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Bolehill very small forest

Sean Barker

Bolehill Very Small Forest

 

1)  Where We Start From

 

1.1)  Our Environment

 

Bolehill is a small village in the middle of the England, just outside the southern edge of the Peak District National Park, and half a mile across the fields from Wirksworth. Our house looks across a shallow valley, with sublime views of the hills and cliffs opposite, especially at sunrise and sunset. With the house comes a small field, too big for a garden, but too small and too sloping for most crops, so, like much of Derbyshire, it is pasture, grazed by sheep couple of times a year to keep the grass from going rank.

 
   

 

Figure 1: View Across the Field to the Very Small Forest and Beyond

 

A field of grass is mostly boring. Bird life is limited – just the occasional pheasant, jackdaw or pigeon. Overhead there are buzzards and peregrine falcons, but apart from the occasional kestrel dropping onto something in the marsh, they are indifferent to the field. By comparison, our garden bird feeders see several species of tit and finch, plus nuthatches and greater spotted woodpeckers. As for mammals, there must be the usual mice, shrews and moles, but they are generally invisible, although at night we see the flitting shadows of bats.

We could continue as we are, with the sheep eating everything – except for thistles and

 

docks. We could just leave the field to run wild, but the grass would smother any wild flowers, and judging by other areas left alone, we’d end up with a field of thistles and nettles but probably not much else for the next twenty years. But we would rather work to promote a diverse ecology, planting trees, bushes and flowers in a way that ensures that they continue to flourish, and which can support a wider range of birds and insects. For a whole field, that is a lot of work – more than we can manage in one go – so we do a bit at a time.

 

1.2)  What is the Field Like?

 

The field is irregular, roughly rectangular (figure 2), and about the size of a football pitch, but you wouldn’t want to play football on it, as it is all slopes, some quite steep. Our house, which is at the top, is some sixty feet higher than the pond at the bottom. It’s a big pond, fringed with bull rushes and we have started a small reed bed. It feeds a small stream that is one of the head waters of the Ecclesborne River.

 
   

 

 

Figure 2: Plan of the field

 

Water is an important, but often hidden feature. In winter, extra little streams appear, and

 

water can be heard flowing underground at various points. At one such place, a large stone can be lifted to reveal a shallow sough (or drain), and there is another stone-lined sough behind the trough just above the pond. On the shoulder of one of the slopes is the base of a shallow well, and below that, half a tennis court’s worth of marsh.

The field is about 600ft up, which means is colder and gets more snow that lowlands to the south. But it is only half the height of the limestone hills on the opposite side of the valley or Barrel Edge and the gritstone moors on the hill above. The limestone dips underneath the gritstone, and there were significant seams of lead between 170 and 300 feet beneath Bolehill – here the name bole refers to an open lead smelting furnace[1]. Bolehill is built on a layer of Edale Shales that lies between the gritstone and the limestone, which means that the soils are mostly clay. Soil is one of the defining factors in ecology, so the local geology means we are in a different ecological landscape from the surrounding hills.

The Miyawaki method, on which Tiny Forests are based, stresses the use of species native to the area. Although there a plenty of trees now, pictures of Bolehill taken in the first half of the twentieth century show a landscape almost denuded of trees, and the best guess on local species comes from the trees and hedges on field boundaries. On the lower boundary of our field are typical hedgerow species such as hawthorn, elder and wild rose. Around the pond, there are ash, lime and holly, although ash dieback has affected many trees in the area.

The plot chosen for the Bolehill Very Small Forest (BVSF) is on one of the banks above the pond, its top edge defined by an orchard we are slowly extending. Just in front of it is a dip, which is possibly where water from the marsh drains down. On the opposite bank is the site of our Very Small Wood (VSW). A fence line cuts off the forest, the wood and the pond from the rest of the field (and the greedy sheep), and any grass behind that fence line will be developed to be wild flower friendly.

 

1.3  The Aims BVSF Project

 

When I started investigating Tiny Forests, it quickly became clear that a proper Tiny Forest would be too expensive, and being on one corner of our field, would not easily translate to a community forest. However, a diverse, quick growing stand of trees, with little need for maintenance would be exactly what we wanted. So I decided to go head, while making the compromises needed to make it affordable.

Independently, the local Labour Party – Wirksworth and Masson – started a group looking at planting a Tiny Forest, and, separately, a new group Wilder Wirksworth was formed to promote a more diverse ecology around the town. There is often a gap between an idea and its implementation. To help the community groups with any future plantings, I offered to record my experience, and note any gaps in the descriptions of what to do. This is a record of that experience.

An important source is “Tiny Forests Zaanstad” [2] which follows the progress of a Tiny Forest in Holland. The report describes doing citizen science, where non-specialists contribute to a scientific project. There is a citizen science aspect to the BVSF: I plan to follow its progress over several years, to see if the compromises made have had a significant impact on how quickly the forest grows.

We also had the opportunity to start a second, smaller planting in a separate part of the field, which I call our Very Small Wood. This has been planted less densely, and with less soil preparation, in the hope we can show more clearly the advantages of the Tiny Forest approach.

Why? I’ve spent most of the last forty years in research and development, so it’s just that I am interested. And we get another element in the patchwork of environments in our field.

 

1.4  What We Bring

 

Neither I nor my wife are country folk. I am a mathematician by training, recently retired as software/systems engineer. As a mathematician I know how to calculate exactly – the area of a circle is pi times the square of the radius. As an engineer, I find good enough approximations – the area of a circle is three times the radius squared (to within 5%). Engineering compromise accounts for much of the difference between the BVSF and a Tiny Forest. My wife is still working, so her main role has been to approve, encourage and occasionally provide physical labour.

Practical experience is limited to growing vegetables and looking after the field for three years. I have learned that sheep will strip the leaves off a tree and will find any gap in a fence which they can crawl through or under. We chose the plot to be straightforward to fence off.

