Trees for the people

Unusually, the UK government found a way to spend money that met pretty general approval last month (January). It gives a boost to a feature of our landscape many feel strongly about: trees.

Specifically, it will support a new “Northern Forest”, covering a stretch of countryside between Liverpool and Hull. It’s a modest (£6m) first step toward a £500m, project that will see 50 million new trees planted over 35 years in a region that currently has poor tree cover. That’ll help flood prevention, reduce soil loss, and lock up carbon, as well as creating new woodland for people to enjoy.

That’s a lot of trees, right? It’s certainly a lot larger than most such schemes. A planting plan announced last year for £600,000 trees covering 350 hectares on Doddington Moor in Northumberland was touted at the time as the largest in the UK for decades.

 If we shared Britain's land, and trees, equally amongst its 63 million inhabitants this is what we'd each have.

If we shared Britain's land, and trees, equally amongst its 63 million inhabitants this is what we'd each have.

But is it enough to alter the picture, nationally? As it happens, we’ve been thinking about our tree population. Trees aren’t that easy to count once you go beyond your local park. A major reappraisal published in the science journal Nature in 2015 estimated that there were more than seven times as many trees in the whole world as previously believed - around three trillion.

A global figure like that takes in lots of variation in types of landscape, plant growth (when does a sapling become a tree?) and rates of deforestation - legal and illegal - and replanting. Still, the data for some individual countries is pretty accurate, relying more on counts on the ground, less on satellite imaging. Britain is one.

That’s partly because we have relatively few trees. Brazil, with its tropical rain forest, has 35,000 trees for every square kilometre. Some northern nations, with tracts of conifers, have a lot more - Finland and Sweden can boast 70,000 trees per square kilometre.

Britain has only a sixth of that tree density, roughly 12,000 per square kilometre, according to the Nature report. However, we chose a different starting point. The Forestry Commission has lots of statistics of tree cover - but up to date ones are only given in terms of area of woodland. We wanted to show how our trees might look if they were shared equally between everyone on the country - 63 million people.

That means using some slightly older figures, from a tree survey in 1995-1999, which indicates there were 3.8 billion trees altogether. That means that “your” trees, if they were shared equally, would number just 60.

We used the inventory to sketch the diagram below, as part of a conversation about trees with the Woodland Trust.

Those 60 trees, if they were average size, would fit onto a plot of land measuring just under 450 square metres. The graphic shows how that compares with one person’s share of the total land area of Great Britain, which is much bigger at 3,750 square metres. Our representative citizen also enjoys wetland, grassland, pasture, heath, as shown. And “their” trees - a number, perhaps, that you could imagine taking a personal interest in - occupy only a little more than an individual’s portion of cityscape. The great new Northern Forest, adding a bit less than one tree per person, won’t change the picture perceptibly in this “little Britain” way of looking at things. But it’s a start.

Sources:

T.W. Crowther et al. Mapping tree density on a global scale. Nature, 523, p201-207. 10 Sep, 2015

National Inventory of woodland and trees 1995-99

National inventory of woodland and trees (1995–99): methodology

Jawed Khan and Tamara Powell, ONS, Land Use in the UK

 

Land use low
 Area per person in square metres:  Urban and associated developed areas:    434  Rainfed herbaceous crops:    657  Permanent crops:    8  Pastures:    824  Semi-natural grassland:    638  Broadleaved, mixed and yew woodland:    224  Coniferous woodland:    219  Shrubland, bushland, heathland:    202  Barren land/Sparsely vegetated areas:    15  Open wetlands:    430  Inland water bodies:    48  Coastal margins:    23  Unknown :    28  Total:    3,750

Area per person in square metres:

Urban and associated developed areas:    434

Rainfed herbaceous crops:    657

Permanent crops:    8

Pastures:    824

Semi-natural grassland:    638

Broadleaved, mixed and yew woodland:    224

Coniferous woodland:    219

Shrubland, bushland, heathland:    202

Barren land/Sparsely vegetated areas:    15

Open wetlands:    430

Inland water bodies:    48

Coastal margins:    23

Unknown :    28

Total:    3,750