Climate change drives expansion of forestry protection research

By Cynthia Strawson

Climate change in Alberta may affect forests faster than trees can adapt to evolving conditions.

Drs. Hamann and Tyree

Spence's concerns are the inspiration for expanding his Forest Management Research Team through the appointment of two new scientists, Dr. Andreas Hamann, a forest geneticist and expert on climate change, and Dr. Mel Tyree, one of the world's leading experts on tree-water relations.

According to Hamann, who comes to the U of A from the University of British Columbia, the mild winter of 2005-2006 could become the norm within 40 years. "As the climate changes, our landscape will change too. Drought-related dieback of trees, increase of forest fires and pest outbreaks such as the mountain pine beetle epidemic in British Columbia will profoundly impact our forest and grassland ecosystems in Alberta."

He explained the need to have solid science to support innovative forestry and environmental conservation policies and practices that will be needed in the future. "Within a few decades our current strategies for conservation and reforestation simply won't work. To maintain healthy and productive ecosystems, we will have to start moving species to new locations as part of our reforestation and conservation programs."

Tyree is the second recent addition to the team. Tyree, who comes to the University of Alberta from the United States Forest Service and has won Marcus Wallenberg Prize for scientific achievement in forestry, will focus on how stresses will impact forests in the next 100 years.

"Change is stressful for people as well as trees but, unlike humans, trees are slow to adapt to change," said Tyree.

Climate change in Alberta may result in more frequent summer droughts and more frequent autumn and spring days with freeze-thaw cycles: both predictions are stressful for trees. Tyree started his studies of tree stress physiology 25 years ago by listening to sounds made by trees.

"Trees are thirsty," he said. "As water evaporates from a tree's leaves, it has to pull new water up from its roots. It pulls so hard that the water actually forms a strand. If it's really thirsty and can't get enough water during a drought, those strands will be under so much tension that they will break, making a snapping sound."

The sound is inaudible to the human ear but Tyree has recorded it using specialized digital recording technology. "If we slow the sound down digitally we can actually hear the snapping sounds. It sort of sounds like calypso drums."

This snapping of the water strand can lead to serious setbacks for trees not well adapted to drought.

Twenty-five years of research by Tyree has shown that trees which are good at transporting water are the most productive trees but are also the most vulnerable to the stresses induced by drought and frequent freeze-thaw cycles. There is a delicate balance between water transportation and production of wood. "Over millions of years trees have adapted a wood structure to adapt to the stresses thrown at them, but the current acceleration of climate change might be too fast for trees to adapt by natural selection and migration," he said.

The task for the new researchers will be to identify which trees (species and individuals) have developed the best balance between maximum growth and maximum tolerance to drought and the freeze-thaw conditions. They need to identify which is the best wood structure to provide a tree with the qualities of efficient water transportation and wood production, while at the same time allowing the tree to survive and adapt in our changing climate.

"In the future we should be able to look under a microscope at the wood structure of a one-year-old tree seedling and know whether it will grow well and be resistant to the stresses of drought," said Tyree.

There is potential for trees better adapted to new climate conditions, to grow to full size in 25 years instead of 80 years. There is also potential to plant these trees on land that has already been cleared for agriculture but doesn't grow agricultural crops well. "If we can capitalize on marginal farm land, while reseeding our existing woodlands with appropriately selected trees, we can help to preserve the wildlife and plants of our native forests."

Source / Credit: University of Alberta