INVESTIGATION OF THE POSSIBILITY OF FOREST TYPE MAPPING IN ARID
AND SEMI-ARID REGIONS USING LANDSAT ETM+ DATA
Farzin Naseri
Assistant professor, Department of Environmental Sciences, International Center of Science & High Technology &
Environmental Sciences, P.O. Box: 76315-117, Kerman, Iran, Email: naseri@icst.ac.ir
Ali A. Darvishsefat
Associate professor, Faculty of Natural Resources, University of Tehran,
P. O. Box: 31585-4314, Karaj, Iran, Email: adarvish@chamran.ut.ac.ir
KEY WORDS: Forest, Classification, Accuracy, Landsat, Fusion, Quality, Soil, Vegetation.
ABSTRACT
Landsat ETM+ data from the National Park of Khabr in Kerman province, dating May 2000, were analyzed to investigate the
possibility of forest type mapping in arid and semi-arid regions.Quality evaluation of the image showed any radiometric distortion.
Orthorectification was implemented to reduce relief displacement. The RMS error obtained was less than half a pixel. The ground
truth map allocating 50% of the total area was prepared by fieldwork, using strip sampling. Different forest types considering the
density, were qualitatively estimated in the strips based on typology definitions,. The original and synthetic bands were obtained
applying tasseled cap transformation, PCA, ratioing and bands fusion. Furthermore, the parameters of the soil line relation were
applied to produce suitable vegetation indices to reduce soil reflect
ance. The best band set, based on the divergence between classes
signatures, using sample areas were selected. Forest type classification utilizing ML, MD, PPD and SAM classifiers were performed
to separate pure and dominant types of Pistacia atlantica, Acer monspessulanum, Amygdalus elaeagnifolia, A. scoparia and a mixed
type. Because of spectral similarity between the pure and dominant types, these classes merged together and the classification was
repeated. In this case the highest overall accuracy and kappa coefficient equal to 47% and 23% respectively, were achieved by MD
classifier. Accuracy assessment and signature separability criterions showed undesirable separation between the whole forest types,
except for Amygdalus scoparia. By merging all of the types but A. scoparia and performing the classification again, the highest
overall accuracy and kappa coefficient equal to 92% and 68% respectively were resulted utilizing MD classifier. Based on the results,
in such regions, low forest canopy, increases the role of background reflection and this makes undesirable results. Therefore high
resolution sensors data and improved classification methods are advised.
1. INTRODUCTION
The forests in arid and semi-arid regions play an effective role
in soil conservation and preventing destructive floods. These
forests are ecologically important due to holding valuable
genetic reserves and causing a rich biodiversity. Sothat it is
necessary to image them based on comprehensive
investigations. The starting point at this field is to achieve
suitable and fresh information to recognize them. In this regard
Satellite data with their own characteristics such as being able to
cover large areas, their revisit frequency and their possibility of
automatic analysis (Darvishsefat, 2002), can be considered to
meet this aim. On the other hand, it seems obvious that these
kinds of data have a great potential to diminish the fieldwork
and cosequently, lowering the costs of forest data acquisition.
These data are applied in different forest researches including
typology studies (May er al., 1997; Mickelson et al., 1998;
Huang ef al., 2001). In arid and semi-arid regions also, various
investigations have been recently carried out using satellite data
(Satterwhite & Henly, 1987; Leprieur et al., 1996; Hurcom &
Harrison, 1998; Todd & Hoffer, 1998). In this study the
potential of ETM+ data for forest type mapping in the national
park of Khabr as a part of arid and semi-arid regions was
investigated.
2. STUDY AREA
The study area measuring 1818 hectares is a part of the national
park of Khabr in Kerman province in the south east of Iran. this
area extends from 28? 46' 00" to 28° 49' 30" N and from 56? 28'
30" to 56? 37' 30"E. The elevation ranges from 2000 to
2600 meters above sea level. The main forest species are
Pistacia atlantica, Acer monspessulanum, Juniperus
excelsa, and Amygdalus spp. Accompnied by secondary
species like Celtis caucasica, Cotoneaster persicus and
Crataegus microphylla.
3. DATA
In this investigation ETM+ data, including 7 spectral bands
dated 19 may 2000, were applied. Furthermore, 1:25000 digital
topographic maps were used to determine GCPs and also to
evaluate the precision of geomatric correction.
4. Methods
4.1 Ground truth map
In this research, based on the present possibilities, a strip ground
truth map, allocating 5096 of the total area measuring 909 ha
was prepared. Forest types were estimated qualitatively in the
strips, based on typologic definitions (Gorgi Bahri, 2000). Large
numbers of recognized forest types and small area of some of
them, made the types to be generalized and consiquently 9
forest types including 4 pure types (Pistacia atlantica, Acer
monspessulanum, Amygdalus | Spp., and Am. Scoparia) 4
dominant types (Pistacia atlantica, Acer monspessulanum,
Amygdalus spp., and Am. Scoparia) and a mixed type were
concluded. In these types if the canopy area of a species was
more than 90% of the total, a pure type and if it was between
50% to 90% a dominant type was resulted. If the canopy area of
the first species was less than 50% of the total and the second
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