Monitoring rangeland vegetation through time series satellite images (NDVI) in Central Anatolia Region

The study was carried out on natural rangeland areas of Central Anatolia Region of Turkey. The objective of this study is to monitor seasonal changes on rangeland vegetation by remote sensing data. Spectral reflectance of plants changes over time based on their phenological period. Differences in topography and climatical factors affect plant phenology. Vegetative growth period from green-up to senescence can be monitored by various vegetation indices. Normalized Difference Vegetation Index (NDVI) is one of the most widely-used indices that indicates the amaount of photosynthetically active green vegetation on the land. In this study, Spot-vegetation data have been used to show seasonal changes of rangeland vegetation in Central Anatolian rangelands. Satellite images cover time series of 1998-2009 years. Every year consist of 36 NDVI images, each representing 10 days composite NDVI data. Sampling points were selected representing certain ecological regions. NDVI values were extracted from those points of composit NDVI images. According to results of the study carried out in the Central Anatolian rangelands, NDVI patterns are similar and vegetation starts green-up at the beginnig of March and NDVI reaches peak values on mid of May. NDVI reaches peak value mid of June in rangeland of Sivas province.