A new study by the University of Zurich, along with colleagues from Leipzig and Jena, analysed the stability of plant biomass production over two decades.
The experiment is one of the longest-running tests on grassland ecosystems in the world and analyses how reduced biodiversity affects the stability of the entire ecosystem.
The results of the study show that grassland plant communities with multiple species need around ten years to adjust to each other and produce an even amount of biomass again.
Analysing reductions in ecosystem functions
Recent experiments have shown that the loss of species from a plant community can reduce ecosystem functions and services, including productivity, carbon storage, and soil health.
This reduced functioning may also contribute to destabilising the ecosystem in its ability to maintain ecosystem functions and services in the long term. However, assessing this is only possible if experiments can be maintained for a sufficient length of time.
To meet this goal, the Zurich researchers conducted the ‘Jena Experiment’, which analysed changes over two decades, making this the longest-running grassland ecosystem experiment in the world. After more than a decade, plant species in more diverse experimental communities complemented each other in producing stable biomass at the community level.
At low plant diversity, by contrast, this compensatory effect was observed and community biomass varied much more from year to year. During the first decade of the experiment, species-rich communities had not yet stabilised due to large fluctuations in species populations.
This long-term research shows that biodiversity plays an increasingly important role in stabilising ecosystem productivity over time as plant communities mature.
How diverse species sustain ecosystems over time
“We now realise that the mechanisms by which diverse species communities maintain ecosystem functioning in the long term are continually developing, even after two decades,” said Cameron Wagg, first author of the study.
These findings highlight the importance of long-term research studies to fully appreciate the invaluable role of biodiversity in supporting ecosystem functions and services in the future.
Bernhard Schmid, a professor at the University of Zurich’s Department of Geography, explained: “These novel results fit with other recent findings of our research group, suggesting that over time evolutionary processes in diverse plant communities select the most ‘collaborative’ plant genotypes among the different species, thus increasing division of labour, community productivity, and ecosystem stability.”
Because ecosystem stability incurs resilience in the face of environmental perturbations, the research concludes that in a changing world, older, more diverse ecosystems should be valued particularly highly.