نوع مقاله : مقاله پژوهشی
نویسندگان
1 کارشناس ارشد سنجش از دور و GIS، دانشکدة علوم زمین، دانشگاه شهید بهشتی، تهران، ایران
2 استادیار مرکز مطالعات سنجش از دور و GIS، دانشکدة علوم زمین، دانشگاه شهید بهشتی، تهران، ایران
3 دانشیار مرکز مطالعات سنجش از دور و GIS، دانشکدة علوم زمین، دانشگاه شهید بهشتی، تهران، ایران
4 استاد مرکز مطالعات سنجش از دور و GIS، دانشکدة علوم زمین، دانشگاه شهید بهشتی، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction: Climate change is considered one of the most significant challenges facing humanity. This phenomenon has had notable impacts on agricultural production in most parts of the world, especially in arid and semi-arid regions. The average temperature has also increased in many areas over the past few decades. Today, various studies utilize remote sensing indices as one of the modern methods for identifying climate change. One of the important remote sensing indices is the phenology characteristics of vegetation cover, which has demonstrated a promising ability in identifying and estimating vegetation cover in recent studies.
Materials and Methods: The five-day time series of the Normalized Difference Vegetation Index (NDVI) from NOAA-AVHRR images and plant phenology parameters were utilized to examine changes in vegetation cover in rangeland and rainfed agricultural lands of the Urmia Lake basin over the years 1984-2013. Temperature and precipitation data were obtained from meteorological stations in the Urmia Lake basin and were used in comparison with satellite image results.
Results and Discussion: The results of the time series analysis over the thirty year period in the Urmia Lake basin revealed that the start of the growing season in Oshnavieh, Saqqez, and Sarab areas in 2013 commenced earlier than in 1984, while in the Maragheh area, it started later. The end of the growing season in Oshnavieh, Saqqez, and Takab ended earlier, and based on the peak growth parameter, vegetation in these counties reached its maximum value earlier. The results also showed the length of the growing season in Oshnavieh, Maragheh, and Saqqez counties has shortened, respectively.
Conclusion: The results obtained from satellite images and climate data indicated that the observed changes in phenology parameters are location-dependent. Cold nights and warm days at the start of the growing season decreasing and increasing, respectively. However, warm days increased at the end of the growing season. These changes have increased the slope of the plant growth phenology curve during the senescence period, ultimately reducing the length of the growing season.
کلیدواژهها [English]