A Walk through an Ancient Forest, 1.
Late February, David Beeson.
A walk from the B3400, south along the footpath from Andover Down to the Middleway.
SU403463. Pisa Cottage stop on the 76 bus route from Andover to Whitchurch and Basingstoke.
Harewood Forest has been woodland forever. It is in north-west Hampshire near the market town of Andover, and its woodland straddles the A303 – a dual carriageway leading from the M3 towards Stonehenge and Exeter. It might be the second largest tract of natural woodland in Hampshire, yet it is hardly a vast tract of wilderness at only around 8 – 10Km². Britain is poorly wooded when compared to most of Europe.
With the clay soil sticking to my boots, I head along the footpath alongside Pisa Cottage and under an intermingling canopy of leafless hazel stems. With the route totally shaded in summer, no plants have managed to survive the tramp of walkers’ feet – hence the winter mud.
Hazel loves calcium-rich areas and here that bedrock lies just a few metres below the clay soil surface, close enough for the roots to reach. Other plants also are adapted to this clay-over-chalk part of the woodland and I soon spot wild clematis (Old Man’s Beard) and honeysuckle clambering high towards the light.
These climbing plants have a good strategy. Growing a woody stem is biologically expensive. If you can clamber up to the sunlight utilising another plant that can be a sound plan. Honeysuckle and clematis have weak stems and produce little wood. The wild rose and blackberry uses a similar technique, except here their spines allow easy scrambling and provide some protection against browsing by deer.
Nearby I spy some plants more associated with gardens and allotments –gooseberry and red currants. This is their origin, but the gardener would hardly recognise their wild, scraggy nature growing in the gloom of the hazel coppice and in the murk of February. None-the-less the birds will keep them in mind when the fruit is ripe a few months later.
Hazel fringes this part of Harewood and it is neglected. This is a species that benefits from a regular cutting down to ground level (coppicing)at around ten-year intervals. The two-centimetre width harvested stems were then traditionally woven to make sheep hurdles. These were transportable fences, around a metre high and two in length, and often used to manage sheep. Hurdle manufacture was once a thriving countryside industry and it still happens in a few selected spots, especially adjacent to wildlife conservation projects.
I first encountered hazel-hurdle making near Odstock, Salisbury. The hurdler was a part-time preacher, spending the winters in the USA and the spring, summer and autumn making his living. And a charming character he was, describing dormice as ‘dorymice’ or occasionally as the ‘sleepers’, and knowing all the creatures of that quiet isolated spot. He wielded his billhook expertly slicing the three-metre long hazel stems in a single movement before moving onto the next. Laying each length in a neat stack after the side shoots and end portion, too thin to be useful, had been removed. These brashings went onto a bonfire, whose smoke always alerted me to where he was working.
The thinner hazel lengths could be used whole, the thicker wood needed spitting. Then his billhook would be sharpened with a grindstone, the blade chopped into the stem’s end and pushed down the length to divide it into two. It was hard manual work, yet he’d done this all his life and the effort never left him short of breath.
The Odstock hurdle maker had a former to help build his product. The thicker stems were inserted into this to become the uprights – three or four or more according to the length of the hurdle. Then slightly thinner, but longer lengths, had to be woven between the uprights – requiring strong hands and powerful wrists, for the stems needed twisting around the end poles to 180 degrees to give the structure strength.
This countryman had established enough hazel woodland that he could work it all in around ten years, so keeping the stems to a perfect size. And the wildlife appreciated it as well. By clearing the canopy light streamed onto the soil. This spurred the purple and white-flowered violets and the multitude of woodland-loving primroses into renewed vigour and exuberant flowering. The fresh leaves, plus the ample nectar and pollen the multitude of species produced gave sustenance to butterflies, moths and an abundance of other invertebrates. These, in turn, fed the warblers and flycatcher birds, and then the sparrow hawk that called this woodland home.
Hazel and other types of coppicing is an important conservation tool. However, it is seldom economically viable unless grants are available.
Split hazel hurdle making
At this time of the year, Harewood’s ground flora is limited. The drifts of snowdrops, garden escapees, are showing the last of their delicate white flowers. Of the native plants, only Dog’s Mercury is showing much sign of life. This is a plant with roving rhizomes below ground that allow it to spread far and wide when conditions suit it. It can be a pest in gardens, thriving in the semi-shade beneath shrubs and needing constant weeding to keep it under control. Here, in the woodland, its dark-green leaves can pick up the limited light that reaches the floor and enables it to be amongst the first flowering plants. Not that the uninitiated walker will notice, for the flowers are not showy. Being wind-pollinated they require no flamboyant petals and their separate male and female flowers are almost the same colour as the leaves. It is a plant that needs close inspection.
Dog’s Mercury, Mercurialis perennis to give it its scientific name, only covers the ground in alkaline ancient woodlands, that it is found here in abundance tells us that this is indeed a place that has never been ploughed. This woodland was here well before humans came along.
