Climate change has rightly moved centre stage, helped by world-wide children’s marches and this week’s UN debate. We gardeners can play a tiny part by simply planting a tree in our gardens.

As we know from Brazil’s unforgivable destruction of its rain forest, trees play a key role in absorbing global CO2. The Scottish government is ahead of the game in tree planting. They estimate that current plantations remove 9.2 million tonnes of CO2 every year.

These conifer plantations are important, but ground preparation and some of the harvested timber do release carbon into the atmosphere. On the other hand, as Carol Evans, chief executive of the Woodland Trust Scotland, has noted, native trees, which she describes as ‘the nation’s green lungs’ are ‘planted for longevity, so lock up carbon for longer.’

That’s why the Woodland Trust [www.woodlandtrust.org.uk] has just launched the ‘Big Climate Fightback’. It’s urging groups, schools, businesses and individuals to plant a tree by St Andrews Day [30 November]. I fully support this initiative and, where possible, urge you to plant one.

The right tree for you should grow to a sensible height and be placed to enhance the garden. And, importantly, it should be a native, preferably Scottish species that will be well equipped to widen the garden’s biodiversity.

Select a tree that you can leave to do its own thing: you don’t want to undo your good work by having to fell it. Try to avoid coppicing, pollarding or a lot of pruning as this also releases stored carbon back into the atmosphere. Coppicing can benefit some wildlife but a freely growing tree also benefits wildlife while capturing carbon.

Buy a tree over the next couple of months. A bare rooted one is cheaper and should thrive when properly planted and kept well watered over the first year.

Check on the final height after 10-20 years, bearing in mind that this varies according to location and soil quality. The Woodland Trust offers detailed information and a good garden centre or nursery should give useful advice.

If you’ve a small to medium sized garden, you’ll want a species that doesn’t finally grow to more than 4 metres. I planted a Spindle, Euonymus europaeus, this spring in a non-too-fertile place so it should reach a couple of metres, not a possible 4 metres.

Spindle’s waxy, shiny leaves turn a brilliant purple and it has showy little pink fruits. More importantly, fruit-bearing or seed-producing trees are invaluable to wildlife and should always be preferred to the likes of ornamental cherries.

Another of my favourites is Cornus mas, Cornelian cherry. It too reaches a modest 2.5-4 metres, with oval leaves turning a blazing purple before falling. Its tiny yellow flowers are followed in late winter by clusters of glossy red, cherry-like fruits.

If you do have space for a larger specimen, a crab apple makes a great choice. It does admittedly climb to 7 metres and you may need to snip off the odd meandering stem, like the one I have next to the goose run gate, but the spring blossom and mass of little crab apples are fantastic.

A Gean, Prunus avium, is a bit taller and also a delight in spring. As is our brilliant Scots Rowan, Sorbus aucuparia, with fetching almost ash-like leaves and a mass of bright red fruits.

Especially with large trees, roots thicken and spread extensively, so keep well away from buildings and walls and make sure a fully grown specimen doesn’t cause too much shade.

Finally, avoid trees that are susceptible to dire disease, like ash, horse chestnut, sweet chestnut and elm.

Plant of the week

Viburnum opulus. ‘Compactum’ Pretty, maple shaped leaves, flat heads of white flowers in spring followed by bright red translucent berries. 1.5 metres