1. Institute of Silviculture, University of Natural Resources and Life Sciences, Vienna (BOKU); Peter-Jordan-Strasse 82, A-1190 Vienna, Austria
2. Institute of Surveying, Remote Sensing and Land Information (IVFL), University of Natural Resources and Life Sciences, Vienna (BOKU); Peter-Jordan-Strasse 82, A-1190 Vienna, Austria
3. Independent Researcher. 5 Via Nobile, 35020 Legnaro, Padova, Italy
4. Kenya Forestry Research Institute, PO Box 20412, Nairobi, Kenya