The purpose of the present study is to determine the density of
natural pistachio and Persian juniper stands using remote-
sensing data, especially Advanced Land Observing Satellite
(ALOS) data, and generally to help in the sustainable
management and production of these forests in northeast Iran.
We applied the local-maxima approach to determine the tree
density of natural pistachio and Persian juniper stands, and
conventional vegetation indices in related to arid and semi-arid.
We propose a new vegetation index, the total ratio vegetation
index (TRVI), for arid and semi-arid regions (Figure 2).
> Juniper
Pistachio
Figure 2. Locations of the study areas in northeast Iran
2. MATERIAL AND METHODS
2.1 Study area
Pistachio area
The study site was located in an arid area of northeast Iran
where pistachio trees grow wild; annual precipitation is 200—
300 mm (Ramazani 2002). The site was 15.21 km2 (3.9 x 3.9
km) with latitudinal and longitudinal ranges of 36?17'2.60"—
36°7'2.09"N and 60°30'21.91"-60°30'18.22"E, respectively.
Natural pistachio forests occur mostly at elevations of 900—
1500 m, and the elevation of the study site was 500—1200 m.
The slope of the site generally ranged from 15 to 35 degrees.
Among 169 grid squares (300 m x 300 m) in a 13 x 13
arrangement, 15 sampling plots were randomly chosen for
analysis (Figure 3). Wild pistachio trees at the study site were
typically 3-4 m high, with crown diameters of 3—5 m (Figure
2). These forests were sparse and trees were widely spaced. The
distance between two pistachio trees was often more than 3 m,
and these gaps contained shrubs adapted to dry terrain, such as
Amygdalus spinosissima, | Atraphaxis spinosa, | Cerasus
pseudprostrata, Ephedra intermedia, Tamarix androssowii, and
Zygophyllum eurypterum. Soil salinity at the study site,
measured by the Natural Resources Organization of Iran, was
0.6-20 mmhos/cm (U.S. Salinity Laboratory Staff, 1969),
indicating that the site is a non-saline to strongly saline area
(U.S. Salinity Laboratory Staff, 1969).
300m
300 m
Figure 3. Arrangement of the 9-ha pistachio sampling plots. The
15 highlighted plots are those randomly chosen for analysis
Juniper area
The study site was located in an arid area of northeast Iran
where Persian Juniper trees are found naturally. Annual
precipitation is 156 mm (Fadaei et al. 2009), and the study site
covers 15.21 km2 (3.9 x 3.9 km) between 37°20'31.19"-
37?18'22.30"N and 58?49'59.13'—58?52'34.40"E. The elevation
is 700-900 m, and the slope ranges from 21 to 27 degrees.
Among 169 grid squares (300 m x 300 m) in a 13 x 13
arrangement, 12 sampling plots were randomly chosen for
analysis. The trees at the study site were typically 3—4 m high,
with crown diameters of 3-5 m (Figure 4). These forests are
typically sparse and the trees widely spaced.
300m
300m
Figure 4. Arrangement of the 9-ha juniper sampling plots. The
12 highlighted plots are those randomly chosen for analysis
Image data
We used satellite imagery that was acquired in July 2008 by
ALOS, which was launched on 24 January 2006. ALOS data
have good resolution in the panchromatic and multispectral
bands, which are appropriate for the study area, and are not too
expensive. Among three remote-sensing instruments on-board
ALOS, the Panchromatic Remote-sensing Instrument for Stereo
Mapping (PRISM) and the Advanced Visible and Near Infrared
Radiometer type 2 (AVNIR-2) were used for digital elevation
mapping and precise land coverage observations, respectively.
PRISM is a panchromatic radiometer with 2.5-m spatial
resolution at nadir, and has one band with a wavelength of
0.52-0.77 um (JAXA EORC). AVNIR-2 is a visible and near
infrared radiometer for observing land and coastal zones with a
10-m spatial resolution at nadir, and has four multispectral
bands: blue (0.42-0.50 um), green (0.52-0.60 um), red (0.61-
0.69 um), and near infrared (0.76—0.89 pm) (JAXA EORC).
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