Data from: Positive biodiversity-productivity relationships in forests: climate matters

While it is widely acknowledged that forest biodiversity contributes to climate change mitigation through improved carbon sequestration, conversely how climate affects tree species diversity - forest productivity relationships is still poorly understood. We combined the results of long-term experiments where forest mixtures and corresponding monocultures were compared on the same site to estimate the yield of mixed-species stands at a global scale, and its response to climatic factors. We found positive mixture effects on productivity using a meta-analysis of 126 cases studies established at 60 sites spread across five continents. Overall, the productivity of mixed-species forests was 15% greater than the average of their component monocultures, and not statistically lower than productivity of the best component monoculture. Productivity gains in mixed-species stands were not affected by tree age or stand species composition but significantly increased with local precipitation. The results should guide better use of tree species combinations in managed forests and suggest that increased drought severity under climate change might reduce the atmospheric carbon sequestration capacity of natural forests.

尽管学界已广泛认可森林生物多样性可通过提升碳固存(carbon sequestration)能力助力气候变化减缓，但与之相对，气候如何调控树木物种多样性与森林生产力的关系，目前仍未得到充分阐释。本研究整合了在同一立地条件下对比森林混交林与对应纯林(monocultures)的长期试验数据，以在全球尺度下估算混交林的生产力及其对气候因子的响应。通过对分布于五大洲60个样地的126项案例研究开展元分析(meta-analysis)，我们发现混交林对生产力具有正向效应。总体而言，混交林的生产力较其组成纯林的平均水平高出15%，且未在统计学上低于表现最优的单一组成纯林的生产力。混交林的生产力增益不受树木年龄或林分物种组成的影响，但随局地降水量的增加而显著提升。本研究结果可为人工林培育中更科学地搭配树木物种组合提供指引，同时也表明，气候变化背景下干旱程度加剧可能会削弱天然林的大气碳固存能力。