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Invasive non-native species (UK) – Cotoneaster

Cotoneaster horizontalis

This week, Elizabeth Kimber (Ecologist), focuses her invasive non-native species article on cotoneaster…

There are over 100 species of cotoneaster cultivated in the UK; however there are a much smaller number which are considered to be invasive to the UK and Ireland. These include Hollyberry cotoneaster (Cotoneaster bullatus), entire-leaved cotoneaster (Cotoneaster integrifolius), small-leaved cotoneaster (Cotoneaster microphyllus), Himalayan cotoneaster (Cotoneaster simonsii) and cotoneaster (Cotoneaster horizontalis). For the purposes of this article when cotoneaster is referred to please assume that it is the before-mentioned invasive species of cotoneaster that are referenced.

Cotoneaster species are native to Eastern Asia and were first introduced to the UK in 1824 as ornamental plants. The seeds are spread by birds, therefore, the plants can easily spread to a wide area.

cotoneaster

Identification & Ecology
Identification features of cotoneaster include:

  • Green shrubs and small trees, some deciduous and some evergreen.
  • All cotoneaster species are without thorns and have shiny leaves.
  • Leaves are hairless on the upper surface and slightly hairy on the underneath of the leaf.
  • The flowers are small – white or pink in the spring, followed by clusters of red/orange berries in the autumn.
  • Wall cotoneaster has branches in a ‘herringbone’ shape.
  • Himalayan cotoneaster is an erect deciduous shrub, with leaves of 1.5-2.5 cm long.
  • Small-leaved cotoneaster is evergreen with very small leaves at 0.5-0.8cm long.

Impact
Once cotoneaster is established, it can dominate areas – outcompeting native flora and creating dense thickets. When plants spread into the wild, they are particularly problematic on limestone cliffs, pavements and screes, through outcompeting rare native plant species.  They can also form an extensive root system which is difficult to remove.

In habitats of lower value, especially in urban areas, it may actually have a net benefit to local ecosystems as its flowers are highly attractive to bees and birds eat its berries in the winter when other food sources may be scarce (NNSS, 2017).

Legislation
Legislation which attempts to control the spread of specific cotoneaster species includes Schedule 9 of the Wildlife and Countryside Act, which makes it illegal to distribute or allow the spread of cotoneaster species into the wild.

Control Measures
Control of cotoneaster species includes mechanical and chemical measures.

  • Mechanical methods of control comprise pulling young seedlings and excavating the root mass. Any material from the cotoneaster/containing cotoneaster waste must be chipped/burnt on site, or removed to licensed landfill as controlled waste.
  • Chemical methods of control include spraying plants with herbicide and treating stumps of larger plants to prevent regrowth.

References: 

  • RHS list of invasive plants covered by legislation in the UK – HERE.
  • Invasive Weed Solutions info – HERE.
  • Plantlife info – HERE.
  • Non-Native Species Secretariat – HERE.

Header Image: Cotoneaster horizontalis – Wikipedia Commons.

About the Author: Elizabeth Kimber works for an ecological consultancy based in Dorset (Lindsay Carrington Ecological Services Ltd). As part of the role she manages the ecological works for a multi-phase development. She conducts protected species surveys and holds a class 1 bat licence, smooth snake and sand lizard licence. She can be contacted via email: liz (at) ecological-services.co.uk.

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