Royal Holloway’s grounds date back to the 1830s as the Mount Lee Estate, where the Grade I Listed Founders building was built in 1888 as one of the first female-accessible institutes of higher education. 

The c135-acre estate has always had a rich landscape. Originally it was part of an extensively worked arable and pasture farm with orchards, aquifer-fed streams, woodland and woodland pasture. Due to the continuity in the landscape and proximity to the ancient landscape of Windsor Great Park, the woodlands are ecologically rich with many veteran trees, dependant species, and floral ancient woodland indicators. Many of these are under threat from established invasive shrubs. 

The surge of invasive shrub species at the University is not new or unique, being a national challenge. Great Britain is estimated to have approximately 98,700 hectares of Rhododendron ponticum cover, accounting for c3.3% of our woodland (Brewer, 2016). Across the country, its impact on the environment extends to evergreen overshading (where only 2% of sunlight is estimated to penetrate the canopy (Hayes & Deane, 2024)), prolific seeding, disease, the prevention of woodland succession, and allelopathic soil alterations (Edwards, 2006). 

At Royal Holloway, we have a hat-trick of invasive shrubs:Rhododenderon ponticum, Cherry Laurel (Prunus laurocerasus) and Portuguese laurel (Prunus lusitanica) all create the same outcome; a near-monoculture. 

In order to tackle the resulting biodiversity decline, we engaged in a firm-but-considered approach to removal and worked to replace the shrubs with native species. We started the whole process by understanding the site’s sensitivities and identifying the potentially useful sections of the invasive scrub. By sectioning it off for clearance every year we elicit a process of stem injection, clearance of dead trees, replanting with native species. Any regrowth is re-treated the following year. Working with the Royal Holloway academic community, we identified that, for our site, keeping specific scrub areas of 4mx4m maintained adequate nesting habitat and thicket. Waste wood was retained in habitat piles, and where possible, the chip was removed to prevent enriching the soil and impacting the development of the floral layer. If chip couldn’t be removed, we kept it in localised piles, often with the deadwood, to limit ground coverage, as this may prevent the woodland floral layer developing.  

Working with Dr William Hayes, Post-doctoral Research Assistant in Fire Governance at Royal Holloway, we were able to develop a very efficient method of stem injection whereby the invasive shrubs have small amounts of lower concentrate treatment directly applied to chainsaw bore cuts into the stem, or cambial wounding via axe. Not only did this speed the process up, compared to foliar spraying, but it was considerably more effective with the lowest amount of regrowth we had yet seen, therefore requiring minimal return treatments. 

Public engagement was a key consideration with visually-impactful clearance such as this, where our second clearance area opened a prominent view of the Founders building in a highly used area. Before we started this second phase we engaged with the public early, offering walking tours and erecting signage (Figure 2) explaining why the shrubs were dying off following treatment, and what the next steps were (i.e.replanting). This was complemented with volunteer sessions that allowed students and staff to come and plant the new trees, native woodland floral plugs and wildflower seed which helped to build investment in the process. 

Two years on, we are seeing the benefits of the initial clearances (Figure 1). Both sites are emergent in the development of the floral layer, with species such as primroses and foxgloves establishing. And despite the harsh summer of 2025, the tree whips we planted are surviving and growing as well. 

Overall, every individual site will come with differing challenges and one system may not fit all scenarios, but this has been our experience of restoring our woodlands from the brink. 

It has been a process that has learnt from the land, developed alongside the changing dynamics of the site, and worked with a wider community to create the best results.