Nature - trees

Trees are climatic stabilisers; they stabilise the soil and prevent erosion, purify the air, generate oxygen, conserve moisture and put into the atmosphere water vapour that will return as rain. They are a beautiful embellishment to the landscape – their leaves give visibility to the wind; they provide a platform for snow and hoar frost in winter, and for light and shadows as the sun interplays with drifting cloud. Trees enrich our lives and are essential for a wide diversity of mammals, birds and invertebrates.

Trees, Shrubs and Associated Insects

Henry Edmunds has spent much of his adult life studying and encouraging the insect populations at Cholderton, and he is especially keen to underline the importance of specific plants to specific insects. The information that follows reflects the vital connection between creature and host plant. There is a special emphasis on butterflies and moths.

Alder A tree of damp ground, this is not a species you would expect to find in any quantity on Cholderton’s dry chalk, but there is one small stand. Dingy shell, blue-bordered carpet, and early tooth-striped are moths whose larvae feed on this plant. Siskins – members of the finch family – find alder seeds particularly attractive.

Ash This is the most successful deciduous tree on shallow chalk soils, spreading from wind-dispersed seed in established woodland. It is able to colonise clearings rapidly with a multitude of saplings. Much of Cholderton’s ash has grown in former narrow beech woodlands, where the beech was windblown or felled, with isolated ash being left as progenitors. It is the foodplant of the ash pug and the centre-barred sallow moth, whose caterpillars live on the ground but climb up the trees at night to feed on flowers and leaves. It is also used by 11 micro moths, as well as privet hawkmoth and tawny pinion.

Aspen This is much the best member of the poplar family to grow on chalk as it will flourish on even the thinnest soils. Known as ‘the money tree’ because of the shape of its leaves, it is a most beautiful tree, with round leathery leaves that flicker in the slightest breeze. It will sucker freely, so once established it is able to spread around woodland or down edge rather like elm. It is a very valuable tree for biodiversity, hosting most of the poplar-feeding species of moth, such as the poplar hawkmoth, puss moth, poplar kitten, swallow prominent, and 17 species of micro moths. A great local rarity is the light orange underwing, a day-flying moth of the early spring. Aspen is an alternative foodplant for the purple emperor butterfly.

Barberry Little known in the countryside today, barberry is a very attractive shrub with prickly leaves and bright yellow flowers. It was destroyed by farmers when it became known that it was the winter host plant of a rust that attacked wheat. This destruction resulted in the near extermination of the beautiful barberry carpet moth. At Cholderton we are now re-introducing barberry, with the hope of providing a new locality for this rare insect. This is an example of the work we are doing in partnership with English Nature.

Beech At first glance, beech seems to be a dominant species on the estate, but in fact this is a false impression. The lobster moth, barred sallow, clay triple lines and barred hooktip are moths that, together with 17 species of micro moths, have larvae that feed on the leaves of beech. Beech has large triangular seeds that are very attractive to pigeons, pheasants and jays.

Birch The silver or gleaming brownish trunk of this species, sometimes known as ‘the lady of the woods’, is always attractive, and the triangular leaves move in any breeze. This is a tree of colonisation, spreading rapidly by windborn seed. Many butterflies and moths use it as their foodplant, including iron prominent, lesser swallow prominent, pebble hooktip, scalloped hooktip, orange underwing, large emerald, scarce prominent, yellow-horned, argent and sable moths, plus 78 species of smaller moths.

Blackthorn This is an excellent but neglected hedging plant that spreads rapidly by suckering, forming an impenetrable thicket. It can be spectacular in the early spring, with a dense mass of pure white flowers on bare wood – this is the blossom that gives the name to ‘blackthorn winter’, a period of cold weather that often interrupts the arrival of spring. It is the source of sloes – the plum-like but very dry fruit used in sloe gin and eaten by many migrating and resident birds. The brown hairstreak butterfly lays its eggs at the point where the thorn meets the twig. They are white and very conspicuous, except in wet conditions, when they tend to become browner. The phoenix and the sloe carpet moths, 39 species of micro moths and some sawflies feed on blackthorn.

Bramble An inescapable component of most woods and hedges, the bramble bears flowers that are attractive to insects, particularly butterflies such as the comma, red admiral and tortoiseshell. The flowers are also visited by beetles, wasps, bees, bumblebees and many other insects.