We have also planted a hedge and discovered how much work is involved in stopping grass smothering saplings. To control the grass on a second tranche of planting, I stripped turf off to make nursery beds, where saplings could grow being before being surrounded by grass. From this I learned how much effort it takes to strip turf – I can do about five square metres a day, twenty in a week – and decided that for anything larger scale, mechanical help would be needed.

 

 

2.  Tiny Forests

 

2.1  What is a Tiny Forest?

 

A Tiny Forest looks like a dense planting of trees over a small area – a minimum of 200 sq.

  1. – about the area of a tennis court. “Dense planting” means at least three trees a square metre, so over 200 sq. m. one would need 600 trees. Dense planting means that the trees develop quickly. This also means that after three years they shade the soil, stopping weeds growing, so that after that only a minimum of maintenance is needed.

But it’s not just any old planting of trees. There should at least twenty-five native species which reflect the combinations in the local environment. There should be trees for each of the four layers of a forest: canopy, understorey, shrub and herbaceous layers. And to help them grow, the soil needs breaking up, and may need supplements adding. And to stop weeds, it needs to be heavily mulched.

And a Tiny Forest has a social dimension, which includes an outdoor classroom, adoption by a local school, and a calendar of events.”Tiny Forest” is a registered trade mark, so that only a planting that meets a set of physical and social criteria should be called a Tiny Forest.

 

2.2  The Bolehill Very Small Forest

 

By 2020, I had planted small numbers of trees, and was aware of memes such as “Rewilding”, and “Plant Trees for Carbon Capture” and was slowly thinking about what to do with the field. In August, I came across “Tiny Forests”, and was immediately interested by “faster growth” and “low maintenance” – being retired in a year of plague focuses the mind on the things you can do before you die. A little Internet research brought up plenty of newspaper articles saying how Tiny Forests are a good thing and the inspirational talks of Shubhendu Sharma (he is the CEO of Afforestt and the founder of Tiny Forests). But as an R&D engineer I was looking for technical detail, and eventually found in in a Dutch report “Tiny Forest Zaanstad” [2], which lead on to the “Tiny Forest Planting Method” [3]. I also found details of a consultancy that would help plant a Tiny Forest for £25,000, which is way more than I could afford.

At this point, my Very Small Forest project was born. Its starting constraints were:

  • Plant by December 2020. rather than wait to 2021 – trees are best planted between November and February, but in Bolehill, there is a greater risk of severe weather after Christmas (I write in January 2021 with snow covering the ground and more forecast);

 

  • Don’t block our views across the valley or down to the pond;
  • A nominal budget of £2,500 (the one-off fee from a book on archiving);
  • I would need to do much of the work.

The Tiny Forest Planting Method (below simply “the Planting Method”) requires community group involvement. Founding a community group, including building consensus and commitment, and then raising funds would take far longer that the schedule allowed. Because the planting would be on private land, enduring access to the community could not be guaranteed. And during the Covid- 19 pandemic, organising group activities, particularly with schools, was going to be tricky and could have been curtailed at any point by government lock downs. However, two community groups – the local Labour Party and Wilder Wirksworth – were separately interested the possibilities of creating one or more Tiny Forests in the area. Consequently, I offered the project as a learning exercise, particularly on the practicalities of the project. This write-up is a first evaluation of that experience.

 

2.3  Project Aims and Compromises

 

My Bolehill Very Small Forest project aimed to enrich the environment in our field by providing cover and a range of food sources for insects and wild birds. It was inspired by the Tiny Forest Planting Method, but I had neither the time nor the resources to follow through the detail of the method.

In the Planting method, planting should be of native species since they provide homes for the widest range of plants, insects and so on. In England, those are species present since the ice age rather than imported sometime since the 16th century. However, the trees and bushes had to be sourced from commercial growers, and in the time available, it was not practical to check that their stock came from UK lineages.

Twenty three different species were used, mainly based on what grows locally. Much local woodlands appear relatively recent, and individual areas within each woodland typically showed a narrow range of 5 to 10 species; local hedgerows are more diverse. Limitations on the range of trees available led to me selecting a few of species that I did not identify locally (aspen, hornbeam, wild cherry, bird cherry, buckthorn and dogwood), though that may be a limitation on my tree spotting.

Three local species that have been excluded are sycamore, as it not native (introduced to the UK c 1500), ash because ash die back is present in the area, and yew because it is poisonous to sheep. The planting did not include any willow, as we have already planted a couple of dozen round the pond and by the marsh. I found later that the list of trees planted corresponds fairly closely with table 1 of Trees and Woodlands of the British Isles [9], an important work on the history and ecology of British woodlands.

The Tiny Forest Planting Method has detailed instructions on soil preparation. These are based around planting in a Dutch urban environment, and it was not clear the extent that these applied in this case. There is a hint in the Method that soils in the countryside need less preparation, but without detail it was cost and practicality that actually set the limits (see below).

Finally, the Method calls for a thick layer of straw as mulch. In the time available, no suitable source of straw could be found, however I did find a local supplier of wood chips.

Moreover, a researcher based at Reading University recommends using wood chip rather than straw when mulching trees, advice I followed.

 

3  Getting into The Detail

 

3.1  The Project

 

Before thinking about planting, you need a project to do it. The Afforestt site [4] provides a

 

good starting point – create a community group, reach a common understanding of its goals, find a suitable plot of land and negotiate its use, fund raise and set up schools liaison – I would guess a minimum of several months if you are lucky, possibly a year, with success depending on finding the right people who could share the work, work together, stay enthusiastic, and not get sidelined by other agendas. Say, 25% chance to getting the project off the ground.

