مقالات رزومه مسعود برهانی

This bulb root plant has essential oil with medicinal property. The great need for this product has led to a large harvest of its bulbs from the rangelands, which has significantly reduced its stands in recent years. The aim of this research is to determine the vegetative characteristics of Allium hirtifolium in Isfahan province. For this purpose, The presence of the plant was determined using field studies of 1395, and the ecological characteristics including topographic(elevation and slope), meteorology (rainfall, temperature, and climatic classes) and soil (Texture, salinity and acidity) were determined. Also using logistic regression model, the main factors influencing the presence of the species were identified. This species occur mainly in Astragalus community. The results showed that the highest presence of the species is in cold semi-arid climate with an average annual rainfall of 300 to 500 mm and an average annual temperature of 11 to 14 ° C. In terms of topographic factors, the species presence is mostly at altitudes between 2400 and 3000 meters above sea level and slopes of more than 20 percent. In terms of soil parameters, this plant is mainly in medium soil texture with a pH of 7 to 8 and an electrical conductivity of zero to 4 dsi Siemens / m. The logistic regression model showed that the two factors of elevation and precipitation had the most effect on presence of species.on species presence showed that topographic and rainfall factors had the most effect on species presence.

Plant species diversity always implies ecosystem stability against environmental and biological disturbances. This study was conducted to investigate the effects of grazing management on diversity indices of plant species in grazed and exclosed rangeland sites of Hanna station- Semirom. Sampling was performed using 30 plots (1 m2) along four transects. Canopy area and density of species were recorded in sampling units, and the floristic list was provided in the whole area. Species richness, heterogeneity and evenness indices were calculated from density data and parametric diversity indices including log normal, geometric, and broken stick were fited in both exclosed and grazed areas. The Chi-Square test was used to examine the significance of measured traits. The results of numerical indices showed a higher species richness, evenness and species diversity indices in grazed than in the ungrazed site. The logarithmic diagram in the exclosed and grazed areas followed the broken stick model, indicating the presence of dominant species. The floristic lists of the study sites showed that the number of specific plant species in the grazed site was higher than that of exclosed site. Overall, the results showed that moderate grazing conditions in Hanna station improved plant species diversity indices and increased climax plant species.

Range management method (RMM) is an important element of range management especially in the case of revegetation and rehabilitation of vegetation. This study aimed to investigate proper RMM and grazing systems for paddocks of Semirom in Esfahan province and comparing them with programs proposed by the offices of natural resources. For this purpose, 29 paddocks under range management plan were selected and proposed RMM and grazing systems were defined. According to range condition and trend in the mentioned paddocks, RMM and grazing system maps were prepared using standards the defined theoretically. The results showed that in most cases, the proposed range management method in rangelands was consistent with the correct method based on rangeland condition. On the other hand, for 20 range management plans, despite artificial RMM, grazing system was predicted, which was not based on correct range management. Our results clearly showed that the proposed grazing systems were not implemented practically in range management plans of the study area due to technical difficulties in range parceling and controlling. In addition, in these areas, grazing schedule in accordance with grazing system does not have considerable advantages.

In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan) were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method) and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee) were compared in two management plans. The mean comparisons were made by independent T Student Test and Mann-Witheny U Test, and correlation was determined between diversity indices and vegetation parameters. Based on the results there was no significant difference between the two management systems regarding environmental features, while the implementation of range management plans caused significant reduction of stocking rate. Among the studied indices, evenness of species in sites without treated plan was significantly more than the sites with treated plan. The correlation matrix showed that there was a significant positive correlation between species richness and vegetation cover, production of perennial plans, and the rangeland condition and trend, while evenness showed significant negative correlation with these indices. Generally, implementation of range management plans has considerable effect on increasing climax species, dominance of Bromus tomentellus and it causes improvement of rangeland condition and reduction of evenness. This behavior could be explained by the balance between species competition and grazing pressure. Further, succession process of the studied communities demonstrates domination of some desirable species, high production and less diversity.

