Liberal leader Justin Trudeau promised last week that a second-term government under his leadership would invest C$3 billion over 10 years to plant two billion trees across the country. But a Liberal Party backgrounder says the cost of the program would be “offset” by revenue from the controversial and financially fragile Trans Mountain pipeline expansion.

“Nature isn’t just part of our identity as Canadians, it’s also a part of the solution to climate change and it’s a solution we can start using today,” Trudeau said. “Trees are remarkable. They pull carbon out of the atmosphere. They are renewable and they’re sustainable and, eventually, they even recycle themselves. All we have to do is plant the first one.”

The tree planting promise is “part of a broader $3-billion fund for natural climate solutions that will support efforts across the country to better manage, conserve, and restore forests, grasslands, agricultural lands, wetlands, and coastal areas,” the backgrounder states. “These landscapes all help store and take carbon pollution out of the air—whether that is grasses taking carbon into their roots and the surrounding soil, or healthy wetlands keeping centuries of carbon in the ground.”

The backgrounder says the program will create 3,500 seasonal jobs per year and offset 30 megatonnes of greenhouse gas emissions. Liberal Party officials told Global that about 600 million trees are already planted across Canada each year, including the successful 50 Million Tree program in Ontario that Ottawa shored up with a four-year, $15-million emergency grant after the Doug Ford government moved to cancel it.

Asked whether unsteady federal funding due to the reliance on Trans Mountain revenue would imperil the program, a spokesperson for one of Canada’s key delivery agents for reforestation efforts, Forest Recovery Canada, told The Energy Mix her organization would still be able to get trees planted, even if it had to adjust its overall target.

The announcement ties in with a hopeful though somewhat contested study in June that found space to plant a trillion trees around the world and remove a large share of the carbon pollution added to the atmosphere since the dawn of the Industrial Revolution, without affecting existing cities or farmland. Global News says it identified Canada as one of six countries with the land mass to help lead the effort.

“Canada can’t plant 500 billion trees inside Canada, but we can do our part,” said University of Ottawa biology professor Jeremy Kerr. While the strategy will only deliver climate benefits if it’s accompanied by other forms of decarbonization, “two billion trees is actually a pretty reasonable contribution to that total global requirement to address the huge pool of carbon that we’ve dumped in the atmosphere. Those trees pull that carbon right back out. This is incredibly timely, because the science is now incredibly clear.”

Global notes that how the reforestation is done is just as important as how many trees are restored, citing past planting efforts around Fort McMurray, Alberta as a factor in the severity of the 2016 wildfire known as The Beast. “In contrast to that sort of thing, where what you’re doing is taking one sort of natural habitat and wrecking it to create a spruce plantation, what you would be doing in this instance to address climate change is look at areas that were historically forested,” Kerr said.

“The consequences of getting it wrong can be really destructive,” agreed U.S. Department of Agriculture forest ecologist Malcolm North said.

In an opinion piece circulated last week, Forests Ontario and Forest Recovery Canada CEO Rob Keen said the current enthusiasm for tree planting is unprecedented in his 38 years as a forester. “The trigger? Climate change,” he wrote. “So now, as Canadians, how do we harness and deploy large-scale tree planting on a national scale?”

Keen added that “the complexity of tree planting is far greater than many realize; from seed forecasting and collection to monitoring tree survival. We conduct site assessments to determine the best-suited species for the site; use native trees grown in local nurseries with source-identified seed stock; and have expert local partners who undertake the planting, conduct survival assessments, and deliver appropriate care. All steps of the process are completed with an unmatched level of accountability and are reported online and in real time.”

While that kind of detail isn’t laid out in the Liberals’ policy announcement, Forest Recovery Canada Director of Operations Kerry McLevan said the operational side of the plan would be left to delivery agents that have the experience get it done. “Each province is different, and each province has a different range of species,” she told The Mix in an interview. “We really do need to rely on the local professionals who know their forest types and topography and know what should be planted.”

Last year, CBC reported on a spraying program in British Columbia forests that was wiping out tree species considered less desirable by the forest products industry, but making the remaining, less diverse forest more vulnerable to wildfire. “The eradication of trees like aspen and birch on regenerating forest stands is meant to make room for more commercially valuable conifer species like pine and Douglas fir,” the national broadcaster explained at the time. “But experts say it also removes one of the best natural defences we have against wildfire, at a time when our warming climate is helping make large, destructive fires more and more common.”

McLevan said a stretch of reforested land that is planted as a monocrop may not end up that way. “In some cases, yes, you can be diverse, where in other cases you do need to stick to a fewer number of species to make sure you achieve the objective of restoring the forest,” she explained. “Forests take many, many years to change, so even if you see a monoculture, that’s just step one. Eventually, the natural hardwoods will fill in those gaps where the others die off. So forestry is a very long-term process, and if you take a snapshot now, that’s not what it’s going to look like in 100 years.”

Asked how Trans Mountain’s mounting financial and operational fragility, documented earlier this month in a blockbuster report by Vancouver-based Stand.earth, would affect the $3-billion funding promise, McLevan said reforestation programs always depend on multiple partners and supporters.

“If funding gets reduced, you definitely have to look at changes to the target,” she said. “We definitely have to be realistic about what we can do with the funding we have.”

But “any investment is a positive investment,” she added. “As a non-profit organization, we’re used to working with whatever we have to make successful programs. Even if we have to scale it down, those trees go in the ground…you don’t walk away just because there’s less funding.”