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Every Rotarian can make a difference by recognizing, reporting, destroying (if feasible), and by not spreading invasive species.  But how do we know what to look for? Barry Slater suggested we have a series of short articles in Ramblings to explain invasive species.
Invasive plants are alien species whose introduction or spread negatively impacts the environment, the economy, and/or society including human health. Alien species are plants, animals, and microorganisms that have been accidentally or deliberately introduced into areas beyond their native range.

Natural areas such as forests, prairies, wetlands, and lakes provide many services and benefits to the economy, society, and the environment. These provide shelter and food for wildlife, remove pollutants from air and water, produce oxygen through photosynthesis, sink (remove) carbon and provide valuable recreational and educational opportunities. Invasive plants can have a negative impact on natural areas and threaten the important services that they provide.
Invasive plants impact species diversity by competing for resources such as light, moisture, and soil nutrients. Changes in diversity and composition affect wildlife that have adapted to native plant communities. Ultimately, invasive plants affect the intricate linkages that make ecosystems strong and resilient.
Invasive species have an impact on approximately 20% of Species at Risk in Ontario For example, garlic mustard out-competes the white trillium (Trillium grandiflorum) by changing the soil chemistry and making it less suitable for our lovely Trillium. We will tackle one unwanted invader at a time (stay tuned for Garlic Mustard). 

Food Production
Invasive plants can have a wide range of impacts on food production. Invasive plants can act as new or additional hosts for new or existing crop diseases and crop pests. They can cause reductions in crop yields and may require increased use of pesticides to control them. This increases costs for farmers and reduces crop values. Invasive plants, such as leafy spurge or some knapweed species (both listed as provincial noxious weeds), can take over farmlands, reducing crop production and foraging space.  The estimated annual economic impact of invasive plants on Canadian agriculture was $2.2 billion in 2010.

Danger to Human Health and Safety. 
Some invasive plants, like giant hogweed and wild parsnip cause human health concerns because their sap is toxic to the skin. Other plants can cause physical injuries to the body; common buckthorn branches end in a short, sharp thorn which may inflict injury. Human safety may also be impacted by fast-growing invasive plants. For example, Phragmites australis grows large and rapidly, and may reduce visibility at rights of way, increasing the risk of car accidents. Dead, dry stalks are also highly combustible and can become a fire hazard. Many of our native plant species can pose a risk too, but a key difference with invasive plants is that they become widespread and prevalent much faster than our native plants, which means their risks may occur at a much higher rate. This makes preventing their spread and controlling them and the risks they pose to humans that much more difficult, but that much more important.

Socio-economic Costs
In Ontario, the invasive Phragmites control project has been ongoing since 2007. Control costs ranged between $865 and $1,112 per hectare (in 2012). Invasive plants can have a large economic impact on individual landowners and municipalities. Leafy spurge infests 340,000 acres of land in Manitoba, costing taxpayers an estimated $19 million per year to protect grazing land, public land, and rights-of-way. Invasive plants directly affect municipalities and reforestation projects. On a municipal scale, the City of Toronto has estimated EAB (emerald ash borer) management costs for 2013-2020 to be $71.2 million for tree removal, wood disposal, pesticide injection, replacement plantings, and staff resources.
Adverse Impacts on Recreation and Aesthetics 
Natural areas in Ontario support a wealth of recreational activities like hunting, fishing, swimming, hiking, bird watching, and mountain biking. Invasive plants often reduce the area’s attractive and enjoyable qualities. For example, invasive plants may reduce native plant biodiversity, affecting the number of songbirds in the area; walking through dense vegetation can prove difficult, and popular swimming areas may become unusable with the presence of invasive aquatic plants. Seeds and other plant parts can hitch rides on hiking boots, clothing, pets, birds, and vehicles, resulting in new infestations, potentially over great distances.

You will see Enviroclub Chatter regularly from now on in Ramblings. We aim to educate and inspire action around environmental sustainability and climate change.  In our next installment, we will introduce some of these invasive, starting with garlic mustard.