1. Tartu Observatory , University of Tartu , Tõravere , Tartumaa , Estonia
2. Institute of Forestry and Rural Engineering , Estonian University of Life Sciences , Kreutzwaldi 5 , Tartu , Estonia
3. Forest Department , Estonian Environment Agency , Mustamäe tee 33 , Tallinn , Estonia
4. Institute of Mathematics and Statistics , University of Tartu , Narva mnt 18 , Tartu , Estonia
5. Reach-U , Riia 24 , Tartu , Estonia