The overarching goal of the Cedar Creek Long Term Ecological Research program is to combine long-term experiments, long-term observations, and theory to gain a mechanistic and predictive understanding of the dynamics and functioning of grassland, savanna, and forest communities and ecosystems. CDR science emphasizes the ways that human-caused environmental changes -- loss of native biodiversity, shifts in species composition and land use, climate change, elevated atmospheric CO₂, nitrogen (N) deposition -- impact the structure and functioning of ecosystems, and their ability to provide the services that support human health and well-being.

CDR's long-term experiments have led to important insights into the long-term effects of global change. For example, a synthesis of results from three grassland experiments showed that chronic N enrichment initially increased plant growth and led to losses of some plant species from the community. These losses reduced the positive effects of N fertilization on plant growth because plant species that were able to use N efficiently to grow were particular vulnerable to being lost (Attachment 1). The interactions between plant diversity and total plant growth were further explored in a study synthesizing data from 12 long-term experiments at CDR that manipulated global change drivers, including biodiversity, N, atmospheric CO₂, fire, herbivory, and water. Those factors that altered the number of plant species in the community also altered how much plant growth fluctuated across years ? communities with more species fluctuated less in the face of year-to-year changes in climate (Attachment 2). A unique feature of the long-term experiments at CDR is their focus on how different global changes interact. For example, in an experiment that manipulates plant diversity, CO₂, nitrogen, and rainfall, plant growth was unchanged by elevated atmospheric CO₂ when both water and N were at low supply, but when either water or N were at higher supply levels, plant growth increased with elevated CO₂ (Attachment 3).

This award supported the establishment of new experiments at CDR that also have led to novel insights. For example, a new experiment examined the importance of the number of tree species, their evolutionary relatedness, and the diversity of their characteristics for forest ecosystems. Just like in grasslands, planting more tree species increased total tree growth because different trees species acquire and use resources (light, water, nutrients) in different ways (Attachment 4). This award also supported the coordination of a long-term experiment at >140 sites around the world, including CDR, of soil fertility and the large mammals that eat plants. This work has demonstrated that nutrient addition will reduce native plant diversity and increase plant species invasions in grasslands worldwide.

CDR?s broader impacts have increased dramatically through the promotion of teaching, training, and learning; enhancement of infrastructure; creative dissemination of results to the broader public; and advising of government official and agencies. Through inquiry-based, standards-driven programming to K-12 students onsite during field trips and offsite in classroom programs, CDR served more than 21,500 teachers and students between 2013-2018, a three-fold increase over the 2007-2012 period. CDR strengthened partnerships to engage Native American students, English Language Learners, and underserved urban schools. Science identity, content knowledge, and career preparedness were assessed following field trips. Teachers also were invited to participate in summer professional development opportunities to improve student achievement in biological science by improving the quality and effectiveness of teachers' delivery of ecological science curriculum. CDR engaged the local community and the broader public through a variety of citizen science projects, monthly lunchtime lectures, an ecology book club, and diverse workshops and outdoors programs, interviews with the press, participation in public forums, and advising government officials.

CDR also trains diverse undergraduates from across the country (about 220 undergraduates from 2013-2018). A June research symposium introduced summer undergraduate to CDR experiments and independent research topics and mentors. Additional professional development occurred through weekly lunchtime research seminars, workshops on topics proposal writing, statistical analysis, and presentation skills, firsthand experience conducting research, and presentation of results at an end-of-summer symposium. Graduate students and postdocs (34 and 24 from 2013-2018, respectively) conducted research at the site and gained mentoring, K12 outreach, and public engagement experience.

Results from research at CDR have continued to impact the larger scientific community through research publications (> 250 during 6-year period of this award, with 10% written by non-CDR researchers) and datasets (ca. 100 new or appended datasets). More broadly, our work has benefited society by increasing understanding of how human activities alter the functioning of the ecosystems on which human health and economic well-being depend. For example, work at CDR has been at the forefront of quantifying the ability of diverse ecosystems to provide a wide array of critical ecosystem services including the sequestration of atmospheric carbon, removal of nutrients and toxins from groundwater, and the sustainable production of biofuels and of developing partnerships with global experimental networks.

Last Modified: 03/31/2020
Modified by: Eric W Seabloom