our research team to analyze and map cate
gories of: red fringe, red riverine, black
and mixed mangroves in addition to
categories of upland and marsh ecosystems /
sand and beach / and man-made surfaces of
roads and urban developments. By compari
son, in the Butera study Landsat MSS data of
digitally mapped categories revealed black
mangroves / mixed mangroves / a category
called damaged mangroves because of hurri
cane damage / water / other / and un
classified. At no time was there a clear
indication of the presence of red fringe or
red riverine mangrove patterns.
We realize that these are uneven compari
sons based on differences in image scale,
resolutions of 80 meters compared to
resolutions of from 3 to 10 meters. All of
which means that with these types of data,
if one needs to investigate mangroves up
close, then one must move close to the
subject through the use of higher resolu
tion aircraft imagery. In future research,
we expect that the 30 meter Thematic Mapper
Landsat data will be of greater use to us
than the MSS data have shown and even may be
comparable to high altitude aircraft data.
2.2 Geographic Information Sysyterns (GIS)
Aircraft imagery from 1952, 1962, 1973, and
1984 were scaled to a common scale of
1:24,000,interpreted and mapped for mangrove
species and communities, and digitized into a
GIS data base. Map overlays were initially
produced from manually interpreted aircraft
imagery in black and white and color infrared.
The mangrove species and communities of red
fringe, red riverine, black mangrove, mixed,
and upland categories were delineated onto
mylar overlays. The completed mylar overlays
were then manually digitized on a Calcomp
digitizer and entered into a GIS on an ERDAS
(Earth Resources Data Analysis System). The
pixel cell size of the digitized maps was 10
meters.
A matrix analysis was used to produce
statistical comparisons between maps for
different dates. Matrix analysis allowed for
cross references and comparisons to be made
for each pixel for each map for any combi
nation of dates from 1952, 1962, 1973, and
1984. The digital mapping of Marco Island
provided a retrievable data base as a GIS
that could be continually updated as eco
systems and landcover changed. Such data
bases, enabled us to inventory several cate
gories of mangrove as well as landcover and
to calculate acreages of change.
3. CHANGE DETECTION
A major concern has been the destruction of
mangrove ecosystems by residential and com
mercial development in the Marco Island area.
As part of our work with aircraft data we
completed a series of analyses of change
detection. Four time periods were analyzed:
1952, 1962, 1973, and 1984.
The Marco Island inventory of mangrove com
munities and landuse provided calculations of
category descriptions and acreages. A clear
trend showed a decline in mangrove acreages
and an increase in the areal extent of resi
dential and commercial land development.
Comparisons between maps xor tne dates oi
1952, 1962, 1973, and 1984 provided visual
and statistical proof of changes in areal
extent and distribution that have occurred to
the categories of: mangrove communities/
converted or urban/ and "other land".
Mangroves changed from a total acreage of
11,285 in 1952 to a total of 8,577 in 1984.
This represented an areal decrease of 2,708
acres of mangroves in the 32 year period. In
terms of species, black mangrove experienced
the most dramatic changes over the 32 year
period. Black mangroves changed from 4,250
in 1952 to 2,344 in 1984. The net loss was
1,906 acres. Despite the rapid growth and
change in the area, mixed mangroves did not
show large declines in acreage. Mixed man
groves occupied 4,755 acres in 1952 and 4,495
in 1984. This became a net loss of only 260
acres. However,this is a misleading figure
as categories changed and were offset by the
natural expansion of the mixed mangrove
category into areas formerly occupied by pure
stands of black mangrove. The red fringe
mangrove communities were reduced by 206
acres by the changes between 1,390 acres
for 1952 to 1,184 acres in 1984.
The precipitous decline in the "other land"
category from 3,506 acres to 845 acres be
tween 1952 and 1984, was the result of water
front development which began in 1962 but
escalated in the 1969 through 1973 period.
The net decline in "other land", pre
dominantly uplands, was 2,661 acres. The
change in the uplands was the most striking
in that nearly all changes were the result of
the land development of Marco Island. The
uplands changed from 2,508 acres in 1952 to
553 acres in 1984, with a net loss of 1,955
acres.
4. CONCLUSIONS
Mangrove ecosystems of the Marco Island area
were successfully mapped through the use of
remote sensing and GIS techniques. Changes
in the areal extent of the mangrove com
munities were successfully identified with
respect to man-induced disturbances. Between
the years of 1952 and 1984, the total of
mangrove acreages declined by 2,708 acres.
Uplands were reduced by 1,955 acres. But
developed urban residential and commercial
property, increased by 5,102 acres at the
expense of some important nutrient producing
mangrove areas.
Although mangroves are prime land for
certain coastal developments, they are also
vital to marine estuarine ecosystems.
Knowledge of mangrove productivity in
detrital(leaf litter) export for fisheries
and map information on the distribution and
areal extent of each mangrove community would
enable researchers to estimate the ecological
significance of site-specific disturbances.
The areal extent of Florida's mangroves, and
the ratio of black, mixed, red fringing, and
red riverine must be measured and mapped in
order to examine the ecological impacts of
coastal development.
The primary objective of this research has
been to demonstrate the remote sensing and
mapping techniques that best provide the
necessary details for mangrove species and
community analysis. Although Landsat MSS
data provide adequate information on the
broadest areal coverage, we must still rely
on aircraft data for proper species identifi
cation until such time we can determine the
full capabilities of Landsat TM data for
mapping the mangrove ecosystems for Florida
and ultimately for much of the world's
tropical mangrove regions.
