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

Ploton, Pierre; Barbier, Nicolas; Takoudjou, Stéphane Momo; Réjou‐Méchain, Maxime; Bosela, Faustin Boyemba; Chuyong, Georges; Dauby, Gilles; Droissart, Vincent; Fayolle, Adeline; Goodman, Rosa C.; Henry, Matieu; Kamdem, Narcisse Guy; Mukirania, John Katembo; Kenfack, David; Libalah, Moses; Ngomanda, Alfred; Rossi, Vivien; Sonké, Bonaventure; Texier, Nicolas; Thomas, Daniel; Zébazé, Donatien; Couteron, Pierre; Berger, Uta; Pélissier, Raphaël

doi:10.5194/bg-13-1571-2016

Cited by 76 publications

(75 citation statements)

References 57 publications

(83 reference statements)

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“…; Goodman, Phillips & Baker ; Ploton et al . ) . This study shows that a higher accuracy on biomass estimates might also be achieved by standardizing the diameter to D area130 on the existing biomass allometric equations.…”

Section: Discussionmentioning

confidence: 97%

Terrestrial photogrammetry: a non‐destructive method for modelling irregularly shaped tropical tree trunks

et al. 2016

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Summary Irregularly shaped trees including trees with buttresses, flutes or stilt roots are frequent in tropical forests. The lack of an international standard to measure the diameter of such trees leads to high uncertainties in biomass estimation, tree growth and carbon budget monitoring. In this study, we developed a new method based on terrestrial close‐range photogrammetry for measuring and modelling irregular stems. This approach is cheap and easy to implement in the field as it only requires a camera and a graduated rod. We validated the approach with destructive cross‐section measurements along the stem of three buttressed trees. To demonstrate the broader utility of this method, we extended the validated approach to 43 additional trees belonging to two species: Celtis mildbraedii (Ulmaceae) and Entandophragma cylindricum (Meliaceae). Based on the three dimensional models, we computed shape indices for each tree, and we analysed the stem morphology of the two species. Finally, we analysed some standardized predictors for the estimation of above‐ground biomass. We found a high concordance between diameters derived from the photogrammetric process and destructive diameter measurements along the stem for the three calibration trees. We found that C. mildbraedii develop much stronger irregularities than E. cylindricum. We also identified a large intraspecific variation in trunk morphology for E. cylindricum. The basal area at 1·3 m height (Darea130) seems to be a more robust predictor for biomass estimates (lowest Akaike information criterion and relative squared error) than diameter measured above buttresses (DAB) or diameter at breast height estimated from available taper model. Finally, Darea130 might be estimated with a good precision [root mean square error (RMSE) < 5%] with linear model based on the field measurements DAB and the perimeter of the convex hull of the buttresses at 1·3 m height (Dconvhull130). In this study, we showed the high potential of the photogrammetry for measuring and modelling irregular stems. Photogrammetry could then be used as a non‐destructive measurement tool to produce correction factors for standardizing the diameter of irregular stems at a reference height which is a key issue in tree growth monitoring and biomass change estimation.

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Section: Discussionmentioning

confidence: 97%

Terrestrial photogrammetry: a non‐destructive method for modelling irregularly shaped tropical tree trunks

et al. 2016

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“…Much work has been devoted to discussing how to adequately estimate individual AGB in trees (Brown, ; Chave et al, ; Feldpausch et al, ; Ketterings et al, ; Ploton et al, ). On the contrary, protocols for shrubs are not well developed (but see Chojnacky & Milton, ).…”

Section: Discussionmentioning

confidence: 99%

“…These results agree with Paul et al () and Jucker et al (), where the inclusion of site‐related factors (stand and climate characteristics) did not markedly improve the predictive ability of the allometric models, but the inclusion of plant architecture‐ or physiognomy‐type did. Varying bioforms or species’ architecture reflect different energy investment strategies likely to result in different crown–mass ratios among woody individuals with similar size (Ploton et al, ). Across our models, the effects of other bioclimatic variables (biome and GAI) significantly improved model fits particularly when height was not included in the model (Models 2 and 3).…”

Section: Discussionmentioning

confidence: 99%

Developing allometric models to predict the individual aboveground biomass of shrubs worldwide

