Gene

Regime shift

Context (archaeology)

Habitat

Climatology

Ecology

Marsh

Biology

Materials science

Wetland

Ecotone

Archaeology

Range (aeronautics)

Biochemistry

Salt marsh

Physical geography

Geology

Dominance (genetics)

Global warming

Climate change

Geography

Temperate climate

Environmental science

Abundance (ecology)

Composite material

Mangrove

Ecosystem

Proceedings of the National Academy of Sciences

Climate change is driving the tropicalization of temperate ecosystems by shifting the range edges of numerous species poleward. Over the past few decades, mangroves have rapidly displaced salt marshes near multiple poleward mangrove range limits, including in northeast Florida. It is uncertain whether such mangrove expansions are due to anthropogenic climate change or natural climate variability. We combined historical accounts from books, personal journals, scientific articles, logbooks, photographs, and maps with climate data to show that the current ecotone between mangroves and salt marshes in northeast Florida has shifted between mangrove and salt marsh dominance at least 6 times between the late 1700s and 2017 due to decadal-scale fluctuations in the frequency and intensity of extreme cold events. Model projections of daily minimum temperature from 2000 through 2100 indicate an increase in annual minimum temperature by 0.5 °C/decade. Thus, although recent mangrove range expansion should indeed be placed into a broader historical context of an oscillating system, climate projections suggest that the recent trend may represent a more permanent regime shift due to the effects of climate change.

Climate-driven regime shifts in a mangrove–salt marsh ecotone over the past 250 years