The Queen’s Green Canopy
Her Majesty the Queen has enjoyed 70 years on the throne this year and we are urged to ‘plant a tree for the jubilee’ to create the Queen’s Green Canopy. This national tree initiative encourages everyone to plant trees – from a single garden specimen to an entire woodland. It is hoped that individuals, community groups, schools, businesses and councils will all take part in a bid to green up the UK and help fight the climate crisis. Trees absorb pollution, store carbon, produce oxygen, stabilise the soil, help prevent flooding, improve biodiversity and provide shelter.
Some trees are better than others in terms of eco-credentials. Oak, beech, London plane, black walnut, many larger maples and eucalyptus are some of the best at carbon storage, and larger trees are generally better than smaller varieties. Broadleaved species have a larger surface area of leaves, which enables them to carry out photosynthesis. They absorb water, sunlight and carbon dioxide in order to produce oxygen.
Oaks are kings of the habitat providers, but smaller trees, including a wide range of birch, are excellent too. Some smaller trees and shrubs excel at this particular role, including elder, spindle, blackthorn, wild cherry, crab apple, hawthorn and holly. The key lies in planting a diverse mix of species in order to provide as many benefits as possible to wildlife. Think in terms of food sources as well as creatures. Insects are just as important when considering the food chain.
Pests and diseases
Avoid planting a monoculture of one species of tree, as disease can potentially kill the entire group. This applies to street trees as much as it does to hedges, copses and woodland. Instead, include a mix of species, which will be more resilient. It is also sensible to extend the range of trees in the UK to include non-native, hardy trees. Always source trees from reliable, ‘plant-healthy’ suppliers.
Be aware of the general health of trees, including disease that causes loss of limbs, thus posing a safety risk in public places.
Ash dieback is likely to cause the loss of up to 80 per cent of this tree in the UK. Affected trees near public areas should be removed.
Phytophthora ramorum is sometimes called a water mould. It causes bleeding canker symptoms on trees, including larch and sweet chestnut in addition to conifers such as Douglas fir. It can also cause sudden oak death.
Phytophthora pluvialis has recently been discovered in western hemlock and Douglas fir in the West Country. It causes needles to turn brown and drop, eventually resulting in dieback.
Oak processionary moth is an insect pest present in London and surrounding counties. There are silken nests and processions of caterpillars that defoliate oak trees, thus leaving them vulnerable and unable to carry out photosynthesis.
The fungal disease Massaria is spreading amongst London plane trees, including those at Buckingham Palace and some of the royal parks. It causes lesions on branches, which die back and are eventually shed.
by Caroline Knight: Gardendesignideas.co.uk