It is not trees that help alleviate flooding – it is how we use the trees.

The recent flooding in Northern England, Scotland and Wales was heartbreaking to watch. I am sure that the last thing those affected need right now is to listen to the rhetoric of pointscoring commentators as to who’s to blame. Sadly trying to hold one’s tongue is difficult as increasingly spurious information is widely touted across social media.

The role of trees and forests in flood mitigation is highly complex. Simply planting lots of trees, (on the uplands, riparian zones and urban areas), does not help at all, without traditional land management and innovative engineering also.

I am in the South of France at the moment helping following a catastrophic flood, it is impossible not to draw comparisons between the two events, particularly when UK work (FC Forest and Water guidelines etc.,) is being used as exemplary examples to follow. This area has seen a massive increase in tree cover since the 1960’s. With almost 70% closed canopy forest outside of towns, where once scrubby maquis on the slopes and intensive horticultural production took place elsewhere, (principally flower growing for the perfume market). This ‘forest’, rich in wild boars and much other wildlife despite the many fences, did not help prevent the catastrophic flooding because of the soil.

Post farm abandonment the natural regeneration and planting did not take account of sub surface consolidation. Such consolidation can be found in ALL human influenced landscapes. Unless tree roots can penetrate this then a severe flooding event would actually be made worse. To try and attempt to encourage every tree root to do so is frankly impossible. What isn’t impossible are plantations with 3 degree drainage, new stone walling following contours, vertidrains and best of all: The dry stone hedgerow, planted with fruiting natives.

Here in Cote d’Azur the dry stone retaining terrace walls had been left unmanaged or replaced with concrete structures (or often cement pointed themselves), which failed dramatically when the rains fell. Whilst these were highly effective slow drainage structures previously, which helped dramatically.

It is a long process to start to repair the landscape features which aided, even longer to build new to compensate for the huge increase in population and resulting infrastructure. But this process can only be made more difficult by politics. To work it has to be community driven, as it was in the past so successfully. And with proper joined up thinking – not the PR tainted point scoring we see now which muddies the water as much as the flooding itself, it is possible to gain through this process with more, much needed, sustainable forestry and opportunities for renewable energy, whilst taking into account insurance and liability which so many commentators; political, academic or NGO rarely take any notice of.

But sadly, we do have to accept that we cannot and never should relax in the believe that we can completely hold back the waters and that any commentator preaching seemingly easy solutions such as ‘Rewilding’ are just a modern Canute with an ego to match.

I went to a meeting recently with only foresters, planners, engineers and the public. Solutions were proferred, budgets tabled and everyone left to get on with it. I can’t see this happening in the UK anymore, only selected ‘stakeholders’ whose only purpose is to continue to be funded as such – but hope I am wrong?

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14 Comments

Filed under Trees and Woodlands

14 responses to “It is not trees that help alleviate flooding – it is how we use the trees.

  1. Ash

    I like your comments above although I do think that “rewilding” should play a role.

    • I agree in part, but the sale of ‘rewilding’ has been poor and pushed hard. Certainly to practitioners it appears little more than another nail in the coffin of an industry to be replaced by a somewhat misanthropic stance which could well have serious consequences to a balanced landscape.

  2. NorthernForester

    That needed to be said! Must borrow your comparing likes of George Monbiot to Canute. To me there are 2 types of meeting. One as you had and then another with professional spokesmen and women for various orgs – these are never productive.

  3. JDH F.

    you mention “dry stone hedgerows” can you explain what you mean by this and how it is an applicable solution in the UK

    Thanks

  4. Jack Pearce

    Can you explain sub surface consolidation more or where I can get more info

    • In virtually all soils which have been subjected for considerable time by human management, particularly drainage, the soil compacts – with the top, more fertile, soils against the lower often rockier clayier soil. This creates a more distinct boundary, which is much more of a shear zone. It is often where in heavy rainfall a subsurface flow occurs undermining the decent soil layers above and creating greater risk of landslip and erosion.

  5. Nice to hear an alternative view from ‘the field’ Pip, but surely the rewilding movement deserves some support in the UK, especially in view of WWF’s report of a 50% decline in native wildlife within my lifetime (which is not very long I hasten to add!). Whilst planting in the uplands may not solve flooding by itself, we all know that trees retain and drain a huge amount of water as opposed to grass or monoculture crops. From my experience recording ancient trees, the evidence is clear that our once vast wood pastures are a mere shadow of their former glorious selves, and any move towards replanting should be welcomed. Rather than isolate Monbiot, I think we should support him and offer advice from different quarters – much as you are doing with your community in France. I found him affable, approachable and open to discussion when I met him. And he’s on a roll – It seems even government ministers are starting to listen to his ideas. I bet he’d be only to pleased to hear yours. Best wishes

    • Dear Julian, Thank you for comment. As George Monbiot and others have made (a very succesfull) living out of bashing farmers and other practioners it is little wonder that many of us have little time for his views – it is sad that some have become so belligerent as to justify some of his more antagonistic comments. Putting that aside and being able to look back into my country the problems are amplified and the worse of all is the massive polarisation between those who should be working together. However the money is the largest factor and the immense flow of cash into nature conservation in the UK has to be questioned as you state ‘a 50% decline in native species’?!?

      It is we foresters, farmers and other land management practitioners who have been isolated. A wee bit of return fire seems perfectly fair.

      Best wishes and further thanks.

      • Thanks for your reply Pip. I understand how Monbiot may have alienated parts of the farming community, especially sheep farmers. But in defence he says he has no quarrel with farmers but with the rules that they have to adhere to, ie; the CAP, which does little to help the wider environment, and in the case of wood pasture as opposed to woodland actively promotes its decline as I’m sure you’re aware. Rewilding at Knepp in Sussex has produced some surprising, often unexpected positive results, they’re learning stuff we have long forgotten.
        In short, debate is good, which is why I think it would be great if people with real experience like yourself get in touch and share the knowledge: http://www.rewildingbritain.org.uk
        I may be naive, but I really don’t think he’s in it for the money – the two events I attended on the subject (both featured Monbiot), paid no fees to the speakers.
        Best wishes

  6. Peter

    All good stuff. I would add that the risk of flooding may also be reduced if local highways departments cleared roadside gullies more often and local planners understood the importance and facilitated SUDs including swales.

    • Heartedly agree Peter – bring back lengthsmen! And there was some fantastic SUDS innovations, which never really got going, I’m guessing due to pressure to develop and confusion over what ‘Sustainable Development’ actually means following NPPF initial furore?

  7. Pingback: Re-Wilding vs Terroir | europeantrees

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