Dog’s mercury, like most plants, is highly poisonous. If its leaves are consumed, symptoms of poisoning appear within a few hours: they can include vomiting, pain, gastric and kidney inflammation. The first-known account of this phenomenon probably dates from 1693, when a family of five became seriously ill from eating the plant (after boiling and frying it); one of the children died some days later. So, I’ll not be tasting it!
Harewood is not named because of the hares that do occasionally frequent it, but probably from the grey trunks of the oak trees that are dotted between the hazel. ‘Hoare’ (or ‘hore’) in old English means grey – this forest was inhabited by the grey trunks of the English oak. Hoare Wood Forest became Harewood Forest over time.
Looking closely, one can soon see that the bark of the oaks is far from a uniform grey. A cloak of evergreen moss grows someway up from soil level and this plant often coats the horizontal branches. Green, grey or blue-grey lichens clothe other parts- with some being crusty in form and others like miniature antlers of fallow deer. The remainder of the trunk shows a distinct green tinge – a powdery alga that’s probably Pleurococcus. These trees are colonised from shoot tip to soil level with a multitude of organisms – epiphytes.
Around the forest, in many places, is a double bank with a ditch between. Centuries ago it would have been quite distinct yet today rainfall, animal digging and the attrition by plants dying and disturbing the structure has left it a shadow of its former self. This structure was the old forest boundary that went back at least to Saxon times (around 800 – 1066AD) and possibly earlier. This forest was once the hunting ground of the Saxon kings and King Alfred the Great, whose palace was in Winchester and who had a hunting lodge nearby, chased the native red and roe deer here.
For the Saxons, any forest was a vital resource. It potentially provided structural timber, from the oaks, the hazel allowed walls to be built, pigs would have eaten the autumnal acorn crop and the green plants provided a source for both herbage and natural medicines. Fallen wood would keep them warm in winter and some of the fungi gave them some diversity of flavour in their food. Not so the deer and wild hogs, they were owned by the local lord. Even today the deer are not available on the locals’ menu – the ‘sport’ shooting of deer (and pheasants) is strictly controlled by the owners of the land.
With clay dominating some parts of Harewood this material was the raw material of a local brick-making industry. Although today the clay pits are hidden away from public view, they still exist.
Beyond the hazel fringe of this forest is one of the sites of previous charcoal manufacture. I first came across this in the 1970s during a time when some of the oak timber was being extracted. In this location was a huge metal cylinder about 5m in diameter and around two high. The side branches, cut off after the oak had been felled, were stacked into the device and finally when filled, the top was covered by a metal cover with a central hole. By starting a fire, allowing it to burn away the oak cuttings until just white steam was emitted, and then sealing the opening to restrict air flow, within days a few tonnes of half-burned wood (charcoal) was produced.
Even today the effects of that charcoal making have influenced the plant life: it is grassier than any surrounding area.
During World War One there was a munitions factory in Harewood – presumably using charcoal. It is said that trees with a trunk width greater than 6 inches (15 cm) were cut down. So, today’s mature trees must be at around 100 years old.
While this woodland can be considered ancient, it has been used by humans for thousands of years and through that time has much changed. Today it is dominated by English oaks, with silver birch and hazel. The oaks have always been cropped when at maturity and much replanting has recently started – but as a monoculture. Other trees do occur in smaller numbers, among them are hawthorns, wild apple and blackthorn (sloe). The rich diversity of that original pre-human forest ecology has been lost to economic profit.
Today, garden centres offer bark products to enhance the appearance and fertility of garden soils. Something soil scientists approve. This is a recent development and formerly the oak’s bark would have been used for something quite different: leather manufacture. Andover was a leather producing town. Animal skins would be seeped in a water and bark mixture. With the tannic acid from the bark attacking the protein in the skins and converting it into what we call leather.
By studying the pollen grains captured in boggy areas, it is possible to say that oak trees moved into Britain around 8,000 years ago. As these trees established themselves they could outcompete smaller, less robust plants and eventually this climax oak woodland developed. The process leading to this potentially self-sustaining community is termed succession.
In other parts of the extensive woodlands, a diversity of trees occurs. For example, along the north-western fringe there are ancient yews and huge beech trees that are slowly decaying and shedding their limbs. Where a Victorian-built railway was in a cutting the spoil was spread locally and here is an isolated stand of sycamore trees.
After the First and Second World Wars, a drive to make our island more self-reliant in timber saw the planting of many exotic conifers. This can be seen here with individual Douglas Fir trees and coniferous plantations scattered around this northern part of Harewood. These trees add to the biological diversity. For example, one can occasionally spot the crossbills that eat the seeds that are found in the cones. The male birds in summer can easily be mistaken for escaped parrots – they are so colourful.
