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STUDYING THE POSSIBILITY OF THE USE OF LANDSAT SATELLITE IMAGERY IN
SEPARATING Fagus orientalis & Carpinus betulus MIXTURE IN THE NORTH FORESTS
OF IRAN
(CASE STUDY OF THE CHOA JIEH FOREST)
B. Bakhshandeh Navrood*, Dj. Oladi^
“ Natural Resources office, Rezvanshahr, Guilan, IRAN - b_bakhshandeh@yahoo.com
° Natural Resources Faculty, university of Mazandaran, Sari, IRAN, P . O. Box 737 —
Oladi123@yahoo.com
Commission PS, WG VII / 3
KEYWORDS: Remote sensing, Landsat, forestry, Satellite, Thematic, Imagery
ABSTRACT:
In recent years satellite knowledge and technology of remote sensing have had many improvements. Using of satellite imagery is
developing in different land studies every day. Earth resources technology satellites supply digital imagery from trees and other
objects based on their spectral reflections. Hence we want to study the possibility of separating different percentages of Fagus
orientalis and Carpinus betulus mixture based on their spectral reflections.
In this study, landsat-7 Enhanced Thematic Mapper plus (ETM^) digital imagery (24 Jun 2000, middle of growth season) of the study
area were acquired. At first, typology map of the study area was prepared, then, sample plots were selected randomly-systematic in
three areas with the mixture of Fagus orientalis and Carpinus betulus, on the map of 1:25000 scale. After field surveying, four
groups of mixture have been determined, that include: first group (pure composition of Fagus orientalis), second group (mixture of
80% Fagus orientalis, 20% Carpinus betulus and others), third group (mixture of 70% Fagus orientalis, 30% Carpinus betulus and
others), fourth group (mixture of 60% Fagus orientalis, 40% Carpinus betulus and others). Roads of the study area and sample plots
were digitized and the images were geometrically corrected (RMSE=0.703). The digitized roads and sample plots were overlaid on
the ETM" bands 1, 2, 3, 4, 5 and 7. All of the digital numbers (DNs) of sample plots were extracted. Differences among groups were
analyzed using t-test. The results showed that the ETM" imagery (middle of growth season) could separate pure composition of
narks
tion from
agers
rises 10 feet
1y5.
or 10-12 days
1gal,
Fagus orientalis from the mixture of 70% Fagus orientalis, 30% Carpinus betulus and others and lower percentages.
1. INTRODUCTION
In recent years new satellite information technology of remote
sensing had a considerable improvement in using satellite
information in different land studies. Earth resources technology
satellites supply digital imagery from trees and other objects
based on their spectral reflections. Hence we want to study the
possibility of separating different percentages of Fagus
orientalis and Carpinus betulus mixtures based on their spectral
reflections.
There is a mixture of Fagus orientalis and Carpinus betulus in
an extensive area in the northern forests of IRAN. Carpinus
betulus is a light demanding species, and after harvesting or
clear-cutting in forest, it quickly grows and dominates other
young trees. If we do not pay attention to thining of the forest,
Carpinus betulus will grow quickly and occupy the Fagus
orientalis sites and won't let them grow normally. To remedy
this problem, foresters must support the growth of Fagus
orientalis and prevent Carpinus betulus growth, with their
proper action (Tabatabaii 1973). To understand domination of
the Carpinus betulus in Fagus orientalis sites, in the extensive
forest areas, providing typology map of forest and forest
inventory is essential. Since typology maps of forest are
necessary for accurate planning and managing forest, it is hoped
that the findings of this research could be used in recognizing
and providing typology maps of forest trees.
2. MATERIALS AND METHODS
The aim of this investigation is to study the possibility of
separating different percentages of Fagus orientalis and
433
Carpinus betulus mixtures in the northern forests of IRAN
based on their spectral reflections. The study area is a portion of
Asalem forest in Guilan province that provides adequate area of
different mixtures of Fagus orientalis and Carpinus betulus. It
is between 48°, 45° to 48°, 53° longitude and 37°, 34° to 37°,
39° latitude. Coordinates of the area based on UTM maps are
307000-310000 E and 4165000-4168000 N.
Landsat-7 Enhanced thematic mapper plus (ETM') digital
imagery (24 Jun 2000, middle of growth season) of study area
were acquired. The ETM' instrument is an eight-band
multispectral scanning radiometer capable of providing high-
resolution information of the Earth's surface which its nominal
ground sample distances or "pixel" size is 30 meters in the
visible, near and short-wave infrared bands. To acquire ground
data at the study area, at first, compartments containing
different mixtures of Fagus orientalis and Carpinus betulus
were selected. Then, sample plots were chosen on the map of
1:25000 scale (prepared from aerial photos of 1994) applying
randomly systematic method.
The size of ground plots in applying remotely-sensed data in
forestry study is normally one hectare (Oladi 1997). Therefore,
plots size were considered 100m x 100m (1 hectare) which is 3
pixels x 3 pixels (9 pixels) on the satellite imagery. The
intervals between the plots were chosen 90 meters from each
other on the ground (3 pixels on the satellite imagery). In total
37 plots were selected. Plots were chosen on three areas on the
ground with regard to the availability of different mixtures of
Fagus orientalis and Carpinus betulus. Distance and azimuth of
first plot were calculated in relation to one control point (i.e.,
sharp bend of road). In order to get as much accuracy as
possible slop correction were made in the study area. Diameters
