Computation of the 'Area Potentially Available' (APA) to Trees

Maps of the 'area potentially available' (APA) of trees is calculated from mapped forest stands using the approach from Gspaltl et al. (2012) . 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) ).

APAtree

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.

Install

Currently, only installation from github is possible

library(devtools)
install_github("JonasGlatthorn/APAtree")

Documentation

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").

References

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.