Developing Allometric Equations for Teak Plantations Located in the Coastal Region of Ecuador from Terrestrial Laser Scanning Data

Traditional studies aimed at developing allometric models to estimate dry above-ground biomass (AGB) and other tree-level variables, such as tree stem commercial volume (TSCV) or tree stem volume (TSV), usually involves cutting down the trees. Although this method has low uncertainty, it is quite costly and inefficient since it requires a very time-consuming field work. In order to assist in data collection and processing, remote sensing is allowing the application of non-destructive sampling methods such as that based on terrestrial laser scanning (TLS). In this work, TLS-derived point clouds were used to digitally reconstruct the tree stem of a set of teak trees (Tectona grandis Linn. F.) from 58 circular reference plots of 18 m radius belonging to three different plantations located in the Coastal Region of Ecuador. After manually selecting the appropriate trees from the entire sample, semi-automatic data processing was performed to provide measurements of TSCV and TSV, together with estimates of AGB values at tree level. These observed values were used to develop allometric models, based on diameter at breast height (DBH), total tree height (h), or the metric DBH2 × h, by applying a robust regression method to remove likely outliers. Results showed that the developed allometric models performed reasonably well, especially those based on the metric DBH2 × h, providing low bias estimates and relative RMSE values of 21.60% and 16.41% for TSCV and TSV, respectively. Allometric models only based on tree height were derived from replacing DBH by h in the expression DBH2 x h, according to adjusted expressions depending on DBH classes (ranges of DBH). This finding can facilitate the obtaining of variables such as AGB (carbon stock) and commercial volume of wood over teak plantations in the Coastal Region of Ecuador from only knowing the tree height, constituting a promising method to address large-scale teak plantations monitoring from the canopy height models derived from digital aerial stereophotogrammetry.

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ESTIMATING SINGLE TREE STEM AND BRANCH BIOMASS USING TERRESTRIAL LASER SCANNING

Jurnal Teknologi ◽

10.11113/jt.v77.6860 ◽

2015 ◽

Vol 77 (26) ◽

Cited By ~ 2

Author(s):

Nurliyana Izzati Ishak ◽

Md Afif Abu Bakar ◽

Muhammad Zulkarnain Abdul Rahman ◽

Abd Wahid Rasib ◽

Kasturi Devi Kanniah ◽

...

Keyword(s):

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Stem Volume ◽

Biomass Estimation ◽

Forest Plot ◽

Individual Tree ◽

Matching Process ◽

Branch Biomass ◽

Individual Trees ◽

Tree Stem

This paper presents a novel non-destructive approach for individual tree stem and branch biomass estimation using terrestrial laser scanning data. The study area is located at the Royal Belum Reserved Forest area, Gerik, Perak. Each forest plot was designed with a circular shape and contains several scanning locations to ensure good visibility of each tree. Unique tree signage was located on trees with diameter at breast height (DBH) of 10cm and above. Extractions of individual trees were done manually and the matching process with the field collected tree properties were relied on the tree signage and tree location as collected by total station. Individual tree stems were reconstructed based on cylinder models from which the total stem volume was calculated. Biomass of individual tree stems was calculated by multiplying stem volume with specific wood density. Biomass of individual was estimated using similar concept of tree stem with the volume estimated from alpha-hull shape. The root mean squared errors (RMSE) of estimated biomass are 50.22kg and 27.20kg for stem and branch respectively.

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Reliable Estimates of Merchantable Timber Volume from Terrestrial Laser Scanning

Remote Sensing ◽

10.3390/rs13183610 ◽

2021 ◽

Vol 13 (18) ◽

pp. 3610

Author(s):

Dimitrios Panagiotidis ◽

Azadeh Abdollahnejad

Keyword(s):

