This article was originally published in the September 2015 issue of Sudbury Mining Solutions Journal.
Restoring the Sudbury Basin to its original state
Delegates to the 6th Mining and Environment International Conference in Sudbury June 20 to 25 received an update on the Sudbury Regreening Program and were able to see for themselves the steady progress the city has made in reversing the devastating effects of early mining activity in the region.
For the first few decades of the program, regreening activity focused on the liming of barren lands, seeding them with a grass and legume mixture and planting a limited variety of trees.
However, a major rethink and broadening of the program was triggered by the release of the Sudbury Soil Study’s ecological risk assessment in 2009, noted Stephen Monet, manager of environmental planning initiatives for the City of Greater Sudbury.
“The ecological risk assessment basically told us that we still had a lot of work to do and that there were still a lot of biologically impoverished areas. That led Vale, Sudbury Integrated Nickel Operations and the City to move forward with a Biodiversity Action Plan.”
The objective was to diversify the vegetation with species native to the region and restore the land to something more closely approximating its original state.
The choice of grass and legume seeds was one example of the rethink.
“Initially, the idea was to lime the area to counteract the acidity of the soil and to create a situation that would allow the metals in the soil to bind more tightly with the soil particles and make it more difficult for the plants to absorb them,” said Monet. “The grass and legume seed mixtures we used were the typical species you’d find in an agricultural setting. They weren’t necessarily native species, but they created a quick ground cover. The following year, we went in and planted pine seedlings.”
The formula worked well for a number of years, but as the trees grew, the grass died because of the shade, while in unshaded areas, the grass grew aggressively, preventing other vegetation from coming in.
“We have now changed to a more native seed mix, so the grass that develops is supposed to be there and is not as aggressive as the agricultural grasses,” said Monet.
“We have also collected local seeds from a plant called Poverty Oak Grass which grows on very rocky and sandy soils. We found some in Hanmer (north of the city). We collected the seed and spread it by hand and were very excited to see it flourishing this year. That will be another species we’ll add to the seed mix.”
The Biodiversity Plan also impacted the species of trees chosen for planting.
“In the early years,” said Monet, “almost 95 per cent of the tree seedlings planted were of four species: white spruce, jack pine, red pine and white pine. They were chosen because they were readily available. They’re easy to plant, they’re inexpensive and they’re produced in the millions for the forest industry. They were also among the species that were knocked back quite hard by the sulphur dioxide fumigations.”
For the rest of this article, click here: http://www.sudburyminingsolutions.com/from-barren-rock-to-lush-forests.html