Increasing Trees on Harford Moor - with Tom Murphy
“In terms of what a common is, it’s complex - many different stakeholders thinking about the future and how human beings are going to live on their planet sustainably. Commons are important testbeds for how you achieve that: a common is shared, and there’s a sense of shared responsibility. ”
Healthy Trees for Tomorrow
It’s a cool September as we walk in an afternoon of off-and-on rain. Tom has brought us out onto Harford common to an area that is due to be planted up with trees. Not just a random addition of trees, but a strategic planting that will, he hopes, bring learning with it.
Tom is a lecturer in environmental sciences, working at the University of Plymouth. He has a love of trees and a curiosity about them - particularly oaks - and the way they interact with and affect the environmental around them. He has been contributing to the ‘Healthy Trees for Tomorrow’ programme, one of the Our Upland Commons projects bringing together commoners and ecological specialists to explore ecosystem health and resilience. Tom has also been working with the Dartmoor Headwaters Natural Flood Management project to determine how best to increase the extent and health of trees on this common: ‘We’re thinking about the next generation of trees.’
On this part of the moor, the land is steep, and while it has a few rowans and hawthorns, willows along the course of the Erme river, and some old, solid oaks, the majority of the higher land is covered with bracken and grass, including vigorous Molinia grass. Up valley, below the wide backs of the higher moors, a patch of darker green is the canopy of Piles Copse, one of Dartmoor’s three remaining clusters of Atlantic Oak woodland. It’s a specialist site, a very, very old ‘rainforest’ woodland where oaks have grown for centuries and are clad with lichens and mosses - all fed by Dartmoor’s historically moist and cool climate.
Looking towards Piles Copse, ancient Atlantic Oak woodland growing around the young River Erme
Thinking about connectivity
Before Rob and I meet Tom, we spend a while chatting with local commoner David Sadler, who just happens to pull his vehicle in where we’ve parked. Our wide-ranging chat touches on this tree planting strategy, which has been developed with the commoners to ensure the plans work with grazing patterns and do not block access to the river. David says it’s tough, how so much is asked of the moor, but he is committed to finding positive ways forward that have multiple benefits. And he is enthusiastic about the idea of work that could help to build connectivity between Piles Copse and woodlands downstream.
This connectivity is vital in nature, just as it is integral to any flood management work. Tom shares his perspective: ‘It’s about dynamics,’ he says. ‘Trees support a wider community, and the leaf litter, twigs and fallen branches create food for worms and beetles. Some of these are rare, like the Blue ground beetle, which is really important but there’s only a handful of sites where you’ll see it.’
“How can a tree modify its environment , affect the soil, slow the flow of water? And what does that mean in terms of providing a habitat for so many other species? Those things can go hand in hand. ”
Tom talks about trees as part of the bigger picture: ‘How can a tree modify its environment , affect the soil, slow the flow of water? And what does that mean in terms of providing a habitat for so many other species? Those things can go hand in hand. What a researcher is doing is trying to identify where they can go hand in hand, and testing that, and asking, well, how quickly?’ Trees and woodlands also help with temperature modification, and provide shelter for animals from wind, rain and sun. ‘I think when we can show that native woodland can have many benefits, we can avoid putting people into ‘conservationist’ camp, ‘farmer’ camp, ‘recreational user’ camp – we don’t need to be stuck in different camps. We can start to say, okay, there's overlaps, and some things provide benefits that we all recognise.’
“When we can show that native woodland can have many benefits, we can avoid putting people into ‘conservationist’, ‘farmer’ or ‘recreational user’ camp – we don’t need to be stuck in different camps. There’s overlaps, and some things provide benefits that we all recognise.”
Trying different methods
The tree planting trial close to the river Erme on Harford Moor will involve small plots planted in different ways. Some will be planted with a very high density using the Miyawaki method, named after a Japanese forester, with around 20,000 trees per hectare; some will be planted lightly with around 1100 stems per hectare, and fenced off to exclude grazing animals; and a third set of plots will involve simply fencing off areas, without any planting, to see what happens in terms of natural growth of trees. Finally, there’ll be a control plot, with no interventions.
The research will help to show the impacts of the different techniques. The overall aim is not to establish blanket woodland here, but to introduce trees in a way that works with grazing and access on the commons. A long-term vision is to increase temperate rainforests in the valleys, with trees acting as ‘stepping stones’ in wildlife corridors and joining up existing patches of woodlands.
The hope is that the work will also provide a seed source, with natural regeneration so that over time the plots will be 'lost' in the landscape. Additional work with Plymouth and South Devon Community Forest will add scattered trees to offer shade and shelter for livestock, something that is likely to become more important with predicted increases in heatwaves and intense rainfall events.