Laser Scanning ◽

Accurate Determination ◽

Laser Scanner ◽

Terrestrial Laser Scanning ◽

Tree Height ◽

Tree Level ◽

Consensus Method ◽

Field Methods ◽

Forest Inventories ◽

Random Sampling Consensus

Simple and accurate determination of merchantable tree height is needed for accurate estimations of merchantable volume. Conventional field methods of forest inventory can lead to biased estimates of tree height and diameter, especially in complex forest structures. Terrestrial laser scanner (TLS) data can be used to determine merchantable height and diameter at different heights with high accuracy and detail. This study focuses on the use of the random sampling consensus method (RANSAC) for generating the length and diameter of logs to estimate merchantable volume at the tree level using Huber’s formula. For this study, we used two plots; plot A contained deciduous trees and plot B consisted of conifers. Our results demonstrated that the TLS-based outputs for stem modelling using the RANSAC method performed very well with low bias (0.02 for deciduous and 0.01 for conifers) and a high degree of accuracy (97.73% for deciduous and 96.14% for conifers). We also found a high correlation between the proposed method and log length (−0.814 for plot A and −0.698 for plot B), which is an important finding because this information can be used to determine the optimum log properties required for analyzing stem curvature changes at different heights. Furthermore, the results of this study provide insight into the applicability and ergonomics during data collection from forest inventories solely from terrestrial laser scanning, thus reducing the need for field reference data.

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Nondestructive Tree Stem and Crown Volume Allometry in Hybrid Poplar Plantations Derived from Terrestrial Laser Scanning

Forest Science ◽

10.1093/forsci/fxaa021 ◽

2020 ◽

Vol 66 (6) ◽

pp. 737-746

Author(s):

Francesco Chianucci ◽

Nicola Puletti ◽

Mirko Grotti ◽

Carlotta Ferrara ◽

Achille Giorcelli ◽

...

Keyword(s):

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Stem Volume ◽

Tree Crown ◽

Crown Volume ◽

Tree Inventory ◽

Entry Models ◽

Poplar Plantations ◽

Volume Estimates ◽

Tree Stem

Abstract Accurate and frequently updated tree volume estimates are required for poplar plantations, which are characterized by fast growth rate and short rotation. In this study, we tested the potential of terrestrial laser scanning (TLS) as a reliable method for developing nondestructive tree volume allometries in poplar plantations. The trial was conducted in Italy, where 4- to 10-year-old hybrid plantations were sampled to develop tree crown volume allometry in leaf-on conditions, tree stem volume, and height-diameter allometries in leaf-off conditions. We tested one-entry models based on diameter and two-entry models based on both diameter and height. Model performance was assessed by residual analysis. Results indicate that TLS can provide accurate models of tree stem and crown volume, with percentage of root-mean-square error of about 20 percent and 15 percent, respectively. The inclusion of height does not bring relevant improvement in the models, so that only diameter can be used to predict tree stem and crown volume. The TLS-measured stem volume estimates agreed with an available formula derived from harvesting. We concluded that TLS is a reliable method for developing nondestructive volume allometries in poplar plantations and holds great potential to enhance conventional tree inventory and monitoring. Study Implications: Terrestrial laser scanning (TLS) is a technique that allows nondestructive measurement of the three-dimensional structure of a tree with high precision and low cost. The ability of TLS to measure both tree crown volume and tree position can be effective to test optimal spacing requirements and also to test innovative schemes such as mixed or polycyclic poplar plantations. The spatially explicit nature of TLS measurements allows better integration with different remotely sensed sensors, which can be used in combination with TLS, enabling a multiscale assessment of poplar plantation structure with different levels of detail, enhancing conventional tree inventory and supporting effective management strategies.

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Exploring the Variability of Tropical Savanna Tree Structural Allometry with Terrestrial Laser Scanning

Remote Sensing ◽

10.3390/rs12233893 ◽

2020 ◽

Vol 12 (23) ◽

pp. 3893

Author(s):

Linda Luck ◽

Lindsay B. Hutley ◽

Kim Calders ◽

Shaun R. Levick

Keyword(s):

