In the heart of Germany, in the Lückenbach rivulet floodplain, the University of Giessen and the Hessian Agency for Environment and Geology operate the Environmental Monitoring and Climate Impact Research Station Linden. The research site is a 4.5-hectare, semi-natural permanent grassland typical of German lowlands. Grasslands like this represent roughly 13% of the agricultural and 6% of the total land area in the nation. Established in the mid-1990s, the site includes a 3-hectare section for micrometeorological measurements and a 1.5-hectare section for experimental studies. This facility is used to study how climate change affects ecological and phenological processes.
In 1998, the University of Giessen established the Free Air Carbon Dioxide Enrichment (FACE) experiment to study how ecosystems respond to elevated atmospheric CO2 levels. This project is unprecedented in Europe due to its long-term data record. Scientists established six ring-shaped experimental units (8 meters in diameter), three of which are used for control purposes. During daylight hours, the CO2 concentration within treatment rings is elevated to 20% above ambient concentrations, which is equivalent to ambient atmospheric CO2 concentrations expected between 2030 and 2040.
So far it has provided some interesting results. Scientists observed a 10% increase in carbon sequestration in biomass but no increase in the carbon content in the soil. Plants grow faster overall, but nighttime respiration is higher. Moreover, they found a positive feedback loop. Soil released more N2O, while its ability to serve as a sink for CH4 was reduced. These results suggest that an increase in atmospheric CO2 concentration may reduce the sequestration of methane in this type of grassland.
In another project, researchers established a variety of plant species, from dandelion and heather to hazel and oak, for phenological monitoring. They systematically record the timing of phenological processes such as flowering, fruit ripening, and leaf fall. Results show that these processes now occur up to 15 days earlier than they did several decades ago. This clearly shows the effects of climate change on these ecosystems and biological processes.
A new experiment is underway in which scientists seek to determine if and how biochar, synthesized by pyrolysis of biomass, can be used for long-term carbon sequestration in soils and, as a benefit, increase soil fertility. They are using this experiment to evaluate the effects of two different chars, a pyrogenic biochar and a hydrochar produced via hydrothermal carbonization, their common feedstock (Miscanthus) as well as a “no addition” control. They are interested in the impact and fate of biochar and hydrochar with respect to N2O and CO2 emissions, plant growth, and carbon sequestration.
Researchers rely on a variety of LI-COR instruments in these experiments, including PAR sensors for light monitoring, CO2 analyzers to measure and control concentrations within the FACE rings, and photosynthesis systems to analyze plant growth. The LI-8150 Soil CO2 Flux Monitoring System is a key instrument in this project. Researchers use it to systematically measure soil CO2 fluxes with minimal disturbance to the site. The instrument software processes the data to provide fast, accurate CO2 flux calculations.
Not only is this a unique research site, but it also is a valuable educational resource. Every spring LI-COR invites customers and students to the University of Giessen to learn about the LI-8100 system. From pertinent scientific research, to important educational opportunities, research sites such as the Environmental Monitoring and Climate Impact Research Station Linden play an important role in advancing the science of climate change. Through experimental manipulation and careful observation, the knowledge gained from this research will help humanity understand some of the most vexing environmental challenges facing the world today.