Indigenous trees of Jersey
Any enquiry into the origin of an island flora involves a consideration of the data we may have in regard to the relative changes in the level of land and sea during past geological ages; therefore in order to determine which species of trees we may claim as being native here it will be necessary to go back in time to the post-glacial forest period.
During the last phase of the glacial period, all but the very sparsest of arctic vegetation disappeared from these latitudes. As ages passed the ice sheet gradually retreated northward. Although Jersey had not been covered by the permanent ice yet, it was near enough to give us the large amount of "head" which may be seen around our cliffs and in the valleys. A marine deposit overlies this debris of the ice age and shows that for a time Jersey was insular. Then a temperate flora spread slowly across Europe from that part of Africa which lies north of the Atlas mountains.
By the time this vegetation had reached this latitude, land elevation had made us deeply continental, the land at the period of maximum elevation extended out into the Atlantic as far as what is now known as the hundred fathom line. Guernsey and Ireland were continental.
It was not only from the south-west of Europe that the flora spread northward; on the south-east of England we find species which have been called Germanic and which must have entered on that side. Plants found mainly or entirely in western England and Wales are often named Atlantic or Lusitanian from Lusitania, the old Latin name for Portugal. It was from this source that most of our native plants came.
Towards the close of the Glacial Period it is probable that the large amount of water released from the melting ice of the retreating glaciers forced a passage through the low land between Calais and Dover and opened a river valley through what is now the English Channel. At first it would seem that the valley was broad and shallow, but as land elevation continued the channel of the river would become deeper but narrower. It was at the time of the full extent of the great forest that most of the Lusitanian plants found there reached the South-west of England and Ireland.
It is a curious fact that the seeds of many of these species are small and light and include few of the larger kinds found on the Continent. It is possible, therefore, that some of the seeds were blown across the river valley during storms and some, such as acorns, hazel nuts, etc, may have fallen into the water and been carried by the stream and its eddies to the other side. Jersey being inland received not only these plants, but some which did not survive the river crossing into England.
The trees which grew in this great forest, the remains of which are found around most of the shores of our sandy bays and under low-lying inland districts, number ten species, these are the oak, Quercus; birch, Betula alba; ash, Fraxinus excelsior; hazel, Corylus avellana; lime, Tilia vulgaris; elm, Ulmus; beech, Fagus sylvatica; pine, Pinus sylvestris; alder, Alnus glutinosa; and strangely enough, cedar, Cedrus.
Pollen grains of all these, with the exception of cedar, beech and ash, have been recognised in the peat. This peat which under St Helier varies from six to 13 feet in thickness shows, by the nature and size of the tree remains found there, the long ages which passed during its growth. At first the climate that accompanied land elevation seems to have favoured particularly the growth of oak and hazel. Early, too, in the forest we find cedar wood. At first the presence of cedar deep down in the peat appeared difficult to explain. At the present time botanists accept three main varieties of cedar: Cedrus libani, the cedar of Lebanon; C atlantica, the Atlas cedar; and C deodara, the Himalayan cedar.
It is now only in some parts of Asia Minor that cedars grow on the lowlands. In the far distant past the common ancestor of these modern trees occupied a continuous area on the plains in the Northern Hemisphere, but the competition of other trees, and possibly changes in climate, drove their descendants to their present homes where they have acquired slight differences, but these changes in habitat and differences in form can only have come about during the passing of long ages. In this connection it is interesting to find that cedars are confined to those places where the snow lies long in the spring. The cedar which is fairly numerous now in Jersey, although all introduced, was certainly indigenous here in early post-glacial times.
The Common Oak, which was formerly known as Quercus robur, is now designated Q pedunculata and Q sessiliflora. These two varieties, or sub-species, with many intermediate forms, are common locally although Q pedunculate seems to be most numerous. They may be most easily distinguished by the acorn-cups which in Q pedunculata are on long stalks but in Q sessiliflora they are placed on the tree-twigs. On the other hand the leaf-blade of Q pedunculata has a short stalk but that of Q sessiliflora is much longer. We have as yet, no means of determining which of these we have in the forest bed. It may be that we have both, or perhaps one common ancestor only is represented there. When our knowledge of pollen grains is greater than it is at present this query may be decided.
