The vegetation of Europe, its conditions and causes

Contents

Page

Chap. I. Introductory . 1

Chap. II. General Influences on the Distribution of Vegetation 11 Chap. III. Special Influences on the Distribution of Vegetation. 42

Chap. IV. Characteristics of the Countries of Europe . 69

Sect. 1. The Scandinavian Peninsula . 79

- 2. Iceland, the Feroes, &c . 125

- 4. The North-European Plain . 172

- 5. The East-European Plain . 189

- - 9. The Italian Peninsula . 313

Chap. V. Conclusion . 366

*** The Explanation of the Map will be found at page 75.

-

THE VEGETATION OF EUROPE.

Chapter I. Introductory

The pages of the book of Nature offer a vast variety of characters for our perusal, but of all we find there in¬ scribed, none surpass in beauty of form or the interest of their revelations those presented by vegetable life. Mountain and valley, flood and lake, plain and undu¬ lating hill, may give the bolder features' of a landscape, but dark and cheerless must the grandest combination of forms appear where the eye can find no green resting-place ; gloomy and repulsive the scene where no trace of vegetation, telling with its varying hue the tale of life and change, breaks the dull monotony of the stark masses of the earth’s crust. It is difficult, indeed, to those who are without the actual experience, to picture in the mind those desert tracts which do actually exist upon the globe, where the burning sun sears out as it were the ordinary covering of the soil ; or those barren rocky shores, clothed

Introduction

but by a few lichens, where the inhospitable climate refuses a resting-place even to a blade of grass. We are connected with the vegetable world by so many ties, of pleasure, interest, and necessity, that we commonly regard its existence as a matter of course, and seldom pause to consider how and why it is, but merely direct our atten¬ tion to those of its peculiarities which relate to its useful qualities, or which lend to it the manifold charms which delight our gaze in natural scenery. From the very infancy of our race the influence of vegetation upon the moral feelings has been recognized, poets have dwelt upon it in all ages, and scarcely a striking form or com¬ monly recurring kind of plant is without its real or fanciful associations. Waving corn-fields ! even the bare mention of them seems to raise a vision of peace, plenty and contentment : traversing the woodland path we cast awhile the cares that press upon us in the busy haunts of congregated man, and share the freedom and inde¬ pendence of the unrestrained life around ; or in the deep and silent solitude of the black pine forest, we feel re¬ vive within us that superstitious awe that gave birth to the strange traditions of our northern ancestors. No temperament at all awake to the influence of external nature can escape the depressing influence of the low swampy plain, where among plashing water-courses the “ cluster’d marish-mosses ” creep, and amid the rustling reeds

Little breezes dusk and shiver.”

Few behold unmoved the brilliant tints of the springbuds, fringing the spray of every re-awakening tree like a joyous decoration celebrating the return of warmth and

INTRODUCTION.

active life, or the graduated hues of autumn’s garb ; — they typify to us too plainly the changeful course of our own existence not to arouse something more than a passing feeling of wonder or admiration.

And descending to particulars, we recognize in common epithets, endless examples of the association of moral qualities with certain plants, as the ‘ sturdy oak,’ the ‘modest daisy,’ the ‘melancholy poplar,’ the ‘humble celandine,’ and the like ; every page of descriptive poetry or imaginative prose, in our own and in all other litera tures, will furnish instances.

In regard, again, to their mere physical beauty, the more conspicuous tribes of the vegetable world, the trees, have furnished the principal materials for the develop¬ ment of one great branch of Art. The infinite variety of forms, the delicacy and multiplicity of lines, surfaces and colours, the changing aspect in different seasons and under varying lights, have presented an inexhaustible field of study to the painter, and one which has attracted and rewarded the most distinguished masters.

But poets had sung, and painters had turned the powers of their art to the representation of the varied landscapes of different regions, commerce had heaped the products of every latitude in the market-places of civi¬ lized nations, and travellers had raised the wonder and curiosity alike of the learned and the ignorant with tales of the strange forms replacing our familiar plants in foreign climes ; yet it was not until about the beginning of the present century that science made any general or systematic inquiries in this direction, and Botanical Geo¬ graphy, as a special subject, owes its origin to the labours of living philosophers, Robert Brown, Alexander von Humboldt, Schouw and others, who during the last fifty

b 2

INTRODUCTION.

years have attempted to arrange the facts and develope the laws of these phsenomena.

