Kazem Saedi; Adel Sepehry; Mohammad Pesarakli; hosein gharehdaghy; Adel siosehmardeh
Abstract
This study conducted to investigate the effects of grazing in a short-term stocking system on the water-soluble carbohydrates (WSC) and nitrogen (N) reserves of permanent parts of Bromus tomentellus, Cephalaria kotschyi and Ferula haussknekhtii in Saral rangelands. A key area was selected with a permanent ...
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This study conducted to investigate the effects of grazing in a short-term stocking system on the water-soluble carbohydrates (WSC) and nitrogen (N) reserves of permanent parts of Bromus tomentellus, Cephalaria kotschyi and Ferula haussknekhtii in Saral rangelands. A key area was selected with a permanent exclosure area and two temporary exclosure areas. Root excavation was conducted at six to nine phenological stages. Five samples of typical plants were randomly selected for each species at each stage at each of these two sites for studying. Before excavation of the plants, their heights, canopy cover and basal area were measured. WSC and N concentrations were determined as a percentage of sample dry matter with phenol-sulphuric acid and Kjeldahl methods, respectively. The WSC concentration of B. tomentellus was not affected neither by studied grazing conditions nor by differences of weather conditions of the studied years. This species had lower carbohydrate concentrations than the forbs. In C. kotschyiWSC level was not affected by grazing or the weather condition each year. The low point of WSC reserves in F. haussknekhtii occurred during the rapid spring growth, and the highest levels were attained at the end of its growing seasons. Grazing increased the WSC concentrations in the storage organs of the plants of F. haussknekhtii and N concentrations of all the studied species. This study suggested that the plant response to grazing increased the resource allocation to storage organs to compensate the deprived reserves in the studied grazing system, so that the rest periods works well to improve the plants’ vigor. It seems that livestock grazing in this grazing system does not significantly harm two of the three studied species in their sizes.
Molouk Royan; Adel Sepehri; Abdolrasoul Salman Mahini
Abstract
Remote sensing and aerial photographs are used to produce medium to small scale images. However, for detailed information especially to estimate rangeland vegetation canopy cover there is a need to larger scale images. It is therefore necessary to study the technical applicability of different devices ...
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Remote sensing and aerial photographs are used to produce medium to small scale images. However, for detailed information especially to estimate rangeland vegetation canopy cover there is a need to larger scale images. It is therefore necessary to study the technical applicability of different devices such as short range light airplanes, kites, gliders and balloons. In this research, we focused on suitable flight height for rangeland vegetation canopy cover estimation using large scale balloon images in Incheh Broon area where we conducted field tests in September 2010. The balloons ascended to heights of 5, 10, 25, 50 and 100 m and higher. Using the taken images, vegetation canopy covers were estimated and compared with those obtained from field measurements. Results show that there is no significant difference between field and image estimation of canopy cover for heights lower than 100 m. We therefore suggest using balloon images acquired from up to 100 m height for estimating rangeland vegetation canopy cover.
