Abstract:
This study aimed
first to investigate the relationsh
ip between Normalized Difference
Vegetation Index (NDVI) and vegetation attributes (vegetation cover, bare soil, litter
frequency, and the amount of biomass) and, then, evaluating the vegetation changes using
NDVI in semi
-
arid rangeland in western Iran. Gr
ound data were collected to assess the
accuracy of
NDVI
index. For this purpose, 14 sampling units were randomly selected for
collection of vegetation attributes including biomass, vegetation cover, litter, and bare
soil. Then, the correlation between di
gital pixel valu
es
and the sampling units were
analyzed. The results showed that NDVI was highly correlated with all vegetation
attributes. The maximum correlation was related to vegetation cover (0.84). So, to
evaluate the vegetation changes, the NDVI maps were created
in 1986, 2001, and 2013.
The results showed that the amount of class 1 (very poor vegetation cover) increased from
0.27 km
2
in 1986 to 12.89 km
2
in 2013, and also class 4 and 5 (good and very good
vegetation cover, respectively) decreased about 27.8 and 3
7.7%, respectively. The
relationship between precipitation and temperature with NDVI was investigated to assess
the sensitivity of NDVI to these parameters. The results showed that the amount of
precipitation decreased during the studied time periods. This
parameter seems to be one
of the most important factors affecting the vegetation in our study area.
Keywords:
Precipitation, Satellite imagery, Temperature,
V
egetation cover.
