jasem yousefi; jamshid ghorbani; maryam shokri; seyed hasan zali
Volume 22, Issue 4 , March 2015, , Pages 757-767
Abstract
Seed production and dispersal are important topics in grassland management as they influence the vegetation structure and dynamics. To understand and better interpretation of changes in vegetation, it needs to identify the species composition in other sources such as the soil seed bank and seed rain. ...
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Seed production and dispersal are important topics in grassland management as they influence the vegetation structure and dynamics. To understand and better interpretation of changes in vegetation, it needs to identify the species composition in other sources such as the soil seed bank and seed rain. The aim of this study was to estimate the potential of seed production and seed dispersal in Sorkh-Abad grassland in SavadKoh, Mazandaran province. During growing season, mature seeds of the plants were collected and then identified and counted in laboratory. For these seeds, some properties were determined such as seed shape, seed weight, and germination percentage and seed color. Seed dispersal (seed rain) was sampled in seed traps, made by small plastic pots. During growing season, in three times, these seed traps were collected and all seeds were identified and counted. Results showed that18 species were in seed production and 17 species in seeds dispersal. The average amount of seed production was 296 seeds per square meter of which 25% belonged to Germaineae. The potential of seed dispersal was 275 seeds per square meter. Most collected seeds were light and small with elongated shape and bright colors. Stachys byzanthina, Marrubium vulgare, Descurainia sophia and Medicago lupulina comprise45% of the seed production. Similarly, the 46% of the seed dispersal was made by Stachys byzanthina, Plantago lanceolata, Descurainia sophia and Medicago lupulina. Small numbers of species in standing vegetation were found in seed production and seed rain of this grassland.
Parvez Gholami; Jamshid Ghorbani; Maryam Shokri
Volume 18, Issue 4 , September 2012, , Pages 662-675
Abstract
Overgrazing can alter rangeland vegetation in different ways. In this study, we used diversity, species richness and plant functional groups as the alternative to assess the vegetation response to different grazing intensities. This was done under three grazing intensities (long-term exclosure as reference ...
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Overgrazing can alter rangeland vegetation in different ways. In this study, we used diversity, species richness and plant functional groups as the alternative to assess the vegetation response to different grazing intensities. This was done under three grazing intensities (long-term exclosure as reference area, key area, and critical area) in rangelands of Mahoor Mamasani in Fars province. Vegetation sampling was carried out by random-systematic method and measuring the cover of plant species. The results showed that species diversity and richness significantly decreased with an increase in grazing intensity. Also, the cover percentage of Gramineae، Papilionaceae، Primulaceae، Umbelliferae and Valerianaceae significantly showed a negative response to grazing intensity while a positive response was found for Cruciferae، Labiatae، Plantaginaceae and Malvaceae. Moreover, some functional groups such as annuals, therophytes and Gramineae were significantly reduced from reference area to key area. The other finding of this study showed that decreaser plants significantly had less cover in critical area whereas increaser plants had greater cover in critical area. Species with storage of seeds in soil seed bank significantly had greater cover in aboveground vegetation in reference area than those species absent from soil seed bank. Due to the damage of some vegetation indices under overgrazing, it is recommended to make some changes in rangeland management and utilization in order to restore vegetation
Golnaz Rokhfirooz; Jamshid Qorbani; Maryam Shokri; Zianab Jafarian
Volume 18, Issue 2 , September 2011, , Pages 322-335
Abstract
Evaluation of changes in rangeland ecosystem after rehabilitation and restoration projects is important to determine the positive or negative effects of these projects. Parts of species composition in rangelands are in the soil seed bank as living seeds which are a potential for regeneration. Management ...
