Non‐destructive allometric estimates of above‐ground and below‐ground biomass of high‐mountain vegetation in the Andes

Abstract

Aim: Studies that monitor high-mountain vegetation, such as paramo grasslands in the Andes, lack non-destructive biomass estimation methods. We aimed to develop and apply allometric models for above-ground, below-ground and total biomass of paramo plants. Location:The paramo of southern Colombia between 1°09′N and 077°50′W, at 3,400 and 3,700 m a.s.l. Methods:We established 61 1-m 2 plots at random locations, excluding disturbed, inaccessible and peat bog areas. We measured heights and basal diameters of all vascular plants in these plots and classified them into seven growth forms. Near each plot, we sampled the biomass from plants of abundant genera, after having measured their height and basal diameter. Hence, we measured the biomass of 476 plants (allometric set). For each growth form we applied power-law functions to develop allometric models of biomass against basal diameter, height, height x basal diameter and height × basal area. The best models were selected using AIC c weights. Using the observed and predicted plant biomass of the allometric set we calculated absolute percentage errors using crossvalidation. The biomass of a plot was estimated by summing the predicted biomass of all plants in a plot. Confidence limits around these sums were calculated by bootstrapping.Results: For groups of <20 plants the biomass predictions yielded large (>15%) errors.Applying groups that resembled the 1-m 2 plots in density and composition, the errors for above-ground and total biomass estimates were <15%. Across all plots, we obtained an above-ground, below-ground and total plot biomass of 329 ± 190, 743 ± 486 and 1011 ± 627 g/m 2 (mean ± SD), respectively. These values were within the range of biomass estimates obtained destructively in the tropical Andes. Conclusions: In new applications, if target vegetation samples are similar regarding growth forms and genera to our allometric set, their biomass might be predicted applying our equations, provided they contain at least 50-100 plants. In other situations, we would recommend gathering additional biomass measurements from local plants to evaluate new regression equations. K E Y W O R D S basal diameter, Colombia, grassland, growth form, paramo, plant height 478 | Additional supporting information may be found online in the Supporting Information section at the end of the article. APPENDIX S1. Location map showing the distribution of the 61 plots in the paramos of Cumbal, Ovejas-Tauso and Paja Blanca, southern Colombia. APPENDIX S2. Biomass and predictor values of the allometric set. APPENDIX S3. Results of allometric models of biomass. N = number of plants used in the allometric modelling. APPENDIX S4. Plot data. APPENDIX S5. Aboveground and belowground biomass of plant communities in extra-Andean and temperate biomes, obtained by destructive harvesting. If available, the standard deviation is added in parentheses. How to cite this article: Cabrera M, Samboni-Guerrero V, Duivenvoorden JF. Non-destructive allometric estimates of above-ground and below-ground biomass ...

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