The trouble with trees

The trouble with trees
Tree planting © Sam Roberts

By Dr Tony Whitbread

President of Sussex Wildlife Trust

The creation of forests and woods can be a major contribution to restoring nature and can draw carbon out of the atmosphere, so helping fight climate change.  Indeed, with a UK average tree cover of just 13%, it would not be unreasonable to double this. 

Done badly, however, tree planting and tree regeneration can cause major ecological damage.  We must make sure that a frantic rush to plant trees does not repeat the errors of the past.

Enormous ecological damage was done in the mid-20th century through tree planting.  Vast areas of the Flow Country in NE Scotland were drained and planted with non-native conifer trees devastating the local ecology and (by causing the drying of peat) was a major emitter of carbon dioxide.  Many other upland areas saw similar devastation.  In Sussex too some of our most valuable habitats were lost to tree planting.  For example, over a period of about 100 years we lost roughly 80% of our heathland, nearly half of that to tree planting.  In the 1990s it was feared that many of our heathland species would disappear altogether as a result.  Fortunately, however, conservation management projects managed to reverse this trend.  Management – mainly tree removal not planting – averted an ecological disaster.

Similarly, loss of chalk grassland to tree planting and the spread of scrub is second only to loss to arable cultivation.  Chalk grassland can have about 40 species of sensitive plant per square metre; this reduces to a small number of common species if scrub invades or trees are planted.  It is likely that we have also lost hay meadows – one of our most threatened habitats – to tree planting. 

Large areas of the most diverse habitats in England have therefore been lost to trees.  These habitats were often as good as trees in locking up carbon and so fighting climate change.  We now have only small areas of these habitats remaining, tree planting on these would be unforgivable.

The desire for trees can come about from a misunderstanding about the natural ecology of Britain.  There is a presumption that a dense canopy of trees is the natural state for our country.  This is not true.  We’ve known it was nonsense since I was in college in the 1970’s.  And it is nonsense still promulgated by people who should know better.  So, let’s try to put this myth to bed!

If dense tree cover was the natural state for Britain, then most of our native species would logically require dense woodland.  They do not.  More than half of our species require open habitats or forest edges; very few require continuous dense trees.  Even species we associate with dense forest often require open habitats at some stage – Oak and Hazel for instance regenerate better in the open.  If the natural state of Britain was dense trees then most of our native species would never have colonised Britain, indeed they could never have evolved, in the first place.  The natural state of our landscape is one of great diversity not a continuous monotonous tree cover.  This diversity of original natural habitats is now maintained as “semi-natural” habitats through of centuries of management. 

We may think of tree growth as natural, but tree growth is not the only natural process.  Importantly, there are processes of natural disturbance that limit or hold back tree growth (think of beavers!).  It is this balance of tree growth against natural disturbance that creates diversity.  Too much of one or the other and nature suffers.  This is the real value of management – it replaces natural disturbance with disturbance caused by management, putting back the diversity that can be lost through a lack of natural disturbance.

Fortunately, the situation is better today than it was in the mid-20th century.  Organisations involved in tree planting (such as Forestry Commission and Woodland Trust) are very aware of the potential problems.  These will plan planting properly, delivering benefit and avoiding problems.  Anyone wishing to plant trees should show similar care.  There are also better alternatives to planting. Natural regeneration and rewilding are more likely to deliver diversity, are cheaper, fit local ecology better and require less aftercare. 

I do worry, however, that a destructively naive view of nature and a rush to get trees in the ground will sweep all before it.  We risk repeating the errors of the past and once again cause great ecological damage.  Simple solutions to complex problems are always wrong.  We should move the conversation from “tree planting” to “natural regeneration” then to “rewilding” and to “natural climate solutions”.  Tree planting may have a role, but only as part of a diverse nature recovery network, not as an unquestioning paradigm.

UPDATE

Dr Tony Whitbread has written a couple of follow-up blogs on this topic

Comments

  • Helen:

    08 Jan 2020 05:03:00

    Can there be an overriding nature body policy that oversees that all organisations and charities are working together so that the environment is more wholey looked after?

