We are being urged — and, in some cases, paid — by the government to plant more trees. Actually, this happens most years. I can even remember ‘Plant a tree in ’73. Plant one more in ’74’. It is a bit like saying ‘Have more babies’, without any provision for their care once born. It all depends which trees, where you plant them and how you tend them. If you walk through the country nowadays, or near new-build housing estates where trees have been planted in ‘mitigation’, you will see large numbers of saplings dead or dying, still in their tree guards, planted too close together and then forgotten. New trees need protection from rabbits, deer, weeds and competition. As a dog is not just for Christmas but for life, so a hardwood tree is not just for COP26, but for centuries. Besides, tree-planting can do ecological harm. Great damage — especially to now-fashionable peat — was done to the Flow Country in Scotland in the 1970s by the heavily subsidised planting of conifers there. According to the Sussex Wildlife Trust, the county lost 80 per cent of its heathland in a century, half of that to tree-planting. And ‘chalk grassland can have about 40 species of sensitive plant per square metre’, far fewer if trees are planted. The simplest and most sustainable way of getting more trees is probably just to pay landowners not to plant new ones, but to let existing ones seed themselves in ungrazed fields. You will get first sycamores and thorns, then oaks or beech; possibly even nightingales. But there is also the question of timescale. If the preachers of climate emergency are right, it is already too late even to plant softwoods.