To the layman, they will look like ordinary saplings but the Serbian spruce trees that are to be planted in Princes Street Gardens in Edinburgh tomorrow are a little bit special.

The six trees are the first to be planted as part of a new agreement between Edinburgh City Council and the Royal Botanic Garden which will see examples of endangered trees being planted in most of the city's parks over the next few years.

The trees will come from all over the world and the aim is not only to increase biodiversity in the parks but also make a valuable contribution to conserving rare and endangered species around the world.

It is an encouraging move and, following the selection of the Scots pine as our national tree, it could serve as a signal that Scotland is giving a higher priority to the worrying risk to trees all over the world.

But the threats remain considerable, not least to the Scots pine itself, which is at risk from climate change and disease. The new project in Edinburgh will, with skill and care, help secure the future of the Serbian spruce, but it could also be the roots of an inspiring new campaign to mark Scotland out as a world leader in reforestation.