Laser Scanning ◽

3D Structure ◽

Terrestrial Laser Scanning ◽

Tree Height ◽

Tree Architecture ◽

Allometric Equations ◽

Environmental Research ◽

Tree Level ◽

Individual Tree ◽

Monitoring Programs

Individual tree carbon stock estimates typically rely on allometric scaling relationships established between field-measured stem diameter (DBH) and destructively harvested biomass. The use of DBH-based allometric equations to estimate the carbon stored over larger areas therefore, assumes that tree architecture, including branching and crown structures, are consistent for a given DBH, and that minor variations cancel out at the plot scale. We aimed to explore the degree of structural variation present at the individual tree level across a range of size-classes. We used terrestrial laser scanning (TLS) to measure the 3D structure of each tree in a 1 ha savanna plot, with coincident field-inventory. We found that stem reconstructions from TLS captured both the spatial distribution pattern and the DBH of individual trees with high confidence when compared with manual measurements (R2 = 0.98, RMSE = 0.0102 m). Our exploration of the relationship between DBH, crown size and tree height revealed significant variability in savanna tree crown structure (measured as crown area). These findings question the reliability of DBH-based allometric equations for adequately representing diversity in tree architecture, and therefore carbon storage, in tropical savannas. However, adoption of TLS outside environmental research has been slow due to considerable capital cost and monitoring programs often continue to rely on sub-plot monitoring and traditional allometric equations. A central aspect of our study explores the utility of a lower-cost TLS system not generally used for vegetation surveys. We discuss the potential benefits of alternative TLS-based approaches, such as explicit modelling of tree structure or voxel-based analyses, to capture the diverse 3D structures of savanna trees. Our research highlights structural heterogeneity as a source of uncertainty in savanna tree carbon estimates and demonstrates the potential for greater inclusion of cost-effective TLS technology in national monitoring programs.

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THE EFFECT OF WIND ON TREE STEM PARAMETER ESTIMATION USING TERRESTRIAL LASER SCANNING

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-annals-iii-8-117-2016 ◽

2016 ◽

Vol III-8 ◽

pp. 117-122 ◽

Cited By ~ 2

Author(s):

M. T. Vaaja ◽

J.-P. Virtanen ◽

M. Kurkela ◽

V. Lehtola ◽

J. Hyyppä ◽

...

Keyword(s):

Parameter Estimation ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Tree Height ◽

Individual Tree ◽

Finnish Meteorological Institute ◽

Wind Speeds ◽

Forest Inventories ◽

Level Data ◽

Tree Stem

The 3D measurement technique of terrestrial laser scanning (TLS) in forest inventories has shown great potential for improving the accuracy and efficiency of both individual tree and plot level data collection. However, the effect of wind has been poorly estimated in the error analysis of TLS tree measurements although it causes varying deformations to the trees. In this paper, we evaluated the effect of wind on tree stem parameter estimation at different heights using TLS. The data consists of one measured Scots pine captured from three different scanning directions with two different scanning resolutions, 6.3 mm and 3.1 mm at 10 m. The measurements were conducted under two different wind speeds, approximately 3 m/s and 9 m/s, as recorded by a nearby weather station of the Finnish Meteorological Institute. Our results show that the wind may cause both the underestimation and overestimation of tree diameter when using TLS. The duration of the scanning is found to have an impact for the measured shape of the tree stem under 9 m/s wind conditions. The results also indicate that a 9 m/s wind does not have a significant effect on the stem parameters of the lower part of a tree (<28% of the tree height). However, as the results imply, the wind conditions should be taken into account more comprehensively in analysis of TLS tree measurements, especially if multiple scans from different positions are registered together. In addition, TLS could potentially be applied to indirectly measure wind speed by observing the tree stem movement.

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THE EFFECT OF WIND ON TREE STEM PARAMETER ESTIMATION USING TERRESTRIAL LASER SCANNING

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsannals-iii-8-117-2016 ◽

2016 ◽

Vol III-8 ◽

pp. 117-122 ◽

Cited By ~ 6

Author(s):

M. T. Vaaja ◽

J.-P. Virtanen ◽

M. Kurkela ◽

V. Lehtola ◽

J. Hyyppä ◽

...

Keyword(s):

Parameter Estimation ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Tree Height ◽

Individual Tree ◽

Finnish Meteorological Institute ◽

Wind Speeds ◽

Forest Inventories ◽

Level Data ◽

Tree Stem

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Comparison of Backpack, Handheld, Under-Canopy UAV, and Above-Canopy UAV Laser Scanning for Field Reference Data Collection in Boreal Forests

Remote Sensing ◽

10.3390/rs12203327 ◽

2020 ◽

Vol 12 (20) ◽

pp. 3327 ◽

Cited By ~ 1

Author(s):

Eric Hyyppä ◽

Xiaowei Yu ◽

Harri Kaartinen ◽

Teemu Hakala ◽

Antero Kukko ◽

...

