Species extinction destroys the ecosystem

How severe is global species extinction? Are material cycles altered in an ecosystem with just a few species? In order to address these issues, the “Jena Experiment”, one of the world’s largest biodiversity experiments, was started in 2002. At the University of Freiburg the working group from Prof. Dr. Michael Scherer-Lorenzen posed the question in the project as to whether the yield-enhancing impact of a larger biodiversity in grasslands would be comparable to the effects of a more intense cultivation. “It turns out both effects were very similar: The increase in yields achieved by farmers through higher fertilization and cutting frequency can also be achieved by increasing biodiversity," summarizes the Freiburg geobotanist.

An ecosystem provides natural services to people - such as soil fertility, groundwater quality, food production or insect pollination, which is essential for many fruits. That is the reason why intact ecosystems are necessary for all living beings to survive. What functional significance does species extinction have, then? Could a global loss of species in the end lead to ecosystems “functioning” less well? Prof. Dr. Wolfgang Weisser from the Technical University of Munich (TUM), who was spokesperson for the research consortium until 2015, summarized the results from the long-term project “Jena Experiment” in a 70-page article in the journal Basic and Applied Ecology.

The researchers concluded that the loss of biodiversity has negative consequences for many individual components and processes in ecosystems. Thus, the worldwide extinction of species does not only mean that part of the Earth's evolutionary heritage is irretrievably lost, but that it has direct unpleasant consequences for humans. The extinction of species, among other things, also affects the material cycles - and these have a direct influence on the water supply, the source of all life.

In the project, interdisciplinary teams from Germany, Austria, Switzerland and the Netherlands sowed different numbers of plant species on more than 500 experimental plots - from monocultures to mixtures of 60 species – and then carried out about 80,000 measurements on these parcels. In addition to plants, they studied many other ecosystem organisms in and above the soil, as well as the cycles of carbon, nitrogen, nitrate and water over the entire 15-year period.

Original publication:
Weisser WW., Roscher C., Meyer S., Ebeling A., Luo G., Allan E., Beßler H., Barnard R., Buchmann N., Buscot F., Engels C., Fischer C., Fischer M., Gessler A., Gleixner G., Halle S., Hildebrandt A., Hillebrand H., Kroon Hd., Lange M., Leimer S., Roux XL., Milcu A., Mommer L., Niklaus P., Oelmann Y., Proulx R., Roy J., Scherber C., Scherer-Lorenzen M., Scheu S., Tscharntke T., Wachendorf M., Wagg C., Weigelt A., Wilcke W., Wirth C., Schulze E-D., Schmid B. and Eisenhauer N.: Biodiversity effects on ecosystem functioning in a 15-year grassland experiment: patterns, mechanisms, and open questions, Basic and Applied Ecology 2017, Nr. 23: 1-73. DOI: https://doi.org/10.1016/j.baae.2017.06.002

Press release from TU Munich:
https://www.tum.de/en/about-tum/news/press-releases/detail/article/34323