Volunteers are needed to wage a battle against a noxious plant that is already entrenched in the green spaces alongside Hudson's Bay Slough and Carrie Jane Grey Park.

Common tansy is a lovely flower that spreads rapidly through ecosystems, consuming fields and shorelines in only a few summers if left unchecked.

On Saturday, city and provincial officials are trying to stop that spread and are calling on public help. All available hands are being called to the two parks to rip out the tansy and plant native plants in their place.

"Our goal is 50 volunteers," said Andrea Eastham, program manager for the Northwest Invasive Plant Council. "We will be uprooting the tansy and we will be replanting the area with trees, shrubs and herbs that are naturally occurring. It is a tough site - a really important project."

The replanting is not just to restore the visual qualities of the area, it is to fight back against future weed attacks. Tall plants shade out the alien invaders. If the unnaturally introduced plants like tansy take over, it can cause unnatural soil erosion into the waterways (it already has in two spots) , which then threaten fish habitat. It can degrade the amounts of cover needed for small animals and birds to thrive. It can empty the food supplies for the wildlife that depends on certain plant life, reducing the available food supply all the way up the food chain.

"They [invasive plant species] all have a detrimental effect," said Claire Watkins, the integrated pest management co-ordinator for the City of Prince George. "When we build these beautiful parks and green spaces, these public assets, we find them especially threatened when major roads run through them. The seeds get carried in on vehicles and blown into the fringes along the roadsides, and then a few plants becomes a lot of plants, and then it becomes an infestation if we don't respond."

In many places, herbicides can be effective but they can't be used alongside waterways like Carrie Jane Grey Park and Hudson's Bay Slough. The only effective counterattack is human hands pulling the bad plants up, and putting good plants in their place.

All volunteers will be trained to do these simple jobs, said Eastham and Watkins. Thanks to a $5,000 grant from the Wal-Mart/Evergreen program, all volunteers will be provided with digging tools, gloves and garbage bags, or volunteers may bring their own. Groups of volunteers will be assigned to a trained leader to work on a specific area.

The weed war will be waged at Hudson's Bay Slough (meet at Gyro Park parking lot on 20th Avenue at the entrance to Exploration Place) from 9 a.m. to noon and at Carrie Jane Grey Park (meet at the Massey Boulevard-20th Avenue entrance) from 1 p.m. to 3 p.m. Follow the ribbons and signs from the parking spots to the restoration sites.