Keyword(s):

Data Collection ◽

Point Cloud ◽

Laser Scanning ◽

Reference Data ◽

Tree Height ◽

Tree Level ◽

Stem Volume ◽

Point Cloud Data ◽

Cloud Data ◽

Individual Trees

In this work, we compared six emerging mobile laser scanning (MLS) technologies for field reference data collection at the individual tree level in boreal forest conditions. The systems under study were an in-house developed AKHKA-R3 backpack laser scanner, a handheld Zeb-Horizon laser scanner, an under-canopy UAV (Unmanned Aircraft Vehicle) laser scanning system, and three above-canopy UAV laser scanning systems providing point clouds with varying point densities. To assess the performance of the methods for automated measurements of diameter at breast height (DBH), stem curve, tree height and stem volume, we utilized all of the six systems to collect point cloud data on two 32 m-by-32 m test sites classified as sparse (n = 42 trees) and obstructed (n = 43 trees). To analyze the data collected with the two ground-based MLS systems and the under-canopy UAV system, we used a workflow based on our recent work featuring simultaneous localization and mapping (SLAM) technology, a stem arc detection algorithm, and an iterative arc matching algorithm. This workflow enabled us to obtain accurate stem diameter estimates from the point cloud data despite a small but relevant time-dependent drift in the SLAM-corrected trajectory of the scanner. We found out that the ground-based MLS systems and the under-canopy UAV system could be used to measure the stem diameter (DBH) with a root mean square error (RMSE) of 2–8%, whereas the stem curve measurements had an RMSE of 2–15% that depended on the system and the measurement height. Furthermore, the backpack and handheld scanners could be employed for sufficiently accurate tree height measurements (RMSE = 2–10%) in order to estimate the stem volumes of individual trees with an RMSE of approximately 10%. A similar accuracy was obtained when combining stem curves estimated with the under-canopy UAV system and tree heights extracted with an above-canopy flying laser scanning unit. Importantly, the volume estimation error of these three MLS systems was found to be of the same level as the error corresponding to manual field measurements on the two test sites. To analyze point cloud data collected with the three above-canopy flying UAV systems, we used a random forest model trained on field reference data collected from nearby plots. Using the random forest model, we were able to estimate the DBH of individual trees with an RMSE of 10–20%, the tree height with an RMSE of 2–8%, and the stem volume with an RMSE of 20–50%. Our results indicate that ground-based and under-canopy MLS systems provide a promising approach for field reference data collection at the individual tree level, whereas the accuracy of above-canopy UAV laser scanning systems is not yet sufficient for predicting stem attributes of individual trees for field reference data with a high accuracy.

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Analysis of stand density effects on the stem form of Norway spruce trees and volume miscalculation by traditional form factor equations using terrestrial laser scanning (TLS)

Canadian Journal of Forest Research ◽

10.1139/cjfr-2019-0121 ◽

2020 ◽

Vol 50 (1) ◽

pp. 51-64 ◽

Cited By ~ 3

Author(s):

Martin Jacobs ◽

Andreas Rais ◽

Hans Pretzsch

Keyword(s):

Form Factor ◽

Norway Spruce ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Volume Estimation ◽

Tree Level ◽

Stem Volume ◽

Stem Form ◽

Stem Wood ◽

Volume Estimates

Tree and stand volume estimates are relevant for forest inventories, forest sales, and carbon stock evaluations. Forest practice commonly uses generalized stem-wood volume functions; however, such generalized approaches neglect the stem form in detail. Hence, trees of a given species with the same diameter at breast height (d1.3) and height (h) are always assumed to have the same form factor and thus the same volume. This case study focused on stem form variation of Norway spruce (Picea abies (L.) Karst.) due to competition effects. Using terrestrial laser scanning (TLS), we measured the stem shape of 868 trees from a long-term spacing and thinning experiment in Germany. The plots covered a broad density range. We analysed the effect of competition and compared the TLS-determined stem volume estimates with those determined conventionally. TLS-based volume estimations showed that the lower the competition was, the lower the tree volume was with a given d1.3 and h. Commonly used functions underestimated the volume stock overall by 4.2%, disregarding any levels. At plot level, underestimation varied from 0.7% to 7.0%. At tree level, the volume was under- and over-estimated by −10% to +10%, respectively. The more precise the examination was, the more suitable the application of TLS was for enhancing volume estimation.

