Saeedeh Nateghi; Morteza Khodagholi; Mahshid Souri
Volume 31, Issue 3 , September 2024, , Pages 301-322
Abstract
Abstract Introduction Rangeland ecosystems are very important and sensitive to changes in environmental factors. Small changes in temperature and rainfall regime or other climatic events can fundamentally reduce the composition, distribution and dispersion of plant species as well as ...
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Abstract Introduction Rangeland ecosystems are very important and sensitive to changes in environmental factors. Small changes in temperature and rainfall regime or other climatic events can fundamentally reduce the composition, distribution and dispersion of plant species as well as their production. To better understand future climate change, it is essential to determine the current and future distribution of species. Species distribution modeling is currently the only tool that can be used to assess the number of changes in the distribution of multiple species in response to climate change. Therefore, considering the importance of climate in the distribution of plant species, this research examines the distribution of plant species in the future, taking into account the relationship between the important pasture species in Alborz province and the climate factor. Materials and methods In this research, four plant species including Stipa arabica, Ferula ovina, Bromus tomentellus and Artemisia aucheri were investigated in Alborz province. In order to determine the amount of precipitation and temperature, the data of the synoptic stations, which were analyzed by the Man-Kendall method, were used. Using the maps of the Ecological Zones Recognition Plan of the Forestry and Rangeland Research Institute and ArcGIS, the vegetation cover map of the province and the current distribution of species, the presence and absence of species were drawn and recorded. In order to prepare the environmental information layer, 19 bio-climates for the present were calculated and downloaded from the WorldClim.org site for 2050 with an accuracy of 30 seconds. These data were obtained for two scenarios RCP4.5 and RCP8.5 for the future period. Then, the values of environmental variables were entered as independent variables and species presence and absence information as dependent variables in SPSS software, and the logistic regression statistical model was obtained from the presence of selected species. This statistical model was defined in the ArcGIS software environment and the potential species map was prepared. Kappa statistical coefficient was used to validate the resulting potential habitat maps model using 22 independent variables and with the help of error matrix. Results The results showed the rising temperature trends in all stations, and 65.76% of the trends were significant. In the northern and eastern heights of Alborz province, the increase in average temperature, especially in the early spring, late autumn and winter seasons, will cause early snow melting in the region, and due to the decrease in precipitation in the mountainous regions, it will cause many problems in water storage. According to the predictions of the logistic regression model, Stipa arabica species, 68626 hectares equivalent to 13% of the province, Bromus tomentellus, 298842 hectares equivalent to 58% of the province, Ferula ovina, 195465 hectares equivalent to 38% of the province, and Artemisia aucheri, 232539 hectares equivalent to 45% of the province have the probability of occurrence of class 75-100 The percentage is for the presence of these species. The evaluation of regression model using Kappa coefficient for Stipa arabica, Bromus tomentellus, Ferula ovina and Artemisia aucheri species was equal to 86, 85, 82 and 79 respectively, which are models with good accuracy according to Koch and Smith classification. 19 bio-climatic maps were prepared under two scenarios 4.5 and 8.5 for the year 2050. The current situation is similar to the 4.5 scenario, but in both models, we will see a decrease in the probability of the floor occurring by 75-100 percent in 2050. Also, the average of all temperature parameters in Karaj station will increase by 1.9 degrees Celsius by 2050 and the amount of precipitation will decrease by 1.33 mm. Discussion and conclusion The researchers reported that although there have been no significant changes in rainfall over the past 50 years, the decrease in rainfall in April and the increase in rainfall in December and July can indicate possible climate change in these areas in the future, and the climate in Iran, especially in spring is warming, which confirms the results of the present study. The minimum and maximum height in which the Stipa Arabica species is present is 1400 and 2400 meters, respectively, and the modeling results in 2050 show this minimum and maximum height in the 4.5 scenario, 2400-2100 meters and in the 8.5 scenario, respectively. It shows 2900 meters. The minimum and maximum altitude where the Ferula ovina species is present is 1850 and 2600 meters, respectively. If the modeling results in 2050 show this minimum and maximum height unchanged in the 4.5 scenario and 2800-3000 meters in the 8.5 scenario, respectively. The Bromus tomentellus species is currently located at an altitude of 1600-2700 m, while in scenario 4.5 (equilibrium conditions) and scenario 8.5 (pessimistic scenario) it is at an altitude above 2500 m, which indicates that this species of There is not much difference in altitude opinion. The minimum and maximum altitudes where Artemisia aucheri is present are 1600 and 2800 meters, respectively. Slope and temperature are the two main parameters affecting the distribution of this species and so that the slope affects the depth of the soil and thus has an effect on the establishment of the roots. Due to heat compensation in pessimistic conditions, this species has moved to higher altitudes, i.e. around 3000 meters, which confirms the results of other researchers. With the increase in temperature due to climate change, the extent of habitat of the species under investigation will decrease and they will move to areas that are higher and therefore have lower temperature.