As the year progresses other plants will show their flowers. March will see the exuberant yellow of the lesser celandine – a plant that dies down when the summer’s dryness and warmth is with us. Beside these plants one can spot the white flowers and feathery leaves of wood anemones – a relative of the pasque flower, a rare native plant that is often grown in gardens. The white anemone is a reluctant seed producer and most of the plants here will have spread by their underground roots.
Both the anemone and the celandine provide much needed nectar and pollen for the emerging queen bumblebees. The harmless furry insects are joined in the woodland in April by bee flies. These insects with a single pair of wings (bees have two pairs) hover above nectar-rich flowers sucking up their sugary donation with a long tongue-like proboscis.
As I wander along the public footpath the ecology changes. There are now more oaks and fewer old clumps of hazel, so the dog’s Mercury is outed by bramble (blackberry) that scrambles over the forest floor but, because of the lack of light, seldom fruits. It is joined by an advancing army of bracken, although in February only the decaying fronds are visible.
Age and wind eddies have caused several oaks to crash to the ground. In their place, rapidly-growing silver birch trees have taken over. These elegant trees only produce weak wood in a rush to capitalise on the break in the woodland canopy and, as a result, are prone to fungal attack and have only a 30 – 60-year lifespan. This suits the lesser and greater-spotted woodpeckers who excavate their nesting holes where they find a weakness in any trunk. Both bird species mark their territories with drumming, that of the smaller bird (Lesser spotted-woodpecker) lasts just a second longer than that of its cousin. Being sparrow-sized, skulking and uncommon the lesser spotted-woodpecker is hard to see. Not so the larger bird that makes its presence easy to spot with its alarm call and undulating flight.
Being late February, the woodpeckers are seeking out nesting locations and their drumming is starting. Spring will soon be here.
Despite being in leaf for only around six months each year, the oaks absorb great quantities of sunlight energy in photosynthesis. Enough energy for a woodland square 12 x 12m to capture enough to keep a human alive for a whole year. Clearly, humans do not and cannot eat oak! But, that gives an idea of how effective they are at collecting sunlight.
The bulk of that captured energy is lost when dead flowers, seeds, twigs and branches or leaves are shed – 88%. Of the rest, about 3% is passed directly to herbivores as they feed and the other 9% is used in building the tree. Obviously, the bulk of the energy is passed to the decomposers, such as fungi and woodlice, on the woodland floor.
Some of the winter migrant birds are still around me. Not so the redwings and fieldfares – they have moved north, but siskins and redpolls are around. These two species benefitted from the cutting of oaks during the 1950s, 1960s and 1970s. The removal of the timber allowed birches to grow and it is their seeds that the birds are adapted to consume. Other birds scoot around the branches – four species of tits, three resident finches and nuthatches. Tree creepers are around too; however, they seem to be in low numbers and rarely show themselves to me.
At the crossroad, where two tracks intersect, I enter a spot I call Badger Valley. This is the loveliest spot in Harewood. Soon the wild cherry trees will burst into blossom (early-April) and later their bitter-sweet berries will be on many birds’ hit list’.
Here there is more open land on either side of the footpath and, with primulas growing in abundance, is the place to find uncommon butterflies. Open glades are often full of nectar-rich flowers and attract these fragile-looking flyers.
Today the track shows signs of a vehicle – the gamekeeper is about, but not with a shooting party as that ‘season’ ended at the start of the month. Scattered through the wood are pens where the young pheasants (natives of Asia) are reared as semi-tame birds. The dozy birds are released at the end of summer but fed daily to keep them in one area – so they can be easily driven onto the awaiting line of shotgun touting individuals from 1st October. These are not street-wise birds, being only months old, and are killed in their dozens … if the keeper has done his job. And here lies a problem – birds of prey, foxes and other predators eat an occasional bird. So many keepers kill any possible opposition.
Badgers do not attack and kill pheasants. They are targeted by some keepers because foxes sometimes co-habit with badgers. The number of active setts that I’ve been told about in Harewood Forest’s northern section is far below the number I would have expected, and the sett here, in Badger Valley, has been inactive for more than a dozen years. There is more badger activity on the southern side of the A303.
The Badger Valley sett had its main complex on one side of the gentle valley with a series of single holes scattered on the other side. These other locations may have been used by a non-dominant female or by males pushed out by a pregnant dominant female. This February all the holes are probably filled with leaves and show no signs of badger activity. Were the sett active today the footpath would be flanked by signs of their feeding and with dung pits filled with damp black droppings. None are to be found.
I have previously found empty tins of ‘Cymag’ (Releases cyanide gas when dampened) by the local badger sett and the animals dug out a fearsome metal Gin trap that had been placed in their entrance. Cymag was made illegal in 1982 and Gin traps in 1958. No one can accuse the current keepers, but it is highly likely someone acted quite illegally in the past.
