Using stationary and mobile laser scanner to detect forest defoliation.

We present results from a terrestrial laser scanner (TLS) and mobile mapping system (MMS) based investigation on forest defoliation caused by the European pine sawfly (Neodiprion sertifer) in a Scots pine dominated forest. The TLS and MMS results are compared with simultaneous visual estimation of the defoliation intensity as percentage of needle loss in the living crown. The capability of TLS of deriving changes on the standing tree biomass and defoliation degree was also confirmed by destructive, consecutive defoliation operations in laboratory. The biomass of the tree was measured simultaneously with the TLS measurements. The point cloud agreed with standing biomass with 92-99% coefficient of determination implying that terrestrial laser can be a powerful tool for biomass change reporting, and thus, usable for defoliation measurement.