The area potentially available of trees is calculated from mapped forest stands. 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 the most important stand characteristics based on APA-maps.
Currently, only installation from github is possible
After Installing, see the package Vignette for details (vignette("APAtree-vignette", package = "APAtree"))
Additionally, the scripts to produce some of the Figures in Glatthorn (accepted) can be found in the folder paste0(path.package("APAtree"), "/glatthorn_2021").
Glatthorn, Jonas (2021). A spatially explicit index for tree species or trait diversity at neighborhood and stand level. Ecological Indicators, 130, 108073. https://doi.org/10.1016/j.ecolind.2021.108073.
Gspaltl, M., Sterba, H., & O’hara, K. L. (2012). The relationship between available area efficiency and area exploitation index in an even-aged coast redwood (Sequoia sempervirens) stand. Forestry, 85(5), 567-577.
Römisch,K. (1995) Durchmesserwachstum und ebene Bestandesstruktur am Beispiel der Kiefernversuchsfläche Markersbach. In Deutscher Verband forstl. Forschungsanstalten, Sektion Biometrie und Informatik. Gottfried Hempel (ed.) Tagung Tharanth/Grillenburg, Vol. 8, pp. 84–103.