Since early historical times there are records which show that acorns have ranked high in importance as food, and we have reason to believe that this must have extended far back into pre-historic ages. Although acorns are recorded as usually being consumed by swine and other domestic animals, in years of scarcity they were eaten by man himself; this is especially mentioned by early writers as occurring in Italy, Greece and Ancient Britain. In Jersey the right of pannage, that is, the right of turning out the pigs in autumn to feed on the newly fallen acorns, is an old institution.
The beech is one of our most beautiful forest trees, and while often planted as an ornamental tree it is undoubtedly native, beech-nuts being found in the post-glacial forest bed. It seems to have been a fairly late arrival in this latitude at that period, because although considered native in England and Wales, it is not so considered in Ireland and Guernsey, and we know that both these islands became insular soon after the land commenced to subside following the full extent of the forest.
The ash is so graceful in form that it has been named the 'Venus of the Forest', but like many other beautiful forms of life, it seems shy of showing its full beauty, for it is the last of our native trees to come into leaf and the first to shed its leaves in autumn. It may be found growing in Jersey in many places where it has certainly not been planted and its remains occur in the peat of the great forest.
The Common Birch is another graceful tree, and was called by Coleridge the 'Lady of the Woods'. The slender, graceful form of this tree, with its delicate tracery of twigs, is shared by a variety known as the Silver Birch. They are most easily distinguished by the twigs which, in the Common Birch, have a rough surface, while those of the Silver Birch are smooth and downy; also the bark of the base of the trunk of the Common Birch is thick and deeply fissured, while that of the Silver Birch is white and smooth down to the ground. Birch bark is common and easily recognised in the peat of the great forest.
The rarity of the Hazel nowadays in the Island is rather surprising. It is abundant in Britain, and is not partial to any particular soil. Its remains are very plentiful in the forest bed where hazel-nuts may be found in almost every spade-full of peat.
The Common Alder is another rare tree in Jersey. There are two very fine specimens at Town Mills, and a few isolated ones at other parts of the Island. The Town Mills trees are not only the finest in the Island, but probably the finest in the British Isles. This is the opinion of Mr St Barbe Baker, the founder of the Men of the Trees. The writer has not seen their equal either in England or on the Continent. The remains of this species are very plentiful in the forest bed, especially in some parts under St Helier where conditions were probably swampy, and indeed the alder may have been the cause of a good deal of the swamp conditions of that district, for the nature of the alder is to attract and retain the moisture around it.
This is caused by the nature of its roots, which are chiefly composed of a mass of small fibres whose capillary attraction prevents the escape of a large quantity of surplus water in the neighbourhood of the trees. This peculiarity would, in time, render ground that was previously tolerably dry into a soft, spongy soil, and this was the condition of large areas of the forest at certain periods of its growth. In this connection we note that the oak does well in damp places and there the hazel is often the most common shrub of the undergrowth. Like all the other trees whose remains are found in this wonderful forest, the alder is best propagated by seed.
The lime is considered as being probably not indigenous to England. Although not very demanding as to the composition of soil, it requires a fairly warm climate. Pollen analysis from the peat under St Helier shows lime pollen in three different districts. There is no doubt as to the lime being indigenous here.
The Wych Elm is not usually as tall as the Common Elm but is more robust. It occurs on some of our cliffs, where it certainly was never planted. Of course, it is dwarfed there owing to its surroundings. It is easily recognised as its leaves normally reach a length of three inches, whereas the leaves of the Common Elm are only about an inch long. The Jersey Elm, which is also the Cornish Elm, is common in Jersey, Cornwall and Devon. It would therefore seem to have reached Jersey and the Southwest of England at a time when there was forest connection across what is now the English Channel. The leaves of this elm are folded along the mid-rib and are smooth on the upper surface. It is so often subject to lopping - it is usually found on hedgerows - that the beauty of its tall pyramidal shape with the trunk extending almost to the top of the tree is seldom seen. Elm pollen occurs in the peat under St Helier in several places.