And to follow the details of the Tiny Forest Planting method, one would probably still need to find the right experts, or bring in an organization like Afforestt that specialises in Tiny Forests (and raise funds to pay them). Afforestt helpfully lists eight roles that a project like this needs.

I started out with the land to plant on, the money to pay for the Very Small Forest, no initial community involvement, and the skills to research and run the project – project set up time was therefore only a few days. Most of my project was about following the Tiny Forest Planting Method, which identifies six steps:

  1. Forest Cover Type Field Survey
  2. Soil Survey
  3. Soil Preparation
  4. Draw up a Planing Plan
  5. Planting Day
  6. Maintenance

In later sections I compare the six steps to what was actually done. To give a rough time line to my project:

  • August – initial reading and deciding where we might plant;
  • September – checking layout, examining soil, finding potential suppliers, estimating costs and deciding it could be affordable, all while walking the district to see what grows locally;
  • October – adjusting the plot, planning for planting, ordering trees and soil conditioner, engaging a contractor;
  • November – contractor strips turf – then, stop: Avian flu alert – most of November was actually spent rehousing chickens and ducks, but with community help, this did not wreck the schedule;
  • December – finish preparing plot, planting, tidying up;
  • January start mulching and further

The first lesson is that the six steps need not follow sequentially. Step 4 must follow after Step 1, and 2; Step 3 comes after Step 2, but steps 3 and 4 can run parallel, to converge at Step 5. The community engagement element would also run in parallel.

 

3.2  Deciding where to Plant

 

The Planting Method is about planting, not about getting the project going, so this section is about our “Before the planting” stage. The most important decision was deciding where we would plant – checking sight lines so we can still enjoy the views across the valley when the trees grow, and checking with our neighbours if they had any concerns (“could you avoid shading our orchard”

– a fair concern given we would be planting oaks). The area marked out covered about 220 sq. m.

Once the area had been initially staked out, it was then a matter of tweaking it. The biggest constraint after sight-lines was making the shape simple, which in turn would simplify the planting plan and explaining the planting process to volunteers.

One further constraint was the fence lines. For a tensioned stock fence, it should ideally should be straight and with no changes of slope. In very dry conditions, the soil in our field shrinks, making the holes bigger than the fence posts. Where there is a dip, the tension in the fence is enough to pull the stakes out of the ground, leaving a gap under the fence which sheep are adept at exploiting. This is not usually a problem for a Tiny Forest. Our easiest course was to join up the existing fences between our orchard and the pond, and simply cut off the end of the field. The

 

grassed area not used for the Very Small Forest could then be converted to wildflower meadow – another ecological niche.

 

3.3  Step 1 – Forest Cover Type Field Survey

 

The survey aims to establish what trees grow locally, and which grow well together, preferably by looking at old forests in the local area. The grandfather of Tiny Forests is Akira Miyawaki, and worked in Japan. Japan has 0.3% of pristine forest, but he realised that the woods surrounding temples were undisturbed, providing examples of what a local forest looks like.

As noted, old photographs of Bolehill show it almost bare of trees. Maps dated 1880 and 1895 show only a few small patches of woodland, and their placings are not entirely consistent with each other. An 18th century book [5] on the area round Wirksworth notes only that there was a plantation of firs below Black Rocks (a prominent local feature). Because they are difficult to work on, it is probable that the steeper slopes have been continuously wooded, but the woods are unlikely to be undisturbed. There is limited access to these woods, but although there few if any large, old trees visibile from the road, it is more likely that the woods would have been coppiced [cf. 9].

Interpreting these woods needs more expertise than I have.

The Edale Shales which lie under Bolehill surface in a narrow band about 1 km wide going down the valley. The gritstone moors above Bolehill are dominated by forestry plantations, and the limestone hills opposite provide quite different soils. The Planting Method suggests a survey of 2km around the proposed site, however most of the observations of trees are based on the area where the Edale Shales surface.

The most frequently seen trees are ash and sycamore, both of which have wind blown seeds, so would be spread from further away. There are substantial sycamores a couple of hundred metres away on the spoil heap for George Mine – believed closed in the 19th century – evidence that larger trees can still be relatively modern. The old photos show some trees along the field boundaries, and the hedges seem more diverse than the woodlands, but they are not forests. So, there is no strong evidence of what might be considered local forests.

Tree identification can be tricky. A field guide [6, 7] will usefully show you the range of trees you might encounter, and may include maps showing if they are found locally. But they usually include only one or two photos, and their identifying features – such as leaves – may not be present at certain times of year, and some, such as flowers or seeds may not be present on all trees. The Woodland Trust [8] app is designed to help identify trees from leaves, bark or branches. If you plan to do the survey yourself, start learning what trees look like as soon as possible, and be aware of confirmation bias – the tendency to look for features that confirm your first guess rather than features that tell you that you are wrong. Eventually, with the help of a local expert, I identified nearly twenty species of trees on the Bolehill side of the valley, but probably missed a few.

 

3.4  Soil Survey

 

The soil survey identifies what is under the surface in order to plan soil preparation and identify what sort of woodland is suitable for the site. This is the activity which needs most specialist expertise. However, the Planting Method prefaces the detail with the remark “If the location is outside of a built-up area, such as along a river or stream, or on a glacial moraine, then the soil is probably an old forest soil, so you fortunately won’t have to do much work to prepare the ground for planting.” This leaves a lot to interpretation – and given that this project takes a cheap and cheerful approach, it was taken as a licence to skip most of the detail.

