The response of the Everglades ecosystem to climatic and environmental changes are documented over the last two millennia using pollen records. From A.D. 0-800, marsh and slough vegetation characteristic of deeper water and longer hydroperiods (annual duration of inundation) than today dominated the region. Drier conditions between about A.D. 800 and A.D. 1200 resulted in shallower water depths and shorter, fluctuating hydroperiods in Everglades marshes as well as salinity increases near Florida Bay. After a recovery to deep-water conditions in the 14th century, slightly drier conditions are indicated from the 17th through 19th centuries. These climatically induced periods of relative dryness are correlated with regional droughts during the intervals known as the Medieval Warm Period (9th -14th centuries) and Little Ice Age (15th -19th centuries).

Broad-scale vegetational changes are documented in Everglades wetlands beginning by 1930, indicating shallower water depths and shorter hydroperiods, even though regional precipitation increased concomitantly. Further, more localized changes occurred after 1960, when the Central & South Florida (C&SF) Project was completed. Thus, restoration goals of achieving pre-C&SF Project hydrologic regimes are aimed at an already disrupted system; a more “natural” restoration target would be the 19th century Everglades, which had been stable for the past few centuries. Recent land-use changes have resulted in localized rather than system-wide ecosystem responses, at least in part because of the fragmentation of the wetland. This artificially induced ecological heterogeneity makes prediction of future wetland responses to climatic changes problematic.

(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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