Kazem Saedi; Adel Sepehri; Mohammad Pesarakli; Hosein Gharedaghi; Reza Azizinejad
Volume 21, Issue 3 , December 2014, , Pages 518-529
Abstract
In most Iranian rangelands, continuous grazing begins with melting snow and continues until the beginning of snow. This study was conducted to evaluate the effects of continuous grazing system on a number of morphological attributes of Bromus tomentellus and Ferula haussknechtii during 2010-2011 in Saral ...
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In most Iranian rangelands, continuous grazing begins with melting snow and continues until the beginning of snow. This study was conducted to evaluate the effects of continuous grazing system on a number of morphological attributes of Bromus tomentellus and Ferula haussknechtii during 2010-2011 in Saral Rangelands of Kurdistan Province. The 30-year exclosure was selected as control area inside the Saral Research Station. In different growth stages, the morphological attributes including the shortest and longest basal area diameter, the shortest and longest canopy diameter, and the height of 10 plants were measured. The annual yield of 30 plants of each species in each year was clipped and weighed to determine forage consumption intensity. All data were subjected to statistical analysis in a completely randomized design using combined analysis. Mean comparisons were performed using Duncan’s Multiple Range Test. Continuous grazing caused to the increase of basal area diameter and canopy diameter of B. tomentellus significantly; however, the height varied in two studied treatments, depending on the year. The three studied morphological attributes of F. haussknekhtii were affected drastically by continuous grazing. In this species, basal area diameter was more affected by the conditions of the year. In both species, ungrazed plants used seasonable rainfall more efficiently as compared to the grazed plants.
Hosein Gharadaghi; Hosein Arzani; Hasan Ebrahimzadeh; Mohammad reza Ghnnadha; Naser Baghestani
Volume 14, Issue 1 , January 2007, , Pages 19-32
Abstract
Rangelands are one of the important natural ecosystems in our country that were deteriorated during recent decades because of many causes especially earlier and intensive grazing. Grazing management need to determine beginning of grazing season and intensity in rangelands. It is very important to know ...
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Rangelands are one of the important natural ecosystems in our country that were deteriorated during recent decades because of many causes especially earlier and intensive grazing. Grazing management need to determine beginning of grazing season and intensity in rangelands. It is very important to know much about physiological and phenological status of rangeland species. Total nonstructural carbohydrates (TNC) and their changes during seasonal growth is one of the important physiological parameter in perennial plants. Also these reserves are primary source of energy in respiration, growth and survival of perennial plants during their quiescence and growth season and regrowth after grazing or cutting. In this research seasonal changes of TNC reserves in three perennial and desirable grass species(Bromus tomentellus, Festuca ovina, Dactylis glomerata) were studied in Polor summer rangelands(altitude, 2600m; annual precipitation, 535mm; with cold mountain climatic) at the north of Tehran province. Samples were collected in ten stages of plants phenology stages with three replications from above and underground matter (canopy and roots). Samples were oven dried at 70◦C during 48 houres. TNC concentration were measured by phenol-solpheric method (mg per gr dry matter). Data of all attributes were analyzed in the frame of rondomized compeletly block design by using Minitab software, and ANOVA one and two ways. Seasonal changes of TNC reserves in any of studied species and also their root and canopy were shown in annual curves. The results indicated that all species have distinct seasonal changes and they had the lowest TNC reserves at early spring and end of the seasonal growth and then increased. The results showed significant differences in TNC reserves between phenology Stages in root and canopy during seasonal growth (P= 0.05 & 0.01) and all species had higher amount of TNC reserves in root than canopy (P=0.01). The rate of TNC restoration was different between studied species. These differences were related to phenology and seasonal growth along. So in this area Dactylis glomerata is more sensitive to grazing and Bromus tomentellus conversely is more resistant to grazing. At the end we concluded that critical period for all species in relate of their TNC reserves is from starting growth in early spring till early May and at the end of seasonal growth, mid August. Beginning of grazing season from late may until early August is recommended for this area.