Metal snares have been used locally and have killed badgers. I have found a snared badger adjacent to a nature reserve in the past. The animal was throttled to death. The snare was illegal as it was self-tightening. The police were informed.
Badgers mainly consume earthworms. A place, such as this woodland, will not be rich in such food and most woodland setts are located where they have access to damp grassland.
Now the woodland gives way to an open field. It has been cultivated for many years and ploughing has shown it to be a very thin soil onto chalk at one end and chalk and clay in the distance. Now only the far part of the field is in cultivation, the thin soil grew almost no crop so has been left to develop into a grassy area beloved by the fallow and roe deer often seen here. I have, in years past, seen and photographed red deer in this part of the forest, yet their time seems to be passed.
By the year 2010, with no natural predators, the deer population of Harewood Forest had grown. Herds of thirty or more fallow could be seen here and it was surprising not to spot two or three family groups of roe during a short walk. On the other hand, muntjac deer were seldom noticed. Deer numbers were probably outstripping the woodland food and mainly feeding in the arable fields. Not so recently. Now muntjac deer are today the commonest species observed and the other deer’s numbers have been controlled by shooting. I guess part of the reason for that control is because of the oak replanting – deer browse such trees, so killing off deer has its advantages.
Muntjac are small, non-native, dog-sized animals and most often seen individually, so harder to kill. The only time I spot two together is when a mother has a youngster with her. Only roe and red deer are native to the UK.
Roe calls for warning and during the mating period – a sharp single bark with an echo-like repeat or rumble. Scary the first time you encounter it! The neat and gentle fallow, currently in their darker winter coats, are mostly silent although they stamp their feet to warn others of danger. Not that a single human elicits much concern and I’m mostly ignored. Muntjac females are the noisy deer in winter. The females breed through the year and the sound of one barking at two-second intervals, for up to half-an-hour, is common. The barking serves to attract males. As a warning, the muntjacs lift their thick tail as a flag and disappear into dense undergrowth.
The observant explorer will, by now, have spotted more deer signs. The slots (footprints) in the mud will vary in size from those of the muntjac through to the fallow deer.
The second sign of deer activity will have been on the hazel stems close to the footpath. While two deer species advertise themselves principally with sound, roe males mark their territory in the spring – and the marks are still there now. At around 2/3M above soil level, you may spot centimetres long scars on some branches. These were put there by last year’s dominant male and they also added their scent to intimidate rivals.
This open field is a great wildlife location at dusk, and the walk here often rewarding. Tawny owls are vocal in February with their proclaiming their ownership of this territory. Unusually, both the male and female call. T’wit (female) – t’woo (male) is the usual pattern. In most avian species the females are non-vocal in territorial bouts.
There is a contrast between the arable field, the grassy area and woodland surrounding these two. The arable field is stopped from moving through succession to grassland by ploughing. Work is carried out. The grassland is cut in autumn. It is this work that stops it establishing scrub vegetation, such as hawthorn and blackthorn. If left alone the grassland would move, by succession, to the climax community of the area: oak woodland.
If you explore the grassy field, you may spot shrubs and even birches trying to establish themselves. With light, wind-blown seeds the plant easily spreads into new locations. It survives in hostile, infertile places, even having root nodules in which bacteria fix atmospheric nitrogen into growth enhancing nitrates.
As you wander along the edge of the open field notice how the wind, light level and temperature are markedly different to within the woodland. This will affect what wildlife can survive here.
We will only have walked a kilometre, but even in late winter, there is plenty to keep a wildlife watcher interested.
A glance at the soil on either side of the path will show not only the clay and chalky nature of the area, but also smoothened river-worn stones. These are not sharp-edged, broken flint nodules, which you would expect in a chalky soil. When the chalk was laid down in warm tropical seas some silt arrived from distant rivers and mixed in. Over millions of years, the rain has eaten away (Leached) at the chalky calcium carbonate and washed it deeper into the soil, leaving the silt on the surface – today’s clay. So, when you travel through a chalk or limestone environment notice how the hilltops are often covered in forest – the clay making ploughing too difficult.
Nearer to the mouth of those ancient rivers, in times of flood, stones and gravel will have been washed down. Parts of Harewood have a topping of river gravels and these will influence the vegetation, often making it more porous, less alkaline, and so conversely slightly more acidic – allowing small patches of ling heather.
During World War Two Harewood was used to store munitions for D-Day. That required concrete tracks, which are now covered in humus from the decades of fallen leaves. Humus is acidic, and so gives another twist to the diversity of the vegetation.
The Middleway lane is now close yet one needs to keep an eye on the sky for buzzards and red kites often soar here looking for unwary rabbits and other prey.
