New research pinpoints which trees are climate change-ready

Research involving Essex scientists have discovered that “penny-pinching” evergreen species such as holly and ivy are more climate change-ready in the face of warming temperatures than deciduous “big-spending” water consumers like oak.

This shows which species are more likely to prosper in the near future – with this pattern set to be felt more strongly in cooler climates, such as Ireland’s.

Theory predicts that rising global carbon dioxide (CO2) concentrations in our atmosphere will make the world’s trees grow in a more water-efficient way but, until now, few studies have tested these predictions.

The study, led by botanists from Trinity College Dublin, found that atmospheric CO2 rise over the last 25 years has already had a demonstrable impact on the water use of forests, making them more water-wise. However, not all tree species behave in the same way.

Professor Jennifer McElwain, who led the research, which has been published in leading international journal Science Advances said: “As well as offering a fresh insight our results allow us to make some concrete predictions on how future modification of our atmosphere and climate will impact the world’s forests.”

Professor Tracy Lawson, from our School of Life Sciences, who led the Essex team on this research added: “It has been great to be involved in this work led by Jennifer McElwain’s group at Trinity, where they have found that with rising CO2 concentrations, evergreen trees and shrubs are more efficient in using water than deciduous plant in cooler climates, but there is limited evidence for such patterns in locations with warmer climates.”

Gardeners are well aware that water is a precious commodity for all plants. Water is essential for healthy growth and development and plants will soon desiccate and die without it. In the wild however, where plants do not receive daily water from a caring gardener, species compete for it and all other essential resources like light, nutrients and space.

The team’s results therefore imply that the evergreen woody species – because they are more water-wise – will have a distinct ecological advantage over their deciduous neighbours if atmospheric CO2 concentrations continue to rise. During times of water scarcity – such as in droughts that are increasing in frequency and duration due to climate change – this predicted advantage should be even greater.

This newly discovered impact of recent global climate change on evergreen and deciduous plants becomes more apparent as we travel from the warmer to cooler zones of the planet.

The discovery has a wider importance as the results can now be used to feed into climate models to reflect as much as possible the situation of real plant and vegetation responses to climate change on the ground.