Use of LiDAR data during multi-annual periods for estimating forestry variables

Abstract

Aim of study: To test the use of LiDAR data from a single acquisition in order to estimate volume over_bark variations in a 5-yr period of Pinus radiata D. Don. Area of study: Province of Bizkaia in the Autonomous Community of the Basque Country (Spain). Material and methods: Two field plot measurements were made in 2011 and 2015 and two wood volume models (one for each year) were fitted using the metric variables of the 2012 LiDAR points cloud. The models were applied to a 26.59 m raster covering the study area and the increase in volume at each pixel was calculated by subtraction. Main results: The increase in estimated wood volume, when added to the volume of timber extracted in the area during the 5-yr period under consideration, yielded an average increase of 13.74 m3 ha-1 yr-1, which corresponds to the average growth of the P. radiata in that area. The harvest area estimated using this procedure largely coincides with the actual harvest area in the same period. The value of R2 (85%) of the wood volume model for 2011 is similar to that obtained in other studies. However, as expected, the one obtained for the wood volume model for 2015 (80%) is significantly lower. Research highlights: The increase in wood volume can be estimated using a single LiDAR flight and field data from the 5-yr period provided that data from plots subjected to this kind of harvest is included in the models.