I decide on a right turn at the lane. This takes me slightly westwards and, on the left-hand side, is a recently layered hedge. The mature hazel and other shrubs have been cut back or laid down and interwoven into stakes to form a dense barrier. Amongst this network climbing plants have thrived and bramble has filled in some of the gaps. It has formed a perfect wildlife corridor and dormice have taken advantage to move in from adjacent coppiced woodland stands. In December I spotted a compact breeding nest that had been in use during the warmer months of the year. Now the occupants of that ball of woven grasses were fast asleep, in hibernation until April, May or even June depending on the weather.
I encountered my first wild dormouse some years before. I was with a group of young adults coppicing a woodland to enhance its wildlife. There was snow on the ground and I’d taken a snowy battering before work had commenced. Then, one of the group had knelt to cut a hazel stem when he reported hearing a squeak. We discovered that the student was squashing a hibernating female dormouse! Even asleep she’d cried out. With a wet and squashed animal, I decided she required rescue. Happily, she recovered, became the star of BBC2’s A Mouse’s Tale, had several litters of babies before they were all released back into the wild.
Dormouse signs are difficult to spot, and I missed signs in this part of the forest for many years. For I have sought out dormouse-eaten nuts with their characteristic small neat hole several times, and had never seen a nest before in this area. That December day I had been lucky, and it is only in the early part of winter that nests are visible. Before then they are hidden by vegetation, and by January they are mostly destroyed by the winter’s weather.
Whenever I spot a new or unusual mammal I pass the observation onto the Mammal Society for it to be officially recorded. Such data allow distributions to be plotted and experts can determine if an animal is in decline or doing well. Happily, I have friends who do a similar job for butterflies, birds and plants.
One trick, when exploring a new area, is to visit the local library and view the historic maps. You will gain insight into how the countryside has changed with time. Woods are lost to development and ploughing, and some are gained by planting. So, I know that the fields on either side of this single-track road have been in cultivation for hundreds of years.
The field on my right is regularly ploughed; not so that on my left. With permanent grass and sundry herbs growing there, and open to the woodland, it is a feeding ground for deer, hares and should offer earthworms for badgers. Soon there could be a dozen or more long-eared hares rushing around the field – but not yet. Today they are hunkered down, resembling brown rocks. They know I’m crossing the field, heading up the slope on the footpath that leads to The Monument and another section of the forest. They are watching me, and I know that because they seem to get smaller with time as they crouch even lower to hopefully stay un-noticed. Once they decide their security has been breached they are up and off at a gallop.
The hare’s cousin, the rabbit, has been in fast decline locally. Indeed, they are almost exterminated by a viral disease that has badly disrupted the early 21st Century food chain. The cunning stoat, a daytime predator of rabbits, has lost its main food source and has vanished from its old haunts. No longer do I spot a buzzard with a young rabbit clasped in its talons flying off to feed its youngsters.
Rabbits are not native mammals. They were introduced from Southern Spain and kept in captivity as a winter meat source – only to escape and to colonise the lush, green, British countryside. Experts also say that the brown hares seen here were also introduced, with only the mountain hare being a true British animal.
We gain and lose animals all the time. While the rabbit has declined in numbers locally we are regaining some important creatures. The red kites now frequent the air because of their re-introduction. Polecats have a made a welcome re-appearance having spread slowly from their last stronghold in Mid-Wales, otters are again gracing our waterways and pine martens, while still rare, have a foothold not only in Scotland but mid-Wales and The New Forest.
This field is colonised by grass and other small, non-woody plants whose seeds have been carried to this spot. It should be moving along succession but is stopped especially by the grazing of sheep and deer.
It is always a sensible move, when reaching the brow of even a modest incline, to stop and view the scene. From here the extent of the woodland cover and the amount of the clear felling and replanting becomes obvious. The rolling countryside is pleasing to the eye and the diversity of habitats obvious: arable fields, pasture, hedgerows, re-planted and mature woodland. Each zone will have its own food resources and cover, and so an area like this should support a good diversity of wildlife. Harewood has an exuberance of moths and butterflies.
Oxford University has been studying the population dynamics of great tits in their outdoor laboratory of Wytham Woods for many years. The woodland is peppered with nest boxes and all the breeding birds use them, so set themselves up to be studied. Adults can be weighed and their eggs (usually around 10 or 12) counted. Cameras record the type of food being fed to the youngsters and the mortality rate at the nest, while in-nest weighing machines record the weight of the insect food. Young and fledgling birds can be caught and weighed. Indeed, their whole lives can be studied and the effect of weasels, who can climb up and enter some of the nest boxes, and the impact of their main aerial predators, sparrow hawks, assessed.
After a hard winter more eggs are laid as competition for food has decreased with many tits killed. If the spring is wet and cold the supply of insect food is reduced and more than average young birds die in the nest. If mouse and vole populations are low the resident sparrow hawks target more fledgling great tits.