Though this land is very wet, trees may become well established here
The plots will be monitored on regular visits and with sensors. ‘We're going to monitor soil compaction, soil infiltration, soil organic matters, the amount of carbon that's in the soils, as well as soil diversity - the invertebrate communities – and the temperature modifications.’ Tom tells us that monitoring will be going on for at least 10 years and may be complemented by citizen science and university research projects. The collected data will show what benefits occur - and how quickly – on the different plots.
While we talk, the rushing of the river Erm is constant. Tom comments more than once how he likes its sound and takes a lot of pleasure from watching the water behind the veil of riverside willows. The willows though, don’t quite cut it when a heavy downpour arrives; we clamber up the slope to shelter under a huge old oak where we can stay (almost) dry. When the sun comes out again, the leaves glow against the black-and-white of the river below us. It feels as if we’re in another world, and in some ways, we are: it is populated by beetles, spiders, invertebrates, mosses and fungi, and is a vital source of shelter and food for birds. ‘Something like this old oak tree will support over 2000 species,’ says Tom.
Choosing trees
Among the species Tom lists that will be added here are willow, birch, hazel, alder, blackthorn, rowan and holly – tree types that are going to fit into the landscape and provide the best nature conservation impact. Sheep wool may be used around some of the stems to help keep moisture in the soil.
Ongoing work on this common, as is the case on many others across the national park, combines many different strands of research and action plans, with tree planting just one of them. As Tom keeps emphasising, ecosystems are all connected - individual trees, the flow of water, grasses, animals, peat, woodlands – as well as human communities.
‘The commoners are very much part of the plan,’ says Tom. ‘A lot of work has been done to understand their perspective in terms of the trees that are here already, and in specifying the type of trees, and the location of plots. On this common, both active grazers and non-active grazers, as well as landowners, have had been part of designing and okaying this experimental setup, which is all about learning.’
In between heavy rain showers, the light is dramatic
“On this common, both active grazers and non-active grazers, as well as landowners, have had been part of designing and okaying this experimental setup, which is all about learning.”
And there’s learning across Dartmoor. A huge amount of work is being done by groups of people working together to shape joined-up practices in specific areas and across the National Park. Tree time may be slow time, and this study may take longer to show results than the rewetting of peat (more on that here), but all the pieces of the puzzle are important.
‘In terms of what a common is, it’s complex, and it’s many different stakeholders thinking about the future and how human beings are going to live on their planet sustainably. Commons are important testbeds for how you achieve that: a common is shared, and there’s a sense of shared responsibility. There are many overlapping perspectives and different uses, and it can be tricky to find solutions - you are drawing people together from different backgrounds, and saying, Okay, what are we going to do in terms of how we move forward?’
This kind of question spools a conversation that continues as we walk back across the open moor, talking about trees, moorland, and science. And before we go our separate ways, I ask Tom about what he’d like to see here in the future. He leaves us with a good dose of positive energy.
‘I would love to see a natural environment going from strength to strength. So many species are under pressure, and there’s quite a depressing outlook for nature. Can we turn that on its head, so we're not just clinging on, asking what we can preserve, but we're supporting restoration of biodiversity and recognising its value to us all?’
‘I've seen the impact of habitat restoration, and it's incredible what can change. It'd be fantastic, in fifty to a hundred years’ time, to see a vibrant corridor of wood pasture, areas of beautiful Atlantic oak woodland, of hedgerows, of blanket bogs, valley mire, grassland, heavy shrub, and heather - a landscape that looks and feels really vibrant. I think that’s not just good for nature, for the biodiversity impact measured in a metric-focused approach. I think it's good for the human soul, to come out into these landscapes and see them thriving. It’s magical – just like it was standing under that beautiful oak tree.’
“It’d be fantastic, in fifty to a hundred years’ time, to see a vibrant corridor of wood pasture, areas of beautiful Atlantic oak woodland, of hedgerows, of blanket bogs, valley mire, grassland, heavy shrub, and heather - a landscape that looks and feels really vibrant. I think that’s not just good for nature, I think it’s good for the human soul, to come out into these landscapes and see them thriving”
Tree growth along the River Erme’s banks is likely to expand through the work of this project, and other actions to enable regeneration of trees.
More information …
For more information about Natural Flood Management and spring mire restoration on Harford Moor, visit this page.
To find out more about the tree survey that preceded this work, read the interview with Jez Relph here.
And another perspective from Harford Common with Anne Wilcocks here.