Burdock Brigade: Battling the Invaders (3/17/2012)

Volunteering with the Burdock Brigade at the UEC focuses on land management issues, such as the removal of invasive species and planting of native species.  Since the founding of Milwaukee, industrial and residential development has re-shaped the Milwaukee River Valley.  Much of this area has been remediated in the past two decades, but many areas are still a work in progress.

The area we worked in today is the site of the former North Avenue dam.  The dam was built in 1835 with the initial purpose of providing water for a canal that would link the Milwaukee and Rock Rivers.  That canal was never completed, so the dam was used to generate hydroelectric power for industry and ice harvesting in the winter.  The dammed water was also a year-round recreation destination for the city's residents

As time went on, the water and sediments behind the dam became more and more polluted.  In 1992 the Wisconsin DNR and several local and regional governmental groups began a study to determine what to do with the situation at the North Avenue dam.  They recommended its removal alongside measures to control polluted sediments at the location.  This project was completed in 1997.

Restoring the course of the river left the banks of the old reservoir high and dry.  These banks are a continuing erosion concern.  The project also created flat acreage along the new banks.  This newly disturbed land was ripe for r-strategists to move in and colonize.

Former banks upstream of the North Avenue dam

Reed canary grass is one of the invasive species that has taken over the river flats.  It reproduces by sending out rhizomes.  The rhizomes travel underground and re-emerge as a new ramet, genetically identical to the parent grass.  Reed canary grass was brought over from Europe and Asia for use as cattle feed.  However, the cattle preferred other grasses and grains and didn't graze extensively on the reed canary grass.

The land stewardship team at the UEC is in the process of restoring a wet-mesic prairie on the riverbank.  A wet-mesic prairie is a grassland found on moist soils that are occasionally flooded, like a river floodplain.  This restoration involves removal of the invasive species and replanting of native species.  Many staff and hundreds of volunteers have been involved in this process.

Covered area with reed canary grass growing at the edges

In order to kill off the reed canary grass, it is being smothered by black plastic sheeting, which blocks sunlight.  Today, we fastened down sheeting that had been pulled up in recent high winds.  The river flats will be covered all year, then native species will be planted in late fall.  The goal is for the native plants to establish themselves and out-compete the reed canary grass.  When native plants re-colonize an area, native insects, birds and animals follow.
 
After the plastic sheeting had been secured, the group spent the rest of the time spent digging out garlic mustard.  I suspect I will have many future encounters with garlic mustard, so I'll save this discussion for a later post.