Elm This once-common tree was depleted by Dutch elm disease, which eradicated all our wych elm and most English elm. However, there are some large elms that show a degree of resistance, and although affected by the disease and showing conspicuous dieback, they are not killed and continue to grow. These trees foster colonies of the white letter hairstreak, lesser spotted pinion, white-spotted pinion and clouded magpie moths, plus 11 micro moths. Many other insects feed on this tree. It is important to preserve trees exhibiting resistance to Dutch elm disease, as it is these that may give rise to a fully resistant variety.

Hawthorn This is one of the best-known hedging species – its pinky white blossoms can in exceptional years turn the hedgerows white in May. It flowers after the leaf has come out, unlike blackthorn. The bright red berries are very important to many birds but especially to the large flocks of redwing and fieldfare that spend their winter here as refugees from the north. The brimstone moth, yellow tail, buff arches, pinion-spotted pug, small eggar, early moth and green-brindled crescent, plus 62 micro moths, all feed on the leaves of hawthorn.

Hazel For thousands of years hazel was one of the most important woodland plants so far as men were concerned. The uses to which it has been put are numerous, and it is the bedrock of coppiced woodland, harvested on a regular basis and always throwing up a new crop of poles. Hazel was used to make the vast quantities of hurdles that were required as fencing for the folded sheep flocks on the downs. Smaller stems were split and woven into hurdles, larger ones were cut and pointed to be used as ‘shores’ to support the standing hurdles, which were secured to the ‘shores’ by using ‘shackles’ – a loop of twisted hazel. Hazel is also vital in thatching, where bent ‘staples’ of hazel, called spars, hold the straw in place. Hazel once played a crucial role in the countryside, since it can be used for everything from fuel to building material. It is a food as well: hazelnuts are beloved by grey squirrels, but are also important for dormice, yellow-necked mice and wood mice. Several species of moth and 32 micro moths feed on hazel.

Hornbeam This elegant tree is less vulnerable to squirrel attack than beech. Like beech, it retains the dead leaves on young trees in the winter, making it a very suitable hedging plant. Adult trees have silvery bark with a ripple or twist in the trunk. Twenty-two species of our smaller butterflies and moths are recorded as feeding on this plant. Hawfinches are attracted to the seed.

Juniper One of just three coniferous species native to Britain, juniper is a shrubby plant that once clothed the downs – juniper and yew are the only conifers truly native to chalk downland. Only relict specimens remain on the Cholderton Estate, but restorative measures are being taken that include planting and the casting of seed in suitable places. It is extraordinarily difficult to germinate the seed; this seems to occur naturally only where the seed is weathered and in an exposed area free from competitive grass. Junipers are very attractive, with tight structure and a dense growth of greeny grey, sharp-pointed needles. They have a variety of shapes, from tall and upright to low and prostrate. The plant has an attractive fragrance, particularly apparent on hot, dry afternoons. Juniper is the foodplant of the juniper carpet, a very local moth in southern England. Flying in the late autumn, they can be seen on bushes by torchlight in the evening. Beating bushes in July and August will reveal the juniper pug, and it appears that a recent immigrant moth to the UK, Blair’s shoulder-knot, feeds on juniper. Twelve micro moths are specific to it. Juniper offers a useful nesting site for birds as its dense structure is resistant to attack by predators.

Lime This is a very suitable tree for shallow chalk soils, growing rapidly and tolerating drought. The flowers, which open in midsummer, are very attractive to bees. The silver lime (spp. T. Tomentosa), is not planted because its flowers are poisonous to bees. The beautiful lime hawkmoth, the orange sallow, nine micro moths and many other insects depend on it. Lime is very attractive to aphids, which secrete copious amounts of honeydew. Lime should not be planted near thatch since the depositing sugars from the honeydew on the straw or reed will encourage it to rot quickly because of the proliferation of moulds such as Fusarium zamin and aspergillus.

