Delimitation of Homogeneous Zones in Vineyards Using Geostatistics and Multivariate Analysis of Different Vegetation Indices

Abstract

Vegetation indices (VIs) are quantitative measures used to describe the distribution and spatial variability of the vegetation cover of natural or cultivated areas. The aim of this study was to delimit homogeneous zones (HZs) of different VIs using geostatistics and multivariate analysis in order to identify vegetation patterns in Cabernet Franc and Cabernet Sauvignon vineyards. The evaluation was performed in two vineyards in the municipality of Espírito Santo do Pinhal in the state of São Paulo, Brazil. Reflectance (ρ) was measured at three wavelengths of the electromagnetic spectrum (670, 730, and 780 nm) at canopy height in georeferenced points along planting rows using the Crop Circle ACS-430 active sensor. Nine VIs were calculated based on the ratios between the ρ values. Geostatistical data analysis allowed the spatial prediction of VIs by ordinary kriging interpolation. Principal component analysis and fuzzy k-means clustering were applied for HZs delimitation and the optimal number of zones was defined according to cluster validity functions. Despite the variations of the VIs spatial distribution patterns, the multivariate analysis resulted in a representative categorization of the grapevine vegetative vigor and delimitation of HZs for this characteristic. This was validated according to the observed significant differences between VIs.

Remote and Proximal Sensing-Derived Spectral Indices and Biophysical Variables for Spatial Variation Determination in Vineyards

“…Moreover, the narrowband greenness VIs, such as NDRE, are combinations of reflectance measurements sensitive to the combined effects of foliage chlorophyll concentration, canopy leaf area, foliage clumping, and canopy architecture. Thus, it is apparent from the results that these parameters in our case in the specific vineyard field are not ideal to reach a satisfactory correlation [88].…”

Tree Health Condition in Urban Green Areas Assessed through Crown Indicators and Vegetation Indices

“…Also, the coefficient of variation (Equation ( 2)) of each vegetation index per crown was determined; this allows for a better comparison between indices, and it is a widely used measure in vegetation research that reflects the discrete degree of the data. The CVs were categorized into High and Low using the percentile ranges of >3rd percentile and <3rd percentile, respectively [35,47,48].…”