  • Kate:

    10 Feb 2020 17:21:00

    I have found this article really interesting. I am also concerned as to how/who will manage all these new woodlands in the future?

  • Mike Douglass:

    27 Feb 2020 14:00:00

    “ The hidden life of trees “ by Peter Wohlleben is an excellent , fascinating and informative book

  • Ros:

    27 Feb 2020 14:09:00

    Very glad to read this. Now I’m better informed to debate this issue with my friends. I had a debate about this with them not long ago and they just don’t get about the need to graze the Downs to retain the carbon friendly grasslands we and our wildlife love so much. They’re convinced they need to give up meat altogether rather than being selective about where to source our meat – local, grass-fed animals.

  • Mike Croker:

    27 Feb 2020 14:40:00

    Enlightening post: “Simple solutions to complex problems are always wrong.” Unfortunately simple solutions tend to make good soundbites: must try and remember Tony’s response!

  • Mike Croker:

    27 Feb 2020 14:41:00

    Enlightening post: “Simple solutions to complex problems are always wrong.” Unfortunately simple solutions tend to make good soundbites: must try and remember Tony’s response!

  • Leanne Roberts:

    27 Feb 2020 16:06:00

    Its good to know that the Forestry Commission and Woodland Trust, both organisations that we recognise from paper/tree related products, recognise the problems involved in incorrect and non-native planting.

  • Colin Upton:

    27 Feb 2020 17:01:00

    Well said Tony, there is certainly much to be said for planting many more trees in our towns, here in Shoreham there are many places where trees could be grown, in our parks and schools for example, and on verges, there is plenty of space for trees. As I walk around I often see places where trees and hedges could live happily, and help to combat the pollution that is such a problem in our town these days.
    It would be great if the SWT. could launch a project to increase the tree cover in towns and villages throughout Sussex. In my opinion Councils these days are not keen on trees because it cost money to manage them.

  • Phillip Ellis:

    27 Feb 2020 17:28:00

    I agree with a more natural approach to tree planting and natural regeneration but very unsure about full scale rewilding. Farmland just needs to be kept in production for food so that the UK has some food security.

  • Peter Varlow:

    27 Feb 2020 18:34:00

    Good to read this, at a time when we might otherwise all run off and plant, plant, plant indiscrimately. On an allied subject, we need a huge campaign for better hedgerow management: the every year flails are smashing hedges ever shorter and ever narrower, and long before the dormant season, rendering many of the them useless to wildlife in the spring. Very noticeable just now to be cycling past silent closely-flailed hedges compared to the birdsong coming from good wide hedges.

  • Ron Marsh:

    27 Feb 2020 19:37:00

    ReWilding land doesn’t make it unproductive, it makes, it productive in a different and it appears, (see ‘Wilding’ by Isabella Tree), more wholesome way.

  • Martin Turner:

    28 Feb 2020 09:40:00

    “Done badly, however, tree planting and tree regeneration can cause major ecological damage. We must make sure that a frantic rush to plant trees does not repeat the errors of the past.”
    Dr Whitbread’s article is a bit typical of its type and it does not provide much helpful advice. I live in the High Weald which was once very largely thick forest. I have a ten acre field should I reforest it or not?

  • 28 Feb 2020 11:17:00

    @Martin Turner: Thank you for your comment, Tony has written a follow-up blog which includes a 10-stage process to decide whether to plant trees or not: https://sussexwildlifetrust.org.uk/news/tree-to-plant-or-not-to-plant-that-is-the-question or get in touch for further advice

  • Julie Payne:

    28 Feb 2020 11:19:00

    Yes, care needs to be taken…but considering all the hedgerows and trees that are taken out in more urban areas, the loss of rainforests and now the loss of all of Oz’s trees…..it really isn’t surIrising that there is more ‘free CO2 and H20’. The world is a closed system, if chemicals aren’t stored somewhere, i.e. in trees, then they will be released into the environment.

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