The Effects ofTree stand layers on Resident Bird Species in Belgrade Forest, Istanbul, Turkey

摘要

This study aims at determining the effect of tree stand layers on the variety of bird species and show that there is a clear difference in the number of bird species between single layer and double layer tree stands. The Belgrade Forest, where the research was carried out, covers 5408.29 hectare and is located in the north of the Istanbul province in the Marmara Region, between 28°53'25" and 29°00'55" eastern longitude and 41°09'44" and 41°14'40" of northern latitude. The study area is a protected natural forest in the north-west Turkish Cas-tanetum-Fagetum transition zone, with oaks accounting for almost 75% of the forest flora. To count all the observed birds in this study for five years the "point count method" was used. At each point every bird species, their numbers and reproduction information for the resident birds was collected for 10 minutes once a month from March to June. The sampling points, 93 in number and 750 m apart in every direction, were spread over the whole study area. The93 observation points were classified into 15 stand types. One-Way ANOVA was used to investigate whether the one independent variable of the tree stand layers has any effect on the dependent variables of bird species. It was found that from 33 native bird species less species were breeding in single layered stands than in two-layered ones (n = 93, p = 0.05). In the two-layered stands, the breeding bird counts were m = 20.05 ± 1.731, whilst in the single layered ones the counts amounted to 14.82 ±2.480. According to our results there is a significant difference in the number of breeding bird species between single and double stand layers. The multiple tree stand layers contain more nesting native bird species and are therefore esteemed to have a positive effect on avifauna.