پاسخ گونه های گیاهی و گروه های کارکردی به قرق در مرتع لزور، استان تهران

مطالعه تغییرات پوشش گیاهی در مراتع قرق شده و تحت چرای دام به عنوان یکی از پیش نیازهای اساسی جهت به کارگیری در امر اصلاح مراتع مطرح می باشد. دراین پژوهش ترکیب گونه های گیاهی و گروه های کارکردی گیاهی در دو سایت قرق (با طول دوره 6 سال) و خارج قرق، در مراتع نیمه استپی لزور در استان تهران مقایسه شد. نمونه برداری به روش تصادفی سیستماتیک و با استفاده از ترانسکت و پلات انجام شد. نتایج نشان داد 23 گونه به صورت مشترک در هر دو منطقه قرق و خارج قرق، 4 گونه فقط در منطقه قرق و 8 گونه فقط در منطقه خارج قرق حضور داشتند. نتایج آزمون t نشان داد قرق سبب افزایش معنی دار درصد پوشش تاجی گونه های علوفه ایagropyron intermedium، bromus tomentellus، festuca ovina و thymus fedtschenkoiشد (0.01

Plant species and functional groups response to exclosure in Lazour rangeland of Tehran province

The study of vegetation dynamics under grazed and nongrazed rangelands is one of the most important prerequisites for range improvement. In this research, vegetation composition and the vegetation functional groups were compared in an exclosure site (livestock excluded for six years) and grazed area in semisteppe rangelands in Tehran province. Systematic random sampling technique through the use of transects and quadrats was employed to collect vegetation data. Results showed that there were 23 species common in both areas of exclosure and grazing while 4 and 8 species were restricted to exclosure and grazing areas, respectively. Results of ttest showed that exclosure significantly increased the percentage of canopy cover of some desirable species such as Agropyron intermedium, Bromus tomentellus, Festuca ovina, and Thymus Fedtschenkoi (p<0.01) Also, the rate of canopy cover of grasses, perennials and hemicryptophytes significantly increased in exclosure area (p<0.01). Moreover, exclosure significantly increased the canopy cover percentage of some vegetation families such as Gramineae, Lamiaceae, and Rubiaceae. However, it significantly decreased the canopy cover percentage of Apiaceae family. The results of this study showed that grazing performance for six years had produced favorable changes in vegetation composition of the area. Another result of this study is the use of hemicryptophyte and trophyte functional groups to detect grazing rate in summer rangelands. The predominance of hemicryptophytes and the reduction of trophytes also indicate the grazing intensity of the low to medium. In addition, the increase of trophytes and decrease of hemicryptophytes in the plant composition indicates a high grazing intensity of the livestock.