, few studies have explicitly proposed a perspective that regards salt marshes as potential indicators of climate change. This review article evaluates the possibility of salt marshes as indicators of global climate change, focusing upon three major aspects: sedimentary, vegetation, and biogeochemical dynamics. The previous literature concerned with these aspects commonly argues that the primary impact of climate change on salt marshes occurs via sea-level variations, because hydrologic fluctuations regulate the frequency, duration, and depth of over-marsh flooding events. Sedimentary, floristic, and biogeochemical dynamics prove to be significantly influenced by sea-level changes regardless of climate zones, and hence, undoubtedly possess a potential for indicating climate signatures. However, where plant-plant interactions such as facilitation and competition are important, vegetation dynamics in salt marshes may not be an immediate, sole function of sea-level and climate variations. Also, specifically in the field of salt marsh biogeochemistry, enough long-term data have not been collected to convincingly conclude that biogeochemistry is a useful indicator of climate change. Therefore, while this review is concerned mainly with the possibility of salt marshes as indicators of climate change, their suitability or usefulness is a different matter to be resolved through further data collection and discussion in future investigations.