Interestingly, if the researchers removed breeding pairs of great tits other soon took over their territories. They discovered that the newcomers had moved in from established territories in local hedgerows. They were sensible birds, as the food supply and chance of predation in hedgerows was not as advantageous as living in the wood! (Only 20% of hedgerow nesting birds produced fledgling young birds – compared to most of the woodland nests.)
The research showed that the dynamics was complicated, but, on average, the population of great tits in Wytham Wood remained nearly constant from year to year.
The life history of Wytham’s great tits (Parus major).
- Imagine a population of ten birds. Five females and five males.
- The five females lay 50 eggs.
- 84% of those eggs hatch, giving 42 nestlings at one month old.
- 71% of those surviving hatchlings escape the nest as fledglings.
- So, we have 30 fledglings at 3 months old.
- Only about 10% find enough food during summer, autumn and winter to survive to breed the next year.
- These 3 birds join with the parental survivors to give a breeding population at the start of year two of about 10 birds.
- The population remains stable, the non-survivors are ‘fed’ into the woodland food chain.
- (The maximum lifespan of this species is normally 5 years.)
As I enter the woodland at the top of the slope the difference between the vegetation to left and right is a contrast. On the left the felling has allowed light to flood in, while to the right the tree canopy absorbs most in the warmer months of the year, leaving the soil cooler, moister and, with more leaves falling, with slightly more humus in the soil.
February might appear to be a time when there is a lack of food in woodlands, yet that depends on where and what you desire to eat. If you dwell on the woodland floor your time of plenty is in the autumn and early winter. Because this is when the annual glut of leaves arrive – and they represent food to the fungi, bacteria and the invertebrates that feed on these. The deciduous trees have removed many of the nutrients into storage, yet the plant left behind a cellulose skeleton and these fallen plant powerhouses contain many complex organic chemicals that can keep other organisms alive. To see the animals of this part of the food chain the easiest spot to peer is amongst rotten wood. Peel back any well-rotted bark and this world will be reviled: woodlice, minute spiders and their allies and the white filaments of fungi. A sample of leaves and topsoil will also give good results if hand lens is available.
Collecting, drying and then setting light to leaves soon demonstrates the energy they contain; energy that can give life to other organisms.
Much of the wildlife diversity is hidden from view. A twelve-year study near Oxford of an area occupied by only twenty-one oak trees identified more than a thousand insect species. Many were small or lived in the leaf litter at soil level or in the multitude of crevices provided by the trees’ bark. It will be these insects that help feed the birds that flit around the woodland.
Mosses are often overlooked in woodland. Mostly they are living on the bark of the oak trees (the birch shed their bark too quickly to allow mosses to thrive), while some are found colonising damper spots on the ground. Amongst the latter is the haircap moss (Polytrichum sp). This non-woody, small, clump-forming, Christmas tree-like moss has such a primitive transport system for water that it can only survive in damp conditions.
Goldfinches, at this time of the year, eat haircap mosses and lichens and their roof and tree-living relatives.
Mnium moss is the one most often found climbing up the trunk of oak trees. In the summer these small plants look unhappy but now will show their leafy best and are worth investigating.
With the diversity of plants, this woodland holds the huge species diversity in the moths, butterflies and invertebrates generally is not a surprise. However, the wingless female moths that live here could even attract you out at night! In the depths of winter, you might spot the Winter Moth and in March and April the March Moth. In both cases, the males are the flyers and the ladies can only walk.
As you can imagine, ecologists love these moths. Using small tunnel traps it is possible to catch the females as they crawl up the trunks to attract the males. Their egg numbers and the numbers of resulting caterpillars can be counted. When fully grown the caterpillars descend to pupate underground – and can be caught and counted. Hence, the whole life cycle can be studied and the effects of disease, lack of food, predators and parasites discerned.
With cool temperatures, little sunlight and sometimes waterlogged soils, it is no surprise that just beyond the minor trackway crossroads few plants are showing any sign of flowering. The exception being the hazel, which is nearing the end of its season. The elongated catkins, packed full of wind-blown pollen when fresh and just opened, are now looking bedraggled and it requires a sharp eye to pick out the ‘female’ flowers. These appear bud-like with a pair of crimson stigma peering out to pick up any pollen that should drift onto them. I say ‘female’, although the purist botanist would rightly point out that the sexual cycle of plants is more complex than almost all books admit. Correctly, the buds I referred to potentially contain the female parts but are not themselves female.
Let me digress. Ferns, of course, do not flower. The green plant we see produces and releases spores from the underside of their fronds. These are made asexually and are spread by wind currents. When they land and germinate they grow not into a new big fern plant but into often minute flat leafy structures. These (gametophytes) produce the equivalent of eggs and mobile sperm that can join in fertilization producing a zygote. This zygote can then grow into a big leafy fern plant (Correctly termed a sporophyte). Spores never directly grow into a fern plant.
