APAtree

Maps of the 'area potentially available' (APA) of trees is calculated from mapped forest stands using the approach from Gspaltl et al. (2012) doi:10.1093/forestry/cps052. This is done by computing a rasterized version of 'weighted voronoi diagrams' using a an approximation of the trees competitive ability (e.g., crown radius, leaf area) as weight. The main output are 'Raster*'- objects from the 'raster' package that are stored together with the raw data in apa_list's, the main class of the 'APAtree' package. Aggregation functions are provided to calculate stand characteristics based on APA-maps such as relative proportions according to APA-size and the neighborhood diversity index NDiv (Glatthorn (2021) doi:10.1016/j.ecolind.2021.108073).