A new study by Professor Dan Bebber should sound some serious alarms. It last year warned that the threat of new pests and diseases was potentially causing the future growth of trees to collapse across the UK. Now, overall biodiversity in UK forests is at a low ebb. Research has shown that this can raise the risks associated with tree health and growth. These results stress the importance of promoting tree diversity and resilience through reforestation.
The study emphasizes a crucial point: “The defense against uncertain risk is always diversity.” That’s why Professor Bebber is calling for a complete reevaluation of our tree planting practices. This urgency comes because as a nation we are now on average discovering about one new pest or disease a year. Unfortunately, this trend indicates that the future of the country’s tree canopy growth is at greater risk than ever.
Current State of Tree Cover
UK’s tree cover has experienced waves of increases and decreases over past centuries. At the start of the 20th century, it fell below 5% of the land cover. Through successful reforestation efforts, this number increased to about 13% in 2018. This level remains significantly short of the European average of 39% of territory being forested. We need to move quickly to fill this gap.
Although this is a step forward after years of decline, ancient woodlands – habitats that have been continuously tree-covered since 1600 – make up just 2.5% of the UK’s land. This pathetically low percentage means a huge negative impact in terms of biodiversity and ecosystem integrity. As the UK government aims to increase tree cover to 16.5% in England by 2050, 21% in Scotland by 2032, and add 2,000 hectares annually in Wales, the question remains: Will these efforts adequately address the underlying issues related to pests and diseases?
The Threat of Pests and Diseases
Emerging plant pests and pathogens represent a critical risk to UK trees, said Prof Bebber. The research shows that quickly-growing nonnative tree species now make up almost half (48%) of the UK’s entire forest estate. This trend threatens long-term resilience of these forests in the face of invasion.
Professor Bebber pointed out, “This work is a stark reminder that emerging plant pests and diseases pose a severe threat to UK trees, and the biodiversity benefits and ecosystem services they provide.” The overwhelming diversity of potential new invaders indicates that more arrivals are not only possible, but likely. This trend has profound implications that policymakers and conservationists alike need to urgently consider.
It is recent rates of pest and disease arrival that ought to alarm us. Under a business as usual scenario, projections indicate that we stand to lose over 50 percent of tree growth by 2050. This reality emphasizes the urgent need to act now to increase tree resilience.
Prioritizing Diversity in Reforestation Efforts
This study highlights the need to introduce more biodiversity into reforestation efforts. “In the UK, we have relatively low tree diversity. Both in terms of the number of tree species and the genetic diversity within each species,” Professor Bebber noted. He emphasized that such low diversity would limit trees’ chances of enduring against future threats.
Furthermore, he called attention to social and cultural considerations surrounding reforestation: “As well as issues about biosecurity, our research raises social and cultural questions about what we think our woodlands should look like—for example, which species should we plant?” This shows an increasing recognition that effective long-term forestry initiatives require public engagement from the start.