Investigation of efficiency of photographic method for measurement of vegetation cover of different life forms (Case study: Minavand and Fashandak watershed in Taleghan)

Ground cover is a key indicator of rangeland health. Therefore determination of most suitable method of cover measurement in each climatic zone with enough precision and fast is important. To conduct this study four vegetation types (two grass communities and two grass-shrub communities) in Taleghan region were selected. Then in each vegetation type 6 transects were established. Along each transect 10 one meter square plots were located based on random- systematic sampling. Within each plot canopy cover percentage of each species was measured by ocular estimation and photographic methods simultaneously. Also, canopy cover percentage of each species on images was determined using Arc View software at office. Moreover, the spend time for measuring cover percentage using two methods (ocular and photography) was recorded and compared. Then, the percentage of canopy cover by life forms, obtained from ocular and photography methods were compared using SPSS ver.15 software and paired T-test. In general, the results of this study showed that in grass and grass- shrub communities, there were significant differences between canopy cover of grasses measured by two methods. The canopy cover of grasses was measured by photographic method, was more than canopy cover estimated by ocular method. Also differences between means compared with shrubs and forbs were higher. In shrub- grass vegetation type differences between canopy cover percentage of shrubs and forbs obtained from either ocular or photographic methods were not significantly different (P<0.05). The mean of time consumption for field survey at ocular method in order to estimating canopy cover in each plot was more than photography method. As a result we can conclude that photographic method because of less time consumption in ground survey and consequently less ground activities because of using digital images and interpretation by software in office is more applicable.