Condition of tree crowns
Schwyzer, A., Hug, C., & Waldner, P. (2015). Condition of tree crowns. In A. Rigling, H. P. Schaffer, Federal Office for the Environment, & Swiss Federal Institute WSL (Eds.), Forest Report 2015. Condition and Use of Swiss Forests (pp. 50-51). Federal Office for the Environment (FOEN), Swiss Federal Institute for Forest, Snow and Landscape Research (WSL).