efficiency of canopy cover measurement of artemisia sieberi stands by two sampling methods in different lengths (case study: steppe vegetation of baft region, iran)

Seasonal and annual variations of canopy cover in shrub stands of arid ecosystems necessitae a closer look. this research was conducted in 2015 to establish a wheel-point device and evaluate its efficiency (precision, accuracy and time) for estimation of canopy percent in a pilot artemisia stand in khabr region of baft, kerman province, iran. several transects with different lengths (30, 60, 90, 120, 150 and 180 m) were established using a randomized sampling block design with five replicates. measurement of canopy percent of dominant species and the associated plants was carried out by transects as linear-contact (control treatment) and using wheel-point device. the standard deviation and relative error of each treatment, compared to control and the time criterion were considered for precision and accuracy of the sampling method and its efficiency. the relationship between control data and wheel-point method was presented by the help of a regression model. results indicated that in the sampling through linear-contact method, the optimum length was 30 m for dominant species, associated plants and total species population. also, results showed that in sampling through wheel-point device method for dominant species, the optimum transect length was about 60 m; while for the associated species and the total species population the optimum length was 120 and 150 m, respectively. according to the results of regression model on data from wheel-point method and the transect, coefficient of determination was 57 and 67% for the dominant and associated species, respectively.