To mark World Environment Day, Woodland Carbon Code Co-ordinator, Natalie Meiklejohn, provides an insight into her experience of drought and its impacts on forestry.

World Environment Day 

Led by the United Nations Environment Programme and held annually on 5 June since 1973, World Environment Day is the largest global platform for environmental public outreach and is celebrated by millions of people across the world.

This year, World Environment Day is focused on land restoration, halting desertification and building drought resilience. Globally, the number and duration of droughts has increased by 29% since 2000. Without urgent action, droughts may affect over three-quarters of the world's population by 2050. 

My experience with drought

I grew up in Australia during the time of the ‘millennial drought’ - an almost 14-year dry period which had a devastating impact on the natural environment, as well as impacting agricultural output and the security of urban water supplies. Periodically during these years, especially in the summer, there would be times where water restrictions meant that we couldn’t wash our windows, water plants and were only allowed to shower for three minutes. 

Drought in the UK 

Moving to the UK, I couldn’t conceive that drought would ever be a concern for a country where rain seemed to be the default. However, since starting work with Scottish Forestry in 2023, I’ve learnt that while the UK is projected to experience an increase in average daily rainfall under climate change, it is also projected to experience increasingly drier summers and more severe and frequent droughts.  

The Climate Change Risk Assessment (CCRA3) indicates that extremely dry summers, such as the one experienced in 2018, are expected to become commonplace by 2050. We are also experiencing and expecting spring droughts.  

Impacts to forestry

Drought poses significant risks to both productive forestry and other woodland creation projects. It reduces tree growth and productivity, heightens vulnerability to pests, diseases and mortality, decreases carbon sequestration and increases the risks of stem cracking, wildfires and windthrow. This can lead to knock on effects such as loss of habitat. Due to climate change, tree distributions are expected to shift northward and to higher elevations as the climate warms.  

The risk of drought to a particular woodland is influenced by factors such as timing, with dry springs or late summer droughts affecting growth differently and location. Soil type, tree species, root depth, age, geology, antecedent conditions, tree size, spacing, stand management and overall stand health also play crucial roles in determining the impact of drought on forests. 

What can we do to increase drought tolerance in our woodlands? 

To mitigate and adapt to drought risks, forest managers can consider diversifying tree species and structures within stands. Different tree species exhibit varying levels of drought tolerance. For instance, species like Douglas fir and Scots pine show greater resilience compared to Sitka spruce.  

Forest planning must respond to the level of risk. For example, in drought prone areas, planting operations can be matched to the wetter months at the end of the summer / early autumn, allowing time for the young trees to establish well before a potential spring drought. Using natural regeneration can maximise on-site adaptation and thinning can be used to manage tree size and stocking density.  

Research and ongoing monitoring are crucial for understanding the nuances of drought impacts on different species and sites. By employing techniques like dendrochronology to identify the impact of drought on tree growth, in the year the drought occurred and on the following years as the tree recovers, alongside remote sensing and drought indices, we can better predict and manage drought risks. This knowledge empowers us to make informed decisions about species selection, planting timings and site management, ensuring our forests remain robust in the face of climate change. 

Summary 

As drought becomes a more pressing issue due to climate change, building resilience in forestry through diverse planting, proactive management and ongoing research is crucial. On this World Environment Day, let's commit to these sustainable practices to safeguard forest productivity, maintain ecosystem health and ensure effective carbon sequestration in the face of increasing drought conditions in the UK. 

For more information, visit the UK Forestry Standard practice guide Adapting forest and woodland management to the changing climate and Forest Research’s Climate Change Hub.