There’s an increasingly recognized argument in the field of conservation that ecosystems are worth protecting because they provide a monetary value to both humans and the economy. Known as “ecosystem services,” it’s said that as money talks, the only way to get people to listen is to calculate how much an ecosystem is worth. But a recent study of the services provided by wild bees when pollinating crops has shown how this purely economic outlook on the environment can have serious flaws.
An international team of researchers, led by Wageningen University in the Netherlands, has found that 80% of the world’s crops are pollinated by just 2% of wild bee species. The researchers therefore point out that if a management plan was to be drawn up based purely on their ecosystem services, the majority of bee species would be deemed to have less value compared to the important two percent identified, and that this could actually lead to biodiversity loss. This could also spell bad news for the future, as it's possible that our changing climate could ultimately alter which species are crucial to keep food on our plates.
“This study shows us that wild bees provide enormous economic benefits, but reaffirms that the justification for protecting species cannot always be economic,” says Taylor Ricketts from the University of Vermont, and the study’s co-author. “We still have to agree that protecting biodiversity is the right thing to do.”
They reaffirmed that wild bee pollination is a massively important ecosystem service, contributing around $3,251 per hectare of insect-pollinated crops – a value that equals the contribution from managed honey bees. And it adds up to billions of dollars a year in most cases. But was this service spread evenly across species?
The new research, published in Nature Communications, pooled data from 90 studies across five continents. They found that the crops were pollinated by 785 different species of bee, and whilst this may sound like a lot of species, it actually represented only a little under 13% of bee species known to occur in the regions studied. Even so, the team found that only 2% of the wild species, mainly bumblebees and solitary bees, pollinated 80% of the crops.
So whilst bees in general provide a huge ecosystem service to humans, it’s actually only a few percent of species – and the most common and resilient ones at that – which are responsible. This reveals the flaw in management plans based purely on ecosystem services.
The authors say that it’s important to not just focus on those species key to crop pollination. As the climate shifts and ecosystems alter, there is no way to predict which species might become more or less important for the agricultural business in the future. As Ricketts explains: “Species and populations can fluctuate significantly as landscapes and climates change. So protecting a wide variety of our wild bees is crucial.”