Many allometric models to predict tree aboveground biomass have been developed in tropical moist forests, but few models are available for tree belowground biomass. Theory predicts that belowground biomass scales in an isometric way with aboveground biomass. Estimates of belowground biomass could then be derived from aboveground biomass using the root:shoot ratio. Using a dataset of 118 tropical trees for which both aboveground and belowground biomass and other tree and species characteristics were measured in Gabon and Cameroon, we found a near isometric, yet significantly allometric, relationship between belowground biomass (B, in kilograms) and aboveground biomass (A, in kilograms): B = 0.324 A0.939. The root:shoot ratio was 0.20–0.22, regardless of tree size. An efficient model to predict belowground biomass from tree diameter (D, in centimeters), height (H, in meters) and wood density (ρ, in grams per cubic centimeter) was B = 0.0188 (ρD2H)0.977. A significant residual effect of species and leaf habit was found in this model, indicating that further tree and species characteristics are likely to explain additional variation in belowground biomass. Yet, the future development of belowground allometric models can benefit from the many models already developed for aboveground biomass. On the basis of this unprecedented sampling effort on tree belowground biomass in the dense tropical forests of the Congo Basin, we conclude that the scaling of belowground biomass with aboveground biomass should be the relationship to focus on.

中文翻译：

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刚果盆地森林中的树木地下生物量：异速生长方程和地上生物量的缩放

在热带潮湿森林中已经开发了许多预测树木地上生物量的异速生长模型，但很少有模型可用于树木地下生物量。理论预测地下生物量与地上生物量以等距方式缩放。然后可以使用根茎比从地上生物量得出地下生物量的估计值。使用在加蓬和喀麦隆测量了 118 棵热带树木的地上和地下生物量以及其他树木和物种特征的数据集，我们发现地下生物量（B，以千克为单位）和地上生物量之间存在近乎等长但显着异速生长的关系（A，单位为公斤）：B = 0.324 A0.939。无论树木大小如何，根冠比均为 0.20-0.22。根据树木直径（D，以厘米为单位）、高度（H，以米为单位）和木材密度（ρ，以克每立方厘米为单位）预测地下生物量的有效模型为 B = 0.0188 (ρD2H)0.977。在该模型中发现了物种和叶子习性的显着残余效应，表明进一步的树木和物种特征可能解释地下生物量的额外变化。然而，地下异速生长模型的未来发展可以受益于已经为地上生物量开发的许多模型。基于对刚果盆地茂密热带森林树木地下生物量进行的前所未有的采样工作，我们得出结论，地下生物量与地上生物量的比例应该是值得关注的关系。