Exploringthe Forest Edge Effect on the Abundance of Sylvia communisand Phylloscopuscollybita in SiahkalEzbaram Forest

The aim of this study was to examine the effect of forest edge on the abundance of Sylvia communis andPhylloscopuscollybita inEzbaram forest. Ezbaram forest, with an area of 147 acres, is located in the east of Gilan province and within 5 km distance from Siahkal and 25 km distance from Lahijan. To record their abundance, unlimited radius censuses were used; therefore, all heard and observed birds were recorded in the sampling unit. Observing and recording the birds continued everyday from sunrise 5 a.m. until 8 a.m., from mid-spring 2010. The sampling was halted during bad weather conditions and restricted visibility. To study the vegetation as environmental variables, circular plots with a 17-meter radius from the center were considered. The analysis of variance was used to examine the presence of a significant difference in the abundance of the two species in different distances from the edge towards the center of the forest. The results revealed a significant difference in the abundance of Sylvia communis(p= 0.005) andPhylloscopuscollybita (p= 0.001) in different distances from the edge towards the center of the forest and their frequency was less in the edge compared to the central areas. To determine the environmental variables that significantly affect the abundance from edge towards the center, Krouskal-wallis test was applied. The results showed a significant difference between the edge and the center regarding the shrub density, floor number, number of dry-footed tries, and security. The result of ANOVA indicates an increasing pattern from the edge towards the center. Generally speaking, it can be claimed that the abundance of these species in forest areas is largely determined by shrub density, floor number, the number of dry-footed tries, and security factors. Accordingly, it is suggested that protecting the elements that play a key role in the creation of convenient habitats for birds should be considered in managing the northern forests of Iran.