Native Trees: Pests and Diseases

This House of Lords Library briefing provides information ahead of the House of Lords debate on the threats posed by pests and diseases to native trees in the United Kingdom.

As at 31 March 2019, there were an estimated 3.19 million hectares of woodland in the UK, or 13% of the UK’s total land area. This stood at 10% in England, 15% in Wales, 19% in Scotland and 8% in Northern Ireland. The Woodland Trust defines a native species as one which has made its way to the UK naturally, without human intervention. For trees and plants, these are species that recolonised the land after the last ice age. The UK’s native trees include ash, silver birch, English oak, and yew. However, many non-native tree species have become naturalised and are now common in the UK’s treescape. These include horse chestnut, European larch and sycamore.

In recent years a number of pests and diseases have made their way to the UK and are causing damage to the UK’s tree population, including its native species. Acute oak decline, oak wilt, and the bronze birch borer are all notifiable pests or diseases. This means that they must be reported to appropriate authorities if they are suspected. In May 2018, the Government published its Tree Health Resilience Strategy and action plan, which set out the Government’s plans to reduce the risk of pest and disease threats and to improve the resilience of UK trees to such threats. Polling by the Forestry Commission indicates that 85% of people agree or strongly agree that action should be taken by authorities and woodland managers to protect trees from damaging pests and diseases.

This briefing explains the difference between native and non-native trees, as defined by the Woodland Trust. It examines pests and diseases that the Woodland Trust notes are of particular concern and lists those pests and diseases that are currently notifiable in the UK. It then provides a discussion of the Government’s Tree Health Resilience Strategy