Discarded Christmas trees help keep carp at bay
Natural berm beefed up stopping destructive fish from going into marsh
Here is a curious sign that spring is on the way — Christmas trees.
Out in Grindstone Creek, Royal Botanical Gardens workers have been using more than 2,500 trees discarded from Christmas to fortify a berm across the creek that is designed to keep carp from travelling into the marsh.
They want to have the berm in place before the ice melts. And with soaring temperatures this weekend, that’s a real possibility.
“It’s kind of Plan B for not having a carp barrier over i n the Grindstone Creek marsh,” said Tys Theysmeyer, head of natural lands at the Royal Botanical Gardens.
Carp are destructive to marsh areas because they stir up the bottom and cloud the waters, making it difficult for plant life to grow and a healthy food chain to be created.
Back in the 1990s, the RBG built a $2.3-million carp barrier and fishway at the Desjardins Canal.
The barrier stops carp from passing through, but desirable species, such as sport fish are allowed through with hand-sorting of fish caught in baskets.
The Christmas tree barrier stops spawning carp from passing through, but species smaller in size can still pass.
The trees are also used to build up banks of the creek.
Theysmeyer said the marsh has been steadily improving each year.
“It’s been like two steps forward and one step back. The most obvious improvement is the water is a lot clearer most of the time. Aquatic vegetation has gone from nothing to many hectares. It’s growing and amphibians are coming back,” he said.
The trees are acquired from re- tailers clearing out their leftover stock after Christmas and from people dropping off their trees after Christmas.
In a separate project, the city in recent days used old trees it collected to restore the banks of Bronte Creek in Courtcliffe Park, which is in Flamborough.
The recycling and waste department picks up trees in January. Most are then dropped off at the city’s transfer stations, where they are sent to be composted at the municipal leaf and yard facility.
Andrew Borer, left, and Rob Diermair, both biotechnicians with the RBG, toss some of the 2,500 Christmas trees needed for this year’s tree berm buffer at the mouth of Grindstone Creek. The RBG needs to add new trees to maintain berm heights to protect the floodplain ponds during any annual high-water levels.