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

CONTI, G.; GORNÉ, L. D.; ZEBALLOS, S. R.; LIPOMA, M. L.; GATICA, G.; KOWALJOW, E.; WHITWORTH?HULSE, J. I.; CUCHIETTI, A.; POCA, M.; PESTONI, S.; FERNANDES, P. M.

Global Ecology and Biogeography

WILEY-BLACKWELL PUBLISHING, INC

Año: 2019

1466-822X

Aim: Existing global models to predict standing biomass are based on trees characterizedby a single principal stem, well developed in height. However, their use inopen woodlands and shrublands, characterized by multistemmed species with substantialcrown development, generates a high level of uncertainty in biomass estimates.This limitation led us to (a) develop global models of shrub individualaboveground biomass based on simple allometric variables, (b) to compare the fit ofthese models with existing global biomass models, and (c) to assess whether modelsfit 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 distributedworldwide. Including stem basal diameter, height and crown diameter as predictorvariables, we built potential models and compared their fit using generalized leastsquares. We used mixed effects models to determine if bioclimatic variables improvedthe accuracy of biomass models.Results: Although the most important variable in terms of predictive capacity wasstem basal diameter, crown diameter significantly improved the models? fit, followedby height. Four models were finally chosen, with the best model combining all thesevariables in the same equation [R2 = 0.930, root mean square error (RMSE) = 0.476].Selected models performed as well as established global biomass models. Includingthe individual bioform significantly improved the models? fit.Main conclusions: Stem basal diameter, crown diameter and height measures couldbe combined to provide robust aboveground biomass (AGB) estimates of individualshrub species. Our study supplements well‐established models developed for trees,allowing more accurate biomass estimation of multistemmed woody individuals. Wefurther provide tools for a methodological standardization of individual biomassquantification in these species. We expect these results contribute to improve thequality of biomass estimates across ecosystems, but also to generate methodologicalconsensus on field biomass assessments in shrubs.