Wear Invasive Non-native Species (WINNS)
An exploration of invasive species across the Wear catchment
A volunteer bashing balsam in Hopper's Wood during the summer of 2022
Non-native Species are species that have been moved outside their native range by humans, either accidentally (e.g. via crops, footwear, vehicles etc.) or on purpose (e.g. ornamental plants, pest control etc.). Most of these species don't cause any problems for humans or native wildlife, but some have the potential to threaten biodiversity and damage structures. These damaging species are known as Invasive Non-native Species, or INNS for short. Globally, INNS are one of the biggest drivers of biodiversity loss and their impacts are only likely to get worse with climate change. It's hardly surprising, then, that the Wear catchment is badly affected by a variety of invasive species. Check out the interactive map below - can you name the 3 species that are most widespread?
WINNS 23/24_2
The 3 main players
The 3 key invasive species in the Wear catchment are Himalayan Balsam (Impatiens glandulifera) with its pink, nectar-rich, trumpet shaped flowers; Japanese Knotweed (Reynoutria japonica), which forms dense bamboo-like stands and has leaves arranged in a characteristic zigzag pattern, and Giant Hogweed (Heracleum mantegazzianum) with its huge umbrella-shaped flower heads that can reach heights of 5m.
From left to right: 1. Himalayan Balsam flowers, 2. Himalayan Balsam seed pods, 3. Japanese Knotweed leaves, 4. Winter stand of Japanese Knotweed, 5. Man next to fully-grown Giant Hogweed, 6. Giant Hogweed leaves
Himalayan Balsam was introduced to the UK by Victorian plant enthusiasts and was prized for its attractive, nectar rich, pink flowers. Unfortunately, though, it can cause huge problems for our native wildlife and waterways. It spreads extremely quickly thanks to its spring-loaded seed pods, which are able to throw seeds up to 7m away. These regularly land in moving water, spreading the seeds downstream. Once Himalayan Balsam has a foothold, it soon forms dense stands that quickly outcompete surrounding plants. The flowers have large nectar reserves, which are a huge reward for pollinators, consequently lowing the chances of pollination for our native flowers. On top of this, Himalayan Balsam is an annual, meaning it dies back each winter, leaving bare, exposed ground, which increases the risk of erosion and has a negative impact on water quality.
Japanese Knotweed was also introduced to the UK in the 1800s and was once prized within horticultural circles. It is now considered one of the top 10 most damaging invasive plants globally. It spreads along our watercourses via rhizomes and outcompetes native flora. Additionally, it is economically damaging due to its ability to grow through man-made structures such as roads and buildings.
Giant Hogweed, again introduced during the 19th century as an ornamental plant, is an extremely problematic plant. Not only does its vast size allow it to bully native plants, but it also poses severe risk to human health due to its phototoxic sap. If it comes into contact with bare skin, the sap reacts with sunlight and causes burns and blistering that can remain sensitive for several years. Consequently, Giant Hogweed must only be handled by trained professionals and volunteers.
Use the interactive map below to explore how, and where, invasive species are impacting our catchment, and what we are doing to try to control their spread.