The Soil Survey involves five separate activities:

  1. Check for Cables and Pipelines – from the searches made before we bought the property, there were no cables or pipes under the plot;

 

  1. Determine the Type of Soil – two one metre deep holes were dug. At the valley end it was solid clay below about 20cm. At the Barrel Edge end, below 20 cm was shale – a highly fractured soft rock easily broken up with a fork – and below 1m was
  2. Determine the Density of the Soil – not done, although, being clay, the measurement of density will vary greatly with water content. In an extended dry period, deep cracks
  3. Determine the Nutrients – not done. We found an number of agricultural labs who could do soil testing, but they didn’t quote prices. The Planting Method notes that clays are nutrient rich.
  4. Determine the Water Table – the site is on a hillside that drains down to a pond. About 40m away, on top of the next rise, is a shallow well with a marsh below it. I don’t know enough about water tables to make any sense this
 
   

 

Figure 3: Soil Test Pit

 

Given the limitations on time and budget, and that the preliminary investigations had not shown up anything that would cause obvious difficulties, I decided that more detailed investigation wouldn’t make a huge difference to what I could do by way of soil preparation.

 

3.5  Soil Preparation

 

In the Planting Method, soil preparation consists of stripping off the top soil, digging out the plot to the depth of a metre, and then filling it in again while mixing in soil conditioners to make the soil more root friendly. The Planting Method asserts that this will develop a dense network of fungi

 

within a year.

The most relevant fungi are mycorrhizal fungi (see appendix 1). A network of these fungi will work with the tree roots to allow them to gather water and nutrients from a larger volume, and may even help transfer nutrients between trees. It seems likely that the soil preparation described in the Planting Method both provides the materials fungi need to grow, and creates channels in the soil that help the networks spread.

There are mycorrhizal supplements to add these fungi, but research has shown mixed results and notes that a commercially bought soil conditioners may not contain the right fungi for the species planted. The nursery area on the opposite bank is in the root zone of several large trees, and some saplings, notably crab apples, did particularly well. It is therefore hoped that the trees from the nursery will bring appropriate fungi with them.

In developing the soil preparation plan, the physical environment of the plot was important. The plot is on a hillside with slopes of between 20% and 33% (one-in-five to one-in-three). There is limited room around the site to hold spoil and to manoeuvre. Since the site has not suffered compaction by heavy machinery, I decided to limit soil preparation to stripping of the turf, breaking up the soil underneath down to the clay or shale, and mixing in soil conditioner into this surface layer.

 

 
   

 

Figure 4: Three Ton Digger and Dumper,

with 1,700 l of Soil Conditioner in foreground right

 

The slope is steep enough that a digger might roll over, and therefore requires a skilled

 

operator, which ruled out simply hiring a digger and doing it myself. Web sites on hiring diggers also noted the cost and difficulty of insuring the work, which ruled out simply hiring a digger and a driver. Instead I looked for a profession contractor. Only one contractor contacted provided a quote:

£500 a day plus machinery hire for two days. The contractor also suggested using a Rotavator at a cost of £300 to break down the clods and mix in the soil conditioner – so about £1,700 overall.

However, because heavy rain caused the clay to clog the Rotavator blades, this was not done and the actual cost was £1,400.

Turf stripping and soil break up was done with a three ton digger and a one ton dumper track

  • the turves were deposited at the top of the field for later use. The complex of tracks left by the dumper truck remained as testimony to the care and skill needed to drive across the field Stripping the turf took a day, then breaking up the soil took a couple of hours and the remaining time was spent stripping a second, smaller plot on the opposite side of the field for the very small wood – that was the day that a vague idea suddenly became part of the plan.

Scheduling the work was relatively complicated. First, it needed a time when the contractor was available. Second, before the work could be done, the contractor needed to see the exact lie of the land in order to safely operate on it – three weeks work for about 20 sheep. Thirdly, I needed to get the soil conditioner delivered. This typically comes in 1,000 litre (one cubic metre) bags and needed to be dropped off before the contractors started. The access to the field is off the drive to our house, which itself is quite steep, so the bags could only be delivered to the start of our drive, blocking it. They then had to be moved into the field before the digger arrived so it could be parked in the field – fortunately a mate with a tractor helped out there.

The Planting Method makes recommendations on soil conditioner according to soil type,

for clay suggesting 5 to 10 kg per square metre of straw and 5 kg per sq.m. of organic compost. The plot covers about 220 sq. m., so needs something like 2.5 tonnes of conditioners, although, since we were only conditioning the lop layer of soil, less could be used. However, no suppliers could be found locally for large quantities of straw. Moreover, compost is sold by the litre, not by weight, and the density varies between 0.5 and 0.8 kg per litre.

The initial order of soil conditioner was 1,000 litres of green organic conditioner and 1,000 of mushroom compost, although only a 700 l bag of the conditioner was delivered (refund obtained). The contactors distributed the soil conditioner, and then said that additional conditioner was needed – possibly, since the contractor specialised in garden landscaping, they had spread it too thickly. The additional conditioner was ordered and duly delivered a week later, whence it pushed down into the field on an improvised rolling road (shades of Last of the Summer Wine as it sped down the slope and rolled over). 900 litres works out as 16 barrow loads, and wheeling over the field was spread out over three days. In the end, 2,600 litres was used, total cost of soil additives c.

£250.

November then delivered rain every other day, so the contractors cancelled the first date for rotavating the plot, and by the end of November, the Rotavator tines clogged with the heavy clay soil and rotavating was cancelled.

An attempt to dig over the plot by hand was also thwarted by the heavy clay at the valley end of the plot, and I resorted to simply breaking up the clods and loosely forking over the top layer. It might have been possible to dig all of it over had I started immediately after the turf was stripped, but that day coincided with an Avian Flu alert, and most of my November was taken up providing new enclosures for our ducks and hens. Fortunately, an appeal to community groups brought in enough volunteers – several sessions over a few days – so that the plot was ready in time for planting.

