Monday, January 9, 2017

Restoring the Floodplain

Post contributed by Brett Stolpestad and Brad Chatfield, Conservation Corps of Minnesota:

Great Horned Owls are one of the many species that use Saint
Paul's floodplain parks to raise their young.
The Mississippi River floodplain is Minnesota’s centerpiece. A patchwork of cottonwood, maple, boxelder, hackberry, and ash make up the forest ecosystem, providing critical habitat for migratory birds and other river-dependent wildlife. The City of  Saint Paul is home to a beautiful winding chain of parks along the Mississippi and uses a variety of management practices to augment the health of the floodplain ecosystem. One particularly useful and beneficial technique is shelterwood harvesting, the process of gradually removing mature trees in a given area with the goal of establishing the next generation of desirable tree species. This process has the potential to increase biodiversity, improve wildlife habitat, and eliminate invasive species.

How does shelterwood harvesting work?

Step one: Land managers begin by surveying forest transects using satellite images, GPS units, and GIS software. At this stage, typically called a forest composition survey, surveyors attempt to create a map that clearly illustrates the distribution of tree species, the total canopy cover, the average size of the trees and perhaps their age.  

Step two: Surveyors identify potential shelterwood harvest sites by analyzing sections of forest that may lack diversity or contain undesirable species like buckthorn, white mulberry, or Siberian elm.  

Step three: Through several gradual stages, foresters begin removing trees that lie within the designated shelterwood harvest area. Removing these trees helps to open the canopy, allowing sunlight to reach the forest floor where the next generation of saplings can become established.

Step four: Native tree species can then be planted in the newly created pockets, adding to the biodiversity of the ecosystem and improving wildlife habitat. Trees or shrubs such as cottonwood, silver maple, sugar maple, black willow, elderberry, and red osier dogwood might be selected!

A Conservation Corps member completing a canopy survey at Hidden Falls
Regional Park.
In recent years, prominent Saint Paul Parks including Hiddens Falls, Lilydale, and Crosby Farm Regional Parks have all been selected as sites for shelterwood harvest. The decision to focus on these parks has been, in part, a response to ecological threats including the encroachment of emerald ash borer. The threat of emerald ash borer has led to the preemptive removal of ash tree throughout the floodplain, followed by several large-scale volunteer planting events. Over the past few years, volunteers have helped plant hundreds of trees and shrubs throughout Crosby, Lilydale, and Hidden Falls. If you visit these parks today, you will undoubtedly see dozens of young maple, cottonwood, and black willow standing straight in their “tree-tubes,” along with an understory smattering of black willow, dogwood, and elderberry.
Shelterwood harvest areas are replanted with native tree
species. These young trees are protected with tree tubes, which
facilitate growth and protect the saplings from hungry animals.
The Mississippi River floodplain remains a gorgeous and dynamic landscape in the heart of our state. The floodplain parks of the Twin Cities offer the opportunity for city-dwellers to walk the long winding paths through towering floodplain giants, and to become immersed in the wildlife sanctuary that the floodplain provides. 

Tuesday, January 3, 2017

Lake Como Restoration

Post contributed by Liam Krause and Dennis Walsh, Conservation Corps of Minnesota:

Who doesn’t enjoy a refreshing jaunt around Como Lake?  With almost two miles of walking and biking paths, paddleboats available for rent, and refreshments waiting at Como Dockside, there is something to do for everyone.  For over 100 years, Como Lake’s proximity to Saint Paul has been a welcome respite for from urban life for residents, but Como's proximity to the city is beginning to take a toll on the health of our lake. 

The Problem

Have you ever noticed the greenish hue on Como Lake during the summer months? That coloration is indicative of a process called nutrient loading. This phenomenon occurs when too much of one or more nutrients makes its way into a body of water. This can happen when runoff draws sediment off the roads or fertilizers off our lawns as it drains into a lake, pond, or river. When a body of water takes in excessive nutrients, it promotes disproportionate algae growth. The algae soon dies, leaving decaying organic matter. The decomposition process consumes dissolved oxygen in the water, oxygen that other living things in the lake depend on. This could potentially create a "dead zone." This is happening to Como Lake. For a more detailed outline of contributing factors and findings specific to Como Lake, visit the report published by the Capitol Region Watershed District (CRWD).

What We've Done

Huge brush pile of invasive species created by volunteers.
With the help of a CRWD cost-share grant program, and the efforts of the Conservation Corps of Minnesota and Iowa, the City of Saint Paul has taken big steps in reducing the sedimentation and runoff going directly into our lake. The North Lake Como Restoration project has targeted 4.25 acres of disturbed land in order to enhance and restore important oak savanna and woodland habitats. When completed, the changes to the target areas will help recharge groundwater, improve the water quality of the lake, and provide a diverse environment for wildlife.

First, the target areas were swept for invasive species such as buckthorn, black locust, mulberry, and honeysuckle. These species disrupt natural biodiversity and choke out herbaceous ground cover, which can result in increased erosion. Thanks to the hard work of volunteers, all of the cut material was hauled offsite. The site was then prepared for seeding. Along East Como Lake Drive, all of the leaf litter was removed in preparation for a process called hydromulching. Hydromulching is the application of seed and mulch to reestablish vegetation, often used to control erosion and retain soil moisture. A cover crop, and a native grass seed mix was broadcast throughout the project area and erosion control materials have been laid. With any luck, Saint Paul residents will start to see healthy shoots of little bluestem, canada wild rye, and indian grass popping up as they walk around Como Lake this spring.

East Como Lake Drive before invasive species removal and hydromulching (left) and after (right).

What You Can Do

Nutrient loading is the effect of too much moving from our lawns to our lakes. In order to counteract the process, it will take the sustained combined effort of everyone in the area to restore Como Lake to a healthy state. Some of the things you can do to help are limiting the use of lawn fertilizer, install buffer strips or rain gardens, and keep your eye out for volunteer events with the City of Saint Paul. If you are interested in making greater changes to combat the effects of nutrient loading, the Minnesota Pollution Control Agency has a list of steps you can take. Together we can protect this popular Saint Paul destination.