Roadside Pollinator Program

Monarch
Female monarch butterfly sucking nectar from a butterfly milkweed (Asclepias tuberosa) plant in the Columbia City Hall Pollinator Garden along Broadway.

Thirty years ago, monarch butterflies could easily be seen fluttering through Stephens Lake Park, or any Columbia neighborhood. These days, fewer and fewer monarch butterflies are flying around Columbia. In 2013, winter monarch population estimates showed a 90% decrease in their overall population (Figure 1). This decline in the monarch population mirrors the decline of other prairie-dependent insects and songbirds. 

Many of these prairie-dependent insects and songbirds are considered pollinators, fertilizing plants through pollen transfer while feeding. Without them, 88% of the world’s plants would not be able to reproduce (Ollerton 2011). Approximately one-third of our food is pollinated by a bee, butterfly, mammal or bird, contributing $235 to $537 billion in food production to the global economy (Food and Agriculture Organization of the United Nations (FAO) 2016). Similar to the monarch butterfly, more than 40% of the world’s insect pollinators are facing extinction (FAO 2016). 

The City of Columbia is taking action to curb the decline of pollinators and other wildlife through education and outreach, habitat restoration, and policy. In November 2016, City Council signed the National Wildlife Federation’s Mayors’ Monarch Pledge that states that the City of Columbia will take action to educate the public on monarch decline and restore native habitat to support the monarch butterfly and other pollinators.

The Roadside Pollinator Program honors the Mayor’s Monarch Pledge by restoring pollinator habitat along City of Columbia roadsides.

Graph detailing Area Occupied by Monarch Colonies at Overwintering Sites in Mexico
Figure 1. The total area occupied by monarchs at overwintering sites in Mexico. Monarch butterflies hang from Oyamel fir trees high in the mountains of Mexico during winter. Their population is estimated using density measures because counting each individual would be impossible – that’s why the graph uses “hectares”.

Why Should The City Conserve Pollinator Habitat Along Roadsides?

 

Ecosystem Benefits to the City

Ecosystem services are the numerous and varied benefits that people freely gain from the natural environment and from properly-functioning ecosystems (Figure 2). Wetlands provide flood control and erosion services. Urban forests provide shade which cools city space. These ecosystems and the many other systems that exist provide Columbians services every day. They protect us from the heat, clean our air and water, pollinate our food, provide textiles and building material, and more. Additionally, by restoring the native vegetation that existed in Columbia prior to European invasion, we will be conserving Missouri’s natural heritage. 

Chart Detailing Urban Ecosystems benefits
Figure 2. Ecosystem services provided by nature (Image: www.ehu.eus).

Carbon Sequestration

Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide to reduce global climate change (USGS). On June 17, 2019, the City Council adopted Columbia’s first Climate Action and Adaptation Plan (CAAP). This plan is a road map to guide the City to zero carbon emissions by 2060. The CAAP actions for preventing further greenhouse gas emissions include increasing our City’s renewable energy portfolio and reducing the number of trips people make in personal vehicles. In addition, the CAAP also includes actions that address the climate change impacts that Columbia is already experiencing, such as flooding, increased frequency of large storm events and prolonged dry periods. These actions build more resiliency into our infrastructure, ecosystems and community. One major goal of the CAAP is to sequester carbon. 

The native wildflower plantings along Columbia’s roadsides will sequester more carbon than the existing turfgrass. This is because native plants have extensive root systems that can reach to 15+ feet deep (Figure 3). As a plant grows, it pulls carbon dioxide from the atmosphere and turns it into biomass. Most of the biomass in a native wildflower planting exists in the soil (in their roots), therefore, the carbon that is broken down by the plant and used to create biomass is now locked into the soil. Carbon that is locked into the soil can not contribute to climate change. Not only will the roadside native plantings sequester carbon, but this conversion will also reduce our mowing needs, thus decreasing our municipal carbon emissions.

For more information on the CAAP, visit the Office of Sustainability’s webpage at www.como.gov/sustainability.

Graphic Outlines Root Depth of Various Prairie Plants
Figure 3. Comparing native plant root structure to Kentucky blue grass roots (swimga.org).

Stormwater Runoff Mitigation

In Missouri, we have very hard, compact clay soils that the roots of turfgrass hardly penetrate. For this reason, turfgrass does not help prevent erosion or promote stormwater infiltration, resulting in a loss of topsoil, sediment pollution in our local streams and localized flooding. Native wildflowers and grasses solve these stormwater issues by having extensive root systems that create channels for stormwater to follow deep into the soil. These deep roots also hold the soil in place, preventing the erosion of stream banks. The more stormwater that is soaked up by the soil, the less water there will be to inundate and pollute our creeks. Go to our Stormwater Utility to learn more!

How Much Will it Cost?

Cost-Benefit Analysis

In 2016, the Public Works Department hired several interns from the University of Missouri to conduct a cost-benefit analysis to determine if the City would incur additional costs or save money if it was to stop mowing grass and convert roadside vegetation to native habitat. The results of this analysis shows that the annual cost of mowing grass is more expensive than installing and maintaining native vegetation. These values vary with precipitation, fuel costs, vehicle replacement/maintenance, etc., but our best estimate shows that mowing 88 acres of grass costs approximately $230,000 to $350,000 per year. As we convert the majority of the 88 acres into native wildflower plantings, the cost of maintaining our roadside vegetation drops to approximately $20,000 per year*.  

*Does not include initial installment which will cost approximately $90,000 over a 3-year period. 

The Process

Who?

The City of Columbia has hired an ecological services consultant to prepare selected roadsides, medians and roundabouts.

Where?

Sites were selected by the Streets Division and the City’s Community Conservationist. Site selection was based on habitat potential (including location and size), proximity to infrastructure, the safety of pedestrians, motorcyclists, bicyclists and motor vehicle drivers. Additional considerations include the timing of planned construction and road work and neighborhood aesthetics. The first phase of the program will convert selected roadsides, medians and roundabouts on Scott Boulevard, North Providence Road, South Providence Road, Rangeline Street and Discovery Parkway. See the map below for more details.

 

How?

The consultant will prepare the selected sites beginning late spring 2019 using chemical and mechanical techniques, including the controlled use of herbicide, mowing, and possibly, where appropriate, prescribed fire. From November to the end of January, the consultant will broadcast seed the prepared sites with a short (< 3 ft. tall) native wildflower seed mix. The following spring and summer, the consultant will spot-spray encroaching invasive plants and mow the new planting high (blade will be set to 6 inches from the ground) to prevent tall weeds (12 inches tall) from shading the new native seedlings (2-5 inches tall).

Timeline

  • Spring 2019 Site preparation
  • Winter 2019 Broadcast native wildflower seeding
  • Spring and summer 2020 Control invasive plants and weeds 
  • Fall 2020 or spring 2021 Promote growth using prescribed fire
  • Summer 2021 and beyond Control invasive plants and burn when necessary

Won’t habitat along roadsides kill bees and butterflies?

Roadside pollinator habitat will result in some mortality of flying and crawling insects (Keilsohn 2018). However, studies show that this mortality does not always add to the decline in population numbers (Ries et al. 2001).

Feedback

The City of Columbia wants to listen. Please complete the feedback form if you wish to provide input on the Roadside Pollinators Program.