Lesson learned:

  • Access routes, space round the plot and slopes need to be taken into account when planning soil preparation – and these issues should be considered when choosing a site;
  • As every civil engineering contractor knows, the weather (and other events) can wreck a

 

schedule – leave slack in the schedule and have a reversionary plan;

  • Professional contractors are expensive but not necessarily more expensive than non- professionals;
  • Physical labour may be needed to keep things on schedule – and trees need to be heeled in if the schedule slips, which in turn requires somewhere to heel them in;
  • Check the web sites of soil conditioner suppliers carefully as to what they mean by “approx”, and then check the size of the bag

It seems likely that the limited soil preparation will slow the development of the BVSF, but how much may take a couple of years to show up. From a citizen science point of view, this is one of the questions this cheap and cheerful project hopes to answer.

 

3.6  Draw up a Planting Plan

 

In the Planting Method, the planting plan is mainly concerned with what trees to order, with the actual distribution of trees managed on Planting Day. The planting list for the BVSF was based on the Oak-Beech forest column on the Planting Guide (page 15), partly because disease makes woodlands based on ash and elm not viable, and partly because the trees found locally corresponded best to that column. The presence of the hackberry in the Planting Method list appears odd, as this is a North American tree, although it is possible that the names of species were incorrectly translated from the Dutch. For example, linden is more usually translated as lime, sorbus as rowan, and white birch as downy birch. Trees preferring limestone or chalk soils, such as the wayfarer tree, were also excluded.

The Afforestt site includes instructions for growing your own trees – not an option in this project, as that would take too long. Trees were sourced on-line from The Woodland Trust and Trees Please, and locally from Derwent Treescapes.

The trees were chosen according to the proportions in the Planting Method for each layer.

There was an additional constraint of meeting the batch sizes at which the supplier reduces the cost per tree (e.g. most species were bought in batches of 25). Having three separate suppliers allowed me to near the goal of 25 species (actually 23 different species bought), and also limited the complexity of dealing with multiple suppliers. For a list of trees used, see appendix 2.

The Woodland Trust provides some subsidised tree packs, and will supply free trees for community projects with public access (not this project). I bought a Shelterbelt tree pack, a subsidised pack that provided 200 trees in six species covering the canopy, understorey and shrub layer. It included more pedunculate oaks than were needed, and these will be used in the VSW and other plantings in the field. A Wild Wood pack had been planted the previous year in the nursery beds, which provided about 100 or so trees in the lower layers. This year the Woodland Trust site warned of delays in fulfilling orders, and the order process did not allow me to specify a date. So I ordered in October, the trees turned up promptly, and I had to dig an additional nursery bed to protect them until planting day. Woodland Trust trees come as cell grown, so the root ball is enclosed in its own soil package, which makes for easier planting. Many of the trees supplied for the Shelterbelt were quite small (about 20-30 cm), although the trees in the previous purchase from Woodland Trust were taller (about 50 to 90 cm).

The main supplier was Trees Please, which is oriented to larger scale planting. Trees can be ordered individually, but the price comes down significantly for orders of 25 or more for a single species. They have a broad range of trees, although did not have pedunculate oak (they did have sessile oak) or lime. Trees come as bare-rooted whips, and come in various sizes – following the Planting Method I ordered 80cm, but some species in this size come with quite extensive roots, which increases the effort needed to plant them. They agreed to deliver in the first half of December but in the end they delivered a week late – a week before Christmas – which they attributed to a warm autumn, which meant they had to wait for the trees to go dormant, which in turn put their

 

whole delivery schedule back.

 
   

Figure 5 : What a delivery of 300 Trees looks like

 

Derwent Treescape specialises in hedging, so was the only site that would provide many of the species needed in the herbaceous layer, but it also supplied some larger trees. Their prices reduce for orders of 10 or more of a particular species. Trees were ready to collect in late November, and were heeled in with the Woodland Trust trees. Later, they also supplied the additional trees needed for the very small wood.

From Trees Please, prices were £400 for 300 trees including delivery. Woodland Trust supplied a Shelterbelt pack for £150 for 200 trees including delivery and tree guards. From Derwent Treescapes 45 trees and 30 bushes for the herbaceous layer cost £116 which I collected myself – here the total price was pushed up because they did not have the size ordered in one species, and the next size up was about 60p a tree more expensive. Total £816, including £150 from a previous Woodland Trust purchase.

One error made in heeling in the trees was that the groups of trees were not clearly labelled at that point. The trees came tied together by species, and although there was usually label around one tree in a bundle, this was generally in Latin, and often abbreviated, so it needed translation and checking against the order. Once the trees started being used, the label could get detached, and this led to some additional randomisation of tree distribution.

One other element of this step in the Planting Method is the design of the shape of the planting. The outline had been determined earlier to preserve existing sightlines to the valley opposite. In addition, a Z shaped path had been left through the planting, with a small clearing at the middle. This is partly a place to sit quietly, but, with a screen at the bottom end, will also provide a

 

bird watching hide above the pond with a screened approach once the trees have grown.

 

3.7  Planting Day

 

In the Tiny Forest Planting Method, Planting Day is the day you plant the trees. Delays in preparing the plot and in the delivery of trees, plus very changeable weather made it impossible to be certain about what day to start planting. And it was getting close to Christmas, with the attendant risk of frosts, as well as people having other commitments. Plus Covid-19 put a limit on the number of people who could come and plant at any one time. Plus, although the community groups were supportive, it was not their project, so without a day to plan for, it was impossible to know the numbers who would be available. A recipe for disaster?

Fortunately, I had never expected to be able to do mass planting on a single day. What was devised (in October) was a scheme that would:

  • space people out to observe social distancing
  • allow for one group to stop and new people take over
  • allow for 25 different species of tree, most of which were similar looking, small, bare twigs
  • make a clear distinction between species with similar names (e.g. silver birch and downy birch)
  • help people to avoid accidentality treading on trees already planted

The cunning plan involved a large number of lolly sticks, painted in four distinct colours for the four layers of the forest (canopy, understory, etc) – colours chosen from left over paint in the shed. Each stick had a little flag at the top. To reduce the work of making the flags, they were printed on sticky labels, folded in half round the top of the stick. Not folding them in half would leave a sticky area exposed, and they would all stick together, but – note to self – next time add a fold line down the centre. Each flag had the name of the tree printed on it, together with a distinctive symbol in a colour corresponding to that of the stick. This redundancy was to reduce the chance of confusion between flags. These flags would show the planters what tree to plant where.

