Bridging the Cap: Landfills Providing Critical Pollinator Habitat
By Benjamin Reynard
March-April 2014
Scientists tell us that bees and other pollinators, which are all important to our food supply and
ecosystem health, are dying in alarming numbers. Commercial beekeepers estimate that
upward of 40% of their hives were wiped out by “colony collapse disorder” in 2013. This decline
of pollinators means potential disaster for food supplies, because managed honeybees, native
bees, butterflies, wasps, and flies are responsible for one of every three mouthfuls of our food
(Xerxes Society). Furthermore, the fruit, nuts, and seeds produced from plant-pollinator
interactions are essential as the basis of the animal food web.
Among converging factors negatively impacting pollinators are pathogens, parasites, and
environmental factors including agrochemicals. A possible solution?
Creating critical pollinator habitat patches, green spaces, and pollinator parks as part of longterm management of landfill caps and their buffers. Numerous pilot studies indicate that
restored, capped landfills planted in native seed mixes could restore pollinator habitats and
bolster biodiversity while providing an environmentally effective final cover system.
A British study published in Restoration Ecology, January 2013, compared restored landfill sites
to undisturbed reference sites, concluding that restored former landfill sites contained similar
abundance of floral resources and flower-visiting insects. The researchers concluded “restored
landfill sites have the potential to play a role in reversing declining populations of flower-visiting
insects by partly replacing important pollinator habitats such as unimproved flower-rich
grasslands.” The study noted:

The restoration of landfill sites provides pollinators with floral resources later in the
season when they may be absent elsewhere

Restored landfill sites can be managed via sowing and mowing regimes to provide floral
resources earlier in the season

Vegetation should be managed as a mosaic, leaving some standing until spring to
provide over-wintering habitat
An excellent example of pollinator-centered landfill cap design is the decommissioned Eastview
landfill in Guelph, ON. This newly constructed 112-acre restored habitat is called the world’s first
and largest “Pollinator Park.” (http://www.pollinationguelph.ca).
At present, most landfills are planted in their state
DOT grass mix, even though the USEPA
recommends using a native seed mix. Many landfill
operators, engineers, and regulators have concerns
that native vegetation could damage the cap and
allow for additional water infiltration through the cap
and waste. Such concerns are unfounded and
prevent the landfill from taking advantage of the
long-term ecological and financial benefits of
natives.
Final caps planted with native flower-rich grasslands
require installation and management expertise as
the grasses and wildflowers become established.
Landfill owners and their contractors often do not
have experience in establishing native vegetation.
An experienced eco-contractor, however, can
design optimal pollinator habitat with an ideal
vegetation mix for seasonal conditions and growing
parameters.
There is some additional cost in using native seed,
particularly when adding species preferred by pollinators. However, the cost per acre of a typical
highway mix and a comparable native seed mix are similar. For example, a typical DOT mix of
cool-season fescues and grasses costs roughly $200–$300 per acre, depending on seeding
rates. Typical native seed mixes have historically consisted mainly of grasses with a few
inexpensive forbs, and range from $150–$300/acre, depending on species and rates. A true
pollinator mix with higher diversity is going to be more expensive, in the range of $300–$700 per
acre, depending on the species and seeding rates.
Once reduced mowing costs are factored into the maintenance cost of the landfill cap over a 30year life cycle, the long-term cost with a modest mix of flowering natives will be less than a
typical highway mix. Of course, this cost is highly dependent on specific species used and
expertise of those knowing how to make native seed work.
If the Pollinator Park concept were to be incorporated throughout North America, landfill owners
could embrace the opportunity to cultivate positive environmental impacts, generate community
good will, and to save money through reduced mowing.
Author's Bio: Benjamin Reynard restores ecological communities for Applied Ecological
Services.