Changes in established woodlands and the impact on achieving net-zero

The importance of trees in the plans to achieve goals of net zero by 2050 has been recognised at national and international levels, and the need for additional tree planting is embedded in national initiatives and policies such as the England 25-year Environment Plan and Woodland Carbon Guarantee Scheme. Although there are many good arguments for the expansion of UK tree cover with new trees and woodlands, there also needs to be a better understanding of the status and health of existing woodlands, to preserve and optimise existing carbon stores. Many of the tree species in UK woodlands are under increasing stress due to environmental changes and attacks by pests and diseases including acute oak decline, sweet chestnut blight (Cryphonectria parasitica), ash dieback (Hymenoscyphus fraxineus) and Ramorum disease (Phytophthora ramorum) which affects 150 plant species. These non-native and invasive pathogens and other pests weaken the trees, for example through loss of leaves or bleeds on stems and fungal infection, reducing growth and consequently their ability to store and capture carbon dioxide, and may ultimately lead to tree death. It is therefore critical to monitor existing trees and woodlands to assess impact on tree health, tree coverage and ultimately carbon dioxide sequestration of UK landscapes.

Tree biomass and therefore carbon storage is influenced by species, number, health, and size (e.g. trunk DBH, height and crown size) of trees in the landscape. This project will demonstrate the capability of remote imaging methods, mounted on unmanned aerial vehicles (UAVs), or drones, to allow mapping of tree species, structure and health across diverse woodlands and to detect changes in these factors over time. We will also review the potential to integrate such data into existing carbon modelling frameworks, which would allow estimation of potential loss of carbon through tree health declines at landscape scales.