COS 108-4 - Using terrestrial laser scanning to evaluate non-destructive aboveground biomass allometries in diverse Northern California forests

Abstract: A crucial part of carbon accounting is quantifying a tree’s aboveground biomass (AGB) using allometric equations, but species-specific equations are limited because data to inform these equations requires destructive harvesting of many trees which is difficult and time-consuming. Here, we use terrestrial laser scanning (TLS) to non-destructively estimate AGB of trees in Northern California and then compare these data to published allometric equations. We also used traditional forestry approaches to collect diameter at breast height (DBH) and height data for 553 trees from 5 species at 3 locations. For all trees, TLS scans were used to compare traditional and TLS measurements of DBH and height. For 319 of these trees, three-dimensional point clouds of trees were extracted from TLS scans and AGB was calculated using stem and branch volume estimates from quantitative structure models (QSMs). TLS QSM estimates of AGB were compared with AGB estimated from published allometric equations. TLS-based AGB, DBH, and height measured were then used to create new allometric equations. These new equations and their resulting AGB were compared to AGB of published allometric equations and AGB estimated directly from QSMs. TLS-based DBH and height were not significantly different to field inventory data (R²= 0.98 for DBH, R²= 0.95 for height) for all trees. Across all species, AGB calculated from TLS QSM volumes were approximately 20% greater than AGB estimates using published Forest Service’s Forest Inventory and Analysis Program equations. TLS AGB estimates were not significantly different from AGB estimates calculated using published equations, with the exception of Q. agrifolia. New allometric equations created using TLS data with DBH and height performed better than equations that only included DBH and matched most closely with AGB estimates generated from QSMs. When species are identified, TLS can be used as a method to rapidly estimate height, DBH, and AGB of multiple trees at a plot-level. We greatly expanded existing allometries for trees (both in species and forest type) for our region and created new TLS-based allometric equations for 5 species that may have important applications for AGB estimation over larger spatial scales.