Coastal Tree Deaths Linked to Rise in Sea Level
10/20/99
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Title: Tree Deaths Linked to Rise in Sea Level
Source: Environmental News Network
Status: Copyright 1999, contact source for permission to reprint
Date: October 20, 1999
Byline: John Roach
Coastal forests in developed areas around the world are threatened by
rising sea levels, according to research published in the September
issue of the journal Ecology.
The research was conducted along the extremely flat west coast of
Florida where the average 1.5 millimeter annual rise in sea level
turns two meters of forest to salt marsh each year.
"What this does for me is bring home the global problem of sea level
rise," said Francis Putz, a professor of botany at the University of
Florida and co-author of the study.
Rising sea levels expose coastal forests to increasing amounts of
salt water. In the same manner that a human cannot hydrate from
seawater, trees cannot survive either, said Putz. "You get disruption
of biochemical processes."
While sea levels have gone through periods of rise and fall over the
years, the development of homes and farms along the coastline impede
forests from growing anew on higher ground further inland.
"With all the development, forests are stuck between the devil and
the deep blue sea," said Putz. And the developers - i.e. humans - are
most likely to blame for the global warming that has sped up the
process of sea level rise in recent years.
Putz and his colleagues began the project seven years ago at the
Waccasassa Bay State Preserve south of Cedar Key, Fla. They divided
forested islands of differing elevations into 400-square-meter plots.
They then tagged and counted all the trees and seedlings and
monitored groundwater salinity and tidal flooding.
Over the next three years, they returned to the sites periodically to
note changes to the tree populations and correlate them with
measurements of tidal flooding and changes in groundwater salinity.
Despite the relatively short duration of the study, many trees died
by the end of the field research.
"Trees died during the course of the study in several island plots,
changing community composition ... Southern red cedars were lost from
two of the four most frequently flooded stands, leaving cabbage palms
as the only tree species in three plots," the researchers write in
Ecology.
The researchers also found that even when older trees and palms
survived they often failed to produce new seedlings, effectively
making them the last generation of trees on the once densely forested
islands.
The study shows how sea level rise threatens coastal forests around
the world where the forests are sandwiched between the ocean on one
side and residential areas or farms on the other, said Putz.
While the flatness of Florida's west coast enabled the researchers to
drive home the problem of sea level rise, the same thing is happening
around the world. If people want to have coastal forests in the
future, they should ensure that there is space for the forest to
renew itself inland, said Putz.