Somayeh seyed ali; mohammad rahimi; Jafar Dastourani; Mohammad Khosroshahi
Volume 23, Issue 3 , January 2017, , Pages 555-566
Abstract
In this study, the impact of climatological parameters and land use on water yield of the watershed was investigated. Therefore, the trend of climatological parameters (precipitation and temperature) and stream flow discharge were studied monthly, quarterly and annually at the stations located inside ...
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In this study, the impact of climatological parameters and land use on water yield of the watershed was investigated. Therefore, the trend of climatological parameters (precipitation and temperature) and stream flow discharge were studied monthly, quarterly and annually at the stations located inside and near the watershed using Mann-Kendall test. To evaluate the land use changes and its impact on run-off, the Helsel and Hirsch method was employed. In this method, the impact of precipitation (as exogenous variable) and the serial correlation of run-off data were removed, and again the trend test was implemented on the remaining logarithmic data of run-off (adjusted).In addition, the variations of snow line during the last 20 years were investigated to determine the role of climatological variation on watershed landscape.The results revealed that precipitation and mean temperature parameters over monthly, seasonal, and annual scales as well as run-off data after removing the precipitation impact and serial correlation between data had no significant trend.Therefore, it is concluded that climatological parameters and land use changes had no noticeable influence on the surface water of the watershed.Our results clearly showed that the Helsel and Hirsch method could be used in other regions since it could remove the effects of precipitation and its variation carefully.Moreover, the snow line of the study watershed showed no significant trend. According to the minimum and average snow line height, a high annual fluctuation was observed in the watershed during the study period. These factors may be the main reasons for non-significance of stream flow discharge and run-off height trends.
masoud masoudi; maryam vahedi; alireza nematollahi; seyed rashid fallah shamsi
Volume 22, Issue 4 , March 2015, , Pages 802-820
Abstract
This research was aimed to present a new model to determine the areas with higher degradation risk through considering various indicators of land degradation and desertification aspects or criteria, namely, natural, human and trend of degradation. For this purpose, two areas were selected in the north ...
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This research was aimed to present a new model to determine the areas with higher degradation risk through considering various indicators of land degradation and desertification aspects or criteria, namely, natural, human and trend of degradation. For this purpose, two areas were selected in the north (Sepidan) and south of the province (Lamerd). These two areas were selected because of their differences in climatic conditions. The final land degradation risk map was produced by overlaying all three natural, human and trend of degradation layers in comparison with the current status of degradation in GIS. The areas under risk were classified into subclasses with different probability level to show a statistical picture of risk in future. In this study, the percentage of risk probability was evaluated according to the trend and potential of degradation. The results showed that the dominant risk class in Sepidan was moderate, in Lamerd the dominant risk class of natural factors was moderate, and in other cases, the dominant risk class was low or no risk. In addition, the comparison of risk assessment in both areas based on the weighted average indicates that the degradation risk of human factors, current degradation trend and finally land degradation risk in Sepidan is sever as compared with Lamerd. In general, degradation risk in Sepidan with a semi humid to humid climate condition is more sever than that of Lamerd with a dry climate.
Somayeh Dehdari; Hosein Arzani; Hamid Movahed; Mohammad ali Zare Chahouki; Hosein shabanali Fomi
Volume 21, Issue 3 , December 2014, , Pages 383-393
Abstract
This research was aimed to prioritize the factors affecting rangeland utilization as well as comparing 60 rangelands with/without Range Management Plan (RMP) using application of Analytical Hierarchy Process (AHP). Initially, the criteria for rangeland utilization were prioritized using Delphi ...
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This research was aimed to prioritize the factors affecting rangeland utilization as well as comparing 60 rangelands with/without Range Management Plan (RMP) using application of Analytical Hierarchy Process (AHP). Initially, the criteria for rangeland utilization were prioritized using Delphi method and Expert Choice software. Then, 60 rangelands (with/without RMP) were compared to each other. Document and field research methods were used to collect the data. For this purpose, a questionnaire was designed and in the field studies, direct sampling was conducted to calculate the rangeland production, condition, and trend while completing the questionnaires in the statistical population. According to the results, significant differences were found for rangeland production, trend, condition, and early grazing in comparison of rangelands with RMP and those with no RMP (p<0.01). In addition, significant differences were found for the number of available livestock to the allowed number of livestock, encroachment into the rangeland, contention and conflict among rangeland beneficiaries and the beneficiaries' attitude towards range management plan (RMP) in the studied rangelands (p<0.05).