Soil organic matter responses to nutrient enrichment in the Nutrient Network:Nutrient Network. A cross-site investigation of bottom-up control over herbaceous plant community dynamics and ecosystem function.

This experiment is one implementation of a globally distributed experiment, known as the Nutrient Network. At Cedar Creek, as in over 70 other sites in grasslands around the world, the experiment aims to describe impacts of increased nutrients (nitrogen, phosphorus, potassium, sulfur and other metals) and decreased herbivory (removal of mammals by fencing).

Two overarching questions are being explored with these manipulations:

1. To what extent are plant production and diversity co-limited by multiple nutrients in herbaceous-dominated communities?

2. Under what conditions do grazers or fertilization control plant biomass, diversity, and
composition?

By utilizing identical protocols at diverse grassland sites around the world, NutNet aims to uncover both the generalities in ecosystem functioning, and the contingencies or differences which can obscure those common mechanisms.

In addition to the standard NutNet protocol, e247 includes an additional low Nitrogen gradient (1 gram Nitrogen per meter squared per year and 5 grams Nitrogen per meter squared per year in addition to the standard 10 grams Nitrogen per meter squared per year).

本实验是全球分布式实验「养分网络（Nutrient Network）」的一项实施案例。与全球70余个草原样地一致，本实验在锡达克里克（Cedar Creek）样地开展，旨在阐明养分添加（氮、磷、钾、硫及其他金属元素）与植食压力降低（通过围栏移除哺乳动物）对生态系统的影响。

本实验通过上述操纵处理，旨在探索两大核心科学问题：
1. 以草本为主的群落中，植物生产力与多样性在多大程度上受多种养分的共同限制？
2. 在何种条件下，植食动物取食或养分施肥会主导植物生物量、多样性及群落组成？

通过在全球不同草原样地采用统一实验方案，NutNet旨在揭示生态系统功能的普遍规律，以及可能掩盖这些共同机制的情境特异性与差异。

除标准NutNet实验方案外，e247实验额外设置了低氮梯度处理：在标准施氮量（每年每平方米10克氮）的基础上，新增每年每平方米1克氮与每年每平方米5克氮两个施氮水平。