Geerten Hengeveld, Gert-Jan Nabuurs and colleagues showed in Science that high forest biodiversity has a positive effect on productivity. If the number of species increases, the amount of wood that can be harvested increases too. But the reverse is also true: a decline in biodiversity provides an accelerated decrease in forest productivity. And that can cost society billions each year, according to the evidence collected by thousands of forest researchers over the last 150 years.
"If the number of tree species worldwide would decline from the current level to a single species, the wood yield worldwide would decrease by two thirds. This would happen, even if other variables, for example, the total number of trees, would remain constant, "says Geerten Hengeveld. Based on this estimated figure, he and his colleagues state that the reduced productivity due to loss of tree species could bring worldwide economic losses of up to $ 500 billion annually. This amount is more than double that what it would cost to take effective protection measures in all ecosystems of the world. "This study showed us in an unequivocal way the great importance of a high biodiversity in our forests," adds Gert-Jan Nabuurs. "This insight highlights the importance of an integrated approach to forest management and forest protection. Sustainable forest management promotes diversity of forests."
Thanks to this project, researchers from more than 90 institutions combined their data in a single database of more than 770,000 plots that measured more than 30 million trees, belonging to more than 8,700 species. This data allows to cover all major global forest ecosystems in 44 countries and includes the most extreme conditions on earth. From northern Siberia to southern Patagonia. From the cold of Oimyakon in Russia until the heat of Palau, and from the Netherlands to remote archipelagos in the Pacific Ocean.
The economic message from this study is that the returns from a large species diversity is much higher than the cost of maintaining this diversity, even if we only look at the commercial productivity of forests. Besides the economic aspect, low cost-benefit ratio of species also brings substantial social, ecological and environment advantages, such as climate regulation, habitat improvement, improved water quality and erosion limitation. The loss of species reduces the productivity of the forests. Consequently, the uptake of carbon from the atmosphere is also reduced. The preservation of species diversity is therefore an important action in the fight against climate change.