Ants help reveal why sourcing different plants for eco-fuels is crucial for biodiversity

Although a renewable energy source, the use of biofuels is controversial because growing a small number of highly productive crops as fuel can lead to loss of biodiversity in cropping systems where biomass is produced. A cropping system refers to the crops, their sequence and management practices on a given field.

Now, US researchers have compared ant communities in different types of bioenergy crop systems to better understand how these systems shape biotic communities and their functions. The results are published in Frontiers in conservation science.

“We discovered different ant communities when we compared annual crops, perennial systems and various perennial polycultures with many plant species,” said first author Dr. Nathan Haan, who collected data for this study at the Kellogg Biological Station at the University of Michigan and is currently studying the subject. insect ecology as an assistant professor at the University of Kentucky.

“Perennial bioenergy cropping systems, particularly those that incorporate greater plant diversity, give rise to a different and more diverse ant community than simpler systems.”

Ants and Crops

Ants are abundant and influential players in grasslands and agroecosystems. They can be important predators, seed dispersers and soil engineers. “If large parts of our landscapes are devoted to growing fuel crops, ants are the best candidates for studying how insect communities might differ across crops,” Haan explained.

Researchers examined 10 bioenergy growing systems in an experimental setup in Michigan. The systems included annual crops (corn and two types of broom), simple (multi-year) perennial systems (two panicles, miscanthus and a mixture of native grasses) and various perennial systems (reconstructed grassland, spontaneous successional vegetation and a short -rotating coppice system with poplars).

The researchers captured nearly 10,000 individual ants belonging to 22 species. In complex ecosystems, ants fulfill more functional roles (e.g., predators or seed dispersers) than in simple systems. Species richness was highest in diverse systems and lowest in simple systems. Community composition also differed: some common ant species were found in all cropping systems; however, rarer species only appear in plant-diverse perennial systems.

Optimizing Crops for Fuel

The tested crops have different advantages and disadvantages for biofuel production, the researchers pointed out. Some of these are more productive, but have little conservation value; others, although less productive, have conservation benefits. For example, perennial plants can help store carbon underground in their roots. Mixed species grasslands can also be very productive and have much richer biodiversity. However, there are more unknowns about how to use their biomass to generate final products.

“It’s about understanding the tradeoffs and figuring out how to optimize them,” Haan emphasized. Currently, 40% of corn produced in the United States is used to make ethanol, which is often used as a fuel. Growing so much corn in a monoculture, however, is an inherently unsustainable solution to feeding the future.

“There are a whole range of other cropping systems that could be adopted and become mainstays. We need to understand which of these are biodiversity friendly and which are not,” Haan said.

The basics of biofuel production

The researchers hope their study will inform decisions about which crops can be used for sustainable biofuel production, where those crops are grown, and how they are managed.

“Bioenergy appears to be increasingly fashionable in the news and in public discourse, but projections indicate that we will need to deploy large-scale bioenergy crops in the decades to come in order to successfully combat climate change ” Haan said.

Although the present research was conducted in a single experimental set, the general trends should be similar elsewhere, Haan said. However, it is necessary to collect more specific information in other contexts.