Assessing and Adapting to the impact of weather events at the Royal Botanic Garden Edinburgh
The RBGE was established in 1670. The site in Inverleith, Edinburgh was the first garden and during the 20th century three Regional Gardens were acquired. The four gardens experience quite different weather conditions; Inverleith in Edinburgh is the driest, Dawyck in Peebleshire is the coldest, Benmore in Argyll is the wettest and Logan in Dumfries and Galloway is the mildest. Over recent years, all of the Gardens have experienced most kinds of extreme weather.
Adaptation to these severe weather events is site specific but experience from them is shared between the gardens to increase the resilience to future climate change. To enhance this understanding, research has been carried out to examine in more detail how each of the gardens are affected by the current climate and how they can better prepare for the projected changes in future climate.
The research has shown that there are three clear areas where the impacts are felt the most; the plants, the people and the infrastructure.
Getting people on board
The first action was to meet with the garden curators to explain the aim of the project, how it would be of value, and the output that would be produced.
Next, visits to each garden were arranged to interview key personnel and gather information on:
- Observed impacts of current weather conditions and extreme weather conditions experienced – and any adaptive actions taken as a result
- Risks related to weather or climate change that have been identified
- Potential opportunities arising from a changing climate
- Records of garden closures to visitors and staff and historic weather data from garden records
At each garden, the curator also did a walk round to explain the garden features and see weather impacts and adaptive actions first-hand. Visitor services staff, who are well placed to see the impact of weather events on visitors, were also consulted.
The iconic Redwood Avenue of trees at Benmore gardens is at risk of waterlogging due to inadequate drainage in intense rain. The waterlogged soil causes physical stress to the trees due to root death. No air spaces are left in the saturated soil and roots literally drown.
All the gardens have seen trees lost or damaged in storms. This provides both challenges, when specimens are of particular conservation importance, and opportunities for planting new species.
Mild winters increase the risk of pests and diseases. Impacts include an increase in aphids such as green spruce aphid on Picea (spruce), and soft scale, previously considered a glasshouse pest, on rhododendron.
As the climate changes the gardens have to close more frequently due to severe weather. This has a number of impacts:
- Loss of working hours; as staff are also excluded from the garden for safety reasons
- Loss of income; for example at Logan the Potting Shed Bistro has to close if the garden is closed due to weather
- Disappointed visitors
- Staff time to clear up after a storm; for example at Dawyck the removal of one fallen Noble fir took 200 man hours as machinery could not be used safely due to its location.
The increase in heavy rainfall events has made the use of bark and grass paths impractical. All the gardens are now replacing these paths with gravel, or other porous paths together with improved drainage measures.
Storm damage has resulted in multiple broken panes of glass in the glasshouses at Inverleith, leaving tender plants exposed to the elements.
Adaptation is site specific. The four different sites allow the RBGE to draw on a wide range of experience in dealing with different weather events and site impacts. Some adaptation measures include:
- Planting a mix of species increases resilience to pests and diseases, and provides a more effective windbreak and structure to shelter belts.
- When re-designing garden infrastructure, locate facilities such as visitor centres and cafes outside the pay zone to provide access even if the garden is closed.
- When planning staff resource and time, include allowance for clear-up and remedial work following extreme weather events.
- Replace paths with gravel or other porous materials.
- Providing additional drainage and factoring in staff time for keeping drains clear.
- Researching glasshouse structures and glazing systems that are less susceptible to wind damage.
- Adopt a zero tolerance maintenance procedure to glass damage, such as cracks, and keep more glass on site to reduce repair time
- Compare anecdotal evidence about changing weather with actual weather records from the weather stations at each garden.
- Highlight the opportunities such as being able to grow new species in a milder future climate.
- Develop interpretative signage to explain climate impacts and adaptation measures to visitors.
- Gain high-level support for initiatives
- Consider the aims of the organisation and how this process can add value, for example communication and engagement.
- Talk to as many personnel as possible, and listen to their experiences.