Written by Henry Lau
A walk along the Renfrew Ravine corridor promptly reveals the abundance of the thorny Himalayan blackberry bushes that dominates the local flora, resulting in the displacement of the natural plant communities. The loss of these native plant species harms the rich biodiversity of the ravine ecosystem, and ultimately the health of the ecosystem as a whole. Over the years, however, various community groups and neighbours to the Renfrew Ravine have been doing restoration work to quell the spread of non-native species and reintroduce native plant species.
What are native plant species?
Native plant species, including trees, shrubs, ferns, mosses, and more, are species that have traditionally grown in a region and are deeply intertwined with the local ecology. Most people liken native plants to the ones that existed in the ecosystem before the European settlement that brought over various non-native plants.
Why native plants are important
Because they have always grown and thrived in the local ecosystem, native plants are adapted to the areas they grow in and play vital roles in maintaining the health of the flora and fauna. Native plants require a lot less maintenance than non-native plants, partly because of how they’ve grown to support and be supported by the plant community.
In natural landscapes, there tends to be a canopy layer, an understory layer, and a herbaceous cover. These layers create various microclimates allowing for various lifeforms to survive due to the different resources present, such as varying amounts of shade and moisture. Often, native plants have deep roots or are shaded by other plants, so they require less watering and also prevent the erosion of land. They maintain soil health by keeping it from eroding with sufficient groundcover, and they mitigate the growth and spreading of non-native species. Native plants are also often resistant to pests and diseases. By having such thriving plants, nutrients are effectively cycled, and the biodiversity that the pollinators and other animals rely on for food and shelter is preserved.
Himalayan blackberries, Japanese knotweed, and English ivy are among the more aggressive non-native plant species that commonly displace native plants. Not all non-native species are so conspicuous, as many go unnoticed, but the ones that do grow and spread voraciously compete for valuable resources with the native species. If left alone, the non-native species pose a threat to the biodiversity of the ecosystem, resulting in what is known as biotic homogenization. As a result, both the living and non-living landscape is heavily impacted by the disappearance of the native plants.
Efforts at Renfrew Ravine
Grassroots efforts by various groups and dedicated neighbours have seen various parts of the ravine restored with native plants, with a focus on areas that are easily accessible and likely to thrive. Plants such as salmon berry, salal, Oregon grape, and various ferns are flourishing in their native habitat. Various microclimates are created by the canopy of the red alders, elderberries, which in turn allow plants to not only provide ecological benefits, but also bring awareness to the ravine through their diverse offerings. Although much has been done and continues to be done, much more strategic planning and work lies ahead in quelling the spread of non-native plants in the ravine.
Gardening with native plants
Before our homes existed, native plants were here supporting the local ecosystem. With over 3000 native species to choose from in the various regions of BC, native plants can be a great addition to any garden to help attract more pollinators, as well as add biodiversity to the garden. These plants thrive year round, so once established, may not need as much maintenance, such as watering and fertilizing. Be sure to try and incorporate the concept of vertical gardening to capture the benefits of having a canopy, understory, and herbaceous cover layers, thereby increasing the variety of plants.
For more information and identification of native plants, please visit: