Data from: Does biomass growth increase in the largest trees? – flaws, fallacies, and alternative analyses

The longstanding view that biomass growth in trees typically follows a rise-and-fall unimodal pattern has been challenged by studies concluding that biomass growth increases with size even among the largest stems in closed forests and in open competition-free environments. We highlight challenges and pitfalls that influence such views and interpretations. The ability to observe and calibrate biomass change in large stems requires adequate data regarding these specific stems. Data checking and control procedures can bias estimates of biomass growth and generate false increases with stem size. It is important to distinguish aggregate and individual-level trends, as these are distinct: a failure to distinguish how biomass growth varies among and within stems results in flawed interpretations. Our assessment of biomass growth in 706 tropical forest stems indicates that biomass growth patterns often plateau for extended periods, with no significant difference in the number of stems indicating positive and negative trends in all but one of the 14 species. Nonetheless, when comparing individual growth during the most recent five years, 13 out of our 14 species indicate that biomass growth increases with size even among the largest sizes. Thus, individual and aggregate patterns of biomass growth with size are distinct. Claims concerning general biomass growth patterns for large trees remain unconvincing. We suggest how future studies can improve our knowledge of growth patterns in and among large trees.长期以来的传统观点认为，树木的生物量增长通常遵循先升后降的单峰模式（unimodal pattern），但已有相关研究对此提出了质疑——这些研究证实，即便在封闭森林的最大径级茎干以及无竞争开放环境中，生物量增长仍随茎干尺寸增大而提升。本研究梳理了影响此类观点与解读的诸多挑战与潜在误区。 要观测并校准大型茎干的生物量变化，需获取针对这些特定茎干的充足实测数据。 数据核查与质控流程可能会对生物量增长的估算结果产生偏倚，并生成与茎干尺寸正相关的虚假增长趋势。 明确区分聚合级（aggregate）与个体级（individual-level）增长趋势至关重要，二者存在本质差异：若未能厘清生物量增长在不同茎干之间以及同一茎干内部的变化规律，便会得出存在瑕疵的解读结论。 我们对706株热带森林茎干的生物量增长评估显示，生物量增长模式往往会在较长时段内趋于平稳；在14个物种中，除1个物种外，其余物种呈现正增长与负增长趋势的茎干数量均无显著差异。不过，在对比近五年的个体生长情况时，14个物种中的13个显示，即便在最大径级茎干中，生物量增长仍随茎干尺寸增大而提升。由此可见，生物量增长随尺寸变化的聚合级与个体级模式存在显著差异。 有关大型树木通用生物量增长模式的各类论断仍缺乏足够说服力。我们提出了未来研究可如何深化对大型树木内部及种群间增长模式的认知的可行方向。