Soils Bulk Density: 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（Biodiversity 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。本研究通过实验调控物种数量与物种组成、植物生长量及年际变化，以此考察其产生的效应。实验采用的样地规模为9米×9米，需人工管护且重复充足，可同时开展植物病原菌、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。 样地于1994年5月完成播种，设置1、2、4、8或16个物种的处理组，每个物种多样性水平约设30个重复样地。各样地的物种组成从包含18种草原多年生植物的物种库中随机抽取得到，该物种库涵盖4种暖季型（C4）禾草、4种冷季型（C3）禾草、4种豆科植物、4种非豆科草本杂类草以及2种木本植物。所有供试物种均可进行单种栽培，便于对比单种栽培下各物种的响应与该类物种组合下的响应差异。 本实验由首席研究员David Tilman、Peter Reich、Johannes Knops及David Wedin于1994年发起建立。实验120与实验123结构类似，但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。