Investigation on Four Sampling Methods for Canopy Cover Estimation in Zagros Oak Forests (Case study: Mehrian Forests of Yasuj City)

Document Type : Scientific article

Authors

1 Associate Professor, Agricultural Sciences and Natural Resources University of Sari

2 Professor, Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran

3 M.Sc. Student in Forestry, Faculty of Agricultural Sciences and Natural Resources, Mazandaran University

4 Ph.D Student in Forestry, Faculty of Natural Resources, Agricultural Sciences and Natural Resources University of Sari

Abstract

In order to investigate and determine an appropriate inventory method for Yasuj Oak forests, considering inventory precision (confidence limit) and accuracy for canopy cover parameter per hectare, four methods consisting of: systematic-random (rectangular plots), transect, strip and stratification were selected and their efficiency in the forest was evaluated. For this purpose, at first 100% inventory was applied in 100 hectare area of Yasuj Mehrian Forests, then geographical characteristics of the total trees were recorded, using GPS apparatus. The geographical data were transmitted to computer and the trees positions were identified on the area’s digital map. The data which had been recorded at 30 replicates by the four inventory methods, were analyzes by AutoCAD, Arc View and Arc Info software's and the outputs were compared with the results of 100% inventory method. The results showed that the real average canopy cover (recorded from 100% inventory) was equal to 2257 m2/ha whereas for the inventory methods of: systematic-random, transect, strip and stratification, was equal to 2390, 2220, 1995 and 2341 m2/ha respectively. The statistical errors for systematic-random, transect and stratification inventory methods were 18, 4 and 14 percent, respectively. Although the strip method is lack of statistical basis, and calculation of sampling error and confidence limit is impossible, but comparing the average canopy cover of this method with the other inventory methods was possible. Overall, the greatest and the lowest accuracy rate belonged to transect and strip methods, respectively. It can be concluded that the transect is the most appropriate inventory method for these forests.

Keywords

References

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