This life history is true from the mosses, through the ferns and horsetails, to the conifers and the flowering plants, with a few changes as we go!
Woodlands have a human history to them. We’ve mentioned timber production, charcoal and hurdle manufacture, now a signpost will lead us leftwards to The Monument, and human influence of a more aggressive nature.
Despite the time of the year, there are plenty of birds in the woodland. Flocks of goldfinches and redwings are especially common, and the many species of the tit family are out and about – coal, blue, greater, long-tailed and marsh tits all are found. Finches move around in mixed flocks yet are often hard to identify unless they wander into gardens and to the bird feeders, then their identities are clear: bramblings, gold, green and chaffinches with near relatives such as redpolls occasionally joining them.
Each type of bird has its own niche. With its niche explaining when, where and how it eats and so how it fits into its environment. The tawny owl’s niche is as a nocturnal, woodland hunter of small mammals and amphibians. Thrushes are snail-eating specialists and the tits fill different niches. Blue tits seek out their preferred insect food on the finest of twigs, their chunkier cousins, the great tits, on the more substantial branches.
Feeding niches may result from morphological differences among species. Blue tits are better adapted anatomically than great tits to forage from buds and leaves of tiny twigs because they have longer and stronger feet which allow them to hang upside down more easily while foraging than great tits.
In an experiment in Norway, blue and great tit eggs were moved between species. The results showed that their feeding behaviour is also determined by learning from their parents i.e. the young birds, for the whole of their lives, moved their feeding location towards that of their adoptive parents.
Treecreepers, also insect feeders, use their narrow beaks to probe for insects in the bark’s cervices, so do not come into conflict with those two tit species.
Subtle changes occur in some niches during the year and their body shape changes to reflect this. For example, the beaks of great tits become shorter and chunkier in winter as their main food source evolves from insects to vegetable foods.
While this exploration has been during daylight hours, I frequently walk it at dawn and dusk. Then the forest feels quite different! Not scary in the slightest, yet the sounds of the darker hours and the dawn light give it a magical quality.
At this time of the year the full dawn chorus is some way off, yet the tawny owls make their presence clear. Often, while standing at the Badger Valley crossroads, I can hear two different males proclaiming their territories with my own location the ‘no-man’s-land’. Tawnies pair for life and locally would hold territories of around 30 – 40 acres (12 – 16 hectares).
In October or November, male owls establish territories while females find nesting locations (holes or old nests of other large birds or squirrels). At this point in the year, males and females roost separately. The pair defend their territory year-round with minor changes to boundaries each year. As winter approaches, territories are finalized and pre-breeding behaviour begins with males and females roosting together. This is the time for courtship feeding, which is centred around the future nesting site.
In February / March their breeding territory should be well established, however, the pair still call out and make contact calls.
One pair of tawny owls nested in my own garden two years on the trot. When the female died the following year the nest site was taken over by stock doves. Presumably the new tawny pair preferred a different location.
Tawny owls hunt primarily between dusk and dawn. They perch and watch for prey, then use silent gliding flight to catch their victim on the ground, extending the wings to cover the prey and killing it with feet and claws. Occasionally they may use the beak to deliver a blow to the base of the victim’s neck. Tawny owls have also been reported to beat their wings to flush smaller birds out of hiding and into flight and then take aerial pursuit. They also fly over grassland, marshland, or bushes looking for bats or incubating birds to pluck from their roosting perches and nests.
At dusk the deer, especially roe, are less wary of humans. Now, if you avoid making too much sound and do not use a light, one can approach them closely and additionally hear the barking of the roe deer and their grunting and complaining as they wander off with their foraging disturbed by these strange human-like creatures.
Details of the route:
The walk starts at the ‘bus stop (Pisa Cottage) on the B3400 Andover to Whitchurch road. It follows the adjacent footpath south, turning left on reaching The Middleway lane and finally takes the footpath, left, across the field after about 400m. It ends at The Monument.
It’s all to easy to not see the woodland for the trees. We have been brought up with the idea that a woodland is composed of individual trees. That is not how ecologists see it anymore!
Research shows us that plants, including mature forest trees of different species, can join underground. Roots from individual specimens can fuse and soil fungi can also join plants together. Resources made in one tree can be passed to their neighbours. Birches can communicate with oaks, possibly hazel with dogwood.
[ See https://www.the-scientist.com/features/plant-talk-38209 ]
In Africa it has been discovered that acacias alert others of the same species of prowling giraffes. Willows, alders, poplars warn others of insect invasion. Plants can communicate by airborne chemicals and via their joined root systems.
Gardeners, when planting a new tree or shrub, are encouraged to add some fungal spores to the soil. The fungus will develop links with the plant and it is more likely to thrive.
