If you took a walk through the Humber Arboretum last month, you may have noticed tarps and carts piled high with pulled-up plants. This was weeding taken to the next level, as Horticulture Technician Andrea Sudak and a team of workstudy students physically removed two invaders from the Arboretum woodlot.
Invasive species are plants and animals that – intentionally or not – have been brought to a new habitat where they have no natural competition and flourish in a way that can completely unbalance the ecosystem. It’s particularly important to keep their growth in check at the Arboretum as Humber College’s North campus is located within the Carolinian Life Zone, a bioregion that is home to a greater variety of plant and animal species than any other ecosystem in Canada.
This past spring staff removed invasive plants from an area covering approximately 9000 square feet in the woodlot, and are always keeping on top of invasives that appear in any of the Arboretum’s 37 botanical beds. First on the woodlot list was Dog Strangling Vine. Originally from Eastern Europe, these vines will climb shrubs and trees, even reaching up to attach themselves to low branches. It spreads both through underground rhizomes – stems that spread out horizontally before sending new shoots up through the soil – and through seedpods. The goal in June was too pull the plants before a new batch of seed pods could appear. Left unchecked, DSV can form a tangled, cascading maze of green that crowds and chokes native plants.
Staff and workstudy students also removed Goutweed, a ground cover which is sometimes known as Snow-on-the-Mountain. No matter what you call it, this aggressive plant will spread quickly and prevent native ground covers like ferns and strawberries from growing. It’s especially important at the Arboretum that Goutweed isn’t allowed to choke out native White Trillium, which is Ontario’s Provincial Flower. Now that the Goutweed has been removed, Sudak and her team will use a technique called lasagna gardening to try to prevent it from coming back, layering cardboard and natural material under the soil before they put in native plants.
Although there is research taking place right now to find new management techniques, this certainly won’t be the last time horticulture staff will have to clear out the clutter in the woodlot. It’s an ongoing challenge to control invasive plant species in a conservation area, but Arboretum staff are dedicated to giving native species a chance to thrive.