Is there any point in planting new trees?
Successive governments have made popular pledges to plant large numbers of new trees. But do these trees ever actually get planted and, where they do, does it ever achieve anything useful?
Woodlands have a vital role to play in our landscape. As well as being a valuable source of homegrown timber, trees store carbon, provide an essential home for wildlife, absorb air pollution, and are important spaces for pleasure and leisure.
Growing attention has also been paid to their role in cutting flood risk. Department for Environment, Food and Rural Affairs (Defra) says that, in the right place, woodland can reduce water flow and siltation in rivers, and is considering its role as part of an ongoing national flood resilience review.
Attempts have also been made to quantify their economic benefits: last year the Office for National Statistics valued woodland's carbon sequestration services alone at £2.4 billion in 2012 - and its recreational value at double that.
Despite this, only 13% of the UK - three million hectares - is currently covered by woodland. The figure is slightly higher in Scotland and Wales, and lower in Northern Ireland.
It is a significant improvement on the low point of just 5% after the First World War, when the Forestry Commission was formed to safeguard the national timber stock. But annual planting levels in England are much the same as they were four decades ago - and have hugely declined in the rest of the UK.
The UK has long been bound by an international commitment to protect and expand its woodland cover, and in 2013, the coalition government said there was scope for increasing it "significantly". Although government has never set a target figure for overall cover, it did promise to plant a million trees in 12 months, followed by another four million the following year.
These pledges have been met in part through the Forestry Commission's Big Tree Plant scheme. In February, it announced that it had surpassed its target of planting one million trees in towns, cities and neighbourhoods throughout England - mainly in poor areas with little greenery.
Now Westminster has upped its game. In the 2015 Autumn Statement, environment minister Rory Stewart promised to plant 11 million new trees over this parliament.
One million will be planted by schools. Defra plans to fulfil the rest through its £900m Countryside Stewardship scheme, which pays farmers and other land managers up to £6,800 per hectare to plant, weed and protect young trees.
But Andrew Heald, technical director of forest industry body Confor, is sceptical. He says the grant schemes are confusing, advice is not easy to access, and the financial incentives are skewed; Countryside Stewardship pays £144 to cut down a tree, but just £1.28 to plant one.
The other limiting factor is the availability of young trees in the nurseries, he says. Saplings can take several years to grow and nurseries that have over-estimated planting requirements may end up burning thousands of young trees.
Austin Brady, director of conservation and external affairs at the Woodland Trust, adds that there is not enough scrutiny of tree health and survival after planting. He says it is not just about the absolute number of trees but the quality of woodland - how diverse its species are, the state of its soil and all the animal and plant life that surrounds it.
The other question is where they should be planted. There are increasingly sophisticated tools to help regulators determine where best to plant trees; to increase biodiversity, for example, or reduce the risk of flooding. But Brady says drawing up a map doesn't make anything happen.
"You still need landowners, farmers, the community, to recognise the benefits and engage in the process either by seeking advice or potentially applying for a grant."
Mr Brady has a reality check. He says planting pledges often sound impressive but spread across a whole country they are relatively small. Eleven million trees over four years works out at just over 6,000 acres a year.
More importantly, he says it is not clear whether enough trees are being planted to replace those that are being lost.
Given the chop
Cutting down a tree normally needs permission from the Forestry Commission, which will take a record and may ask for the tree to be replanted. But applications for developments where small amounts of woodland need to be cut down go through the planning system and that information is not collected centrally.
The Woodland Trust is particularly concerned about the loss of valuable ancient woodland, which now only covers 2% of the UK. Planning authorities must refuse permission for destroying irreplaceable habitats such as these but there is an important caveat: "Unless the need for, and benefits of, the development in that location clearly outweigh the loss."
The Trust is currently challenging 100 different planning applications around England where it believes ancient woodland is under threat from development; the most prominent example is HS2, which it says will directly affect 36 ancient woods another 27 indirectly through disturbance, noise and pollution.
"On an international stage, government is often talking about leading the way in supporting developing countries so that they don't end up with deforestation," says Brady. "But if you try and add up the figures back home in England it's very hard to establish whether we're in a state of deforestation ourselves."
The Trust is also concerned about the loss of woodland from natural causes - through disease, old age or extreme weather - which may never be recorded or replaced.
Mr Heald calls this a "creeping deforestation effect", adding: "It won't become obvious for five or 10 years so we're trying to get people to start thinking about that now and start getting a better handle on the data and the numbers."
The Forestry Commission admits there is a lag in its figures, but says they do eventually catch up. It compiles a National Forest Inventory every few years using a mix of aerial photography and walkovers, and the next results are due in 2018.
Nevertheless, government is under pressure from several sides to be more ambitious.
Heald notes that the UK has comparatively little woodland cover compared with its European neighbours and is the third largest timber importer in the world.
The general public is certainly in support of doing more; most of those responding to the Forestry Commission's latest public perceptions survey agreed that "a lot more trees should be planted" in response to climate change.
Mr Brady admits that cultural attitudes are a barrier. "In some communities there's been nervousness about large-scale afforestation and the history of the Forestry Commission converting large areas of land from farming," he says.
He adds that a creative approach is often required. "It's not necessary to talk about a wholesale shift of land use taking whole farms out of business," he explains.
"At Woodland Trust we're trying to get people used to belts of trees or hedgerows - things that don't take the place of the farming but can help to make it more sustainable and improve it."
Mr Heald is also optimistic. "We have to present tree planting as a solution. You need the landowners and farmers to want to do it, rather than batter them with it. They've got to understand why this is a good thing to do. If we're ever going to get money to plant trees it's going to be now."
Dominic Driver, head of national expertise and strategic development at the Forestry Commission, agrees more could be done.
He says: "We're really ambitious about this. We decided that 12% cover in England by 2060, up from around 10%, is reasonable. That's not a government target - it's a shared ambition with the sector."
But he is tired of comparisons with other European countries, pointing out that many are larger and landlocked.
And he points out that large-scale woodland planting raises tough questions about how to balance the economy, environment and society - particularly the difficult compromise with agriculture.
"We've reversed centuries of deforestation in past 90 years - people need to be patient about it."