بررسی نقش زمان وقوع بارش در میزان تولید علوفۀ مراتع

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار دانشگاه تربت‏ حیدریه، دانشکدة کشاورزی و منابع طبیعی، ایران

2 استاد دانشگاه تهران، دانشکدة منابع طبیعی، ایران

چکیده

مراتع از لحاظ ترکیب پوشش گیاهی، وضعیت، گرایش، تولید و ظرفیت چرایی هرساله دستخوش تغییراتی می‌شوند. این تغییرات اغلب تحت تأثیر دو عامل است: نوسانات اقلیمی و تصمیمات مدیریتی. در این تحقیق نقش پراکنش زمانی بارش بر تولید مراتع سه استان ایلام، قم و مرکزی ارزیابی شد. با بررسی نقشه‏های پوشش گیاهی، 10 تیپ در ایلام، 8 تیپ در قم و 10 تیپ در مرکزی انتخاب شد. در مناطق کلید رویشگاه‌ها هرساله فاکتورهای مربوط به پوشش و خاک از قبیل پوشش تاجی، تراکم، تولید، زادآوری و پوشش سطح خاک در زمان آمادگی مرتع در طول چهار ترانسکت 400 متری در 60 پلات اندازه‌گیری شد. تولید گونه‏های قابل چرای دام از روش قطع و توزین اندازه‌گیری شد. برای تعیین رابطة بارش و تولید از روابط رگرسیون و ضریب همبستگی استفاده شد. برای تعیین نقش زمان وقوع بارش در میزان تولید، رابطة بارش با تولید سالانة هر سایت در هفت پایة زمانی‌ـ شامل سال، بارش اسفند تا تیرماه، بارش بهمن تا تیرماه، بارش اسفند تا خرداد، بارش اسفند تا اردیبهشت، بارش اسفند و فروردین و بارش اسفند‌ـ محاسبه شد. نتایج این بررسی نشان داد که در سایت‌های مورد مطالعه فقط در 4 درصد موارد تولید کل با بارش سالانه رابطه داشته است و در 96 درصد سایت‌ها تولید کل با بارش اسفندماه (شروع فصل رشد) و بارش فصل رشد ارتباط دارد. این نتیجه اهمیت بارش فصل رشد را در میزان تولید گیاهان عرصة مراتع نشان می‏دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of the role of temporal distribution of precipitation on forage production value of the rangeland

نویسندگان [English]

  • Maryam Azarakhshi 1
  • Mohammad Mahdavi 2
  • Hasan Ahmadi 2
  • Hosein Arzani 2
  • Jalil Farzadmehr 1
1 Assistant Prof., University of Torbat Heydarieh, Faculty of Agriculture and Natural Resources
2 Full professor, University of Tehran, Faculty of Natural Resources
چکیده [English]

Plants cover composition, condition, trend, production, and grazing capacity of the rangeland change annually. In this research, the role of temporal rainfall distribution on rangeland production was assessed. This research had down in the rangelands of Ilam (with semiarid to semi humid climate) and Qom and Markazi (with arid to semiarid climate) provinces. By attention on plant cover maps in each province 10 main types of plant cover in Ilam, 8 types in Qom and 10 types in Markazi were selected. In these sites, relative factor to plant cover and soil contains: canopy cover, density, production, germination and, soil cover were measured along four 400m transects into 60 plots .the production of the graze able species was measured by clipping and weighting method. The regression techniques and correlation coefficient were used to the relation between production and precipitation. to determination the role of the temporal distribution of rainfall of the rangeland production, the relationship between rainfall and production was calculated in seven time steps contains. The results show that only 4% of the total forage production is explained by annual precipitation but in 96% cases there were related with start of growth season (March) and growth season(early March to late July).this result shows the importance of growth season precipitation on the forage yield in rangelands.

کلیدواژه‌ها [English]

  • growth season
  • Ilam
  • Markazi
  • Qom
  • temporal distribution of precipitation
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