The next step of the cunning plan was to divide the plot into six strips, each five metres wide, and then mark out one metre squares using garden canes. A volunteer from Wilder Wirksworth helped with the marking out. A corresponding map of the plot was drawn, and the trees allocated to each strip roughly proportionally to the area of a strip. Note, 650 trees is a lot to allocate in one go, but subdividing it into 5m strips and working one strip at a time was far more manageable. The individual trees were allocated semi-randomly across each strip:

  • Canopy trees were allocated first by throwing dice to see which in 1m square they would be planted, and then in which 20cm subdivision;
  • No 1m square could have more than one canopy tree;
  • Then understorey, shrub and herbaceous layers were allocated in a similar way;
  • Trees which fell in the same 20 cm subdivision as an existing tree were reallocated;
  • No 1m square could contain more than five trees;
  • After allocation, trees were moved so that
    • Every 1m square contained at least two trees;
    • Aspens were moved closer to the lower edge of the planting so their foliage would be more visible in autumn;
    • Alders were moved nearer the possible water course from the marsh;
    • Thorny trees were move away from the edge of path though the

The Planting Method uses a manual distibution of three trees per each square metre. But humans are not that good at dealing with randomness – for example, they feel that if similar trees appear near each other, then that is not random. I made the assumption that in a forest, there is quite a strong random element in tree distribution, with trees often growing tight against each other in one

 

place and with a big gap in another.

For the more mathematically inclined, I distributed the trees using a uniform distribution over a single strip and over the subdivisions in a strip. The numbers were generated by throwing two dice, and ignoring the sixes. Where the number of squares was 16 or fewer – some of the irregular shapes around the path – I used cumulative distribution functions to map the throw to the range needed, but it would have been easier to use percentile dice.

To aid planting the flags, they were held in a block of wood (about 300 mm of 100 by 50) with large holes drilled to hold the base of the flags. With the block in one hand and a map of the strip in another, it took the best part of an hour to lay out a strip. One worry was that rain would leach the ink, but the problem was not significant.

My original plan for planting day included a large tent for shelter with an exhibition board to show how to plant. That didn’t happen due to a combination of no time (lost to soil preparation and Avian flu) and, because the area had been churned by the digger, the ground was too slippery. The trees were held three large tubs – six or seven species per tub – plus several large flower pots containing each a single species. Labels showed which trees were in which part of the tub or flowerpot. I did not use stakes and tree guards, as from experience, we have learned that there are no rabbits in our field.

 

 
   

 

Figure 6: Wirksworth Mayor Andy Pollock Planting the First Tree

 

In the end, the planting ran through several days. Planting was done in two, two hour sessions each day to leave me time to set out the flags and tidy up at the and of the day. Planters arrived in ones and twos at irregular intervals, when they were available, with no more than six planters on site at a time. Most formed teams of two, with one person fetching trees, the other planting. Fetching trees was complicated by the need to remember which tree was which when bringing from the tubs to the plot, and the practical limit was three trees.

Lessons learned:

  • The flag system worked – but took quite a lot of extra effort
  • The trees for planting should have been more systematically arranged to make them easier to find
  • The planting tubs needed bigger labels/flags to make them easier to spot (labels were about 60 by 30mm)

A separate person to greet the planters and explain the procedure would have helped – I was dividing my time between putting out flags, digging up trees from the nursery and other minor jobs, and couldn’t focus enough on explaining.

The first strip to start planting was the one near the valley end. A week before planting day, the Wirksworth Mayor, Andy Pollock, came and planted the first tree. This end of the plot was very heavy clay, which clogged spades and boots. Consequently, planting was moved to the third strip along and beyond. The area above the first three strips was very slippery from the plot preparation, and became unsafe even to walk across – even with boards put down – which was another reason to do the Barrel Edge end. Once a good proportion of the trees had been planted, the tubs were moved to the slope below the plot to avoid people slipping over.

 
   

Figure 7: Three Households from Community Groups doing Soil Preparation

 

The trees in the tubs had their roots covered with compost to protect them from drying out, and from frost. In later days of the planting, the nights were very cold, and the tubs were drawn together overnight and put under a tarpaulin to protect them. The trees in the nursery were not dug up until just before they were needed.

The planting was spread out over a week, interrupted by days of bad weather. I spent Boxing Day planting the last few trees in the clay sections, where a moderately hard overnight frost made it easier to walk over over the soil. By the last day, the trees available did not match the trees planned

  • probably a combination of labels on the tubs not being clear enough, mistakes in picking out trees and in the maps showing where to put flags. Here the colour coding of the flags proved particularly useful, as it made it straightforward to substitute one tree for another according to layer – e.g. for the understorey, I would substituted a crab apple for a silver

By comparison, the VSW on the opposite bank was much easier to plant. Firstly, it was much smaller, at about 80 sq. metres. Secondly, the planting was at a lower density of one tree per square metre, so only 90 or so trees were planted. These mostly came from the nursery patch, though another thirty or so understorey trees were bought from Derwent Treescape. Thirdly, the soil was less heavy – it had been stripped of turf and the soil broken up when the work on the main plot finished early. The clods were broken up by hand, but no soil conditioner added. On the evidence of the strong growth it the nursery plots, a few metres away, soil conditioner should be unnecessary.

Trees were distributed over half the plot at a time just in case the planting took more than a day – flags were not needed – although we planted the whole plot within a day.

