Hamidreza Akafi; Hamid Ejtehadi; Adel Sepehri
Volume 24, Issue 4 , January 2018, , Pages 907-919
Abstract
Recognition of spatial distribution pattern of plants is useful in describing the ecosystem stability, designing management plans and protective rehabilitative measures. In order to determine the distribution pattern of certain plant species in Ghamishloo National Park, six safe regions were selected. ...
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Recognition of spatial distribution pattern of plants is useful in describing the ecosystem stability, designing management plans and protective rehabilitative measures. In order to determine the distribution pattern of certain plant species in Ghamishloo National Park, six safe regions were selected. Three hundred sixty quadrates with the size of 1×1 m2 were established by using random-systematic method along six transects and the number of individuals of each species was recorded. In this study, dispersion indices such as clustering, Green, Lloyd and Morisita were used. Since a large number of plants with different densities were selected, the results of indices showed that density had no effect on distribution pattern. The values of Green's index showed a pattern between random and non-random (clumped) distribution pattern. Therefore, it is recommended to use maximum clumped values to determine the exact type of distribution pattern. Among the study indices, no specified maximum value was defined for Lioyd and Morisita regarding the clumped pattern. For this purpose, two formulas were defined to determine the maximum clumping and the results of indices were interpreted according to these formula.
kosar vahidi; Bahram Gholinejad; Parviz karami
Volume 23, Issue 4 , March 2017, , Pages 856-863
Abstract
Knowledge of species distribution patterns in each area is the basis of vegetation measurement. Determining the species distribution pattern helps us select the appropriate methods for measuring quantitative properties such as species density and abundance. In order to study the distribution pattern ...
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Knowledge of species distribution patterns in each area is the basis of vegetation measurement. Determining the species distribution pattern helps us select the appropriate methods for measuring quantitative properties such as species density and abundance. In order to study the distribution pattern of three shrub specie, a part of Kurdistan rangelands was selected as the study area. A random systematic sampling method was used along four transects of 300 meters. The first point on each transect was randomly selected and the rest (14 points) were selected along each of the transects with 20-meter intervals from each other. In each vegetation type, criteria such as density and abundance were measured in plots, and the distance from a random point to the nearest plant and to the nearest neighbors was determined along the transects. In addition, the distribution pattern of Acantholimon bracteatum, Astragalus gossypinus and Acanthophyllum mucronatum was determined using distance indices (Eberhardt, Hopkins, Johnson and Zimmer) and the quadrate indices (Green, Morisitas index, Morisitas standard, and Lioyd). The results of analysis showed that the distance indices had more accuracy than quadrate indices with the same performance.
Anahita Rashtian; Ali Akbar Karimian
Volume 21, Issue 4 , March 2015, , Pages 747-755
Abstract
Investigation on the vegetation cover of rangelands under grazing and exclosure conditions is important in improvement of range management. Therefore, this research was aimed to investigate the effect of exclosure on production, density, frequency, importance value and vitally of Artemisia sieberi as ...
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Investigation on the vegetation cover of rangelands under grazing and exclosure conditions is important in improvement of range management. Therefore, this research was aimed to investigate the effect of exclosure on production, density, frequency, importance value and vitally of Artemisia sieberi as the most important species of steppe rangelands of Iran. The study was conducted in Nodushan rangelands of Yazd province under grazing and exclosure conditions. Sampling was done randomly in both grazing and exclosure areas, with 10 transects and 40 quadrates of 1m2. In addition, 30 individuals of Ar. sieberi were selected randomly in each area and plant height, maximum and minimum diameter, canopy caver, vitality and dry matter production were measured. According to the obtained results, the studied species showed no significant differences for production, average diameter, height and canopy cover percentage. However, the vitally of Ar. sieberi showed significant differences between grazing and exclosure areas. The results of importance value indicated the increased relative importance of Ar. sieberi under moderate grazing intensity. The distribution pattern of Ar. sieberi under exclosure was uniform while under grazing condition a clumped distribution pattern was observed.
Esfandiar Jahantab; Yaser Ghasemi Aryan; Adel Sepehri; Bahareh Hanafi; Enayat allah Yazdan panah
Volume 19, Issue 3 , December 2012, , Pages 482-489
Abstract
Knowledge of the plant distribution pattern in each region is of principles and fundamentals of vegetation survey and measurement that plays an important role in the selection of management approaches. A study was performed to determine the distribution pattern of three dominant species of Artemisi aaucheri, ...
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Knowledge of the plant distribution pattern in each region is of principles and fundamentals of vegetation survey and measurement that plays an important role in the selection of management approaches. A study was performed to determine the distribution pattern of three dominant species of Artemisi aaucheri, Kelussiao doratissima and Prangos ferulaceae in Dyshmuk region in northwestern Kohgilouyeh and Boyer Ahmad province. One hundred quadrates of 2×2 m were randomly located along six transects of 100-m length and the number of each species was recorded. Using this information, the most appropriate and accurate quadrate-based distribution indices (Green and standard Morisitat indices) were calculated. According to the results, Kelussia odoratissima and Prangos ferulaceae showed a random distribution pattern while distribution pattern of Artemisia aucheri was uniform to random.