Plant species percent cover data: Biodiversity II: Effects of Plant Biodiversity on Population and Ecosystem Processes

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、群落及生态系统尺度下的生态过程动态。通过实验调控物种数量与物种类型，可对植物生长量及年度变化开展观测分析。实验样地规模较大（9米×9米，定期维护）且重复设置充足，可同步开展植物病原菌、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研究。
该实验于1994年5月播种构建样地，设置1、2、4、8、16个物种的多样性梯度，每个多样性水平约设置30个重复样地。每个样地的物种组成通过从18种草原多年生植物池中随机抽取确定，该物种池包含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。所有物种均可单一栽培，从而可对比单一栽培下各物种的响应与该类物种组合的响应差异。本实验由核心研究者David Tilman、Peter Reich、Johannes Knops及David Wedin于1994年搭建完成。
E120实验与E123实验结构相似，但采用更大规模的样地，可为长期子实验提供充足的开展空间。