Pedunculate oak This is the ‘classic’ tree of English lowland woods. At Cholderton we grow new trees developed from our own acorns. It is not really suited to the chalk, but nevertheless is planted here because of its importance to biodiversity. An indication is the number of butterflies and moths that depend upon it: purple hairstreak, grey shoulder-knot, dark crimson underwing, light crimson underwing, September thorn, brindled whitespot, great oak beauty, lesser marbled brown, lesser lutestring, pale oak beauty, oak hooktip, and over 80 micro moths. A multiplicity of other invertebrates can also be found. Jays, pigeons and pheasants eat the acorns, as do yellow-necked mice and wood mice. Jays are the primary distributors and planters of acorns cached for the winter. Some acorns are never found and thus have a chance to grow.

Sallow This shrubby willow is an early coloniser of recently cleared or felled woodland. Its prolific seeds are spread by the wind and it tends to be treated as a weed by professional foresters, but it is a very important food plant for many species, including the purple emperor, our most spectacular butterfly. Moths include the pink-barred sallow, the sallow, the herald, July highflyer, poplar hawkmoth, eyed hawkmoth, lunar hornet clearwing, sallow kitten and clouded border, and 49 species of micro moths.

Scots pine A superb tree when mature, with a spreading crown and resinous scent, this tree has reddish fissured bark, spectacular in sunlight. There are many mature specimens in the woodlands on richer soil on the estate, but those growing on the shallower soils were mostly blown over in the great storms of 1989 and 1992. At the waterworks there is an interesting stand of young trees, entirely the result of the wind dispersion of seeds from plantation trees. This group has been extensively thinned to prevent the downland flora from disappearing. Many seedlings are coming up through the grass at the waterworks but these are suppressed by periodic grazing. Pine hawkmoth, pine beauty and pine carpet, plus 26 micro moths, feed on this tree. Several species of bird feed on the seed, particularly greenfinch, goldfinch and crossbills. Parties of tits in search of insects are regular visitors to pine bark, especially in winter. Hobbies – spectacular summer-visiting birds of prey – favour old crow nests in pine trees for breeding sites.

Spindle This is one of the glories of the autumnal hedge, with cascades of pink, incandescent berries splitting to reveal scarlet interiors. It is the food plant of the scorched carpet moth and several micro moths, including a pyralid, whose larvae bind two or three berries together and eat them.

Wayfaring tree A lovely embellishment to the edge of any woodland or hedge, it grows on the thinnest chalk soils and produces spectacular umbels of white flowers in early summer. The orange-tailed clearwing feeds on the pith in the centre of the stems; it is easy to spot the exit holes left by the adult moths when they emerge from their pupae.

Whitebeam A medium sized but spectacular local tree, widely distributed on chalk. In the spring this tree, as its buds open, could be mistaken for a magnolia in full flower: its soft white hairy leaves reveal a cascade of slim silver tulips. As the season progresses, the leaves stay white beneath and are dusty green on the upper surfaces. Clusters of white flowers appear in early summer followed by large panicles of orange berries in the autumn.

Ten species of micromoths are recorded as feeding from whitebeam. The rare sawfly Tricosoma sorbi may also utilise it. Whitebeam yields a yellowish grained timber which is very hard and was formerly used for making cartwheels, agricultural implements and cogs for old driving gear.

Yew The dark, evergreen, poisonous foliage of this sombre tree gives contrast in the winter to the leafless, deciduous trees. The young yew trees can be thick in some of Cholderton’s woodlands, particularly under beech. They are cropped by hares and deer with impunity. Yew provides an autumnal harvest of luscious red berries, which are eaten by a variety of birds who then spread the seed through their droppings. The seed is poisonous if crushed, but will otherwise pass through the gut. Mistle thrushes generally nest in yew trees; they breed very early in the year, protected by the evergreen foliage. Yew is the foodplant of the satin beauty and two micro moths. The algae growing on yew can be utilised by the red-necked footman.

In February the yew releases huge clouds of yellow pollen. It is particularly attractive to cattle at this time and is lethal. Cattle need eat only a couple of pounds of foliage to be killed. The process of digesting yew releases hydrogen cyanide into the bloodstream, which stops the heart. Yew provides excellent firewood, burning slowly and giving great heat, but it needs to be stored for at least two years before use to avoid excessive spitting. The colour of the timber is beautiful – pale orange to reddish, with white areas – and is popular for art work and veneering. Yew is an ancient symbol of immortality, and was the source of timber for the famous British longbow.