Understanding the drivers of aboveground biomass (AGB) variation in present-day tropical forests can contribute to management strategies that help mitigate against CO2-driven climate change and provide other services related to high AGB. Higher tree diversity can lead to higher woody productivity and carbon storage, but how diversity interacts with land-use history is less certain. We assessed variation in AGB across forests with different land-use histories and surrounding landscapes in southeastern Brazil and how AGB relates to tree diversity per se, while controlling for important factors such as mean functional trait values, stem density and soil fertility. Our findings indicate that aboveground biomass of forests is dependent on land-use history and the landscape matrix in which they occur (urban or non-urban). We found that tree diversity, measured as the average evolutionary divergence among close relatives, shows a strong positive relationship to AGB, but only in old-growth, non-urban forests. This suggests that higher niche complementarity leads to higher AGB in certain ecological contexts. Forests in an urban matrix, and those that regenerated from cropland (in an urban or non-urban matrix), showed weak or insignificant relationships between AGB and diversity, and forests that regenerated from completely denuded landscapes, including soil removal, actually showed a negative relationship between diversity and AGB. Meanwhile, across all forest classes, the abundance-weighted mean wood density of tree species present showed a consistent positive correlation with AGB, indicating the ubiquity of mass-ratio effects on AGB. Overall, our study suggests that strategies for conservation and restoration should account for past land-use and the matrix where forests are inserted, as the distribution of carbon stocks and biodiversity may need to be considered separately.

了解当今热带森林地上生物量 (AGB) 变化的驱动因素有助于制定有助于缓解二氧化碳驱动的气候变化的管理策略，并提供与高 AGB 相关的其他服务。更高的树木多样性可以导致更高的木本生产力和碳储存，但多样性如何与土地利用历史相互作用尚不确定。我们评估了巴西东南部具有不同土地利用历史和周围景观的森林中 AGB 的变化，以及 AGB 与树木多样性本身的关系，同时控制重要因素，如平均功能性状值、茎密度和土壤肥力。我们的研究结果表明，森林的地上生物量取决于土地利用历史和它们发生的景观矩阵（城市或非城市）。我们发现，以近亲之间的平均进化差异来衡量的树木多样性与 AGB 呈强正相关，但仅限于古老的非城市森林。这表明在某些生态环境中，较高的生态位互补性会导致较高的 AGB。城市矩阵中的森林以及从农田（在城市或非城市矩阵中）再生的森林，在 AGB 与多样性之间显示出微弱或不显着的关系，以及从完全裸露的景观中再生的森林，包括土壤去除，实际上表现出多样性和 AGB 之间的负相关关系。同时，在所有森林类别中，存在的树种的丰度加权平均木材密度与 AGB 呈一致的正相关，表明质量比对 AGB 的影响无处不在。总的来说，我们的研究表明，保护和恢复战略应该考虑过去的土地利用和森林插入的矩阵，因为可能需要单独考虑碳储量和生物多样性的分布。