 

Figure 8: Planting Finished for the Day

 

The final step for planting day – mulching – was deferred until January. The Planting Method suggests 15 cm of straw or leaf mould. Firstly, neither mulch is easy to obtain locally in large quantities, and also the approach to Little Bolehill is along narrow roads (the compost lorries had a job getting through) so there was a significant risk that a lorry carrying straw would get stuck.

Moreover, later investigations suggested that straw is not the best mulch for trees, and Bartlett Tree Experts – a company identified when I was looking at academic papers on mycorrhizal fungi – recommends 5 to 10 cm of wood chip, but keeping away from the trunks of trees. Derwent Treescapes delivers bulk woodchip, and can deliver 6 cubic metres at a time, which is a convenient amount to shift off the drive. 6 cu. m is enough to cover 200sq m in 3 cm of mulch, so two and a bit loads are needed to mulch the plot. The plot also needed to be raked level after planting but before mulching to ensure that the mulch depth is consistent. Cost is approximately £180 per load including VAT, or about £400 overall. 6 cu. m comes out as 86 wheelbarrow loads.

In a final element of plot preparation – something not in the scope of the Planting Method – the border of each plot was sown with Yellow Rattle. Yellow Rattle is a semi-parasitic plant, which reduces the vigour of growth in grass, and is recommended for this purpose when sowing a wild flow meadow. The aim here is to stop the grass spreading into the Very Small Forest. There is also a plan to turn the current pasture below the BVSF into wild flow meadow. A strip of grass below the planting was heavily scarified and a wild flower mix sown there, and also on the path through the plot.

 

3.8  Cost Summary

 

The table below summarises the main costs of the project. Costs are approximate, and do not include the costs for the very small wood, except that the stripping of the turf was done in time unused in the stripping of the main plot

 

Contractor and Digger Hire – 2 days

1400

Soil Conditioner (2,600 litres)

250

650 Trees

810

14 cubic metres Mulch

400

Misc (printing, marker string, …)

90

Total

2950

 

 

In terms of time and effort, planning and preparation took up a substantial part of the period mid August to October. This included learning about Tiny Forests, walks through the local area looking more closely at the trees, laying out and checking the shape of the plot, finding suppliers and ordering, and planning for planting day. It also took up a couple of days of physical work, digging test holes and preparing to take down a section of fence. November and early December were mostly taken up by Avian Flu, although four or five days of effort went into moving soil conditioner and digging over the surface.

In December, several person days of help from the community groups helped prepare the plot for planting, and then several more person days from the groups helped plant the trees. Given this was during the run up to Christmas, this was very generous.

Since then, a day’s effort went into planting the Very Small Wood, a couple of days into scarifying and planting Yellow Rattle, a day or so into tidying up, and half a day into shifting the first 6 cu. m of mulch into the top of the field, and five days of two hour sessions wheeling across the field. Due to wet weather, at the time of writing it had not been possible to rake the plot to level

 

the soil, or distribute the mulch across the plot.

The costs do not include fencing. The plot needs to be protected from sheep, so more expensive stock fencing is needed. However, the fence between the BVSF and the orchard was taken down, and will reused to fence off the BVSF. The cost is therefore only a few days effort to put in the new fence and a couple of new straining posts.

Costs of tools have not been included. The tools used include a wheel barrow, fork (one per volunteer), a spade, a shovel, and a 5 m tape measure. String, short posts, a sledge hammer and a 5m baton marked off in metres were used when laying out the plot. A couple of boot-scrape posts knocked in next to the plot also proved very useful.

 

4  The Future

 

The Planting Method suggests that weeding will be needed over the next three years, some maintenance of the layer of mulch, and pruning to keep the path through open, but other than that leave the forest to get on with growing on its own.

 
   

 

Figure 9 The Bolehill Very Small Forest, 1 Jan 2021

 

I intend to photograph the forest regularly, so people can see how it grows, and also how it grows in comparison the the very small wood on the opposite bank. The BVSF is likely to be open to the public during the annual Bolehill Open Gardens weekend. I also hope to run events for the community groups so they can see its progress, and possibly do some citizen science such as biodiversity surveys. Once the Covid pandemic is under control, I hope local schools will be able to

 

visit and possibly do some field work on the Very Small Forest and the other very small environments in the field.

And I am continuing reading round the subject, looking what other ecological niches I might create, and thinking about possible extensions to the forest. Perhaps I should consider creating a coppice? – coppicing has a common woodland feature for millennia.

In the longer term, I hope to add more ecological niches to the field, probably including more woodland, but such planning will have to wait. In the mean time, I continue my investigations on Tiny Forests and related questions – and perhaps one day plant an actual Tiny Forest.

 

Appendix 1: Note on Mycorrhizal Fungi

 

Mycorrhizal fungi are soil fungi, which help plants and trees by effectively extending their root network, thus providing additional nutrients and water to the plants, and improving their health, growth and resistance to environmental stresses such as drought. The interest here is their effects on tree growth, and ways of promoting them in the BVSF.

Following a brief review of online blogs, articles and academic papers on Mycorrhizal Fungi, I made the following notes. The overall consensus is that mycorrhizal fungi are a good thing, but that there are a large number of different species, and the effect of a particular species of fungus depends on the tree species present. Commercial mycorrhizal additives feature only a very few species.

Methods and additives give mixed results, sometimes reducing growth, so it would take a considerably longer research to steer a clear path through the various results. The practical conclusions are that the BVSF will not use commercial products to seed the fungi, and that it will mulch with woodchip, which may help promote them.

 

Selected Sources – All accessed 8/1/2021

 

  • FARM & ACREAGE — “Beneficial Fungi and Tree Health” Sarah Browning University of Nebraska https://newsroom.unl.edu/announce/lancasterextension/9262/54821

“Two types of fungi commonly associated with trees are ectomycorrhizae (EM) and arbuscular mycorrhizae (AM, also syn. endomycorrhizae).

