Data from: Tree genetics strongly affect forest productivity, but intraspecific diversity-productivity relationships do not

1. Numerous studies have demonstrated biodiversity-productivity relationships in plant communities, and analogous genetic diversity-productivity studies using genotype mixtures of single species may show similar patterns. Alternatively, competing individuals among genotypes within a species are less likely to exhibit resource-use complementarity, even when they exhibit large differences in their effects on ecosystem function. 2. In this study, we test the impact of genotype diversity and genetic identity on ecosystem function using an ecosystem-scale common garden experiment. Distinct tree genotypes were collected across the entire natural range of the riparian tree Populus fremontii in the USA, and grown in 1-16 genotype combination forest stands. Due to the warm climate and irrigation of the planting location along the Colorado River (AZ, USA), mature forest physiognomy with trees up to 19m tall was achieved in just five years. 3. Several key patterns emerged: 1) genotype richness did not predict forest productivity, suggesting a lack of net biodiversity effects; 2) we found differences among genotype monoculture stands comparable to differences in average productivity across all forest biomes on Earth; 3) productivity was predicted based on genetic marker similarity in trees; 4) genetic-based differences in leaf phenology (early leaf-on, and late leaf-fall timing) was correlated with >80% of the variation in tree and forest productivity irrespective of home-site conditions. 4. Large differences in productivity among genotypes can result in dramatic differences in forest productivity without resulting in diversity-productivity relationships that are present in species-scale biodiversity studies.1. 大量研究已证实植物群落中的生物多样性-生产力关系（biodiversity-productivity relationship），针对单物种内的基因型混合体开展的类似遗传多样性-生产力研究（genetic diversity-productivity study）或许也会呈现相似规律。但与之相悖的是，同一物种内不同基因型间的竞争个体，即便其对生态系统功能（ecosystem function）的影响存在显著差异，也不太可能表现出资源利用互补性（resource-use complementarity）。 2. 本研究依托一项生态系统尺度的同质园实验（common garden experiment），验证基因型多样性与遗传身份对生态系统功能的影响。研究人员采集了美国境内河岸树种弗里蒙特杨（Populus fremontii）全部自然分布范围内的不同树基因型，将其以1至16种基因型组合的方式营造林分。由于种植地位于美国亚利桑那州科罗拉多河沿岸，气候温暖且具备灌溉条件，仅用5年时间便培育出了树高可达19米的成熟森林外貌。 3. 本研究揭示了多项关键规律：1）基因型丰富度（genotype richness）无法预测森林生产力，表明净生物多样性效应（net biodiversity effects）缺失；2）单基因型林分间的生产力差异，可与全球所有森林生物群系的平均生产力水平相媲美；3）树木的遗传标记相似性（genetic marker similarity）可用于预测生产力；4）叶片物候（leaf phenology）的遗传差异——即展叶早、落叶晚的物候特征——与树木及森林生产力80%以上的变异量呈显著相关，且不受原产地环境条件（home-site conditions）的影响。 4. 不同基因型间的生产力差异巨大，可导致森林生产力出现显著波动，却不会呈现物种尺度生物多样性研究中所观测到的多样性-生产力关系。