The Long-Term Ecological Research program at Cedar Creek Ecosystem Science Reserve, Minnesota, was started in 1982. From 2006 to 2013 more than fifty new ecological research projects were initiated. These projects, and many long-established experiments, have provided unique insights into how and why biodiversity loss, nitrogen deposition, climatic warming, elevated CO2 and other variables impact the functioning of ecosystems. This recent work has expanded the scientific understanding of the processes and principals that govern the dynamics and functioning of ecological communities and ecosystems. Experiments at Cedar Creek are complemented by cross-site studies and syntheses that extend beyond the geographical boundaries of CCESR. These include the Nutrient Network (NutNet), which is a cross-site project at 70 sites on 5 continents that tests how herbivores and fertilization impact plant diversity and productivity; a global database of plant physiological traits that is called GLOPNET; and a database and software for investigating how phylogenetic history and plant traits impact community structure and ecosystem processes. The current Cedar Creek data catalog contains more than 400 unique data sets. Cedar Creek has also contributed data to many large-scale repositories such as the National Phenology Network, GenBank (NIH genetic sequence database) and the TRY global plant traits database. 

Some Key Outcomes:

Ecosystems are increasingly being valued for the multiple services that they can provide. Results of our biodiversity experiment show that local diversity was sufficient to maximize some ecosystem services, but that diverse landscape mosaics were needed to assure the provisioning of multiple services.

Our 30 year old nitrogen enrichment experiment has uncovered a plant diversity “regime shift.” In particular, we found that the effects of a decade of nutrient enrichment were not reversed by 20 years of cessation of N addition. Rather an alternative low-diversity state had been created that persisted despite decreases in soil nitrate and annual supply of seeds from nearby high-diversity plots.

It has long been suggested that plants will show a tradeoff between competition and defense. NutNet research found no support for a competition-defense tradeoff in 500 species subjected to identical fencing and nutrient addition treatments at 39 sites around the world. Further, we found that there is a strong general tradeoff between species growth rates and defense.

In a grassland experiment that manipulated atmospheric CO2, soil nitrogen, and summer rainfall for five years, elevated CO2 increased plant biomass by >33% when summer rainfall and/or nitrogen supply were at higher levels. However, elevated CO2 did not do so when rainfall and nitrogen supply were low. These results suggest that large stimulation of biomass by rising CO2 may be unlikely when water is limiting.

In a cross-site comparison of five grassland sites, elevated inputs of nitrogen increased decomposition of fast-cycling soil carbon, but slowed decomposition of slow-cycling carbon, mirroring effects of nitrogen found previously for litter decomposition and suggesting that effects of atmospheric nitrogen deposition on ecosystem carbon sequestration will depend on the balance between these opposing processes.

Preliminary results suggest that, while many urban yards contain different naturally regenerating species, those different species are closely related to one another and have similar leaf morphologies. This suggests that the same kinds of species live in different cities throughout the US, and that US urban plant communities are becoming homogenized. However, the plants within the cities are different to those we find in more natural areas surrounding them.

Broader Impacts:

Beyond their ow...

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