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Evaluation of changes in rangeland ecosystem after rehabilitation and restoration projects is important to determine the positive or negative effects of these projects. Parts of species composition in rangelands are in the soil seed bank as living seeds which are a potential for regeneration. Management and environmental factors may change the soil seed bank. This Study was carried out in mountain rangelands in Kabir watershed in Mazandaran province. A restoration project was done in this area 7 years ago and this study aimed to assess the effect of this project on soil seed bank. Soil was sampled random-systematically in control and restoration sites (210 samples) from 0-5 and 5-10 cm depths. Then seed bank composition was identified after seed germination in greenhouse. The results of this study showed that there were 38 species in soil seed bank whereas 71 species were existent in vegetation. Only 16 species were common between seed bank and vegetation. We found greater species diversity and richness in vegetation than that of soil seed bank. Only 18 species were common in the soil seed bank of control and restoration sites. Seventeen species were restricted to the seed bank of restored site. Among common species between soil seed bank of two sites, the project significantly influenced the seed bank of two species. Also, the restoration project significantly increased the richness and diversity of soil seed bank. Some species were unique to the specific soil depth. The results of this study showed that the soil seed bank would be altered by restoration and rehabilitation project and this depended on vegetation change due to restoration, type of treatment and time since project was performed.
Ali Taya; Hamid reza Naseri; Jamshid Ghorbani; Maryam Shokri
Volume 16, Issue 4 , January 2010, , Pages 456-467
Abstract
Species richness and biological diversity have been declined throughout the world as a result of human activities. Protected areas are an attempt to conserve the remaining species. Measuring species richness is important for understanding resource condition but heterogeneity in plant distribution make ...
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Species richness and biological diversity have been declined throughout the world as a result of human activities. Protected areas are an attempt to conserve the remaining species. Measuring species richness is important for understanding resource condition but heterogeneity in plant distribution make inventories difficult. Salok National Park with 6000 ha space located in North-west of Esfarayen County, Iran. In this study, species richness was measured by Modified – Whittaker plot for this National Park. For analysis of this richness a regression model as have been used. Totally, 184 plant species was found belonging to 137 geniuses and 40 plant family which Poaceae, Asteraceae, Fabaceae and Lamiaceae families with 28, 26, 19 and 17 plant species, respectively had the most species richness abundant among the others. As a biological spectral and life form, prevailing relations in studied area were HC>TH>GE>CH>PH and herbaceous Forbs>Grass>Bush>Shrub, respectively. The most plant species are perennial totally.
Seyed Alireza Mousavi; Mahdi farahpour; Maryam Shokri; Karim Solaimani; Mahmood Godarzi
Volume 13, Issue 3 , February 2006, , Pages 186-200
Abstract
Landsat 7 ETM+ satellite data of 2002 versus vegetation cover map of 1976 were used to: 1- assess the capability of satellite data to prepare vegetation cover classes map and 2- study the vegetation changes trend in an area of about 26858.6 ha in Lar Dam Basin. Field Sample spots were defined after accomplishing ...
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Landsat 7 ETM+ satellite data of 2002 versus vegetation cover map of 1976 were used to: 1- assess the capability of satellite data to prepare vegetation cover classes map and 2- study the vegetation changes trend in an area of about 26858.6 ha in Lar Dam Basin. Field Sample spots were defined after accomplishing necessary corrections of satellite images. Suitable band compositions were selected by considering the Optimum Index Factor (OIF), correlation matrix, Principal Components Analysis (PCA) and 2-dimensional diagram analysis. These compositions were classified using Maximum Likelihood, Minimum Distance and Box Classifier algorithms and then Majority Filter was used. Accuracy of resulted maps was evaluated by pixel to pixel method. Then Overall Accuracy Coefficient and Kappa Index were calculated. The map resulted from classification of band composition 123457 through Maximum Likelihood and Majority Filter was selected as the vegetation cover map of 2002. Vegetation cover map of 1976 prepared by Asgari-khah (1977) via field survey was used as "vegetation cover classes" map of that year. Then the changes happened in each class were assessed by operation of cross function on the mentioned maps. Due to complexity of initial classes, more homogenous classes were merged resorting to more detectable maps having only four classes. Overall Accuracy Coefficient of final map was promoted by using these classes. Then the changes happened during 1976-2002 were detected. The results showed that 28.55% of total area which was covered by rangeland vegetation types in 1976, is unchanged, 14.03% is dropped into lower and 57.42% into higher classes. The map of vegetation cover changes was produced, finally.