Climate change could begin to impact the density of tree species and in turn the effectiveness of ecosystem conservation, finds new study.

The research, led by the University of Alcalá (UAH), in Spain, and including researchers at the University of Birmingham, draws data from across Europe and North America to show that tree species in the Northern Hemisphere are starting to become denser in colder and wetter regions.

Researchers analysed data from over two million trees, representing over 70 species widely distributed across Europe and the United States; investigating whether the changes in density could be attributed to species characteristics.

No single trait of the tree species analysed were identified as being related to these changes, Julen Astigarraga, from UAH and lead author of the study, comments:

“This lack of a definitive trait suggests that most species possess a degree of acclimation capability.”

Understanding how species are responding to climate change is essential for planning ecosystem conservation, management and restoration, says the University of Birmingham.

“Some tree species which are currently used for ecosystem restoration in Europe may no longer be suitable in these regions in the near future,” says co-author Dr Thomas Pugh, of the University of Birmingham and Lund University.

“In addition, massive reforestation programmes planned as a solution for capturing and storing carbon dioxide from the atmosphere might be limited in their effectiveness if they do not account for these responses.”

The study, published in Proceedings of the National Academy of Sciences (PNAS) provides the first quantitative evidence that climate change is driving this change in the numbers of trees of each species across temperate forests on a continental scale.