The competitive juices that run through trees

By Costa Maragos Posted: January 11, 2016 6:00 a.m.

Dr. Mark Vanderwel (r) working in the field with U of R student Matt Schultz.
Dr. Mark Vanderwel (r) working in the field with U of R student Matt Schultz. Photo courtesy of Bryttni Nameth.

A University of Regina professor is part of a research team that has produced the most extensive study on tree competition to date.

The study’s results have recently been published in the influential journal Nature, which is the most highly-cited scientific journal in the world.

Dr. Mark Vanderwel, assistant professor of biology, contributed to the research along with more than three dozen ecologists worldwide.

"It was a fantastic group of leading forest ecologists. I was very excited to be working with them on this project,” says Vanderwel.

The project is unprecedented in scope, bringing together data from 3 million trees covering 2500 species from all of the forested continents. What might be a surprise is that traits that determine how trees respond to competition act in a common manner, whether they are in tropical forests of the Amazon or boreal forests in Canada.

Dr. Mark Vanderwel
The research “helps us to develop models that can predict how forests will change over time:” - Dr. Mark Vanderwel. (Photo by Geremy Lague)

“We know that trees need light for growth. But there are different ways a tree can allocate its resources to achieve that growth,” says Vanderwel. “We find there are globally consistent trade-offs related to wood density and leaf construction that explain how trees compete with one another.”

Here’s what else the research found.

Traits that allow trees to grow well in open areas also make them less competitive in crowded forests.

As a result, different species do well in different environments.

For example, species with high wood density grew more slowly in open ground but had the advantage in heavily crowded stands.

The findings support the established idea of how forest succession influences tree diversity.

In young forests, the advantage goes to the fast growing species. But as that forest matures, and neighbouring trees establish themselves, the competition for resources heats up. In crowded forests, trees with more conservative growth strategies can take over as they have a stronger ability to compete for water and light.
“This helps us to predict how forests will change over time and what traits are favoured under different environments,“ says Vanderwel, who compiled data for the study from forests in Canada and the U.S.

Vanderwel says the findings also help us better understand forest growth through time. Models developed from these data can help predict how much CO2 trees can absorb from the atmosphere.

Vanderwel participated in the data analysis at a workshop held at Macquarie University in Sydney, Australia. The study’s lead author is Dr. Georges Kunstler, who is based in Grenoble, at the French Research Institute for Environment and Agriculture.

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