Nondestructive estimates of above‐ground biomass using terrestrial laser scanning

Abstract

Summary1. Allometric equations are currently used to estimate above-ground biomass (AGB) based on the indirect relationship with tree parameters. Terrestrial laser scanning (TLS) can measure the canopy structure in 3D with high detail. In this study, we develop an approach to estimate AGB from TLS data, which does not need any prior information about allometry. We compare these estimates against destructively harvested AGB estimates and AGB derived from allometric equations. We also evaluate tree parameters, diameter at breast height (DBH) and tree height, estimated from traditional field inventory and TLS data. 2. Tree height, DBH and AGB data are collected through traditional forest inventory, TLS and destructive sampling of 65 trees in a native Eucalypt Open Forest in Victoria, Australia. Single trees are extracted from the TLS data and quantitative structure models are used to estimate the tree volume directly from the point cloud data. AGB is inferred from these volumes and basic density information and is then compared with the estimates derived from allometric equations and destructive sampling. 3. AGB estimates derived from TLS show a high agreement with the reference values from destructive sampling, with a concordance correlation coefficient (CCC) of 0Á98. The agreement between AGB estimates from allometric equations and the reference is lower (CCC = 0Á68-0Á78). Our TLS approach shows a total AGB overestimation of 9Á68% compared to an underestimation of 36Á57-29Á85% for the allometric equations. 4. The error for AGB estimates using allometric equations increases exponentially with increasing DBH, whereas the error for AGB estimates from TLS is not dependent on DBH. The TLS method does not rely on indirect relationships with tree parameters or calibration data and shows better agreement with the reference data compared to estimates from allometric equations. Using 3D data also enables us to look at the height distributions of AGB, and we demonstrate that 80% of the AGB at plot level is located in the lower 60% of the trees for a Eucalypt Open Forest. This method can be applied in many forest types and can assist in the calibration and validation of broad-scale biomass maps.

Closing a gap in tropical forest biomass estimation: taking crown mass variation into account in pantropical allometries

“…We agree that such an effect cannot be completely ruled out, and it is probably all the more significant that trees ≥ 10 Mg represent only 3 % of the reference data set of Chave et al (2014). Collecting more field data on large trees should therefore constitute a priority if we are to improve multi-specific, broad-scale allometric models, and the recent development of nondestructive AGB estimation methods based on terrestrial lidar data should help in this regard (e.g., Calders et al, 2015). However, regardless of whether the nonlinear increase in crown mass ratio with tree mass held to a sampling artifact, we have shown that it was the source of systematic error in the reference model that used a unique geometric approximation with an average form factor for all trees.…”

Assessment of Aboveground Woody Biomass Dynamics Using Terrestrial Laser Scanner and L-Band ALOS PALSAR Data in South African Savanna

“…Despite being a relatively new field, TLS allows a rapid acquisition of 3-D data with various applications [20][21][22][23]. Similar to Lidar, TLS represents a non-destructive method of obtaining biomass estimates, however, unlike Lidar, which covers large areas, TLS data capture is restricted to only a few meters [24,25]. Given its ability to acquire data on the ground, it can be used for validation of other remote sensing datasets [17,19].…”

An overview of existing and promising technologies for national forest monitoring

“…Because of its high level of detail and accuracy, TLS has the potential to estimate in a standardized and automatic way tree diameters, tree height, tree volume, and thus tree biomass Hosoi et al 2013). This technology may constitute a great alternative to biomass destructive measurements and may improve considerably the local biomass estimates (Calders et al 2014). The analysis of such three-dimensional large datasets is still in progress, but several ongoing methodological developments should make this technology useful soon.…”

“…Here, we show that some new technologies, such as terrestrial LiDAR or stereo-photogrammetry may be a promising way to improve significantly tree volume or biomass estimation without any destructive measurement. For instance, large trees that contribute a large fraction of the overall forest biomass (Chave et al 2003) are difficult to measure through destructive sampling (Picard et al 2012), and terrestrial LiDAR could make the volume measurement easier (Calders et al 2014).…”