Removing Yellow Flag Iris from the Lower Pond
As Yellow Flag Irises spread over the surface of the lower pond, the pond has begun to lose ecosystem integrity, habitats and native plant diversity. Red Alders and other deciduous trees at the end of their life cycles have fallen into the upper pond, thereby significantly reducing the open water surface and contributing to anaerobic water conditions. Several red alders are established in the Yellow Flag Iris mat in the lower pond, which accelerates the loss of open water habitat.
A Yellow Iris removal pilot exercise conducted in November, 2013 was successful, with two truckloads of Yellow Iris roots and plants removed to the Hartland invasive species disposal site. This pilot was important for the development of the strategies for removing the plant mats.
Pilot exercise - Marking the removal area with yellow tape.
Pilot exercise - Plywood used to protect existing vegetation.
Pilot exercise - Loading irises into the truck.
Pilot exercise - Collecting seeds and rhizomes floating in the cleared area.
Pilot exercise - The pond in the following summer.
Full Removal of the Yellow Flag Iris
In October, 2014, the CRD was successful in removing most of the Yellow Iris from the lower ponds.
The work took less than two days and the CRD took 5 truckloads of the material to the landfill. The rest of the material will be removed in the spring.
Special thanks to Brian White who coordinated this effort and Ron Hamilton and Cam Woodsend from the CRD.
The pond just before the dredging started.
On the day before the iris removal and the next morning, there was a search for frogs on the site. Only three were found and were relocated to another pond off-site.
Iris dredging underway. In wetter areas, plywood was put down to prevent sinking. Existing sedges and spatterdocks were left in the pond.
The irises were piled up along the side for removal to the Hartland site.
The pond is very shallow and has a clay bottom.
A small dam was built at the outlet to raise the level of the pond.
The pond started to fill once the rains started. About five truckloads of irises were removed. Another five truckloads will be removed in the spring.
The pond after the iris removal.