TreeGeneration

08 March 2019 | Posted in Fran Southgate
TreeGeneration
planting hedgerow © Fran Southgate

By Fran Southgate

Living Landscapes Advisor

We are a generation of tree lovers, most of whom appreciate the majesty of our ancient oaks, the beauty of our ancient woodlands, and the pleasure of planting a tree. Although planting trees in the right place is as important as how  many we plant, we know that we need a lot more tree planting overall, to provide shade and carbon storage for climate change mitigation, to shield our landscapes from noise and air pollution, to provide habitat for pollinators and wildlife, and much more. 

Each year, our Sussex Flow Initiative project works with local communities to plant thousands of trees across Sussex. In this season alone we planted around 12,000 trees as hedgerows, shaws and new woodlands, which is a fantastic achievement in itself. We do this to provide multiple benefits to society and to wildlife, but particularly to improve soils and slow flood flows, and to help mitigate flooding problems brought on by changes in weather patterns and how we manage our landscapes. 

We do sometimes feel conflicted about our tree planting however. To guarantee to our funders that a specific number of trees survive each planting, we have to put a plastic tube around each tree – usually a nursery grown tree sapling. Often nursery grown trees are transported from another County (or sometimes even another Country). Tree whips are often grown from unknown seed or root stock – usually non-organically, and probably resulting in the loss of beneficial mycorrhizal fungi and soil fauna in the roots which would otherwise comprise an important part of the tree’s survival when planted. It also has implications around what we import on the soil which comes with each tree. Most often plastic tags and softwood stakes are used to hold up the tree tube.

Many of us are wondering what the real environmental cost of 12,000 plastic tubes and softwood stakes is, balanced against the potential gains? Although each plastic tube provides valuable protection for a small tree from deer and rabbit browsing, how much of the overall benefit is removed from planting that tree, by placing plastic around it? Stock and deer fencing has a high carbon footprint too. 

Many of you will have heard of the Knepp Wilding project. Knepp has taken a more hands off approach to habitat restoration, and has unsurprisingly shown that the natural regeneration of scrub and woodland can have huge benefits for wildlife and society. In the Southern ‘Wildland’ block of Knepp Estate, a natural wooded landscape has been allowed to evolve, unplanted, slowly in its own time, in the way that is described by the pre-eminent ecologist Frans Vera. The emergent scrub woodland mosaic at Knepp is now home to nationally important populations of a number of different species including turtle doves, nightingales and purple emperor butterflies. 

In the Vera landscape, bramble and thorn bushes provide nursery habitats for tree saplings such as oaks, which might otherwise be destroyed by grazing animals such as deer. We can see this natural woodland restoration process in action all across the Knepp estate. Jays and small mammals hide nuts and seeds. Trees produce tannins and spiky leaves which protect them against browsing by animals. Birds and other animals disperse berries and seeds in their droppings and fur – and through these natural actions and more, young trees start to regenerate.

More importantly, trees grow in the natural environmental conditions that they ‘choose’ to survive - perhaps a damp spot for a willow, or an established mycorrhizal fungi network which can support the new saplings growth. New research is also showing that because of mycorrhizal networks etc., existing scrub is a much better nursery for trees than a cleared, open landscape. At Knepp, the rootling of pigs disturbs plant matter and old seedbanks, which also appears to play a role in the regeneration of trees. It helped at Knepp, that livestock were kept away from fields which were left fallow for a few years, before a range of grazing animals were re-introduced to act as managers of the emerging habitats. 

At the moment, the main things that stop us from being able to count natural regeneration as woodland planting, is that people see it as ‘messy’, and that the systems which fund woodland planting work are not set up to accommodate natural regeneration. Grant systems are generally outcome focused (how many trees are planted in one year, and remain on the site after 10 years), rather than process focused (how can we produce the most healthy, biodiverse natural woodland with minimal human intervention and impact). Current grant schemes are also generally aimed at forestry rather than creating woodlands for wildlife and natural capital. 

Nature regen

Nature-led woodland regeneration can be problematic, because we can’t predict the outcomes. In nature-led woodland restoration, we might have 50 trees, or 5,000 trees regenerating over 10, 20 or 50 years. Unfortunately because we don’t know, funders are often averse to support an unknown outcome, even though natural regeneration is better for wildlife and for the trees. Generally it is also not acceptable to funders to say that we’d like to work on a 200 year natural woodland regeneration timescale. It is difficult, if not impossible to get funding to leave a field in fallow, allowing natural woodland of unknown species to regenerate from natural seed over a long timescale. We can easily get funding for putting a specified number of trees, of a known species mix from a nursery, in plastic tubes and promising they will still be there in ten years’ time. 

Nature often knows best, and natural woodland generation will almost always produce the best variety of habitat, and therefore the best results for wildlife - although for tree forestry (timber farming), we still probably need to plant trees in tubes for a known outcome. If we are prepared to accept messy margins, thorny understorey and fuzzy edges as a part of our woodlands, rather than something that should be removed, then our regenerating woodland habitat is also likely to be much healthier and more diverse. 

There is hopefully a middle ground, some point at which we will be able to count self-willed, natural process led woodland regeneration as woodland restoration. I hope that those of us involved in woodland restoration can start to allow nature to lead its own recovery in wooded landscapes and other habitat mosaics soon, and I know a number of landowners who are doing this of their own free will. On balance, it is fairly certain that even a tree with a plastic tube will have greater positive benefits for wildlife and society over its life span, than negative impacts. 

We work very closely with the Woodland Trust, who provide grants and advice for vast amounts of tree planting across the Country, and we are sincerely grateful for all their support. The Woodland Trust who fund our work take great care to sow from native seed stock and to know seed provenance, and are supporting us to trial new ways of restoring woodland more naturally. In the long term, hopefully it will see us all thinking more creatively around working with those who would like to restore tree’d landscapes, using nature’s own methods.

Tree1

Tree planting © C Burrell

Links

Sussex Flow Initiative

Woodland Trust tree planting grants

Guardian – ‘We need to bring back the wildwoods of Britain to fight climate change’. Isabella Tree. Knepp Estate. 

Comments

  • 08 Mar 2019 20:21:00

    A very good article – thank you! This issue has been making my blood boil for over twenty years. It doesn’t take a Knepp Estate to work it out – just witness what happens to virtually any old field that has been left fallow for any length of time… It’s a crying shame that grant funders seem unable to recognise this common sense approach (of natural regeneration). But surely the Sussex Wildlife Trust and all the other Wildlife Trusts can somehow be persuasive? My thoughts are getting a bit carried away with me but – knowing how justification for capital expenditure (sadly) always seems to have to be evidence based – how about you launch an appeal to raise enough money to buy one solitary field – say, 5 acres that is currently ‘pasture’ – divide it in half, and then plant one half using the labour- intensive sticks-with-tubes technique and simply leave the other half fallow by way of a control. As the above article would suggest, I’d put money on the fallow ‘control’ area having the better outcome for wildlife. Sorry, I forgot to say ‘and monitor the progress of both (halves)’ If that was one of your appeals, I’d certainly donate! It’s this kind of evidence you could present to the grant funders. I would love to see something like this happen, as I get so frustrated by the money that’s spent on less-than-best-practice labour which could otherwise be spent on the acquisition of land. Thanks.

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