What doesn’t kill them makes them strong: A study shows that drought stress can make plant communities more resilient to droughts in subsequent generations. According to the researchers, the effect is an evolutionary process that increases the ability of each species to better complement each other. In this way, they can continue to grow as a community more quickly after a period of drought. The scientists say that biodiversity can also have a cross-generational positive effect on the adaptability of ecosystems to the effects of climate change.
It’s all in diversity: Various studies have already shown that biologically diverse plant communities cope better with difficult environmental conditions than species-poor ones. This is attributed to the fact that certain characteristics of the plants, such as root penetration, water consumption or heat tolerance, differ in a favorable way, resulting in a synergy effect that benefits everyone. It is obvious that the long common development history of plant species has also led to evolutionary processes that promote the “team skills” of plants. As part of their study, the international research team led by Bernhard Schmid from the University of Zurich has now investigated the extent to which plant communities can adapt to adverse environmental conditions across generations.
Long-term project of biodiversity research
In a large field experiment, the scientists partially shielded mixtures of meadow plants from natural precipitation over a period of eight years, so that they had to contend with drought stress, which just barely allowed them to survive. Plants were then grown from the seeds of twelve of the species and cultivated in monocultures or in mixtures. The researchers then also exposed these test units to experimental drought events and recorded their reactions. Plants from neighboring test plots that had not been affected by the artificially increased drought stress in the past eight years served as a comparison.
As the team reports, the test results showed that the offspring of the plants that had experienced drought stress survived another water shortage much better than the controls. However, this effect was only achieved when the species grew in mixtures and not in monocultures. So resilience had increased at the community level. As the researchers explain: In mixtures, species under drought stress undergo evolutionary changes that lead to improved resilience of the mixtures to future water shortages. “The results make it clear that evolution can change not only the species themselves, but also their interactions in such a way that they complement each other better and can therefore continue to grow more quickly as a community after an extreme event,” explains Schmid.
Plants complement each other better
In scientific terms, the offspring of the ‘thirst-hardened’ plants behaved in a more complementary manner, explains co-author Yuxin Chen from the University of Zurich: “Complementarity means that individuals compete more strongly within the same species than between different species. This is an important mechanism that promotes coexistence between species, thereby preserving biodiversity and increasing ecosystem resilience to extreme climatic events,” says Chen. “Evolution of complementarity between species may allow mixed plant communities to maintain their biodiversity and ecosystem services under future conditions with more frequent extreme climatic events.”
Since extreme climatic events will probably occur more and more frequently in the course of climate change, the resilience of ecosystems is of particularly great importance. The scientists emphasize that what strengthens this resilience should therefore be promoted. “The study makes it clear that we should not only protect biodiversity because of the direct positive effects on the performance of ecosystems, but also to preserve this potential for adaptation to changing global environmental conditions, especially more frequent extreme climatic events,” says co-author Nico Eisenhauer from the University of Leipzig.
Source: German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, specialist article: Nature Communications, doi: s41467-022-30954-9