Volume 18, Issue 1 (7-2024)
مرتع 2024, 18(1): 1-22 |
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Shobeiri S M, Khosravi H, Azarnivan H, Eskandari Dameneh H. Spatiotemporal Dynamics of Vegetation Cover and Their Relationships with Climate Change and Land Use in North-Eastern Iran (2001-2020). مرتع 2024; 18 (1) :1-22
URL: http://rangelandsrm.ir/article-1-1192-en.html
URL: http://rangelandsrm.ir/article-1-1192-en.html
Department of Arid and Mountains Regions Reclamation, Faculty of Natural Resources, University of Tehran, Karaj
Abstract: (1490 Views)
Background and objectives: Terrestrial ecosystems depend on vegetation to connect water, soil, air, and other components. Using remote sensing technology, this study explores vegetation dynamics in Khorasan, including their response to land use changes and climate changes between 2001 and 2020. This study aimed to investigate and analyze the effects of climatic factors on vegetation dynamics.
Methodology: In this study, satellite and climate data are used. The National Meteorological Organization provided climate data, and the USGS provided satellite data on vegetation indicators. This research used monthly NDVI and EVI indices to investigate the vegetation cover from 2001 to 2020. These monthly images with a spatial resolution of 1 km were prepared from the MODIS terra sensor satellite. Using the IDW interpolation method, the climate data of 39 investigated stations were prepared, and their maps were prepared in ArcGIS. Linear regression simulated trends in vegetation index and climate parameters over 2001-2020 in QGIS. NDVI and EVI indices were correlated with climatic parameters to investigate changes in vegetation cover.
Results: Based on the trend of land use changes in Khorasan, the main land uses are barren lands, agricultural lands, forests, rangelands, open shrubland, savanna, and built-up areas. During this period, barren lands, agricultural lands, forests, and rangelands decreased by 2.57, 0.41, 0.0009, and 1.02 %, respectively, while open shrubland, savannas, and built-up areas increase by 3.98, 0.0031, and 0.0072 %. Examining the change slope of the vegetation cover index and climatic parameters in these 20 years showed that the change slope of the vegetation cover index EVI and NDVI in these 20 years are positive and increasing, respectively 72.81% and 85.46% of Khorasan, which can be said in general According to these two indicators, vegetation cover is increasing in more than 85% of Khorasan's natural lands. Examining the slope of rainfall and temperature changes in this period of time showed that these indicators had positive and increasing changes in 76.59 and 58.71% of the area of Khorasan, respectively. The correlation results between EVI and NDVI vegetation indices with rainfall show that there was a positive correlation between these two indices in 87.27 and 90.71 % of Khorasan. Correlation between vegetation indices EVI and NDVI and temperature showed that there was a negative correlation of about 74.27 and 77.26% respectively in the studied area. Most land use areas barren lands, agricultural lands, rangelands, and open shrublands have a positive correlation between the EVI vegetation cover index and rainfall in semi-arid, dry, and semi-arid climates. These correlation results show open shrublands, rangelands, and barren lands had 49.18, 80.96, and 100% positive correlations, respectively. The results of this correlation in the semi-humid climate in rangelands and forest land uses were positive at 95.30% and 1.15%, respectively. The results of the correlation between EVI and temperature in the semi-arid climate in semi-arid, dry and semi-arid climates show that this relationship in most barren lands, rangelands and open shrublands is negative. Also, the results of this correlation in the Mediterranean climate show that this correlation is positive in the use of barren lands, rangelands and open shrublands 40.99, 91.02 and 23.08 %. The results of this correlation in the semi-humid climate show that this relationship is 100 and 98.06 % positive in barren lands, and rangelands, respectively, and 1.94 % negative in open shrublands. In the majority of areas, such as barren lands, agricultural lands, rangelands, and open shrublands, there is a positive correlation between NDVI and rainfall in extra-arid, dry, semi-arid, and Mediterranean climates. In the Mediterranean climate, barren lands, rangelands, and open shrubland use are all 100% positive, 62.15 and 77.0.1 respectively. In semi-humid climates, barren lands and pastures are used 52.56 % and 38.63 %, respectively. A negative correlation was found between NDVI and temperature in extra-arid, dry, semi-arid and Mediterranean climates in most of the land use areas barren lands, agricultural lands, rangelands, and open shrublands. Based on the results of the correlation, barren lands, rangelands, and open shrublands are 99.60, 93.66, and 100% positive, respectively. According to the correlation results between NDVI and temperature in semi-humid climates, barren lands and rangelands have a 100% positive correlation.
