Invasive river bank plant species
Some plants have proved highly invasive, colonising a habitat often to the detriment of native species and habitats. Once established they are very difficult and costly to eradicate or control.
Japenese Knotweed - We have the Victorians to thank for Knotweed - one of the world's worst invasive species. Native to Eastern Asia, the plant has an aggressive root system and growth that’s been known to damage concrete foundations, roads, retaining walls and even flood defences. It alters the habitat structure and wildlife on river banks which is known to directly impact on salmonid fisheries. It restricts access for angling and hinders conservation efforts of rivers.
Giant Hogweed – This monster plan can grow up to 12 feet high. It grows mainly along river banks and burns, shading out the native vegetation and leads to bank erosion and the sap of this plant can cause skin burns. Repeated and coordinated spraying with herbicide is the best control method.
Himalayan Balsam – This river bank plant is an annual and shades out native ground plants. It has explosive seed pods that shoot the seeds a few metres from the plant onto the ground or into the river. This mean it can spread rapidly. Simple control measures of pulling this plant up by the roots is very effective and after a few years can be eradicated.
More information on invasive species can be found on the Scottish Invasive Species Initiative website
Shady Characters needed to cool our rivers
Fish in Britain’s rivers are under threat from warmer waters. Cold-water species such as Atlantic salmon and brown trout, are struggling to cope as climate change brings significant increases in temperature.
Today there is a call for urgent action to Keep Rivers Cool by planting broadleaf native trees alongside river banks, creating dappled shading and stopping water from warming up. Shade can reduce temperatures in small rivers by on average 2- 3 degrees C compared to unshaded streams; and by more on hot summer days.
Now Keeping Rivers Cool is calling for action. Speaking on behalf of the KRC partnership Diane Millis, from the Woodland Trust said: "We are asking people who value our rivers to survey their local river bank and look at specific areas which may need shade. Landowners, Rivers Trusts, anglers, farmers and ecological groups can all help."
The KRC partnership is asking groups working in catchment areas to take up the challenge using a practical guide for planting along river margins, available on the Woodland Trust website.
Some climate predictions indicate water temperatures will exceed the safe thresholds for river fish; and trees alongside riverbanks are a crucial part of the biodiversity of our waterways.
The Woodlands Trust's Diane Millis warned; "Figures show that stocks are already decreasing and if we don’t start taking the temperature threat seriously, iconic fish like salmon, will face even more serious decline. Rivers, and the ecosystems they support, are one of our most valuable natural resources. Salmon are already under pressure, from sediment and pollution run-off, barriers to swimming up-river, lower flows and changes in habitat. The annual fisheries report from the Environment Agency show a continued decline in salmon populations, with over 90 % of stocks in England’s principal salmon rivers assessed as being at risk, or probably at risk."
At sea, marine survival of salmon has nearly halved over the last 20 years; making it more important that their freshwater habitat is improved and protected.