Stop Invasives

What is an invasive species?
Invasive species are non-native and cause harm to the environment, human health, and the economy.

The proliferation of invasive species in an ecosystem disrupts the complex and critical relationships that our native species have with their environment and other organisms and is responsible for degrading and destroying thousands of acres of Indiana’s native plant communities.
Shockingly, 83% of invasive plants that are harming Indiana’s naturally occurring green-spaces come from our own home landscapes. Gardeners, not knowing the danger that some non-natives plants pose, have unintentionally purchased, planted and set loose this serious threat to our natural areas.

Our goal is to educate the community about the harmful nature and negative impacts of invasive species and ultimately to inspire and spur corrective action by the citizens of Hamilton County.

Invasive periwinkle overtaking a natural area

Invasive burning bush creating a monoculture in a woods

SOME BACKGROUND ON INVASIVE PLANTS
Not all non-natives plants are invasive, in fact, most are not. However, the majority of all non-natives (whether invasive or not) provide little ecological value in comparison to natives and can become invasive over time. It’s unquestionably better for the environment to avoid planting non-natives whenever feasible!

Some non-native species, uninhibited by environmental conditions and their natural predators, are able to reproduce and spread, becoming invasive and causing environmental destruction in their path.

The vast majority of invasive plant species have been introduced to the US through the horticultural trade industry and escaped into the wild from our home landscapes. Astonishingly, 83% of the invasive plants that are found in naturally occurring green spaces come from our own gardens.

WHERE DO THEY COME FROM?
Some species were introduced accidentally in packing material, as crop contaminants, in shipping containers or from the cargo holds of ships. However, many invasive species have been brought here deliberately. We grow non-native species for food, as ornamentals in gardens, for their usefulness in feeding wildlife, or controlling our environment in some way (from EDDMAps Invasive Species Mapping Handbook).

The unforeseen consequences of this can often be tragic:

Autumn Olive was planted along highways as food for birds which were often struck by cars while flying across the highway to feed on their enticing berries.
Kudzu was planted for erosion control unaware of the devastating threat it’s explosive growth rate posed to the environment and human infrastructure.

WHAT MAKES THEM SO INVASIVE?
Invasive plants species often exhibit the following common characteristics:

High adaptability to variety of soil, water and light conditions
Aggressive growth rates
High reproductive rates
Lack of natural pests to keep them in check
Early leaf out/later leaf drop or evergreen nature enabling them to outcompete natives for nutrients
Utilization of chemical warfare (allelopathy) that poisons the soil
Difficult to control/eradicate

Many non-native plants in the landscape trade possess some of the same attributes as invasive species, making them potential candidates for escaping your yard and becoming a future problem. Consider choosing a native plant instead!

Indiana Invasive Species List
The Indiana Invasive Species Council (IISC) was established by the state legislature to enhance the ability of government agencies to detect, prevent, monitor, and manage new and long established invasions, as well as to increase public awareness about invasive species.

In 2009, the IISC appointed the Invasive Plant Advisory Committee to develop a comprehension list of invasive plants and to assess and rank each species as low, medium, or high as well as identify other species that need monitoring for potential invasiveness.

Indiana Invasive Species List

The Indiana Invasive Species List was then used as the basis for regulating highly invasive plants in Indiana and led to the creation of the “Terrestrial Plant Rule” which went into effect in April of 2020. Currently there is no mandate to eradicate existing invasive plantings in nurseries, landscapes or forested areas.

The Terrestrial Plant Rule (312 IAC 18-3-25) designates 44 species of plants as invasive and makes it illegal to: sell, gift, barter, exchange, transport, or introduce these plants in the State of Indiana.

Terrestrial Plant Rule FAQ Sheet

Terrestrial Plant rule Guide (with photos)

Why should we care?

The serious threat that invasive plant species pose cannot not be overstated. They displace native plant communities, disrupt vital food webs, degrade wildlife populations, harm the environment, affect human health and cost billions in economic damages and control efforts just to name a few!

Wildlife

DEGRADES WILDLIFE POPULATIONS
Invasive plants are poor substitutes for native species resulting in the loss of biodiversity, native food webs, and ultimately entire ecosystems.

