Increase of Invasive Species Locally

Keely Gilham shared the following observation

With the arrival of spring in Medicine Hat, Alberta comes new shoots, buds and greenery, some of which is not a good thing for our environment. Many invasive species such as baby's breath (Gypsophila paniculata), leafy spurge (Euphorbia esula), and purple loosestrife (Lythrum salicaria) have been identified recently within our city.

During spring of 2014, Medicine Hat saw catastrophic flooding events, which resulted in many homes being damaged or destroyed. Much of the flooding was blamed on anthropogenic modification of water flows and drain tillage on the agricultural landscape, which may be reducing our native ecosystems' adaptive capacity and resilience to such events. The city responded to the floods by constructing berms to protect river valley homes.

The new berms resulted in a large amount of construction along the river banks leaving much of the soil exposed during slow reclamation of these areas. While out walking in our local Police Point Park, I observed a large patch of disturbed soil from one of these construction projects that was started 2 years ago. Invasive species are being spotted in these areas of exposed soils throughout the city. The amount of invasive non-native species in the area that were not there last year has become more noticeable. This highlights the threat of many more invasive species taking over within this area if reclamation is not completed promptly.

Tom Okey shared the following comment:

All three of the species mentioned in this observation are Eurasian in origin. The North American invasion of such Eurasian weedy plants is known to be facilitated by soil disturbance because Eurasian plants co-evolved with domestic livestock for ~20,000 years in Europe, whereas North American native plants are not as highly adapted to such disturbance since domestic livestock have been in North America for only a few hundred years. This generally one-directional invasion of flora and fauna from Eurasia to the climatic "Neo-Europes" is described in Crosby's 2004 book Ecological Imperialism.

Literature cited

Crosby, A.W., 2004. Ecological imperialism: the biological expansion of Europe, 900-1900. Cambridge University Press.