Invasive plants

Managing invasive plants is essential to reduce ecological, economic, and health issues they cause due to their challenging growth patterns. However, because of how they grow, this can be very difficult.

There are two main types of invasive plants:

• UK native invasive weeds – e.g. Field horsetail
• Invasive Non-Native Plants (INNPs) from other parts of the world – e.g. Himalayan balsam

While Invasive Non-Native Plants (INNPs) and UK native invasive weeds can grow and spread quickly, INNPs introduced to the UK from other ecosystems are much more of a problem, as they don’t have their natural predators and diseases to keep them in check. As a result, they displace native plants (reducing native biodiversity), spread quickly along rivers and roadsides, and because they can grow very large and quickly, they can cause damage to property. In short, INNPs have few obvious benefits for the UK environment, society and economy, while they create many proven negative impacts.

In contrast, many difficult to manage UK native invasive weeds cause problems when people disturb and modify habitats – these plants are good at occupying the gaps that we create (admittedly, INNPs are also good at this!). Consequently, where we change our cultural practices, we can reduce the impact of many UK native invasive weeds without resorting to control measures. Also, UK native invasive weeds do have benefits, particularly with respect to the UK environment.

For example, Spear thistle seeds provide food for farmland birds such as Goldfinches, as well as thistledown which is used for nesting material. It is also a source of nectar for butterflies and a range of invertebrates overwinter in the stems.

Making this distinction between INNPs and UK native invasive weeds is important from an ecological perspective and understanding why targeted, long-term and effective (sustainable) management of INNPs is essential for the UK environment, society and economy.