The extraordinary weather in 2012 has prompted the Royal Botanic Garden Edinburgh (RBGE) to assess how trees and plants in its four Gardens across Scotland have been affected. Click here for a full analysis and pictures.
The most significant impacts resulting from the weather have been: the loss of around 130 trees during January’s hurricane-force storm; dry soil caused by low rainfall during an unusually dry and warm February and March; frost damage to young leaves and shrubs during a cool and unsettled period in early April; saturated ground and floods resulting from one of the wettest summers on record.
At RBGE’s Edinburgh Garden alone 34 trees were felled by the 100mph winds on January 3, some of which were up to 125 years old. The Garden also experienced the warmest March on record and during summer, an exceptionally dull and cloudy July with persistent rainfall which caused flooding.
Commenting, Curator David Knott says: “The inclement weather has suited some plants and we have seen phenomenal growth. For others, flowering has been hindered. The full impact of the weather is difficult to determine immediately on, for example, the roots of trees which have been so saturated. It could take seasons or even years to see the full picture.”
Edinburgh’s iconic Glasshouses were damaged during the January storms with over 600 panes of glass shattered, exposing many plants from lush regions of South East Asia to the cold. Supervisor Louise Galloway says: “Aside from the damage caused by falling glass, some of our rare ginger plants died right back and disappeared underground. We didn’t know if we’d lost them and made the decision to leave them in-situ and to monitor. We were incredibly lucky that after the storm the temperature stayed around 6°C and with incredible staff support we successfully re-glazed the glasshouses within a week - within five months small green ginger shoots began to appear - the plants in general proved to be surprisingly resilient.”
Benmore Botanic Garden, located at the gateway of the Loch Lomond and Trossachs National Park, bore the brunt of the January storms, losing over 100 trees of varying species. April saw double the average occurrences of ground frosts. In June, rainfall was 45% above average – the wettest June in 10 years. Benmore also recorded record rainfall of 125mm or 4.9 inches on November 18, the greatest amount of rain to fall at the Garden in one day ever.
Curator Peter Baxter says: “Extreme weather events at Benmore can be very destructive although damage to the plant collection can be hard to quantify as much of the effect can be latent. It is crucial that new appropriate plant material is always available in order to maintain and develop the collections.”
Logan Botanic Garden near Stranraer in Dumfries and Galloway is Scotland’s most exotic Garden being warmed by the Gulf Stream. This year, Logan had the wettest summer since records began and, as a result, has witnessed a reduction in the flowering of plants but an increase in vegetative growth.
Curator Richard Baines says: “Many plants grown at Logan originate from South Africa and depend on bright conditions to induce flowering. Wet, cool cloudy weather has promoted vegetative growth in plants such as Argyranthemum and Diascia.”
Some plants have thrived. He adds: “The extension growth on rhododendrons was probably the greatest that I have ever known due to the continuous supply of moisture. Gingers have also enjoyed the warm, muggy, cloudy days as these conditions are endured in their native habitats in Vietnam.
“Even with the poor summer some of the Logan regulars such as Echium pininana from the Canaries put on a great show and a first for Logan was the tree dandelion Sonchus arboreus still in flower in Late November due to the mild weather. Where else could you see a Tree Dandelion from Madeira flowering outside in November?
Dawyck Botanic Garden in the Scottish Borders lost 13 trees in January’s storm, the most notable being a 50 metre fine old Noble fir tree dating back around 100 years. Curator Graham Stewart says: “Losing a notable tree can be like losing an old friend. They are impossible to replace. It was sad for everyone to see. However, we have to be philosophical about it, and look upon any loss as an opportunity for replanting.
“We have an annual planting programme with around 200 new species being added to the collections every year. New plantings are from wild-collected plant material, sourced in the wild by garden staff in line with the gardens’ collections policy. Significantly, at Dawyck, plant collections and recent additions include tree species of abies, picea, betula, sorbus, acer and shrubby species of spiraea, cotoneaster and berberis, as well as rhododendron sp.
“This year we have been overwhelmed by the vegetative growth of many plants, in many cases it has been to the detriment of the flowers. Herbaceous perennials such as rodgersias, astilbe, hosta and ferns needed constantly pruning to keep them from overtaking our paths. Grass growth has also been phenomenal with the added problem that sometimes we couldn’t cut it because the ground was saturated.”
Scotland’s extraordinary wet, cool and dull summer in 2012 can be traced to fluctuations in the position of the Jet Stream high above the UK. Scientific evidence also shows that globally, carbon dioxide levels are increasing, temperatures are rising and the atmosphere is becoming more moist. These factors will have consequences on the weather and the natural environment including botanic and domestic gardens.
Suzanne Martin, RBGE’s climate officer with ClimateXChange, Scottish Government’s centre of expertise on climate change says: “We need to start considering how the climate is predicted to change and to understand the types of impact that may have on our botanic gardens. The experience of more extreme events such as heavy rainfall and storms is broadly consistent with climate change predictions while providing a powerful example of a degree of uncertainty to which we must adapt. We can use our experience of responding to and recovering from this year’s extreme weather to help us better cope with longer term changes in climate.”