Climate change could increase biodiversity – if a location already has biodiversity

There’s a recent paper in Science Advances, where the conclusion is pretty well condensed into the paper title: Climate warming promotes species diversity, but with greater taxonomic redundancy, in complex environments. If you ignore the two modifiers it sounds like good news, but those commas add some important information.

The question of whether climate change will drive an increase in biodiversity is a puzzle. Adapting to the new conditions could lead life to find multiple solutions to similar problems – or it could just eliminate species that can’t cope. What Thakur et al. have done is peered into the future by creating some local warming.

In a long-running field experiment in Cedar Creek, Minnesota, the researchers established more than 30 different meadow plots, some with only one plant species (monocultures), and others with up to 16 different plant species. Then, they warmed the meadows with heating lamps to approximately 3°C above the ambient temperature. Subsequently, the researchers recorded how this affected nematodes, little worms that live in the soil in high abundance and of which many different species exist. Nematodes play important roles for several ecosystem functions, for example they help to make the soil fertile which is crucial for plant production.

What they found was that the complexity of the environment was important. Warming increased nematode species diversity in complex plant communities by over a third but decreased it in monocultures by a third compared to the control – ambient temperatures. Dr Madhav P. Thakur, the lead author of the study said: “The story is simple; you need biodiversity to conserve biodiversity in a warmer world”.

It’s not that simple though. While there’s an increase in biodiversity, it’s a less diverse kind of diversity. So while the researchers did find a greater number of nematode species in the warmed plots with high plant diversity, those nematode species were also more closely related, or in other words, more similar, to each other. “The reason was that these species had all been selected for a common characteristic, namely tolerance to a warmer environment”, Thakur explains.

This increase in similarity can have implications for how well biological communities can respond to future environmental changes, potentially limiting the “insurance” effect inherent in a higher numbers of species,” says Dr Jane Cowles, a co-author and postdoctoral researcher at the University of Minnesota.

The monoculture meadow created for the experiment resembled meadows found in intensively managed agricultural land. These new research findings therefore support conservationists who are advocating for maintaining species-rich ecosystems and farmland to sustain biodiversity, and thus human well-being, in a warmer world. This may help to prevent negative effects of climate warming, although likely with some limitations. As Pretty and Bharucha have noted, sustainable intensification will have to account for biodiversity if production is to increase.

Source material: Eurekalert