The Scots Pine is the only pine indigenous to Britain and seems to be the species represented by pollen in our peat. The bark of the living tree gives an easy means of identifying this species for it is of a warm copper-red colour.
These are the ten species of trees the pollen, fruit or wood of which has been recognised in the post-glacial forest bed. There are others which are almost certainly native and which reached Jersey while it was connected with the Continent, probably during the upper peat period. These are the sallow, salix caprea; aspen, Populus tremula; holm oak, Quercus ilex; maple, Acer campestre; pear, Pyrus communis; apple, Malus pumila; medlar, Mespilus germanica; and cherry, Prunus.
The Grey Sallow is undoubtedly native in damp situations on the cliffs. It may be recognised by its small leaves. The Goat Sallow and the Round-eared Sallow occur in some of our valleys, where they are possibly native. The Goat Sallow may be seen on hedgerows and when the male catkins are covered with golden pollen during the months of March and April, is often called the Pussy Willow. The Roundeared Sallow would seem to have been a late arrival in this latitude, for it is found in Jersey and Alderney but not in Guernsey. If it is native, as it appears to be, like many other of our native plants it shows the greater age of Guernsey as an Island.
The aspen is our only native poplar. It does well in a moist soil and seems to dislike the shade of other trees. It may be easily recognised by the continual trembling of its leaves, which occurs even on an almost windless day.
The Holm or Evergreen Oak is not usually considered native in this latitude, but it grows in places on the cliffs and on Grosse Tete near Mont Fiquet, St. Brelade, where it could never have been planted. It is considered as native in South Brittany and thrives best when within the influence of sea breezes, and it is quite possible for it to have reached here, during land connection, from the western continental seaboard.
The wild pear is not common in Britain, the usual species seen there, as in Jersey, is Pyrus communis, but in Jersey we have also a very rare variety known as Pyrus achras. It occurs in Cornwall, the only known station for it in England. It seems to be another of those trees which reached Jersey and the South-West or England in far back times.
The wild, or crab apple, occurs in several places on the cliffs. It was formerly known scientifically as Pyrus malus, but as the genus Pyrus was also shared by the pear, the apple has now been given a genus of its own, Malus pumila.
The maple is indigenous to most of Europe, including Britain. It occurs here on the cliffs at Vicart, in a locality where it has certainly never been planted. It may be claimed as being truly native.
The wild cherry occurs on the cliffs at Le Saix and St Aubin, in St Peter, and Waterworks Valley. They appear in these localities to be truly wild. Those on the cliffs seem to be varieties of Gean, Prunus avium, the flowers of which are borne in clusters, while those in the valleys seem to be P cerasus, whose flowers grow in looser formation.
The Wild Medlar is found in abundance on the cliffs at Le Saix, Le Sauchet, Crabbé and other places. It is so widespread that it cannot be otherwise than truly native. The trees are thorny, whereas cultivated Medlars have no thorns.
These eighteen species, with a few of their varieties, complete the list of our native trees. The destruction of some of our woods has been stayed because of the public-spirited generosity of their owners, who have given them into the keeping of the National Trust for Jersey, but more must be done if we are to save and pass on to future generations the heritage we have received from the past. The beauty of our Island, away from the coastal areas, depends largely on the trees, but many of our hedgerow trees have been bereft of their branches, robbed of their foliage so that their vitality is reduced, and they sicken from the attacks of insect foes and fungus diseases, and during the German occupation thousands of trees were cut down. It is our duty to replace these on our hillsides, on the hedgerows and in the valleys wherever possible. Besides the aesthetic value of trees there is an economic one; trees are beneficial to the agriculturist; countries denuded of trees soon become deserts.