Vegetation indices, FAPAR and spatial seasonality analysis of crops in southern Sweden
2010
Jahan, Raunaq
Remote sensing is an extensively used technique in ecosystem monitoring or analyzing the carbon balance on the earth surface. The most dominant part of south west Skåne is agricultural land and MODIS derived Vegetation Indexes (VIs) are able to investigate the seasonality of crop fields. The values of VIs represent the different stages of spring greening up of crops and it shows the non-linear and strong relationship with groundmeasured fraction of absorbed photosynthetically active radiation (FAPAR). Crop productivity is related to absorbed radiation and there are some evident from previous studies which are able to provide relationship between VIs and Gross Primary Productivity (GPP). So, when the measured FAPAR describe more than 70% of NDVI (Normalized difference vegetation index) and WDRVI (Wide dynamic range vegetation index) of MODIS data, it is possible to monitor the productivity of crops through remote sensing tool. TIMESAT software was used to analyze graphical as well as image based vegetation indices and seasonality parameters. As there were two growing seasons in the study area, TIMESAT sometimes failed to cover the second season in seasonality analysis. Spatial analysis of crop phenology revealed dynamic for the area, and the phonological parameters varied according to VIs. Seasonality analysis for the four study area showed slight decreasing trend of the parameters in both indices, but image based spatial analysis was able to distinguish both increase and decrease of the parameters in different parts of south west Skåne. Spatial analysis of phenology requires more than one index results of an area to get less problematic results.
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