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Zeballos

et al. 2019

Global Ecol Biogeogr

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Aim Existing global models to predict standing biomass are based on trees characterized by a single principal stem, well developed in height. However, their use in open woodlands and shrublands, characterized by multistemmed species with substantial crown development, generates a high level of uncertainty in biomass estimates. This limitation led us to (a) develop global models of shrub individual aboveground biomass based on simple allometric variables, (b) to compare the fit of these models with existing global biomass models, and (c) to assess whether models fit change when bioclimatic variables are considered. Location Global. Time period Present. Major taxa studied 118 species of shrubs. Methods We compile a database of 3,243 individuals across 49 sites distributed worldwide. Including stem basal diameter, height and crown diameter as predictor variables, we built potential models and compared their fit using generalized least squares. We used mixed effects models to determine if bioclimatic variables improved the accuracy of biomass models. Results Although the most important variable in terms of predictive capacity was stem basal diameter, crown diameter significantly improved the models’ fit, followed by height. Four models were finally chosen, with the best model combining all these variables in the same equation [R2 = 0.930, root mean square error (RMSE) = 0.476]. Selected models performed as well as established global biomass models. Including the individual bioform significantly improved the models’ fit. Main conclusions Stem basal diameter, crown diameter and height measures could be combined to provide robust aboveground biomass (AGB) estimates of individual shrub species. Our study supplements well‐established models developed for trees, allowing more accurate biomass estimation of multistemmed woody individuals. We further provide tools for a methodological standardization of individual biomass quantification in these species. We expect these results contribute to improve the quality of biomass estimates across ecosystems, but also to generate methodological consensus on field biomass assessments in shrubs.

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“…The latter are calibrated on destructive datasets and combine easily as measurable tree descriptors—typically diameter at breast height (DBH), tree height (H) and wood density (WD)—to derive tree AGB estimate. Calibrating an AGB model requires to account for a number of factors known to affect allometric relationships, such as tree architecture (Goodman, Phillips, & Baker, ; Ploton et al., ), species wood density (e.g. Bastin, Fayolle, et al., ; Chave et al., , ; Zanne et al., ), edaphic and climatic contraints (e.g.…”

Section: Introductionmentioning

confidence: 99%

Using terrestrial laser scanning data to estimate large tropical trees biomass and calibrate allometric models: A comparison with traditional destructive approach

et al. 2017

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Calibration of local, regional or global allometric equations to estimate biomass at the tree level constitutes a significant burden on projects aiming at reducing Carbon emissions from forest degradation and deforestation. The objective of this contribution is to assess the precision and accuracy of Terrestrial Laser Scanning (TLS) for estimating volumes and above‐ground biomass (AGB) of the woody parts of tropical trees, and for the calibration of allometric models. We used a destructive dataset of 61 trees, with diameters and AGB of up to 186.6 cm and 60 Mg respectively, which were scanned, felled and weighed in the semi‐deciduous forests of eastern Cameroon. We present an operational approach based on available software allowing the retrieving of TLS volume with low bias and high accuracy for large tropical trees. Edition of the obtained models proved necessary, mainly to account for the complexity of buttressed parts of tree trunks, which were separately modelled through a meshing approach, and to bring a few corrections in the topology and geometry of branches, thanks to the amapstudio‐scan software. Over the entire dataset, TLS‐derived volumes proved highly reliable for branches larger than 5 cm in diameter. The volumes of the remaining woody parts estimated for stumps, stems and crowns as well as for the whole tree proved very accurate (RMSE below 2.81% and R² above of .98) and unbiased. Once converted into AGB using mean local‐specific wood density values, TLS estimates allowed calibrating a biomass allometric model with coefficients statistically undistinguishable from those of a model based on destructive data. The Unedited Quantitative Structure Model (QSM) however leads to systematic overestimations of woody volumes and subsequently to significantly different allometric parameters. We can therefore conclude that a non‐destructive TLS approach can now be used as an operational alternative to traditional destructive sampling to build the allometric equations, although attention must be paid to the quality of QSM model adjustments to avoid systematic bias.

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

Cited by 76 publications

References 57 publications

Terrestrial photogrammetry: a non‐destructive method for modelling irregularly shaped tropical tree trunks

Terrestrial photogrammetry: a non‐destructive method for modelling irregularly shaped tropical tree trunks

Developing allometric models to predict the individual aboveground biomass of shrubs worldwide

Using terrestrial laser scanning data to estimate large tropical trees biomass and calibrate allometric models: A comparison with traditional destructive approach

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