Consider what you plant, Choose native species! (archive)
Published on Wednesday May 20, 2015
Authored by PEIISC
You may have noticed that many of the recent posts have been about invasive plants that started out in our yards or gardens. We bring them in, we plant them, or seeds migrate from a neighbour’s garden. Many of the posts encourage you to make wise choices about what to plant, and what not to buy. But I’d like to encourage you to also ask retailers, garden centers, and nurseries to also make wise choices. I have (“Do you sell any native plants?”), and upon doing so have been given strange looks, and even asked why I might want native plants. I have been told that native plants are not as hardy, they won’t cover the ground, their flowers are not as pretty.
What? Here are some reasons to carefully consider what you plant, and to further encourage retailers to sell more native species.
Environment Canada lists Horticultural Plantings as one of the primary sources of invasive species.
The IUCN (International Union for Conservation of Nature) includes invasive species as a primary threat type to native biodiversity.
Horticultural plantings brought us Norway Maple, periwinkle, Japanese knotweed, goutweed, and purple loosestrife among others. The list also includes flowers I enjoy, such as lily of the valley and flowering rush. See other posts for more examples.
A large proportion of plant species at-risk in Canada are loosing habitat due to encroachment of invasive species. The invasive species threat is second only to human disturbance as the main threat to native flora. Such threats are well documented in the scientific literature, but also in species at-risk status reports (published by the Committee on the Status of Endangered species in Canada, COSEWIC) and Recovery Plans (posted by the Species At Risk Public Registry, SARA).
A recent study by McCune and colleagues (*Threats to Canadian species at risk: an analysis of finalized recovery strategies*, published in 2013 by the journal Biological Conservation) reported that of 129 recovery strategies assessed for the study (across all species), invasive species were documented as a primary threat for 55% of species. Within this group, 43 of 64 plant species were documented as threatened by invasive species.
It is not just the presence of non-native species that threatens native habitats, but the genetic material they bring with them. Native plants ARE hardy because they are adapted to local climates. Non-native species introduce genetic variation that is not locally adapted and may overwhelm or diminish local genotypes.
Closely related species can hybridize and alter the genetic make-up of native species. A good example is the loss of Canadian Red Mulberry (*Morus rubra*) due to hybridization with White Mulberry (*M. alba*), which was introduced for the commercial silkworm industry and spread into local habitats.
You may wonder what is the risk of the few non-native species you want to plant this year. It’s hard to say, it may be small and or it may be great (see previous posts for some worrisome examples). But, there is no risk to planting native species. Why take the chance?
Can’t find native species at your local garden center. First – complain. Second, use local sources. The MacPhail Woods 2015 nursery catalog is now available!!
– Karen Samis, PEIISC Member and UPEI Department of Biology faculty member