Farid Dadjou; Ardavan Ghorbani; Mehdi Moameri; Mahmoud Bidarlord
Volume 25, Issue 3 , November 2018, , Pages 577-593
Abstract
The purpose of this study was to investigate the relationship between rangeland aboveground production based on total aboveground production and life forms of grasses, forbs, and shrubs with 25-year temperature and precipitation data, the year before sampling, and the year of sampling in Hir and Neur ...
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The purpose of this study was to investigate the relationship between rangeland aboveground production based on total aboveground production and life forms of grasses, forbs, and shrubs with 25-year temperature and precipitation data, the year before sampling, and the year of sampling in Hir and Neur rangelands in Ardabil province. To determine the aboveground production, the amount of production was estimated using the harvesting method in one square meter plots (totally 330 plots) in three elevation classes under the range of 1446-2750 meters. Temperature and precipitation were calculated for each plot. Aboveground production maps were prepared in a GIS environment using extracted regression equations. The results showed that over the years, precipitation decreased and temperature increased, and aboveground production also decreased in relation to those climatic factors. Moreover, there is a significant relationship (P<0.01) between the aboveground production of life forms and total aboveground production with climatic factors, and aboveground production of grasses and total have a direct relationship with precipitation; however the maximum aboveground production of forbs was recorded in the middle ranges and maximum aboveground production of shrubs was recorded in the higher ranges of annual precipitation. Grasses and total aboveground production had an inverse relationship with temperature, and the maximum aboveground production of forbs and shrubs was recorded in the middle and lower ranges of annual temperatures, respectively. According to the accuracy of derived regression equations, the maps prepared by climatic data of 1394 and 1395 were better than 25-year climate data. The results of this study can be used for the supply-demand balance of aboveground production, biomass accounts, and ecosystem carbon balance indicator that is potentially an important tool for sustainable development.
Mina Bayat; Hosein Arzani; Adel Jalili
Volume 23, Issue 2 , September 2016, , Pages 372-357
Abstract
In this study, the effects of three important climate factors including rainfall, temperature, and relative humidity were studied on vegetation cover and forage production for ten years (1997-2007) as well as in the Alavijeh and Khondab steppe rangelands, Isfahan province, in 2013. The results of the ...
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In this study, the effects of three important climate factors including rainfall, temperature, and relative humidity were studied on vegetation cover and forage production for ten years (1997-2007) as well as in the Alavijeh and Khondab steppe rangelands, Isfahan province, in 2013. The results of the eleven-year study in steppe rangelands showed that shrubs and grasses had the highest and lowest vegetation cover and production and the average vegetation cover and average production were calculated to be 12% and 124.5 kg per hectare. The results of simple regression analysis showed that in steppe rangelands, the total vegetation cover is affected by annual rainfall and temperature, so that vegetation cover increased with increasing annual rainfall and decreasing temperature. The total production in the study rangelands is affected by annual rainfall, cold season rainfall, and minimum temperature. The long-term production was calculated to be 55 and 176.6 kg per hectare for the Khondab and Alavijeh sites, respectively. According to the results of stepwise regression, using climatic factors, the relative humidity with temperature of December and annual rainfall was identified as the best equation to estimate the annual vegetation cover in the Khondab and Alavijeh sites. In the Khondab site, the temperature of November and total rainfall from March to May was identified as the best equation to estimate the annual production. However, in the Alavijeh site, the total rainfall of growing season, minimum temperature of March, and temperature of May and December was the best. Therefore, the impact of climate conditions on vegetation cover and annual production and different life forms are not similar in the steppe rangelands.
Zahra Pakzad; Mahmoud Raeini Sarjaz; Morteza Khodagholi
Volume 20, Issue 1 , June 2013, , Pages 199-212
Abstract
To investigate the effect of climatic factors on distribution of Astragalus adscendens in rangelands of Isfahan province, 57 climatic variables with most importance in terms of ecology of this species were selected. Data were tested by factor analysis in SPSS 16. The maps of Isfahan climatic factors ...
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To investigate the effect of climatic factors on distribution of Astragalus adscendens in rangelands of Isfahan province, 57 climatic variables with most importance in terms of ecology of this species were selected. Data were tested by factor analysis in SPSS 16. The maps of Isfahan climatic factors in the factor analysis were drawn and integrated with the map of vegetation types and digital elevation map to identify the habitat of Astragalus adscendens. According to the results, the first three factors could explain 90.2% of total variance in selected variables as follows: temperature, precipitation, and radiation and wind, with 47.4, 30, and 12.8% of variance, respectively. The three climate factors were compared with the average of climate elements in the habitats of Astragalus adscendens and the areas without this species. Results showed that the areas with an altitude of 2400 m which have approximately 50% relative humidity, with more than 400 mm of rainfall per year and relative radiation are considered as the main habitat for Astragalus adscendens. The tolerance of this species to climatic factors is limited.