Conclusion: The destruction and restoration of vegetation have become a major challenge in Iran. Land degradation and desertification conditions will increase due to the interaction of human activities and climate change. North Khorasan, Razavi and South Khorasan were studied separately and in detail at the climate and land use levels. Consequently, the findings of this study can be very useful and necessary for the implementation of policies and projects to promote vegetation restoration by men and politicians in the field of natural resources and the environment.
Methodology: In this study, satellite and climate data are used. The National Meteorological Organization provided climate data, and the USGS provided satellite data on vegetation indicators. This research used monthly NDVI and EVI indices to investigate the vegetation cover from 2001 to 2020. These monthly images with a spatial resolution of 1 km were prepared from the MODIS terra sensor satellite. Using the IDW interpolation method, the climate data of 39 investigated stations were prepared, and their maps were prepared in ArcGIS. Linear regression simulated trends in vegetation index and climate parameters over 2001-2020 in QGIS. NDVI and EVI indices were correlated with climatic parameters to investigate changes in vegetation cover.
Results: Based on the trend of land use changes in Khorasan, the main land uses are barren lands, agricultural lands, forests, rangelands, open shrubland, savanna, and built-up areas. During this period, barren lands, agricultural lands, forests, and rangelands decreased by 2.57, 0.41, 0.0009, and 1.02 %, respectively, while open shrubland, savannas, and built-up areas increase by 3.98, 0.0031, and 0.0072 %. Examining the change slope of the vegetation cover index and climatic parameters in these 20 years showed that the change slope of the vegetation cover index EVI and NDVI in these 20 years are positive and increasing, respectively 72.81% and 85.46% of Khorasan, which can be said in general According to these two indicators, vegetation cover is increasing in more than 85% of Khorasan's natural lands. Examining the slope of rainfall and temperature changes in this period of time showed that these indicators had positive and increasing changes in 76.59 and 58.71% of the area of Khorasan, respectively. The correlation results between EVI and NDVI vegetation indices with rainfall show that there was a positive correlation between these two indices in 87.27 and 90.71 % of Khorasan. Correlation between vegetation indices EVI and NDVI and temperature showed that there was a negative correlation of about 74.27 and 77.26% respectively in the studied area. Most land use areas barren lands, agricultural lands, rangelands, and open shrublands have a positive correlation between the EVI vegetation cover index and rainfall in semi-arid, dry, and semi-arid climates. These correlation results show open shrublands, rangelands, and barren lands had 49.18, 80.96, and 100% positive correlations, respectively. The results of this correlation in the semi-humid climate in rangelands and forest land uses were positive at 95.30% and 1.15%, respectively. The results of the correlation between EVI and temperature in the semi-arid climate in semi-arid, dry and semi-arid climates show that this relationship in most barren lands, rangelands and open shrublands is negative. Also, the results of this correlation in the Mediterranean climate show that this correlation is positive in the use of barren lands, rangelands and open shrublands 40.99, 91.02 and 23.08 %. The results of this correlation in the semi-humid climate show that this relationship is 100 and 98.06 % positive in barren lands, and rangelands, respectively, and 1.94 % negative in open shrublands. In the majority of areas, such as barren lands, agricultural lands, rangelands, and open shrublands, there is a positive correlation between NDVI and rainfall in extra-arid, dry, semi-arid, and Mediterranean climates. In the Mediterranean climate, barren lands, rangelands, and open shrubland use are all 100% positive, 62.15 and 77.0.1 respectively. In semi-humid climates, barren lands and pastures are used 52.56 % and 38.63 %, respectively. A negative correlation was found between NDVI and temperature in extra-arid, dry, semi-arid and Mediterranean climates in most of the land use areas barren lands, agricultural lands, rangelands, and open shrublands. Based on the results of the correlation, barren lands, rangelands, and open shrublands are 99.60, 93.66, and 100% positive, respectively. According to the correlation results between NDVI and temperature in semi-humid climates, barren lands and rangelands have a 100% positive correlation.
Conclusion: The destruction and restoration of vegetation have become a major challenge in Iran. Land degradation and desertification conditions will increase due to the interaction of human activities and climate change. North Khorasan, Razavi and South Khorasan were studied separately and in detail at the climate and land use levels. Consequently, the findings of this study can be very useful and necessary for the implementation of policies and projects to promote vegetation restoration by men and politicians in the field of natural resources and the environment.
Type of Study: Research |
Subject:
Special
Received: 2023/03/7 | Accepted: 2023/07/2 | Published: 2024/07/31
Received: 2023/03/7 | Accepted: 2023/07/2 | Published: 2024/07/31
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