International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
The available secondary data on natural resources and
characteristics of coffee production systems of these regions
was reviewed. To complement this information, field surveys
were carried out in each area, in order to assess the relationships
between coffee and the environment and collect georeferenced
data from coffee fields, soils and geomorphology. Topographic
maps from the Brazilian Institute of Geography and Statistics
(IBGE), at the scale of 1:50.000 were used as à cartographic
sis. Published soil surveys, geologic and geomorphic maps
were also used, as well as aerial photographs, at the scale of
1:25.000, and images from the TM Landsat 7 satellite, from
1999 and 2000. The implementation of a digital database for the
pilot arcas and the treatment of the satellite images were carried
out using the geographic information system SPRING.
Thematic layers of different physiographic aspects of the study
regions, such as urban areas, roads and drainage networks,
contours and spot heights information, were obtained from the
topographic maps by digitizing. The areas occupied by coffee,
surveyed and georeferenced during field surveys, were also
digitized to create the correspondent digital overlay in the
database.
The TM Landsat images were treated in the SPRING's IMAGE
module. Only three spectral bands were used for the
classification of the image, viz. band 3 (red), band 4 (near
infrared) and band 5 (mid infrared), since these bands represent
more than 80% of the spectral information. Controlled samples
of the main land cover types were used to train the classifier.
These samples were obtained from areas identified and
georeferenced during the field surveys. The segmentation of the
images was performed using a region growing method and a
supervised classification was carried out using the Maxver
classifier (maximum likelihood algorithm available in the
SPRING) on band 4. The thematic maps generated from the
classified images identified the following land cover classes:
Productive coffee: coffee fields with plants with more than 4
years of age, 2 meters or more of height, and canopies covering
more than 50% of the ground; Forest: correspondent to areas
occupied by natural vegetation from “cerradäo” (Brazilian
savanna woodlands) to remnants of semi deciduous Atlantic
forest; Other uses: correspondent to areas occupied by small
size natural vegetation (bush trees and other types of cerrado),
natural and cultivated pastures, annual crops and even coffee
fields still in formation, i.e. recently planted coffec areas which
covered less than 50% of the ground; Bare Soil:
comprehending areas prepared for cultivation and urban areas.
These classes were chosen taking into account the main interest
of the project, which was the coffee and the difficulty to
distinguish this crop among natural forest and other land cover
classes that spectrally overlap with it when sensed at the coarse
spectral resolution of the TM Landsat. The thematic layer
Actual Land Use was generated from the classified images.
The Delaunay triangulation was used to construct a TIN and
create a digital elevation model (DEM) and a digital terrain
model (DTM) for each area, based on the digital contours and
spot heights data obtained from the topographic maps. Slope,
aspect and hypsometry class maps were derived from these
models. The slope classes used in the segmentation of the DTM
were selected based on the relations between geomorphology
and the soils distribution, according to the field observations of
the regional landscapes studied (Andrade ef al 1998). The
geomorpho-pedologic model, validated for the regions of Sáo
Sebastiào do Paraíso and Machado in field campaigns, is
presented in Table 1.
According to the Brazilian Soil Classification system, the main
soil classes occurring in these regions are Latosols (soils with
oxic B horizons), Argisols (soils with argillic B horizons),
Cambisols (soils with cambic B horizons) Neosols (soils
without diagnostic B horizons — Litholic and Alluvial soils) and
Gleysols (Hidromorphic soils). As shown in table 1, Latosols
occur predominantly where the slope gradient is lower than
12%, although Hidromorphic and Alluvial soils might occur at
flooded plains where the slope gradient is lower than 3%,
Argisols occur where the slope gradient is higher than 12% ang
lower than 45%, although Cambisols and Lithosols might occur
locally where the slope gradient is higher than 24%. For the area
of Sdo Sebstido do Paraiso the soil map was obtained from the
overlay of the slope classes map and the geology domains map,
according to the criteria established in Table 2. At the region of
Machado however, the geology was more homogeneous and
geomorphology and altitude were the primary factors
determining the distribution of soil types over the local
landscape. Therefore the model used the criteria shown in Table
3. The soil map of the pilot area of Patrocínio was obtained
from an unpublished pedological survey carried out by the soil
research center of EMBRAPA. The mapping units delimited
were checked in the field and adjusted to the scale of the work.
The maps generated were crossed using the LEGAL/SPRING
program. The thematic layers Land Use Classes x Soil Classes
and Land Use Classes x Slope Classes, for cach pilot area, were
overlayed and the quantitative relations were evaluated.
3 RESULTS
3.1 Study area of Patrocínio
The results of the crossed tabulations (Land Use Classes x Soil
Classes and Land Use Classes x Slope Classes) of the study
area of Patrocínio are presented in tables 4 and 5, respectively.
The geomorphology of the pilot area of Patrocinio is
represented, predominantly, by flat to gently sloping surfaces of
great extensions. In these areas Red Latosols and Yellow Red
Latosols occur and are discriminated according to the content of
iron of the parent material. Coffee is cropped in this
environment, occupying 13, 86% of the lands of the pilot area,
distributed mainly in the areas with plain and gently undulated
relief. In this region the crop is characterized by large fields,
generally in contiguous areas of great dimensions, where
Latosols, correspondent mainly to the Ld! + Lea9 and Led16 +
Ldl mapping units occur. Due to climactic conditions, irrigation
is a frequent agricultural practice and mechanic harvest is also
favored by the geomorphologic characteristics. These practices
condition the management of the crop in the region and
influence many of its parameters, such as maximum plant high
(2.2 m) and planting density (3.8 m x 0.6 m). These parameters
influence the percentage of soil cover by the coffee plants
canopies, favoring the interpretation and survey of coffee fields
in TM/Landsat satellite images, as well as propitiating the
automatic classification and mapping of land use classes.
3.2 Study area of Machado
According to the geological maps available (DNPM/CPRM,
1979), the pilot area of the region of Machado presents
homogeneous geology, corresponding to the Complexo
Varginha, constituted basically by ophthalmic gneiss and
migmatites, whose mineral and chemical compositions do not
Internation
MA
Slope Cla:
0-129
20-45%
>45%
Table 2.
* Geologicc
Qa: Quater
TQi: Undiff
Kb: Bauru
coarse sand
KJsg: Sdo b
KJb: Sao Be
locally with
Pci: Tubare
developmen,
stratification
** This soil
Slope
Class
0-399 [—
0-12% |—
12-24% |—
24-45%
>45% |—
et tis
reflect in vat
obtained fro
the model es
evaluation, p
fieldwork, sc
distributed i
between slop
these soil-m:
described an
Tables 6 an
between Lan
X Slope Clas: