Stability in ecosystems: It’s a bit like the stock market ‘portfolio effect’

For their study, researchers evaluated over 2,600 species ranging from insects and spiders, to birds and bats and herbaceous plants over a period of six years. Photo: Dave Bedard

OrganicBiz staff

If all your investments are in similar stocks that react to the same triggers, you’re vulnerable to volatility and losses in the stock markets. So it goes in Nature.

It’s well-known that diversity in species is important to a resilient ecosystem, but European researchers now say it’s not only a function of what is occupying the space, but a matter of timing that is important.

In fact, these researchers have concluded asynchrony of species is more valuable than diversity when it comes to building stable ecosystems.

The intensification of land use results in the destabilization of the animal and plant community and this, in turn, impairs the entire ecosystem. – Nadja Simons, Technical University of Munich

A team of scientists spearheaded by the TU Munich and TU Darmstadt have published their findings in the journal Nature Communications, a release from the Technical University of Munich.

“The more asynchronous the species in an ecosystem fluctuate in their abundances, the less likely it becomes unstable,” the researchers saying in a release “As a result, diversity takes second place in terms of the factors to be considered in the context of ecosystem stability.”

The release said long-term functioning of ecosystems depends on the stability of their species communities, as these ensure the functioning of the entire system.

“However, land use causes a reduction of the number of species in many ecosystems. Accordingly, when it comes to conserving species diversity and providing sustainable protection for natural resources, the stability of such animal and plant communities is the main goal of nature conservation and ecosystem management.”

For their study, the researchers evaluated over 2,600 species ranging from insects and spiders, to birds and bats and through to herbaceous plants over a period of six years. Data from 150 forests and 150 pastures and meadows located in three regions in Germany were collated, the release said.

“The results show that a change in the use of a landscape, for example when a managed forest is converted into grassland, destabilizes the animal and plant community,” saids Martin Gossner from the Terrestrial Ecology Research Group at the TU Munich.

“Similarly, the intensification of land use results in the destabilization of the animal and plant community and this, in turn, impairs the entire ecosystem,” added Nadja Simons (also from the TU Munich).

Animal communities presented a stronger reaction here than their plant counterparts. The most severe reaction by far was observed among birds and bats, which can therefore be seen as indicators of land-use intensity.

What is new about the insights gained in this study is the extent to which the asynchrony of the species can increase the stable interplay of animals and plants in an ecosystem.

“The more asynchronously the species develop and act, the more stable the system,” says Prof. Nico Bluethgen from the Department of Biology at TU Darmstadt in the release.

“We can compare it to the stock exchange, where risk-averse investors are encouraged not to put all their eggs in one basket and to create a portfolio of different securities instead. This is referred to as the portfolio effect. And, just as in nature, in order to cushion the impact of fluctuations in the investments over time, it is important that the portfolio not only contains a lot of investments but also different types of investments.”

Asynchrony thus assumes a key role in the interaction between diversity and stability. The scientists plan to investigate the factors that lead to greater asynchrony in further studies.

The following universities participated in the research:

  • TU Munich
  • TU Darmstadt
  • Ulm University
  • University of Bern
  • University of Vienna
  • WWU Münster