Javad Motamedi
Abstract
Access to basic and up-to-date information on rangeland ecosystems; needs continuous and long-term vegetation measurement. For this purpose, during the years 2018-2021 at a specific time, from the vegetation of plant types representing the saline habitats of Lake Urmia, including; Salicornia europaea, ...
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Access to basic and up-to-date information on rangeland ecosystems; needs continuous and long-term vegetation measurement. For this purpose, during the years 2018-2021 at a specific time, from the vegetation of plant types representing the saline habitats of Lake Urmia, including; Salicornia europaea, Halocnemum strobilaceum, Aeluropus littoralis- Aeluropus lagopoides- Salicornia europaea, Aeluropus littoralis- Aeluropus lagopoides and Atriplex verrucifera were recorded in the customary system of Osalo. In each of the plant types, considering the dimensions and space between the plant spots, four 300-meter transects with the same azimuth were used, along the salinity gradient, at a distance of 25-50 meters from each other. On each transect, 10 plots were placed at a distance of 30 meters from each other. The plotting was done in such a way that while the distances of the plots were the same, the principle of randomness was observed. Therefore, the starting points of different transects were not the same. Size of sampling units and their dimensions; due to the different distribution of vegetation, the plant types were not considered the same. Plot size for plant types Salicornia europaea, Halocnemum strobilaceum, Aeluropus littoralis- Aeluropus lagopoides- Salicornia europaea, Aeluropus littoralis- Aeluropus lagopoides and Atriplex verrucifera, respectively; 0.5, 2, 0.5, 0.25 and 2 square meters were considered. Average forage production of the study site during 1397, 1398, 1399 and 1400, respectively; 404.6, 456.6, 478.6 and 338.2 kg/ha and the average percentage of canopy cover were 48.4, 54.6, 58.8 and 41.1%. During this period,
Javad Motamedi; Morteza Khodagholi
Abstract
Climate change has been a serious issue in the last two decades, and many studies have focused on its various aspects. In the present study, the effect of climate change on the distribution of Bromus tomentellus was investigated. To do this, 19 bioclimatic variables and three physiographic variables ...
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Climate change has been a serious issue in the last two decades, and many studies have focused on its various aspects. In the present study, the effect of climate change on the distribution of Bromus tomentellus was investigated. To do this, 19 bioclimatic variables and three physiographic variables and logistic regression model were used to quantify climate change in 2050 and to study its effects on the change of B.tomentellus species. First, using 17 synoptic stations in and near the province, a database of precipitation variables, night temperature, daily temperature and average temperature was formed and 19 climatic measures were calculated. Also using the digital model of height, with an accuracy of 30 meters; physiographic variables of slope, direction and height were prepared. Then, the presence and absence points of the species were determined and using logistic regression, its vegetative behavior was determined and the modeled map and related equations in the current conditions were calculated. Using current equations and inserting data extracted from the Worldclime database; the future distribution map for 2050 was generated under RCP4.5 and RCP8.5 climate scenarios. The results showed; the average annual temperature (BIO1), the annual temperature range (BIO7) and the average temperature of the coldest season (BIO11) are the most important for habitat fit, the values of which increase with increasing climatic conditions. Average annual temperature in places with a probability of more than 75%; over the next three decades, it will rise by 1.6 to 1.2 degrees Celsius.
Javad Motamedi; Shookofeh Ebrahimi; Esmaeil Sheidai Karkaj
Abstract
Estimation of carbon storage is one of the essential requirements for evaluating rangeland ecosystem services and economic evaluation of carbon storage in rangeland plans. Plant performance in carbon storage is a function of plant characteristics, environmental and management factors. Therefore, the ...
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Estimation of carbon storage is one of the essential requirements for evaluating rangeland ecosystem services and economic evaluation of carbon storage in rangeland plans. Plant performance in carbon storage is a function of plant characteristics, environmental and management factors. Therefore, the relationship of annual carbon storage of Astragalus brachyanus with plant traits, habitat characteristics and range management in the mountainous rangelands of Rajan was investigated. The five sites in which the species were distributed and differed in physical characteristics were selected and coded based on the type of management (exclosure or exclosure; intensity of grazing, medium and low grazing) and geographical direction. At each site, vegetation was measured within 30 two-by-two-square-meter plots, located 10 m apart along six 50 m transects. At each location, 15 A. brachyanus plant stands with different dimensions were selected and measured while measuring their appearance characteristics, and their current year growth was cut to estimate carbon storage. Samples were transferred to the laboratory to estimate the carbon conversion factor. Two composite soil samples were also taken from each site. Topographic factors (slope, geographical direction and altitude) and management (grazing in study units) were also recorded at each location. In order to investigate the relationship between annual carbon biomass storage and environmental and management , partial least squares regression was used. Based on the results, carbon storage of A. brachyanus was significantly different. Annual carbon biomass carbon storage, with crown diameter, number of base and plant height, was directly correlated with type of management (grazing intensity).
Esmaeil Sheidai Karkaj; isa jafari; roghayeh jahdi
Abstract
Fires are one of the most important factors affecting natural ecosystems. This study was done in order to investigate the effects of fire on soil chemical properties, soil seed bank and vegetation cover in Yeke Bermagh, Highland ranegelands in the southern part of Golestan National Park. After determination ...
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Fires are one of the most important factors affecting natural ecosystems. This study was done in order to investigate the effects of fire on soil chemical properties, soil seed bank and vegetation cover in Yeke Bermagh, Highland ranegelands in the southern part of Golestan National Park. After determination of control and burned area, sampling was done with 5 transects and 5 plots. Vegetation cover, density and production were recorded in each site. One plot was chosen for analysis of soil chemical properties and soil seed bank along transects. Sampling for seed soil bank determination was accomplished in two depths, 0-5 cm and 5-10 cm. In order to distinguish the differences between the two depths in each site, the independent t-test, and pair t-test were used. Comparison of soil properties in the two control and burned areas showed that pH, potassium, nitrogen, phosphors, carbon, EC and CEC in the burned area was more than control area. According to the results the amount of richness and diversity of seed bank in the control area was higher than the burned area. Furthermore, richness and diversity in the first depth was more than the second depth, in both areas.
