Document Type : Research Paper
Author
Assistant professor, Forests and Rangelands Research Department, Kurdistan Agricultural and Natural Resources Research and Education Center, AREEO, Sanandaj, Iran
Abstract
Background and objectives: Producing basic knowledge about a rangeland ecosystem is a necessary instrument for any management practice in rangelands. This study is one of the prior attempts to determine vulnerability or persistence of key species in response to grazing in Saral rangeland, Kurdistan province, Iran.
Methodology: For assessing clipping (simulated grazing) effects on important species Ferula haussknechtii, a 0.5 ha exclosure established before 2007 growing season in Zardawan paddock. Inside the exclosure, 40 plants selected of which 10 replications allocated to a specific treatment of ocular clipping of the 20-40, 40-60, and 60-80% of aboveground annual growth. For a precise clipping intensity, the whole clipped and the rest of the forage after the sleeping stage were caculated.10 replications were assigned as control (unclipped) plants. The grazing season in the traditional livestock grazing system called "Shagaldari" is about 3-4 months. Clippings were done every month for the three-month current grazing season in April, May and June. Monthly-clipped plant materials were dried to calculate the accurate clipping intensity as well as the residues of all plants (except controls) at the end of growth season. Each year, vigor, mortality, plant maximum height, yield, and reproductive shoot number measured or estimated. This was done for 4 years. In the fifth year, to monitor the effects of clipping treatments in the resting growing season, these attributes were measured without clipping. Split plot in time was used as the statistical design. During these four years, only one case of death was recorded among the 40 selected plants. Duncan's multiple range test was used to compare the means.
Results: Mean density of the species in the studied exclosure area was 0.41 plants per m2 and in some patches make it was dominant species and sometimes the main species of the vegetation composition. The results showed that only one of the treated plants was dead. None of the clipping treatments resulted to a death case or even decrease in their vigors. The plants that were clipped in different intensities produce the similar weight of annual yields, had the similar final heights (P ≥ 0.01). The interaction treatment×yaer was significant for annual aboveground yield (P ≤ 0.001) but not significant for final height (P ≥ 0.05).
Conclusion: The high density of the species in the ranch, despite the high palatability, indicates the resistance of the plant to livestock grazing. In confirmation of this issue, the treatment of harvesting the annual growth of aerial parts with an intensity of about 70% could not damage the plant. However, the results clearly showed that the rest year should be included in the grazing system of this species. A rest grazing system is an unavoidable necessity for seed production. This species is very important in the indigenous knowledge of ranch management, especially in the traditional grazing system of "Shagaldari". Also, considering the high palatability of the species for native sheep, the abundant presence of the species is a sign of the health of the rangeland and the closeness of the plant community to its climax.
Keywords
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