Mississippi Valley Field Naturalists
February 1, 2012
Green Aliens in Lanark County!
by Cathy Keddy, MVFN Program Chair
The Mississippi Valley Field Naturalists’ (MVFN) public lecture series, Trends in Fauna and Flora, continues February 16 with the fifth presentation, “Green Aliens Invading Lanark County.” You do not need to be an expert to enjoy the presentations—just possess a curiosity or appreciation for wild nature. Cottagers, hunters, fishermen, canoeists, hikers, campers, artists and seasoned field naturalists alike will find something to interest them as we explore what lives in Lanark County and how best to protect it for future generations. Refreshments are offered at each lecture.
This lecture will be presented by Ken Allison, botanist with the Plant and Biotechnology Risk Assessment Unit of the Canadian Food Inspection Agency in Ottawa. He will talk about the ecology of alien plants, including their impact on native species of plants and our natural habitats. Ken is an expert at dealing with aliens, particularly green ones.
The growth and spread of North America’s alien flora has long been the subject of practical observation. As early as the 1600s, the entry of alien plants was being noted. These plant species arrived by many means, some accidentally in ship ballast, as packing material, as seeds or vegetative dispersal units attached to animals, or in feces. Others were deliberately imported for medical or herbal purposes, as forage, and as ornamentals.
According to David White’s authoritative Plants of Lanark County, Ontario (http://www.lanarkflora.com/Lanark_plants_revised_2011.pdf), one-third of all the 1296 plants in the County are considered aliens (they are not native to the area and were not here before European settlement). Most are rare (208), sparse (49), or uncommon (53), while the remainder (103) are common. No signs of triffids have yet been reported.
Next to habitat loss, the impact of alien species is the second most frequent cause of native species being at risk in the province. Alien plant species can detrimentally affect the native flora through many avenues such as habitat modification (soil, light, water availability, geomorphological processes), competition (leading to reduced growth and reproduction), and hybridization (loss of genetic variability).
Not all alien species are of equal concern. They can be sorted into several ecological groups. These include species that persist in the wild, but do not spread and dominate native species (e.g., Helleborine orchid in forests), those that become common in man-modified environments like roadsides, lawns and cultivated fields (e.g., bladder campion, ox-eye daisy, dandelion), and those termed ‘invasive’ that can become common, sometimes dominant, and invade natural habitats such as woodlands and wetlands, displacing native species (e.g., purple loosestrife, garlic mustard, buckthorn).
Hundreds of green aliens of all kinds are among us. Where should we direct our efforts to maintain the ecological integrity of Lanark County’s natural heritage? Four foci come to mind: 1) target alien species with the ability to invade intact, natural habitats, 2) target native habitats that are naturally vulnerable to invasive alien species (those that frequently experience natural forces that perturb them such as river and lake shorelines that are exposed to ice scour, flowing water, and wave wash), rare habitats, and habitats with rare species, 3) minimize opportunities for alien species invasion through human activities, and 4) keep informed, be able to recognize the most harmful aliens, and be vigilant for new arrivals. To find out which green aliens belong on our top 10 most wanted list, come to the lecture.
How bright is the future for green aliens in our county? Which new species should we expect and how quickly might they arrive on our doorstep? How are we doing with options for controlling or eliminating these species before they get a foothold? Come to the lecture.
Learn what you should know about these aliens among us and those poised to enter our county, and see how you can help to keep them at bay by attending Ken Allison’s presentation, “Green Aliens Invading Lanark County,” at 7:30p.m. on Thurs. Feb. 16, 2012, Almonte United Church, 106 Elgin St., Almonte. All are welcome ($5 fee for non-members). For further information please contact MVFN’s Program Chair Cathy Keddy at 613-257-3089.