Invasive Plants - Michigan Natural Features Inventory - Michigan ...

Nature Conservancy shared many of their photos from TNC’s invasive
photo gallery.
Two photo galleries maintained by The University of Georgia were
incredible resources: Forestry Images, supported by the USDA
Forest Service; and the Bugwood Image Database System, which
is supported by the National Park Service and the USDA Forest
Service. We truly appreciate the many people who have posted
their images there and have made them available for educational
use.
Since there is not room to list more than the photographer’s name
on the photos themselves, photographer affiliations and in some
cases, the websites where they have so graciously made their work
available are listed in the back of the booklet on page 114.
While it is not possible to individually thank the many people who
have assisted us, there are a few without whose help this guide
would not have been possible. Mark Sargent, Sue Tangora, Ray
Rustem, Ray Fahlsing, Bob Clancy, Glenn Palmgren, Sherri Laier,
Bob Grese, Vern Stephens, Larry Pedersen, Ellen Jaquert, David
Mindell and Robert Schutzki all provided extensive, thoughtful
assistance and reviews at various stages of the project. Their
expertise has been invaluable and any errors that remain are solely
our own.
Phyllis Higman
Suzan Campbell
Michigan Natural Features Inventory, Lansing, Michigan
September 3, 2009
What is an invasive plant?
The National Invasive Species Management Plan, developed in
response to Executive Order 13112, defines an invasive species as
“a species that is non-native to the ecosystem under consideration
and whose introduction causes or is likely to cause economic or
environmental harm or harm to human health.” For the purposes of
this field guide, non-native species are those that did not occur in
Michigan’s ecological communities prior to widespread European
settlement.
Only a small fraction of the hundreds of non-native plants that
have evolved elsewhere and been brought to Michigan are
invasive. The few that are, however, can be very aggressive and
spread rapidly once established. In our native forests, grasslands,
wetlands and dunes, they pose a threat to management goals by
displacing native species or altering ecosystem processes. It is
these harmful non-native species that are the focus of this field
guide.
Impacts of non-native invasive plants
Invasive species are a significant threat to Michigan’s native
biodiversity and their impacts are wide-ranging. They are aggressive
competitors, often dominating an ecosystem and reducing native
diversity dramatically. They have effective reproductive and
dispersal mechanisms; many are capable of spreading by rhizomes
and some can produce new plants from tiny root or stem fragments.
Many store energy in extensive root systems and can sprout back
repeatedly after cutting. Most invasive plants produce abundant
fruit and seeds that are widely dispersed and remain viable in the
soil for years.
Some invasive shrubs and trees create dense shade, preventing the
growth of native herbs beneath them. They often leaf out early in
spring and retain leaves late into the season, gaining as much as an
extra month of productivity compared to some of their native associates.
Some species secrete chemicals that inhibit the growth of
neighboring plants or beneficial soil fungi. Invasive plants simplify
ecosystem structure, and may alter site hydrology, nutrient cycles
or patterns of natural disturbance, such as fire regimes.
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