EM grow into a tree’s root by pushing between the outer cortical cells. They can also form a thick, outer layer on tree root hairs, which is visible to the naked eye. Each EM fungal species tends to form an association with a specific tree species. Trees colonized by EM include fir, hemlock, pine, spruce, alder, aspen, beech, birch, hickory, linden, oak and poplar. These fungi reproduce through spores produced on mushrooms and puffballs, which can easily move through the air and recolonize disturbed soil.

AM fungal roots enter into tree root cells and are so small they cannot be seen without a microscope. In contrast to EM, AM fungal species are generalists and can associate with hundreds of host species. Tree species colonized by AM include apple, arborvitae, ash, buckeye, catalpa, cedar, cherry, cypress, dogwood, elm, gingko, hawthorn, juniper, magnolia, maple, redbud, redwood, serviceberry, sycamore, sweetgum, tulip tree, viburnum and walnut. They reproduce through soil-borne spores, which are not spread as easily through the wind as EM. Tree species highly dependent on these fungi can exhibit slower growth when planted on disturbed soil if low quantities of fungi are present. “

 

An academic review paper, looking mostly at field trials. “success is unpredictable since different plant species vary their response to the same AMF species mix. Many factors can affect the success of inoculation and AMF persistence in soil, including species compatibility with the target environment, the degree of spatial competition with other soil organisms in the target niche and the timing of inoculation.”

Takeaway from this note: trials results are variable, and at the date of review, an unreliable guide because the full range of relevant factors were not examined (and possibly not known about at the time)

 

  • “Planting Trees And Aftercare” G. Percival, Bartlett Tree, Univ Reading. Focus of the

 

presentation appears to be on individual trees, with initial focus on planting lone trees in urban environment.

“One of the best treatments for a tree … 5-10 cm of wood chip…no grass”

 

  • Bartlett tree research papers: https://bartlett.com/expert-advice-and-resources.cfm
    • Fresh Woodchip Mulch – useful
    • Vertical mulching – not currently useful
    • Influence of Pure Mulches – academic paper, probably the basis for “Planting Trees And Aftercare” (source 3 above)
    • Mulching best practice – useful (extracts below)

“As a rule, keep mulch, regardless of type, at least 3-6 inches away from the trunk of young trees and shrubs, and at least 8-12 inches away from the trunks of more mature trees. Don’t mulch at all in wet or poorly drained sites. Most importantly, don’t apply mulch more than 2-4 inches deep, total. This means 2-4 inches of mulch above soil, measured from the proper soil level. If the soil is too high around the trunk or

if the tree is planted too deeply, you might have even bigger problems.

Freshen or replace mulch every 2-3 years. Fine-textured mulches, such as sawdust, double shredded bark or buckwheat hulls should be applied only 2-3 inches thick, while coarse-textured mulches such as nuggets or wood chips may be piled up to 4 inches. Take care not to add these amounts to what is already in place.

Measure, rake the surface of old mulch to improve its appearance, and then add fresh mulch to a total depth of 2-4 inches.

Removal of old mulch is necessary only if it has compacted and sheds water. If needed, rake away and dispose of old decayed mulch. Put down the fresh product to the proper final depth.”

 

Appendix 2 List of Trees Planted and Number if Trees

 

Canopy                             BVSF

 

BVSW

 

Beech

25

 

p.oak

25

 

8

s.oak

25

 

 

lime small

25

 

 

aspen

25

 

 

 

125

 

 

Understory                        

 

 

 

silver birch

25

 

 

downy birch

55

 

10

Alder

25

 

 

field maple

25

 

 

hornbeam

25

 

 

crab apple

45

yes

 

wild cherry

30

 

10

bird cherry

30

 

 

 

260

 

 

Shrub                               

 

 

 

holly

25

yes

 

rowan

65

yes

 

blackthorn

30

yes

 

hawthorn

30

yes

 

 

150

 

 

Herbaceous                     

 

 

 

hazel

43

yes

 

dogwood

10

 

 

privet

10

 

 

guelder rose

20

yes

 

dog rose

10

 

 

common buckthorn

20

 

 

 

113

 

90

Note: For the Very Small Wood, I did not count exact numbers of trees transplanted from the nursery area. The nursery beds will also be used to extend the very small wood in due course.

 

References

  1. Wikipedia “Bole-hill” https://en.wikipedia.org/wiki/Bole_hill. accessed 16/1/2021
  2. Fabrice Ottburg, Dennis Lammertsma, Jaap Bloem, Wim Dimmers, Hugh Jansman, M.A. Wegman “Tiny Forest Zaanstad; citizen science and determining biodiversity in Tiny Forest Zaanstad” https://research.wur.nl/en/publications/tiny-forest-zaanstad-citizen-science-and- determining-biodiversity Last accessed 8 Feb 2021
  3. IVN “Tiny Forest Planting Method” https://www.ivn.nl › file › download Accessed 8 Feb 2021
  4. Afforestt https://www.afforestt.com/ Accessed 8 Feb 2021
  5. Hackett R. “Wirksworth and Five Miles Round. An historical Sketch, etc.” 1863, republished by the British Library
  6. Sterry P, Collins Complete Guide to British Trees Haroer Collins, London 2007
  7. Reader’s Digest Association Woodland Trees and Shrubs Reader’s Digest Association, London 1981
  8. Identify trees with our Tree ID app https://www.woodlandtrust.org.uk/trees-woods-and- wildlife/british-trees/tree-id-app/ Accessed 26/1/2021
  9. Oliver Rackham “Trees and Woodlands in the British Isles” 1990 revision, 2001 paperback reprint from Phoenix Press

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