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Remote sensing for resources development and environmental management
Damen, M. C. J.

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986
Mangrove mapping and monitoring
John B.Rehder
University of Tennessee, Knoxville, USA
Samuel G.Patterson
University of Virginia, Charlottesville, USA
ABSTRACT: Mangroves and other ecosystems of the Marco Island area of Florida, were analyzed for
boundary interpretations and changes in acreage between 1952, 1962, 1973, and 1984. Comparisons were
made between Landsat MSS data and aircraft data. It was found that medium and high altitude black and
white and color infrared imagery were best for mapping species of red mangrove (Rhizophora) and black
mangrove (Avicennia) and their ecological communities. Mapped data were entered into a geographic
information system (GIS) data base to produce maps of total mangrove acreages, and measures of
landscape change in the mangrove communities from 1952 through 1984.
This project focuses on the detailed mapping
of coastal mangrove ecosystems in the Marco
Island area of southwestern Florida. Mangroves
are tropical and subtropical trees and shrubs
in coastal areas located between the high
water mark of spring tides and mean sea level
(MacNae, 1968).
The major mangrove species are red mangrove
(Rhizophora mangle 1.) and black mangrove
(Avicennia germinans). Red mangrove have a
closed canopy and narrow,thick leaves. The
spongy mesophyll of the red mangrove leaf
structure produces high spectral reflectance
responses in the near infrared part of the
electromagnetic spectrum. Conversely, black
mangroves have a more open canopy and greater
tree height, and have thin, translucent leaves
that exhibit lower spectral reflectance
responses in the near infrared. These diff
erences are important for the detection and
identification of species and ecological zones
and for measuring the impact on detrital leaf
litter transport for nutrients in the food
chain. Mangroves occur in specific ecological
zones on islands, coastal and riverine shore
lines, and in mainland locations.
Mangrove ecological communities are:
1. Red Fringe - red mangrove species which
occur along marine shorelines.
2. Red Riverine- red mangrove species that
occur as corridors of thick vegetation along
streams and narrow estuaries.
3. Black Basin- black mangrove species
found in the centers of islands and
mainland interior locations.
4. Mixed- communities of a mixture of both
species of red and black mangrove.
5. Uplands - composed of topographic highs
(2 to 10 feet elevation) containing hardwood
hammocks, relic orchards, coconut, palm, and
palmetto (Lugo and Snedaker, 1974).
Mangrove ecosystems are important to the
stability of coastal lands, to the main
tenance of water clarity, and to the signifi
cant productivity of the esturine eco
systems. The transportation of mangrove
leaf litter forms the basis of the coastal
marine food web. The rich nutrients from
the detrital export support some 75Ï of the
Gulf marine commercial and sport fisheries
in southwest Florida. Among the mangrove
species and ecological communities, red
riverine mangrove will transport 94Ï of its
productive nutrients to the food chain. Red
fringe mangrove will transport 42t of the
total leaf litter it produces. However,
black basin mangrove, which can produce only
3/5 the leaf litter that red riverine pro
duces for an equal area, will transport only
21Ï of its leaf litter to the marine food
chain (Twilley, 1982). Therefore it is
important to recognize the need for species
identification for ecological zone mapping
and management.
Since 1974, general estimates of the geo
graphical extent of Florida's mangrove eco
systems have been made but specific species
mapping and inventories of mangrove com
munities and zones have been limited. In
1979, Butera and Shines mapped the south
western Floridian mangroves with Landsat MSS
data. The results provided general cover
age of the mangrove ecosystem but lacked
accurate demarcation of species and zones
(Butera,1979/ Shines, 1979). The intricate
land and water interface in mangrove
communities and the subtle vari
ations among species present a challenge
to mapping mangrove communities from Landsat
MSS data.
2.1 Landsat and aircraft data comparisons
In a visual comparison, on a Landsat MSS
image, islands and shorelines can be de
tected and mapped because of reasonable
contrasts in spectral reflectances at the
land-water interface. However, with man
groves often growing in narrow linear bands
of 20 to 30 meters width, the 80 meter
ground resolutions of Landsat MSS data can
not reveal the same spatial resolutions that
can be obtained from aircraft imagery.
In a comparison of digital remote sensing
products, digitized aircraft data enabled