UNB climate-change researchers study how seedlings react in range of temperatures

Two scientists from the University of New Brunswick are working together to understand the impact of climate change on the Acadian forest.

Anthony Taylor and Rob Vaughn are conducting a two-year experiment studying how different species of tree seedlings will grow under different climate change conditions.

 The Acadian forest is what's growing across New Brunswick and in the other two Maritime provinces as well as in the U.S northeast.

The UNB experiment, mostly funded by the federal Department of Natural Resources, exposes seven different coniferous species native to the Acadian forest to 12 levels of warming.

The species are the red, white, and black spruce, balsam fir, white pine, jack pine and hemlock, all species. 

A closer understanding

Under climate conditions that the trees face now to 12 degrees warmer than outside, the data is expected to show how these seedlings will react to climate warming. 

"Climate change is going to have a big impact on our forests," Taylor said. "And so understanding how our forest will respond to climate change, especially at the regeneration stage is vitally important to the future of our forest."

Close to 30 million seedlings are planted in New Brunswick's forests per year, according to Taylor. Seedlings are the most vulnerable stage of trees, so if climate change were to have a big effect, it will be on that stage.

Inside the greenhouse at the Hugh John Flemming Forestry Centre in Fredericton, the species are being grown in five-foot-tall, house-shaped chambers. Each chamber houses the seven different coniferous seedling species in pots.

According to Vaughn, they're growing the species under 12 different temperature treatments ranging from baseline, which is roughly the average daily baseline climate conditions for Fredericton from early May to September, to18 degrees above that baseline.

"That data can then be used to inform forest models and to get some really good empirical data that will allow those models to be more accurate," said Vaughn. 

The coolest treatment mimics the average daily temperatures in Fredericton over the last 30 years, said Vaughn. The hottest it got was 25 C inside the chamber. At this point, the seedlings' survival is good, according to Vaughn. 

"They maybe haven't hit the optimum growth temperature yet,' Vaughn said. "It's a little cold for them, but their survival is really good and they look very healthy overall."

The seedlings are watered regularly, said Vaughn. However, the colder treatments are watered less often than the hotter ones because there's a lot more evaporation in the hotter treatments.

In the experiment, the chambers' temperatures are controlled and the soil moisture in the seedling pots are maintained. But in the natural environment and the change in climate, soil moisture will be a lot less, says Taylor. 

"You'd likely see negative detrimental effects at lower temperatures than what we're seeing here, so it's important to keep in mind," said Taylor. 

In the hottest chamber, the pots are heavy and they're moist. Sitting at 43 C, there are clear signs of decline and mortality in the chamber compared to the other chambers. 

Vaughn says he wanted to have the hottest treatment to go past what the seedlings could handle to examine extreme conditions of climate change. Around late June, there were clear signs that this treatment was causing "a lot of heat stress" on these seedlings. 

The black spruce, the Canadian hemlock, the balsam fir, and the red spruce are crunchy and browning because of the heat stress. However, the white and jack pine, and white spruce look a little better. 

"Over time, you still see there may still be some negative effects, some show up later in the season or even next year when they start to break bud," said Vaughn.

If this scientific work wasn't happening, "it'd be like walking with your eyes closed, basically into the future," said Taylor. 

Their findings will be published in peer reviewed scientific journals. Taylor said the data will help inform groups and companies that work in and use the forestry sector in New Brunswick. 

"As the climate continues to warm, those species are maladaptive to warmer conditions, and they're not projected to fare that well," said Taylor.

"That'll have a potential major impact on the growth and volume that these tree species could provide the forestry sector for things like lumber and paper."