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

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.
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 19 m tall was achieved in just five years.
Several key patterns emerged: (i) genotype richness did not predict forest productivity, suggesting a lack of net biodiversity effects; (ii) we found differences among genotype monoculture stands comparable to differences in average productivity across all forest biomes on Earth; (iii) productivity was predicted based on genetic marker similarity in trees; (iv) genetic-based differences in leaf phenology (early leaf-on and late leaf-fall timing) were correlated with >80% of the variation in tree and forest productivity irrespective of home-site conditions.
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.

诸多研究已证实植物群落中生物多样性与生产力的关联，而基于单物种种内基因型（genotype）混合的同类遗传多样性-生产力研究，或可呈现相似规律。与之相对，同一物种种内不同基因型的竞争个体，即便对生态系统功能的影响存在显著差异，也较难表现出资源利用互补性。
本研究借助一项生态系统尺度的同质园试验（common garden experiment），探究基因型多样性与遗传身份（genetic identity）对生态系统功能的影响。研究采集了美国境内河岸树种弗雷蒙特杨（Populus fremontii）整个自然分布范围内的不同树木基因型，并将其配置为包含1至16种基因型组合的林分样地。由于试验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，仅用五年时间便培育出树高可达19米的成熟林分结构。
研究得到若干关键规律：（1）基因型丰富度无法预测林分生产力，表明净生物多样性效应并不存在；（2）不同基因型单种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差异相媲美；（3）树木的遗传标记相似性可用于预测林分生产力；（4）基于遗传差异的叶片物候差异（展叶早、落叶晚的物候类型），与树木及林分生产力超过80%的变异相关，且不受原生境条件的影响。
不同基因型间的生产力差异可导致林分生产力产生显著变化，却不会呈现物种尺度生物多样性研究中常见的多样性-生产力关联规律。