تنوع زيستي گونه هاي چوبي و علفي در رابطه با عوامل محيطي در جنگلهاي پايين بند شرق نوشهر

This study was done to investigate of the relationship between biodiversity of woody and herbaceous species and environmental factors in lowland forests of eastern Nowshahr. Selective sampling method

اين پژوهش به منظور بررسي رابطه تنوع زيستي گونه هاي چوبي و علفي با عوامل محيطي در جنگلهاي پايين بند شرق نوشهر انجام گرفت. روش نمونه برداري به صورت انتخابي و با تعداد 46 قطعه نمونه بود. سطح قطعات نمونه با استفاده از روش سطح حداقل تعيين شد. در منطقه مورد مطالعه تعداد 100 گونه متعلق به 92 جنس و 48 خانواده شناسايي گرديد. براي محاسبه تنوع زيستي از شاخصهاي تنوع شانون- وينر و سمپسون و شاخصهاي غناي مارگارلف و منهنيك استفاده گرديد. پوشش گياهي و عوامل محيطي شامل فيزيوگرافي و خصوصيات فيزيكوشيميايي خاك بر اساس رسته بندي DCA وCCA بررسي شد و پس از انجام رسته بندي، محورهاي حاصله استخراج گرديد. در مرحله بعد همبستگي شاخصهاي تنوع زيستي با اين محورها بررسي گرديد و محورهايي كه با شاخصهاي تنوع زيستي همبستگي معني دار داشتند، تعيين شدند. سپس همبستگي بين محورهاي تعيين شده و عوامل محيطي بررسي شد و عوامل محيطي داراي همبستگي معني دار مشخص شدند و در آخر همبستگي شاخصهاي تنوع زيستي با عوامل محيطي مذكور تعيين گرديد. نتايج نشان داد كه هر چهار شاخص مذكور با درصد شيب و ارتفاع از سطح دريا همبستگي معني دار مثبت و با درصد سيلت، درصد رس، پتاسيم و نيتروژن همبستگي معني دار منفي دارند.

This study was done to investigate of the relationship between biodiversity of woody and herbaceous species and environmental factors in lowland forests of eastern Nowshahr. Selective sampling method was considered with 46 sample plots and the area of sample plots was determined by using minimal area method. In studied area100 species of 92 genera in 48 families were recognized. Biodiversity indices of Shannon-Wiener and richness index of Margalef and Menhenic were used for calculation of biodiversity. Vegetation cover and environmental factors including physiography, soil physical and chemical properties were studied on the basis of deterned correspondence analysis and canonical correspondence analysis and after ordination method performance, obtained axes were extracted. At the next stage the correlation between biodiversity indices and CCA and DCA ordination axes were studied. Then correlation between determined axes and environmental factors as studied and environmental factors that had significant correlation was recognized. Finally the correlation between biodiversity indicators and mentioned environmental factors was studied. The results indicated that each 4 mentioned indices have positive significant correlation with sand, slope and elevation and they have negative correlation with silt, clay, potassium and nitrogen.