Investigation of environmental factors affecting the characteristics of pyrus syriaca Boiss in Zarddalan forest, Ilam

Ilam province is one of the natural habitats of wild pear (Pyrus syriaca Boiss) in Iran. Fruit harvesting, inappropriate grazing forest areas, deforestation and agricultural development in recent years has endangered the existence of the species. In this study, the major habitats of the species in Ilam province, which located in the forest area of Zardalan in the north eastern city of Chardavol in Ilam province, is studied. After specifying the study area on the map 1:50000, using desired parameters, the maps of slope, aspect and elevation were prepared and then by combined together, work units were determined. In each unit, according to its area, at least three random circular sample plots with area of 1000 m2 randomly settled and environmental characteristics such as slope, aspect, elevation, geographical longitude and latitude were determined. Then all the qualitative and quantitative parameters of wild pear were measured and recorded in the plots. The results showed that wild pear in intermediate slopes (15 to 30 percent) have the highest height and diameter at breast height. It was observed that, in point of health crown, crown shape and trunk quality, north aspects for wild pear are the best conditions. The findings also showed that the best trunk quality is at altitude between (1500 to 1750m), but no significant correlation between altitude and other qualitative and quantitative variables of wild pear was found.