Mixed forests mensurationLooking for a tls data extraction methodology

Resumen

Mixed forests are increasingly important due to its bigger productivity regarding pure forests. Nevertheless this fact is barely tested with empirical data due the complexity of mixed forests. Terrestrial Laser Scanning (TLS) is a device relatively recent applied in forest research inventories, since it is able to provide us with the minimal error a view of the plots in 3D point clouds. However, the extraction of each measure is time consuming and in many cases, difficult. For this reason, is important to develop a methodology which speeds up the process so this tool starts to be profitable in professional forest managements. In this study we have developed a methodology combining several computer programs (Polyworks, CompuTree and Photoshop) that allows us to obtain data in a semi-automatic manner and objectively in a mixed stand of Pinus sylvestris and Quercus pyrenaica in northern Spain. Our data have been evaluated on 20 trees of each species adjusting basic predictive models of variable (Crown volume, Diameter at Breast Height (DBH), Crown ratio, and height at largest crown width) and expanded models to evaluate the effect of the mixture on the each dendrometric variables. The results show that through the methodology followed can be obtained good estimates of dendrometric studied variables (except the crown ratio) but not for the expanded models, possibly due to the small number of data. In addition, DBH TLS data were compared with caliper data by doing a simple linear regression, where non significance differences between them were found. Thanks to this work we have become familiar with the programs used in the data processing, which will allowingus to conduct future studies on this mixed stand and thus, deepen the understanding of the growth dynamics of mixed forests.