CDR LTER Cross-Site Experiments

Nutrient Network Cross-Site Experiment (NutNet). CDR scientists Borer and Seabloom helped found and now coordinate one of the largest experimental networks in ecology, the Nutrient Network (NutNet; www.nutnet.org). NutNet is composed of two experiments replicated in herbaceous ecosystems at >100 sites in 25 countries: (1) a factorial addition of N, P, and K plus micronutrients (NPK), and (2) a factorial NPK x herbivore exclusion. CDR supports NutNet coordination and data management. CDR is also the location of one of the longest running NutNet sites (started in 2007). NutNet has provided direct tests of predictions arising from CDR research, including demonstrating that increased nutrient supplies reduce species diversity and increase species invasions in grasslands worldwide. NutNet manipulations are now of sufficient duration to determine how human-driven enrichment of terrestrial ecosystems with N and P will alter soil C dynamics, a critical unresolved question for global ecosystem models.

Drought-Net Cross-Site Experiment. CDR also runs two experiments that are part of Drought-Net’s distributed experiment, the International Drought Experiment, which will allow further global-scale tests of key results from long-term experiments at CDR. These drought experiments were designed to test whether high plant diversity stabilizes ecosystem productivity in response to experimental drought, a prediction based in part on observational, theoretical, and experimental studies at CDR. CDR is providing data and intellectual expertise to this international effort, as well as experiments that uniquely cross Drought-Net rainfall reduction treatments with additional treatments to test effects of changes in nutrients, biodiversity, and temperature on ecosystem responses to drought.

ACE-Adaptation to Changing Environments A new experiment that falls within the umbrella of the Forest and Biodiversity experiment (FAB) tests for adaptive differentiation and local adaptation of bur oak trees (Quercus macrocarpa) from populations across a latitudinal gradient from Oklahoma, Illinois, Minnesota in collaboration with Morton Arboretum and the University of Oklahoma. The goal is to test whether populations and genotypes have adapted to different climates and microbial environments and how variation within a species impacts ecosystems.