It many not look like it right now, but Sudbury really is green.
Since the first bag of lime was emptied onto the city's barren landscape some 32 years ago as part of the municipality's regreening program, more than 3,400 hectares of land have been treated and nine million trees have been planted.
Those millions of trees are part of the city's ongoing regreening efforts to rehabilitate land that has been devastated by years of sulphur dioxide emissions. That pollution resulted in thousands of hectares of barren land that was incapable of growing new vegetation, Stephen Monet, manager of Environment Initiatives for the city, said.
When the area was originally opened up for mining, people built “open roast yards,” where they would pile timber several metres high and football fields wide, load the ore onto it, and allow it to smoulder for weeks or even months at a time. This was done to remove the sulphur from the ore. It was the sulphur dioxide resulting from that process that was the No. 1
killer of the plants, Monet said.
Everything around these roast yards was immediately wiped out, and then they started putting up smoke stacks that only served to spread out the impact even further, he said. At the end of the day, it resulted in a vast area of de-vegetation and erosion.
The industrial improvements adopted by local mining companies to capture more of the sulphur dioxide has resulted in a reduction of about 90 per cent to the sulphur dioxide emissions, as well as in fine metal particles, which would tend to build up in the soil over time and make it difficult for the plants to re-establish themselves.
Those improvements also helped the work being done by the city's regreening program to take root.
The idea of regreening Sudbury was first introduced in 1978, following a number of years of studies looking at ways to bring back vegetation to barren black hills left lifeless by sulphur dioxide emissions.
“For a lot of people, this idea wasn't even in the realm of possibilities,” Monet said. “The regional municipality took those early experiments and expanded them into a full-blown program. The scope was expanded to encompass hundreds of hectares of land.”
Lime was used, because it raises the pH balance of the soil, making it less acidic, and the small metal particles released from the ore that were preventing vegetation from growing back can bind to the soil particles, so it isn't taken up by the plant roots, Monet said.
“That made all the difference, and the plants can grow as if the soil was normal,” he said.
The first efforts saw small conifer seedlings planted on the limed soil. Today, those seedlings tower to about 25 feet in height. The vast majority of trees planted in the past and still planted today are conifers, and about 90 per cent of the nine million trees are jack pine, red pine, white pine and white spruce. The city quickly recognized the need to diversify the species for numerous reasons, “because the more species we have, the more resilient the ecosystem, and it can more effectively bounce back from diseases or insect infestations,”
Monet said.
The city's landscape is now bearing the fruit of the regreening labour.
“It's really remarkable, because in areas that have been treated where seedlings are planted, there is growth of two to three feet a year, and that's very reasonable for anywhere in Ontario, let alone an area that succumbed to such damage,” Monet said.
That being said, trees alone don't make a forest, and a healthy self-sustaining forest requires soil micro-organisms and insects, fungi, lichens, mosses and a broad variety of forest floor plants.
A Sudbury soil study initiated in 2002, funded by two mining companies (Inco and Falconbridge, now Vale and Xtrata, respectively) at a cost of about $15 million, that delved into a human and ecological health risk assessment identified that, although the area is recovering, there are still barriers to it becoming a self-sustaining ecosystem, Monet said.
Many partners, including the mining companies, the city, the Ministry of the Environment and the health unit, came to the table to find out how to manage such risks. This resulted in the launch of the biodiversity action plan, designed to to build on what was done in the past, and to expand the scope even further.
“Once the trees were at a certain height, they started to form a canopy, which ameliorates the conditions on the ground with more shading and less wind, which creates a more moist environment,” Monet said. “There was a very limited number of plants that could re-establish themselves, because the seed source was completely obliterated by the damage from the sulphur dioxide.”
There are many plant species that have very specific dispersion characteristics, so many of them are actually carried by ant species, he added.
“You could imagine how long it would take an ant on the outside of our area to come back and repopulate it with that species – we're talking centuries,” he said. “The idea of the biodiversity plan was to really re-energize the regreening program and give it the new focus. Now that trees were growing, the idea was to re-establish self-sustaining ecosystems.”
To jump start the process, forest floor transplants were removed from an area along Highway 69 South that was subject to construction activity. Those plots were transplanted into local reclamation sites. In 2010, regreening crews dug up 250 plots, enough to cover a football field. Last year, there were fewer plots dug up, about 135, Monet said.
“These transplanted plots were doing very well the last time we checked on them,” he said. “There are these lush, green plots in the middle of an otherwise barren area devoid of any cover. It looked a bit weird, but it means this has been successful, and some of the plots have even started to expand out to about a metre. It is working, but we're not kidding ourselves – we know this will take decades.”
By bringing in these transplanted floor mats, it also helps to diversify the insect population which, in turn, helps with soil aeration and seed dispersal. Increasing the richness and abundance of insects is also an important part of a thriving ecosystem, EarthCare Sudbury initiatives co-ordinator Jennifer Babin-Fenske said.
Studies of the semi-barren plots vs. the insect species at the receptor sites for transplanted forest floor mats revealed a different makeup of the bug population, she said. That shows there are insects being brought in and, after a few years, the city can look even further to see if the populations are growing.
Posted by Jenny Jelen
