September 2023 - 10

NEWS
Game and Fish works to reduce
invasive annual grasses
STATEWIDE - If you've ever grown a
garden, you likely know the terms annual and
perennial. As a refresher and for those who
may not be in-tune with their green thumbs,
perennial plants live for years and come back
on their own for multiple growing seasons.
Annual plants have a life span limited to one
growing season and new plants are produced
each year. Perennial and annual plants aren't
limited to gardens. These terms are also applied
to wild plants. These annual life cycles can give
habitat managers a better chance to control
unwanted plant populations.
Numerous unwanted plants can be found
across Wyoming's landscape, but some are
more concerning than others. Cheatgrass, ventenata
and medusahead are invasive annual
grasses that top the list for the most problematic
plants in the state. While the distribution
of ventenata and medusahead are somewhat
limited to northeast Wyoming, cheatgrass can
be found across the state and much of the West.
These invasive plants cause issues for landowners,
land managers and wildlife, with mule deer
being one species particularly impacted by its
presence and spread.
Much of these grasses' persistence can be
attributed to their life cycle. As annual plants,
they drop seeds which begin to germinate in
fall - well before native plants reach this stage.
The new shoots overwinter and utilize snowmelt
in the spring to get a jump on the growing
season. Being first on the scene, the invasive
grasses are able to take up space and resources
first, growing fast and shading out any burgeoning
native plants. To stay on schedule, the
grasses soak up loads of water and nutrients
before they dry out and drop seeds in early
summer in preparation for fall germination,
and the cycle begins again. Once the seeds
have dropped, the parent plant dries up and
dies having completed its yearlong life cycle.
This process leaves acres of dry biomass on
the landscape, creating a tinderbox awaiting a
spark. If a fire ignites, it does not differentiate
between invasive and native plants - everything
burns, including native plants such as
sagebrush.
One of the most important and destructive
effects of invasive annual grasses is their impact
on the fire cycle of sagebrush ecosystems. These
systems naturally burn, but only every 300
years or so. When plants like cheatgrass are
in the mix, fires become considerably more
common. Instead of 300 years, fires tend to
break out every 3-5 years. Plants like sagebrush
are not adapted to this pace and return slowly.
Cheatgrass, already adapted to growing new
plants each year, can easily return and quickly
dominate an area. This process pushes out
native plants and the animals that depend on
those plants to survive.
Sagebrush is an important food source for
mule deer, especially in winter. When invasive
grasses encroach or replace sagebrush, mule
deer are left with fewer options for food, and
invasive grasses hold almost no nutritional
value for them. As the grasses spread, areas
of suitable mule deer habitat shrink and the
deer are forced into other areas or eventually
starve. If large herds are forced into smaller
areas, available food disappears quickly and
disease is more likely to spread due to their
concentration.
Cheatgrass is an invasive annual grass found through much of
Wyoming and the West. (Photo by Patrick Owen/WGFD)
10 | September 2023
While the issue persists, tools exist to
help habitat managers handle invasive grass
populations. Spraying herbicide is the primary
method of management used by land
Medusahead is another invasive annual grass found in
Wyoming, primarily in the northeast part of the state.
(Photo by Ian Tator/WGFD)
managers, including the Wyoming Game and
Fish Department. Helicopters are often utilized
to apply the herbicide as the affected areas are
typically too large to spray using other methods.
Game and Fish uses a chemical focused
on inhibiting seed germination of cheatgrass,
ventenata and medusahead to prevent root
growth and establishment. Most treatments
are carried out in the late summer and early fall
as the plants are dropping seeds. Intervening
at this stage is ideal timing to stop the cycle
before it restarts.
Members of the public can help prevent the
spread of these plants, even without chemicals
and sprayers. Seeds of these species can
get caught in mud, nooks and crannies of
vehicles, hiking gear and in animal fur. New
populations of invasive grasses tend to be
found in high traffic areas, such as road sides
and trailheads, where tag-along seeds have
been deposited. As you enjoy Wyoming's
outdoors, clean off any and all debris from
the field found on your vehicle, gear and pets
before moving on to your next destination.
- Stephanie Estell, WGFD
SCAN THE QR CODE TO
LEARN MORE ABOUT
WHAT GAME AND FISH
IS DOING TO COMBAT
INVASIVE ANNUAL
GRASSES.
https://wgfd.wyo.gov/Habitat/Habitat-Plans
September 2023

Table of Contents for the Digital Edition of September 2023