In order to investigate the effects of range management plans on cover, production, litter, and regeneration of plants in Semirum rangelands, 54 sites including 29 with plan and 25 without plan were selected. The implementation of range management plans resulted in the decrease of stocking rate, affecting the improvement of vegetation. According to the obtained results, no significant differences were found for the mean total cover, production and number of seedlings between two managements (P<0.05), while in the sites with plan, the cover, production and number of seedlings of class 1 plants, and cover and production of perennial grasses were significantly more than those of the sites without plan. This result was also true in the case of litter. These variations in plant composition were due to the impact of controlling the intensity and timing of grazing on the competition between palatable and perennial species with invasive and annual ones.

Rangeland ecosystems in semi-arid regions are vulnerable systems to climatic changes specially precipitation. In such conditions droughts are predictable. In this study the relationship between rangeland production and spatial and temporal changes of precipitation was investigated. Therefore، rangeland production through 10 years data set (1377-1387) in steppic bioclimatic of Esfahan province (Alavije، Muteh، Kalahrood and Gardaneshadian) using Standard Precipitation Index (SPI)، the relationship between SPI series of 3، 5 and 8 month time scales، and rangeland production of 10 years. Thus Anova and correlation matrix between production and SPI factors were formed. Results indicated that the most severe drought has occurred in 1387 simultaneously، with the least production. A harmony between change trend of production and SPI in the sites showed that in most cases maximum and minimum production have occurred simultaneously with maximum and minimum of SPI series. Also، the production correlated with SPI series of three، five and eight months'' time scales with correlation coefficients more than 63 percent which were significant in 1% and 5% level. Due to efficacy of production from spring precipitation and soil depth less than 30 cm in the sites، it is proposed to use SPI series of three months scale to evaluate drought in similar rangelands.

Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. Many of researchers think of higher species diversity as an index of bio-system’s stability. This research aimed to study parametric models of species diversity on range vegetations of study sites and relationship of ecological factors such as climate, soil and topography with diversity index. Four range sites were selected on different geographic areas in Isfahan province and randomly- systematic sampling was conducted to collect density data on plant species by quadrates along transects of each site during six years (2002-2007). Broken stick, log normal, logarithmic series and geometric series models were fitted for each site, and log normal showed to be the most proper model of distribution with P>0.05. LSD’s test indicated a significant different at? =1% level between species diversity of steppe1 and semi-steppe2 sites. Log normal model seemed to be the most proper model in all sites. Generally, when this model is fitted successfully communities are considered stable. On the basis of some related studies with this research, Hill () showed to be most proper index for species diversity in study sites, therefore effects of ecological factors such as soil, climate and topography on this index were studied by CCA method. Results of CCA revealed a high positive correlation between species diversity and percent organic matters of soil as well as precipitation levels and negative correlation with temperature.

Irrational human activities such as wars, high fossil fuel consumption, deforestation, desertification, chemical pollution and some environmental disasters are important factors for environmental and biological diversity degradations. Biological diversity is based on species diversity which makes gene pools, so any decline in species diversity leads to genetic chute. In this study species diversity was studied by nonparametric methods in 2 steppe and 2 semi-steppe range sites in Isfahan province during 6 years (2002-2007). Species richness, heterogeneity and evenness indices were calculated from density data during study period. In steppe sites because of high species dominance (Hill) index and in semi-steppe sites (Hill) index seemed to be suitable to determine species diversity. Generally statistical test indicated that species richness, evenness and diversity between semi-steppe and steppe vegetations are significantly different. Results indicated that species richness and diversity of Aghcheh and Vardasht sites were significantly different, while evenness was not significantly different in mentioned sites. In steppe sites of Shadian and Khondab evenness and diversity were significantly different but species richness was similar. Ttherefore, based on this study findings, species richness in semi-steppe and evenness in steppe sites were more effective in creation of diversity index.