Not that the facts lay out of common view, for they are among the most striking and prominent in the whole range of knowledge. The contrasts and diversities among the characteristic vegetations of different lands force themselves upon the most superficial observer. Since the earliest period of which we have record, the pecu¬ liarity of certain plants to certain countries or regions has attracted observation, and the narratives of the earlier navigators of European nations are full of glowing pictures of the treasures unfolded to them in the more favoured climes to which they penetrated. The tropics were de¬ picted as earthly paradises, in which

“ Droops the heavy-blossom’d bower, hangs the heavy-fruited tree, Summer isles of Eden lying in dark-purple spheres of sea ; ”

and in which man lies idly waiting while nature pours out at his feet the rich harvest of luxurious fruits, unknown in our temperate regions, where the ever-recurring check periodically arrests the forces of vegetation, and the less favouring climate compels him to the labours of the field, yielding to his toil and unremitting care a limited and frugal recompense. Travellers had told, too, that in the far north even this partial bounty is denied ; that man is cut off altogether from that vegetable food which is lavished in profusion at his slightest demands beneath a warmer sky, while his companion the reindeer scrapes a scanty repast from beneath the snowy covering of the soil.

“The carpet of flowers and of verdure spread over the naked crust of our planet is unequally woven ; it is thicker where the sun rises high in the ever-cloudless heavens, and thinner toward the poles, in the less happy

INTRODUCTION.

climes where returning frosts often destroy the opening buds of spring or the ripening fruits of autumn.”

But even in a smaller compass, on a smaller field, striking differences occur, and facts familiar to every educated person mark the existence of some regulating influence even within the limits of the smallest of the continents of the world. We cultivate the grape in En¬ gland, but it is only in favoured spots, and then even not with certainty, that it will ripen properly in the open air ; yet but a little further south it is so much at home, that it yields one of the necessaries of life to the entire popu¬ lation. Oranges will ripen on the other side of the Alps, but not on this. For those cereal grains, those corn-plants furnishing the principal portion of the food of man, we find distinct lines of demarcation extending across Europe, beyond which, northward, each kind ceases to be capable of ripening its seed. Of trees we know that certain kinds will flourish and form fruits at points far north, where others are arrested by the cold ; the firs, for instance, exclusivelv constitute the most northern woods of Scandinavia, while the dwarf palm, a repre¬ sentative of tropical climates, maintains its footing even so far into the temperate region as Italy and the southern confines of France.

Again, as indeed must be perceptible to every one who has visited mountainous countries, vegetation alters in its characters at different elevations, and it has been shown that these variations correspond to those which are ob¬ served on the level plains in proceeding from the south towards the north ; the increased severity of the climate of the higher localities acting exactly in the same way as the colder climate of the regions lying further from the equator.

INTRODUCTION.

Such facts as these, obvious as they appear to be, re¬ mained unconnected and unaccounted for until recent times, or differences of heat and cold were supposed to he sufficient to explain them. But when a more search¬ ing inquiry arose, and when the vague ideas respecting the influence of heat came to be systematically investi¬ gated, it was found that there were other facts and that other causes were at work, the existence of which had not previously been suspected. In the first place it was seen,, that mere degree of latitude will not indicate the tem¬ perature of a climate ; that the temperature, the average heat and cold, do not alone constitute the climate pro¬ perly so-called, but that humidity, exposure to prevailing winds and many other influences conjoin to produce the atmospheric conditions powerfully affecting vegetation. The chemical and physical conditions of the soil were found to require investigation, in order to the explana¬ tion of facts otherwise anomalous ; and finally it has been discovered that the particular constitutions of the indi¬ vidual species of plants must be studied, if we would rightly understand the causes which give the peculiar characters to the vegetation of different lands.

