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DEFORESTATION IN EQUATORIAL AFRICA:
AN ASSESSMENT BASED ON ANALYSIS OF MULTIDATE LANDSAT MSS DATA
Susan M. Berta, Paul W. Mausel, John A. Harrington, Jr.
Indiana State University Remote Sensing Laboratory, Indiana State University
Terre Haute, IN, USA 47809
Robin Graham, Environmental Sciences Division, Oak Ridge National Laboratory
P.O. Box 2008, Oak Ridge, TN, USA 37831
Abstract
Information on land cover, as interpreted from spectral signatures, is used in assessing rates of
environmental change for three areas in equatorial Africa using LANDSAT MSS data. The three study areas
are: the Berberati - Carnot, Central African Republic region and two sites in Zaire. Four different
information extraction procedures were utilized: maximun likelihood and nonparametric classifiers and
Normalized Difference Vegetation Index (NDVI) analysis and Principal Components Analysis (PCA).
Trends in landscape change are identified with SITE ONE as the primary example. This study revealed that
deforestation is not occurring in the large, contiguous patches of rain forest. The greatest
deforestation pressures exist in close proximity to population centers, along roadways, and at the edges
of the contiguous rain forest. Regional changes are toward less vegetative vigor and degraded nonforest
environments.
KEY WORDS: Central African Republic, parametric, NDVI, land cover change
INTRODUCTION
Global atmospheric CO2 concentrations are rising
and portend a general global warming (Tangley,
1988). Forests, which are an integral part of the
global carbon cycle, represent 90 percent of the
global carbon stored in vegetation. Estimates of
the global carbon emissions from deforestation
suggest that approximately a quarter are from
Africa (Houghton et al., 1987). These estimates
of carbon loss in Africa are uncertain since they
are based on the estimated deforestation rates
published by the 1980 FAO/UNEP Tropical Forest
Resources Assessment Project (FAO/UNEP, 1981).
Reliable, current, and quantitative data on forest
area and deforestation rates are scarce for most
tropical countries (Booth, 1989). Although
satellite imagery has been used previously in
South America, Southeast Asia, Madagascar, and the
Ivory Coast of Africa (Nelson and Holben, 1986;
Woodwell et al., 1987; Malingreau and Tucker,
1988; Malingreau et al., 1985; Singh, 1986; Green
and Sussman, 1990; Repetto, 1990) few analyses
have been done for the rain forests of equatorial
Africa.
DESCRIPTION OF THE STUDY AREAS
This investigation involves three locations in the
Zaire/Central African Republic region (Figure 1).
SITE ONE is located in the southwestern portion of
the Central African Republic, with a small area of
eastern Cameroon included (centered on 4°30’N
latitude, 15°30'E longitude), while SITE TWO is
located along the western edge of Zaire (2°47'S
latitude, 18°17'E longitude) and SITE THREE is
located in northeastern Zaire (2°49'N latitude,
28°31’E longitude).
SITE ONE lies at the northern margin of the
Guineo-Congolian rain forest (Figure 2).
Vegetation characteristics, described by White
(1983), include drier Guineo-Congolian rain forest
(rainfall averages between 1200 and 1600 nm per
year) in the area south of Berberati and a mosaic
of Guineo-Congolian rain forest and secondary
grassland (where secondary grasslands refer to
formerly forested areas destroyed by cultivation
and fire) in the northern two-thirds of the study
area. Within this latter cover type the
grasslands occur in mosaic with small, usually
severely degraded, patches of the original forest
(found in lowland areas), and small patches of
secondary thicket and secondary forest (White,
1983, p. 84). Major waterways include the Mambere
River near the town of Carnot (SITE 1-F) in the
northeastern section of SITE ONE and the Baumbe
River near Amada-Gaza (Site 1-D) which flows south
and empties into the Kadei River.
5*E 10*E 15*E 20*E 25*E 30*E
Figure 1. Location of the study area.