Abstract
Remote sensing data has been broadly used in assessing and monitoring natural resources. Monitoring forest resources with
Landsat Thematic Mapper (TM) and other fine resolution sensors has become a challenging work in a wide variety of forest
applications. In this paper, the relationships between stand crown closure with spectral reflectance values and some vegetation
indices (VIs) obtained from Landsat TM were investigated in a case study area. The Pearson correlation and multiple regression
analysis were used to estimate the crown closure. The regression analysis showed that a linear combination of Soil Adjusted
Vegetation Index (SAVI), normalized difference 32 index (ND32) and normalized difference 57 index (ND57) are better
predictors for estimating crown closure (adjusted R2=0.757; root mean square error (RMSE)=2.5304%) than other TM bands
(adjusted R2=0.529; RMSE=4.0782%). The Pearson correlation analysis results demonstrated that NDVI, Simple ratio (SR),
Difference Vegetation Index (DVI), Transformed Vegetation Index (TVI), Soil Adjusted Vegetation Index (SAVI) had the
highest positive correlation (r=0.84) and Infrared Percentage Vegetation Index (IPWI) had the negative correlation (r=-0.84) with
crown closure measurements. Furthermore, the TM 4 band showed the highest correlation (r=0.64) with crown closure between
TM 1-5 and TM 7. This research concluded that forest managers could use Landsat TM imagery for estimating crown closure
used for generating maps in developing forest management plans.