Since their introduction to Newfoundland in the early 1900s, moose have had a tremendous impact on the island’s forests.
Moose no longer have natural predators, such as wolves, to keep their population in check.
In coastal areas, in particular, intensive browsing (or feeding) on balsam fir — one of the foundation species of Terra Nova National Park’s boreal forest — has created “spruce-moose meadows.”
These are large areas of the park where black spruce trees have taken over with grass under the trees rather than the usual mossy ground, making it difficult for the fir trees to regenerate.
Over the past few years, experimental restoration to support Parks Canada Ecological Integrity targets in Terra Nova National Park was implemented by Dr. Luise Hermanutz, Department of Biology, and her graduate student, Louis Charron, with the support of park staff.
Their work is key in determining which park management actions are likely to be effective.
Due to shading, the canopy trees, made up of predominately balsam fir, usually prevent native grass from getting enough light to grow.
But, with most of the balsam fir becoming lunch for hungry moose in the park, the grass acts as an invasive species — growing fast and irreversibly changing the ground vegetation.
The problem? The fir trees can’t penetrate the thick root mat and regrow; hence the need for restoration.
Working with Janet Feltham and Kirby Tulk, Terra Nova National Park staff members, the researchers carried out experiments to determine if balsam fir would regenerate in the park without assistance or if it was necessary to replant them in the black spruce “savannahs.”
And, if seedlings were planted, did they require specialized treatments to give them a better survival rate?
Seedlings were used for the restoration project instead of seeds because, based on previous Memorial University student research, it was discovered that various seed predators — small mammals like the introduced red-backed vole, birds and slugs — would eat the seeds before they germinated.
“We started looking at where in the park we should focus and what experimental planting treatment we should implement, knowing that financial and staff resources were limited,” said Mr. Charron.
“We also looked at different treatments to see if experimental removal of surrounding plants was needed to lower the competition and provide more light or if decompressing the soil would allow the fir seedlings to better survive and grow.”
Seedling plantings were carried out across a number of sites within the park using various ground preparation treatments. Seedling performance indicators, such as survival, growth and browsing occurrence, was monitored over a two-year period.
The seedlings were provided by the team’s forestry partners at the Wooddale Provincial Tree Nursery.
“We would certainly need to look at the results in 10-20 years to see if, in the long-term, our results are consistent.”
“What we saw during the first two years is the planted balsam fir seedlings had a pretty high survival rate, over 90 per cent in all treatments,” said Mr. Charron.
“We only looked at the first two growing seasons to see if the plants could establish themselves, and we would certainly need to look at the results in 10-20 years to see if, in the long-term, our results are consistent. But the first two years have been successful, so that’s a good start.”
They found that cutting surrounding vegetation and plowing the ground was a lot of work and didn’t do much to help the seedlings. In fact, in areas larger than five hectares, the ground was so open that the drying of the soil caused seedlings to die, regardless of the ground treatment.
Simplicity is key
Considering that no substantial biological benefits were detected following ground treatments, which were costly and time-consuming to implement, the team determined that active restoration in boreal forests can be implemented using standard forestry planting protocols, without ground preparation.
“You don’t need to rely on black spruce, and other species that have been used in past restorations.”
Planting seedlings directly into the vegetation without any preparation actually saw better survival rates with lower browsing intensity from moose, and was much less expensive to implement — a win-win situation.
“More work isn’t always the best solution,” said Mr. Charron.
“Now we know that you can plant balsam fir and it will survive and grow. You don’t need to rely on black spruce, and other species that have been used in past restorations. We know that balsam fir can be a good option for forest restoration too.”
Balsam fir = key species
The researchers feel that, despite little research previously being done on balsam fir, it is a key species.
It acts as an “architect,” helping to acidify the soil, provide necessary shade and provide food and shelter for the many species of plants and animals that use the balsam fir forest, such as rare lichens and cross-bill birds.
“For a park in a natural area, it’s not just about having the structure of a forest back,” said Mr. Charron.
“It’s also about having the right elements. Diversity at the end of the day is also important. In a national park you aren’t looking into the fastest growing trees for financial benefit, you just want to have the best ecosystem possible.”