The forest is an ecosystem with individuals often aiding their neighbours by alerting them to possible attack or of resources available. Amongst the branches are a thousand species of invertebrates, algae, mosses, ferns, lichens and flowering plants. All form part of the forest food chain. Even the insignificant spore capsules of the mosses are eagerly consumed by bands of goldfinches. No oak trees, no epiphytic mosses and so, fewer goldfinches in our gardens.
An additional short Harewood woodland walk: March at Tracy’s Dell.
Snow has come, gone and returned this year – and it came late enough to disturb especially the migrating bird life. Residents know their territories and can eek out their food supplies, not so the insect-eating travellers from the south. One day the queen bumblebees are out and about collecting supplies to feed to their insipient brood, then next they are shut in by several centimetres of snow. Flies visit the open primroses in warm sunshine and the next are comatose. Insectivorous birds will have a devastating time.
Pits, like Tracy’s Dell, about in these woodlands. Some old clay diggings have water in their bases in winter and attract the amorous frogs, others, like this one, were dug to extract the chalk. When this calcium carbonate-rich rock is spread on the clayey fields it causes the microscopic clay particles to stick together (flocculate) improving water drainage, aeration and the ability of roots to penetrate the ground.
The sides of the dell allow anyone to see the profile of the soil. Here the soil layers can be seen as: clay topsoil for only a few centimetres, then chalky soil before we reach the ‘bedrock’ of white chunky chalk that goes down for hundreds of metres.
The short walk down to Longparish Village passes two plants of interest, the first is holly. The plant is not common in Harewood but one of the dominant species on the acidic soils of the New Forest.
The dark-green, leathery, spiny leaves ensure the plant is known by everyone and its dark-red berries are well-known in the period leading up to Christmas. Ecologically it is a valuable plant. Its berries, while poisonous to humans with six or more being lethal, are of great nutritional value to both birds and mice. They are consumed in quantity and mistle thrushes are said to guard their territorial trees. Wrens and dormice often nest there, and their accumulated fallen leaves are the hibernation places of choice for some hedgehogs.
Looking carefully at the leaves it’s easy to spot the fact that many are not pristine: they are blotched, torn open and have trails leading through them. Much of this is caused by the holly leaf miner (Phytomyza ilicis), a fly whose larvae burrow into leaves leaving characteristic pale trails or leaf mines.
Eggs are laid by the female flies in spring when the newly emerging holly leaves are tender enough for the hatchlings to burrow into it. They feed between the upper and lower outer layers of the leaf, growing in size and leaving their characteristic trail. Some fly larvae die, killed by bacterial infection, and the trail ends. Some are predated by tits, who tear open the leaf to reach their food, and others emerge through 1mm wide, circular holes as adults. By observing a few leaves the chances of a hatched egg surviving to adulthood can be studied.
Usually, in May or August, the holly blue butterflies lay single, white, spherical eggs around the tips of branches. The white eggs are laid singly at the base of unopened flower buds of the foodplant. Eggs laid in spring are typically laid on Holly, whereas the summer eggs are typically laid on Ivy. In good years, the eggs can be relatively easy to find on the foodplant and hatch in around 2 weeks. The larva is extremely well camouflaged and is usually a plain green colour. The larva is most-easily found by looking for damage to the developing flower buds, where it may usually be found attached to a neighbouring bud. The larva bores a hole in the side of the flower bud and scoops out the content, leaving a succession of empty flower buds, each with an access hole, in its wake. The larva leaves the foodplant to pupate on or near the ground. The larva spins a very fine silken girdle to attach itself to the chosen pupation site. Pupae from the spring generation emerge in 2 to 3 weeks, whereas those formed in late summer overwinter, so there are two flushes of the adults during the year.
Further along, the footpath is a colony of wild daffodils. The small size of the blooms and the different colours of the two flower layers is characteristic. They look a delight with primroses as their neighbours.
Plants gain nothing by having their leaves eaten, so almost all fill their leaves with toxins. Such complex chemicals are ‘expensive’ for the plant to manufacture and are usually only made once the leaves are fully grown – giving animals an opportunity to feed. Plant toxins are a security system … a bit like the one you have at home. So, would you have the same door lock as everyone else on your street? Unlikely, and so plants have different toxins – so, if one animal finds the correct key to detoxifying the poisons it cannot eat every plant. The poison in foxgloves is different to those in daffodils, holly or snowdrops. But animals have to eat something, so how do they do that? Well, there are three strategies. 1. They eat only young leaves before the plant can make its toxins. 2. They find a cunning plan to detoxify one poison, but that’s expensive. 3. They eat a little of everything and hope they do not get too ill. Small organisms, such as caterpillars follow option 1. Holly leaf miners follow 2, and deer follow 3. Isn’t wildlife wonderful?
Like all Narcissus species, wild daffodils contain the alkaloid poison lycorine, mostly in the bulb, but also in the leaves. Because of this, daffodil bulbs and leaves should never be eaten.