@article{fdi:010083312,
  title = {{A} 3{D} approach to model the taper of irregular tree stems : making plots biomass estimates comparable in tropical forests},
  author = {{B}auwens, {S}. and {P}loton, {P}ierre and {F}ayolle, {A}. and {L}igot, {G}. and {L}oumeto, {J}. {J}. and {L}ejeune, {P}. and {G}ourlet-{F}leury, {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n tropical forests, the high proportion of trees showing irregularities at the stem base complicates forest monitoring. {F}or example, in the presence of buttresses, the height of the point of measurement ({H}-{POM}) of the stem diameter ({D}-{POM}) is raised from 1.3 m, the standard breast height, up to a regular part of the stem. {W}hile {D}-{POM} is the most important predictor for tree aboveground biomass ({AGB}) estimates, the lack of harmonized {H}-{POM} for irregular trees in forest inventory increases the uncertainty in plot-level {AGB} stock and stock change estimates. {I}n this study, we gathered an original non-destructive three-dimensional (3{D}) data set collected with terrestrial laser scanning and close range terrestrial photogrammetry tools in three sites in central {A}frica. {F}or the 228 irregularly shaped stems sampled, we developed a set of taper models to harmonize {H}-{POM} by predicting the equivalent diameter at breast height ({DBH} ') from a {D}-{POM} measured at any height. {W}e analyzed the effect of using {DBH} ' on tree-level and plot-level {AGB} estimates. {T}o do so, we used destructive {AGB} data for 140 trees and forest inventory data from eight 1-ha plots in the {R}epublic of {C}ongo. {O}ur results showed that our best simple taper model predicts {DBH} ' with a relative mean absolute error of 3.7% ({R}-2 = 0.98) over a wide {D}-{POM} range of 17-249 cm. {B}ased on destructive {AGB} data, we found that the {AGB} allometric model calibrated with harmonized {H}-{POM} data was more accurate than the conventional local and pantropical models. {A}t the plot level, the comparison of {AGB} stock estimates with and without {H}-{POM} harmonization showed an increasing divergence with the increasing share of irregular stems (up to -15%). {T}he harmonization procedure developed in this study could be implemented as a standard practice for {AGB} monitoring in tropical forests as no additional forest inventory measurements is required. {T}his would probably lead to important revisions of the {AGB} stock estimates in regions having a large number of irregular tree stems and increase their carbon sink estimates. {T}he growing use of three-dimensional (3{D}) data offers new opportunities to extend our approach and further develop general taper models in other tropical regions.},
  keywords = {allometric aboveground biomass model ; biomass changes ; buttresses ; close-range terrestrial photogrammetry ; point of measurement of stem ; diameter ; stem profile ; structure from motion ; taper ; terrestrial laser ; scanning ; {CONGO} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{E}cological {A}pplications},
  volume = {31},
  numero = {8},
  pages = {e02451 [12 ]},
  ISSN = {1051-0761},
  year = {2021},
  DOI = {10.1002/eap.2451},
  URL = {https://www.documentation.ird.fr/hor/fdi:010083312},
}