Soils pH: Biodiversity II: Effects of Plant Biodiversity on Population and Ecosystem

Biodiversity II (E120) is designed to determine how the number of plant species affects the dynamics of ecological processes at the population, community, and ecosystem levels. By experimentally manipulating the number of species and the kinds of species, the amount of plant growth and the change from year to year, that result can be examined. Plots are large (9m x 9m actively maintained) and well-replicated, allowing responses of plant pathogens, insect herbivores, seed predators, soil parameters, invasive plant species and other variables to also be studied. Plots were seeded in May 1994 to have 1, 2, 4, 8, or 16 species, with roughly 30 replicates of each diversity level. The species composition of each plot was chosen by random draw from a pool of 18 grassland perennials that included four warm-season (C4) grasses, four cool-season (C3) grasses, four legumes, four non-legume forbs, and two woody species. All species occur in monoculture allowing comparison of responses of each species in monoculture to combinations of these same species. The experiment was established in 1994 by the lead investigators David Tilman, Peter Reich, Johannes Knops, and David Wedin. Experiment 120 is similar to Experiment 123, but it uses larger plots to provide a large capacity for long-term subexperiments.

生物多样性II（E120）旨在探究植物物种数量如何影响种群、群落及生态系统层面的生态过程动态。通过实验操控物种数量与物种组成、植物生物量及其年际动态，可对相关研究结果开展验证分析。该数据集的样地规模较大（9米×9米，需定期人工管护），且设置了充足的生物学重复，使得研究者亦可同步探究植物病原菌、昆虫植食者、种子捕食者、土壤参数、入侵植物物种及其他变量的响应特征。
该数据集的样地于1994年5月完成播种，设置了1、2、4、8、16共5个物种丰富度梯度，每个多样性水平设置约30个重复样地。每个样地的物种组成均从由18种草原多年生植物构成的物种库中随机选取，该物种库包含4种暖季型（C4）禾草、4种冷季型（C3）禾草、4种豆科植物、4种非豆科杂类草以及2种木本植物。所有供试物种均可进行单作种植，这使得研究者能够对比单一物种单作时的响应特征与该物种参与的物种组合下的响应特征。
该实验于1994年由首席研究员戴维·蒂尔曼（David Tilman）、彼得·赖克（Peter Reich）、约翰内斯·克诺普斯（Johannes Knops）与戴维·韦丁（David Wedin）建立。E120实验与E123实验设计相似，但E120采用了更大规模的样地，可为长期子实验提供充足的实验容量。