Hansen’s map of forest cover in the year 2000 was aggregated to 100 x 100 pixel grid squares. Within each of these square the number of pixels exceding the threshold of 50% estimated cover was counted. This was expressed as a percentage of the grid cell area. The number of pixels lost to deforestation was subbtracted in order to estimate intact forest cover within each cell for the year 2016
Grid cells with over 80% reaching or exceding the threshold values were then considered to be intact forest at this scale.
The cells were clumped to form polygons for which the area and perimeter of each polygon were calculated.The shape index was calculated using the fomula.
\(shape=\frac{perimeter} {4\sqrt area}\)
The core areas of each polygon were calculated by subtracting the area falling within a 1 km negative buffer from the polygon area.
## [1] TRUE