Received 9 March 2011 / Accepted 22 December 2011 Folia Forestalia Polonica, series A, 2012, Vol. 54 (1), 15–24 ORIGINAL ARTICLE Determination of the best canopy gap area on the basis of soil characteristics using the Analytical Hierarchy Process (AHP) Yahya Kooch 1 , Seyed Mohsen Hosseini 1 , Jahangard Mohammadi 2 and Seyed Mohammad Hojjati 3 1 Tarbiat Modares University, 46417-76489, Noor, Mazandaran, Iran, phone: +98-122-6253101 (-3), fax: +98-122-6253499, e-mail: hosseini@modares.ac.ir 2 Shahrekord University of Medical Sciences, Teheran, Iran 3 Sari Agricultural Sciences and Natural Resources University, Sari, Mazandaran, Iran ABSTRACT The assessment of canopy gap areas on the basis of soil characteristics in forest ecosystems could be one of beneft points for management of forests. This research was conducted in 20 ha areas of Experimental Forest Station of Tar- biat Modares University that is located in a temperate forest of Mazandaran province in the north of Iran. Twenty one canopy gaps with different areas were found in studied areas and classifed as small (85.12 m 2 ), medium (325.21 m 2 ), large (512.11 m 2 ) and very large (723.85 m 2 ) gaps. These areas classes of canopy gaps were assessed with respect to nine criteria (soil pH, carbon to nitrogen ratio, cation exchange capacity, phosphorus, potassium, calcium, nitrogen mineralization, microbial respiration and earthworm’s biomass). Soil samples (0– 45 cm depth from the gap center and edge positions) were measured in the laboratory. The Analytical Hierarchy Process (AHP) was used for as- sessment of canopy gap areas. This method is widely used the Multiple Criteria Decision Support (MCDS) method and perhaps the most popular in many felds, including natural resource management, especially in forest sciences. Results of AHP indicate that the maximum of local priority belongs to small areas of canopy gaps when considering all soil characteristics. However, medium, large and very large canopy gap areas have priorities, respectively. The calculated overall priority showed that with respect to considered criterias, small and medium gap areas have higher, more ideal condition in comparison to large and very large areas. AHP results emphasise that considering soil char- acteristics canopy gap areas should be less than 400 m 2 in Hyrcanian forests of Iran. Also, AHP can be introduced as an effective instrument in decision-making processes for investment planning and prioritization in compliance with environmental regulations. KEY WORDS canopy gap, soil characteristics, Hyrcanian forest, beech, Iran