Since 1970, there’s been a 68% decline in the population sizes of mammals, birds, fish, reptiles, and amphibians (WWF’s Living Planet Report 2020).
North American bird populations are down by 2.9 billion breeding adults, with devastating losses among birds in every biome (Cornell Lab of Ornithology).
Worldwide population of arthropods, chiefly insects, has declined by 45 percent from pre-industrial times (Doug Tallamy).

Where Have all the Insects Gone?
How often do you stop to scrape bugs of your windshield nowadays - not very often! That’s a clear indicator that our wildlife ecosystems are in danger.

The environment

HARMS THE ENVIRONMENT

Reduces growth and reproduction of native trees, shrubs and herbaceous plants through competition for soil nutrients, water, light and space.
Creates monocultures that reduce plant diversity.
- A monoculture of Sweet Autumn Clematis blooms just once in the fall, completely crowding out spring, summer or fall blooming species and displacing the pollinators dependent on them.

Creates ecological traps for birds, mammals, amphibians and invertebrates.
- Honeysuckle creates an ecological trap for birds who eat their berries. Native berries are full of fat and protein while honeysuckle berries are mostly carbohydrates, essentially the equivalent of junk food, providing little nutritional value
Alters hydrology of water sources and shortens time for ephemeral streams and wetlands.
- Honeysuckle can completely choked out a creek altering its natural flow of water
Alters soil health by increasing erosion and depleting it’s moisture levels and nutrients
Creates different microbial communities and negatively affecting mycorrhizal associations
- Mycorrhiza, a fungus, play important roles in plant nutrition, soil biology and soil chemistry by forming a mutually symbiotic association with plant root systems.

Human Health and the economy

HARMS HEALTH & THE ECONOMY

Causes human health issues through increases in mosquito larvae and tick populations.

Introduces plant pests and devastating plant diseases at great economic harm when accidentally imported into the US via nursery stock despite strict controls.
- Emerald Ash Borer, Japanese Beetle and Asian Longhorned Beetle
- Chestnut Blight, Sudden Oak Disease and Dutch Elm Disease

Causes damage to and loss of outdoor recreational opportunities.
The economic damages associated with invasive species in the US currently exceeds $138 billion per year.

Other consequences

EVEN MORE CONSEQUENCES!

Extinction of native species (42% of endangered species are at risk due to invasives)
Exploitation of preserves, national parks, state parks and your own garden.
Loss of forests and other ecosystems
Alteration of microclimate & climate
Alteration of carbon sequestration
Alteration of natural fire regimes

How can you help?

There’s plenty of ways for you to contribute to the fight against invasives. The first step in the struggle to tame and defeat invasive plants is to educate yourself and then to take decisive action. Here’s what you can do as you start your journey...

EDUCATE YOURSELF & REPORT INVASIVES SPECIES

Educate yourself on known invasive species in your area using the Invasive Plant Atlas
Never plant, transmit, spread or release invasive species
Report invasive species occurrences to your local county agent
Report Invasive species on EDDMaps

REMOVE INVASIVES AND REPLANT WITH NATIVES

Remove any invasive plants from your yard, a key priority, even if it’s a gradual process that takes place over time. You can request an invasive species assessment of your property from HIP at Hamilton County Invasives Partnership
Replace invasives with natives and strive for a 70% native plant palette in your landscape to ensure adequate carry capacity for wildlife. Use keystone species which contribute the most to local food webs.
- Trees like Oaks, Willow, Cherry, Plum and Birch
- Shrubs like Viburnums, Dogwoods and Buttonbush
- Perennials like Asters, Goldenrods, Sunflowers, Joe-Pye Weed and Violets
Check out the National Wildlife Foundation and the Indiana Native Plant Society for plant suggestions local to your area.

AVOID COMMERCIAL WILDFLOWER SEED MIXES & INVASIVES AT RETAILERS

Many contain nonnative & some invasive species - that’s a NO GO!
Commercial wildflower mixes are not good for ecosystems.
Wildflower mixes may contain: oxeye daisy, dames rocket, bouncing bet, queen Anne’s lace, Mexican hat, Indian blanket, (a southwestern species) nonnative poppys scarlet flax, polka dot cornflower (native to Europe)
Only purchase seed mixes from reputable native plant sellers.