Species Range and Habitat Reciprocity

CO2 Down to Earth 19

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by Philip Fry

A few days ago, Nick Weissflog, a young friend pursuing environmental studies, came to visit me. Nick is currently doing research on a species of aquatic plant that has moved into our lakes and waterways from the southern United States. As we were chatting, I asked him to explain what he hoped to achieve with his study. His answer was not quite what I expected. Instead of saying that he wanted to determine how bad the “invasion” was – which could lead to knee-jerk programs to eradicate it – he wanted to know more about how this stranger fit into his study lake’s environment. What was the lake giving to this plant species and what was the stranger giving back, if anything, to the lake? Nick’s study is more complex than I make it sound here, but the main point I retained from our conversation was his interest about reciprocity and collaboration of plants and other living things in the lake habitat, not control.

Every species in our patchwork landscape has a history, and now each one is part of our story too. The lilacs that mark settler homesteads speak of an origin in Eastern Europe and the cherished place of their bloom and scent in the gardens of France. Now, in midsummer let us look at what flourishes along our roadside ditches and abandoned fields, and give them their names. The snow-white umbels of Queen Anne’s Lace, some with an evident black dot in the center, are said to have originated in Afghanistan and settled in Britain on their way here. They recall the legend about Queen Anne, who pricked her finger while lace-making, and a drop of blood put a dark spot on her work. The pale blue flowers of chicory are also widespread, but they have come from Mediterranean climes with settlers wishing to savour roasted chicory root. Having come from far away, these species have settled in well, taking advantage of the transformation of the forest into the patchwork landscape we know today. But there are others…

Wild (Poison) Parsnip, native to Eastern Europe and Asia, was brought here by settlers as a garden plant because its root is edible, especially in the first year of its growth. It “escaped” from their gardens and, finding that the land laid bare by clearing was particularly suited to its growth habits, it “went wild” and spread throughout the “new” land. Its “poison” is in its sap which burns one’s skin, especially when exposed to sunlight. But that is not the only problem it brings: in such a welcoming habitat, it tends to displace other plants and thereby reduces the actual and potential biodiversity of the site. It also reduces the quality and quantity of forage in the area and contaminates hay, and is said to have an impact on the weight gain and fertility of ruminant species, including livestock. The story of European Buckthorn is much the same: brought here for medicinal purposes, it escaped cultivation and found semi shaded places to particularly hospitable and widespread. It is now invading much of our township, spreading its deep green leaves over sharp, needle-like thorns.

What should we think about “imported” species, some which have settled in as collaborative neighbours, others which tend to dominate other species with their unfettered growth habits? The first point, I think, is that they are here to stay in our patchwork landscape. Although we must do all we can to conserve the sites that speak of our region’s forested past, we should also look to the future. The key is to adopt a circumspect, differentiated approach which puts the enhancement of biodiversity at the centre of our reflections.

The Giant Swallowtail, Papilio cresphontes and the flower is Bee-Balm, Monarda fistulos. Photo taken in 2013.

The arrival of the Great Swallowtail Butterfly in our region is a good case in point. It arrived in our area from the most southern part of Ontario around 2010 (I observed them here in 2013). They now appear in mid-summer while the light mauve flowers of Bee-balm expand their clusters of tubelike flowers. The relationship between the butterfly and the plant is well-timed and reciprocal. The flower gives nectar, the butterfly distributes pollen.

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