A multi-temporal masking classification method for vineyard monitoring in central Spain

This paper includes the mapping of cultivated areas (vineyards) in the experimental zone of the EFEDA project, where vineyard crop is the dominant one. The study area is located in central Spain with a surface area of about 10 km x 10 km and showing important desertification hazards. The objective of the paper is to establish the mapping of vineyard areas by remote sensing techniques and to establish relationships between the spectral signature and agronomical parameters (biomass, percent of cover, etc.). For these objectives, several vegetation classes have been defined (vineyards, cereals, fallow, olives and forest) and multi-temporal Landsat-5 Thematic Mapper images were used with the maximum likelihood classification method and masking techniques. The results were checked by ground truth and by existing vegetation cover maps (1: 25 000) and show in general a good correspondence between both information sources. Moreover, these results have permitted to define new vineyard categories like abandoned vineyards and young vineyards that explain the difference between the classification results for vineyards and the ground truth. The later stage of the study pays special attention to the correlation of the agronomical parameters, such as the height of the crop and biomass with the spectral signature of the vineyards represented by the normalized index NDVI, using multi-temporal Landsat images between May and July that comprehend the phenological evolution of the vineyards. Good correlation coefficients (r=0.86 and r=0.90) were obtained successively for the biomass, height and (r=0.82) for the vegetation cover surface. Finally, maps representing the spatial distribution of these parameters were generated for 14 July (period of time when the vineyard is most developed) using the adjustment previously obtained between the NDVI of the vineyard and these parameters.