Plant biomass data (measured from 2012 to 2015) and plant trait data (measured in 2015)

The present study was conducted at the Jena Experiment field site from 2011 to 2015. The 48 experimental plant communities included twelve monocultures (of which one was removed from all analyses because it was planted with the wrong species), twelve 2-species mixtures, twelve 4-species mixtures and twelve 8-species mixtures. We used two community-evolution treatments (plant histories); plants with eight years of co-selection history in different plant communities in the Jena Experiment (communities of co-selected plants) and plants without such co-selection history (naïve communities). Community-level plant productivity was measured each year from 2012 to 2015 by collecting species-specific aboveground biomass at the time of peak biomass in spring, whereas the traits plant height and SLA were measured once in 2015.
We harvested plant material 3 cm aboveground from a 50 x 20 cm area in the centre of each half-quadrat, sorted it into species, dried it at 70°C and weighed the dry biomass. At the end of the experiment, in May 2015, we measured plant height and SLA for 30 species in neutral soil. For each species, we collected up to 20 representative leaves (depending on the leaf size of the species) from four individuals and measured the leaf area by scanning fresh leaves immediately after harvest and determining the mass of the same leaves after drying.

本研究于2011年至2015年在耶拿生物多样性实验（Jena Experiment）田间站点开展。共设置48个实验植物群落，包含12个单作群落（其中1个因种植错误物种被排除所有分析）、12个2物种混合群落、12个4物种混合群落及12个8物种混合群落。我们设置了两种群落演化处理（植物起源历史）：一是在耶拿生物多样性实验的不同植物群落中具备8年共同选择历史的植物（共选择植物群落），二是无此类共同选择历史的植物（未经共同选择的初始群落）。群落水平的植物生产力于2012年至2015年每年测定一次，于春季生物量峰值时段采集物种特异性地上生物量；植物高度与比叶面积（Specific Leaf Area, SLA）仅在2015年测定一次。
我们在每个半样方中心的50 cm × 20 cm区域内，采集距地面3 cm处的地上植物材料，将其按物种分类后置于70℃烘箱中烘干，随后称量干生物量。实验末期（2015年5月），我们在中性土壤中测定了30个物种的植物高度与比叶面积。针对每个物种，我们从4个个体上采集至多20片代表性叶片（根据物种叶片大小调整采集数量），收获后立即扫描新鲜叶片以测定叶面积，并对同一批次叶片烘干后称量干重。