November 23, 2016, by Tim Radford
New research looks at 13 ecosystems in 44 countries, including forests in Patagonia.
Image: Douglas Scortegagna via Flickr
The more diverse the trees, the more productive the forest – new research puts a cash value on preserving biodiversity.
LONDON, 23 November, 2016 – Biodiversity is not just a conservationist ideal, it is a high-value strategy, according to new research. It makes forests more productive, and could deliver up to $500bn a year in wealth across the planet.
This would be more than twice the cost of conserving the forests as reservoirs of biodiversity.
In a new study in the journal Science, scientists from 90 institutions worldwide looked at 150 years of data from 777,126 forest plots that were home to 30 million trees of 8,737 species. They did so not just to confirm something they already knew, but to put a cash value on it.
The researchers found that a 10% loss in biodiversity led to a loss of productivity – a notion that includes biomass, the photosynthetic conversion of moisture and carbon to timber, fruit and foliage – of up to 3% in value in terms of timber that can be harvested. A 99% in tree species richness would mean a productivity decline of between 62% and 78% even if the total number of trees remained the same, and the greatest decline would be in the tropical zones. Altogether, the commercial gain from preserving biodiversity added up to between $166bn and $490bn a year.
“The strongest economic message of this study is that the economic benefit of forest species diversity far exceeds the cost of preserving it, even when we consider only its roles in maintaining the global commercial productivity of forests,” says one of the authors, Mo Zhou, who studies forest economics at Davis College of Agriculture at West Virginia University in the US.
“Biodiversity will also promote the uptake of huge amounts of carbon by trees and will, therefore, be critical in the fight against global climate change”
And co-author Thomas Crowther at the Netherlands Institute of Ecology says: “This economic does not take into account the many other ecosystem services provided by forests, so the total value of diversity is likely to be many times higher than this. In particular, biodiversity will also promote the uptake of huge amounts of carbon by trees and will, therefore, be critical in the fight against global climate change.”
All life on Earth depends, ultimately, on photosynthesis: it turns the energy of the sun into shelter, fabric, food and pharmaceuticals for 7 billion humans and, perhaps, 7 million other species. That greater biodiversity is a good thing has become a given in conservation terms: researchers have repeatedly demonstrated that coral reefs, forests, grasslands and wetlands are more productive, and more resilient in times of stress, with higher levels of species richness. In the last few years, groups of scientists have independently shown that human invasion disturbs natural diversity and that species loss diminishes the value of the natural world to human communities.
Forests are the natural wealth exchanges that turn atmospheric carbon into something of value, and release oxygen for the rest of creation to breathe: they are also natural reservoirs and catchments for rainfall. One recent study of forests calculated that the planet could be home to more than 3 trillion trees – 422 for every human – but humans were destroying them at the rate of 15 billion trees a year.
This, conservationists argue, is a way of squandering natural capital, and Brazilian scientists in particular have led a push to learn from, and exploit, nature’s own ingenuity and demonstrate the value to modern industry of maintaining forest diversity, to learn from the astonishing range of products and sophisticated technologies blindly fashioned by 3 billion years of evolutionary experiment.
The study encompassed 13 ecosystems in 44 countries, including forests in Siberia and Patagonia, an archipelago in the Pacific, the Mediterranean woodlands, the temperate grasslands and even the deserts, as well as the tropics. Everywhere, the relationship between biodiversity and productivity held, but the measured decline was greatest in the forests of the Amazon, West Africa, southern China, Nepal, Myanmar and the Malay Archipelago. – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.