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Combining tree height samples produced by airborne laser scanning and stand management records to estimate plot volume in Eucalyptus plantations

Canadian Journal of Forest Research ◽

10.1139/x11-083 ◽

2011 ◽

Vol 41 (8) ◽

pp. 1649-1658 ◽

Cited By ~ 18

Author(s):

Jari Vauhkonen ◽

Lauri MehtÄtalo ◽

Petteri Packalén

Keyword(s):

Laser Scanning ◽

Tree Height ◽

Small Sample ◽

Airborne Laser Scanning ◽

Tree Level ◽

Stem Volume ◽

Data Set ◽

Stand Management ◽

Tree Detection ◽

Airborne Laser

Regular stand structure and availability of precise silvicultural management data produce a special situation regarding remote sensing based assessments of plantation forests. This study tested the use of stand management records to improve single-tree detection in a Eucalyptus plantation. Combined airborne laser scanning (ALS) and planting distance data were used to detect trees and extract their heights. The extracted heights were used as an input for volume estimation using both existing plot-level functions and new tree-level models. The accuracies were evaluated in a test data set of 191 field reference plots in which the diameters of the Eucalyptus urograndis (E. grandis (Hill) Maiden × E. urophylla S.T. Blake) trees varied from 6 to 41 cm and tree heights varied from 12 to 41 m. The constructed mixed-effects model that predicted stem volume from tree height resulted in a root mean squared error (RMSE) of 68 dm3 (15%) in a cross validation of the modeling data. The tree detection produced estimates of stem number with low bias (i.e., average difference between measured and estimated) and an RMSE of 6% of the mean, whereas plot-level mean and dominant heights were estimated with RMSEs of 1.5 m (5%) and 2 m (6%), respectively, using ALS data alone. The difference of about 60 cm observed between the ALS-based and field-measured dominant height was most likely caused by the penetration of the laser pulses through the canopy. A system of plot-level models that employed a small sample of calibration field data gave RMSEs of 1 m (3%) and 2.2 m2/ha (9%) for site index and basal area, respectively. The plot volume was estimated with an RMSE of 44 m3/ha (12%) at best. A similar residual variation was observed in the volume estimates of an area-based method applied to the same data set. The combined results suggest the feasibility of the proposed methodology in a plantation inventory using ALS data with a density of only 1.5 pulses/m2.

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Forest aboveground volume assessments with terrestrial laser scanning: a ground-truth validation experiment in temperate, managed forests

Annals of Botany ◽

10.1093/aob/mcab110 ◽

2021 ◽

Author(s):

Miro Demol ◽

Kim Calders ◽

Hans Verbeeck ◽

Bert Gielen

Keyword(s):

Laser Scanning ◽

Basic Density ◽

Terrestrial Laser Scanning ◽

Ground Truth ◽

Stem Volume ◽

Calibration Data ◽

Ground Truth Data ◽

Allometric Models ◽

Volumetric Errors ◽

Validation Experiment

Abstract Background and Aims Quantifying the Earth’s forest aboveground biomass (AGB) is indispensable for effective climate action and developing forest policy. Yet, current allometric scaling models (ASM) to estimate AGB suffer several drawbacks related to model selection and calibration data traceability uncertainties. Terrestrial laser scanning (TLS) offers a promising non-destructive alternative. Tree volume is reconstructed from TLS point clouds with Quantitative Structure Models (QSM) and converted to AGB with wood basic density. Earlier studies have found overall TLS-derived forest volume estimates to be accurate, but highlighted problems for reconstructing finer branches. Our objective was to evaluate TLS for estimating tree volumes by comparison with reference volumes and volumes from ASMs. Methods We quantified the woody volume of 65 trees in Belgium (77 – 2.800 L; Pinus sylvestris, Fagus sylvatica, Larix decidua, Fraxinus excelsior) with QSMs and destructive reference measurements. We tested a volume expansion factor (VEF) approach by multiplying the solid and merchantable volume from QSM with literature VEF values. Key Results Stem volume was reliably estimated with TLS. Total volume was overestimated by +21% using original QSMs, by +9% and -12% using two sets of VEF-augmented QSMs, and by -7.3% using best-available allometric models. The most accurate method differed per site, and the prediction errors for each method varied considerably between sites. Conclusions VEF-augmented QSMs were only slightly better than original QSMs for estimating tree volume for common species in temperate forests. Despite satisfying estimates with ASMs, the model choice was a large source of uncertainty, and species-specific models did not always exist. Therefore, we advocate for further improving tree volume reconstructions with QSMs, especially for fine branches, instead of collecting more ground-truth data to calibrate VEF and allometric models. Promising developments such as improved coregistration and smarter filtering approaches are ongoing to further constrain volumetric errors in TLS-derived estimates.

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