Investigating the Changes inthe Surface and Density of Middle Zagross Forestsusing Aerial Photo Interpretationand GIS in Different Heightsand Distancesfromthe Village (Case Study: KakarezaRegionof Lorestan Province)

Oak tree forests of Kakareza are situated on 45 km North East of Khorramabadin middle Zagross region. The present experiment was carried out in an attempt to investigate the changes in the surface and canopy density of the region in different heights and distances from the village by interpreting the aerial photos taken in 1955 (1:55000) and 1997 (1:40000) and by means of GIS software. For this purpose, the pictures were first geometrically corrected and then the layers of canopy thickness wereidentified in a 2 millimeter dotted network. The frontier line of separated layers was drawn in the form of closed polygons and the area of these polygons was measured separately. Any changes in the area of these polygons in every stage of photographs were compared through software. At each stage, the photos were compared and the map of the changes in the layers of canopy thickness was developed. The mapsof the heights in threeclasses(1400-1700 m, 1700-2000m, &over 2000m) andthe distancesfromthe villagemapsin threeclasses(0-300 m, 300-600m and600-900m) were prepared for two periods in Arcviewsoftware. By combining each of these maps withthe density mapdesigned in 1955 and 1997,the amount of forest change in different heights and distances from the village were determined. The results indicated that the biggest and the smallest areas of dense (F1), semi-dense (F2), and sparse (F3) densities respectively belonged to the heights of 1700-2000 m beyond 2000 m. The results also indicated that the forest density in dense (F1) and semi-dense layers (F2) had the biggest area in distances far from the village and the smallest areas in parts which were closer to the village. On the contrary, the sparse (F3) layer had the biggest area in places near the village and the smallest areas belonged to longer distances.