And after all these points have been considered, there is still a residuum of phenomena which they totally fail to account for ; we are in possession of another series of facts which require to be explained by a wholly different set of causes, as will appear from the following observa¬ tions.

When we compare the floras, that is, the lists of na¬ tive plants, of two countries closely alike in physical conditions, we generally find a difference resulting from the absence of certain kinds in one which exist in the other, and vice versa ; moreover, these may be kinds,

INTRODUCTION.

which when introduced into the country where they were wanting will flourish there with a luxuriance equalling that in their native habitation. This shows it is not the physical or external conditions which have prevented their growth, and we therefore ask why were not they present at first in both ? This leads to the inquiry into the details of the peculiarities of the vegetation of differ¬ ent countries, and we then become aware that there is some law presiding over the distribution of plants which causes the appearance of particular species arbitrarily, if we may so say it, in particular places ; and following the clue which this affords, we arrive at the conclusion that countries have become populated with plants partly by the spreading of some special kinds from centres within those countries where they were originally exclusively created, and while these have spread outward into the neighbouring regions, colonists from like centres lying in the surrounding countries have invaded and become intermingled with the indigenous inhabitants. The modes in which these processes have gone on, the de¬ tails of the migrations, and similar particulars, are matters of much debate and discussion, and require great care in their determination ; but it is now generally admitted that such centres of creation do exist, and thus we have here, side by side with the climatic and other physical influ¬ ences, a second and totally different set of conditions, which must be thoroughly investigated before we can clearly understand the manner in which the vegetable inha¬ bitants of the world have acquired their present positions and relations toward each other. When we have to deal with a great extent of the earth’s surface, the phsenomena presented by this branch of the subject are very striking, sufficiently so to have enabled M. Schouw, one

INTRODUCTION.

of the most distinguished geographical botanists, to lay down regions on the map of the world, in which parti¬ cular forms are so predominant as to give a peculiar character to the vegetation, these peculiarities not point¬ ing at a difference of climate, but often indicating rather a resemblance, where certain tribes of plants are repre¬ sented, as it were, by other tribes quite distinct in struc¬ ture, hut agreeing very closely in the habits which place them under the influence of the external physical agencies. In a confined space, within the limits of a region so little varied as the continent of Europe, it is not easy to illus¬ trate this part of the subject very clearly to those who are unacquainted with the more minute distinctions be¬ tween different plants ; but facts, and most marked ones, exist in abundance, and to the botanist, the results here are, if possible, even more convincing, because the region has been so much more thoroughly investigated. In Europe every country has its active naturalists ; our own country, Germany, France and Scandinavia have zealous botanists in almost every county, province or depart¬ ment, examining with curious eye every tract within their reach, and eager to detect any new fact respecting the distribution of the plants of their vicinity. By these means, local lists have been prepared, and travellers who have made these points the especial object of their journeys, have furnished tolerably perfect data for the rest of our continent ; thus we are in a condition to draw conclusions with much more certainty, and with a much greater probability of obtaining true results, than can be the case with the vegetation of more distant, and as yet partially explored regions. I shall therefore attempt to unfold the most interesting and important of these con¬ clusions, and the speculations connected with them, and

INTRODUCTION.

endeavour to overcome the difficulties arising from the technicalities involved, by incidental explanations and by the selection of facts and examples which are in some degree familiar to general readers.

The subject before us has then to be treated in its ge¬ neral bearings under two distinct points of view, namely the distribution as affected by physical causes, such as climate, and the distribution as a result of the spreading of different kinds by gradual migration, transport, or other processes from certain points or centres, where alone they have at first existed. In the consideration of these questions, it will be frequently necessary to allude to particular plants or groups of plants, selected as illustra¬ tive of the principles or as examples of the facts brought forward ; it is desirable therefore that a certain amount of acquaintance with these plants should be possessed by the reader before entering upon such inquiries. The limits of the present work preclude the possibility of en¬ tering very minutely into the characters of the European plants, and the only alternative that remains, is to seek for a number of generally known groups or species as representatives of the rest ; this method, however, can only be made available to a certain extent, and it is im¬ possible to avoid bringing into frequent use the botanical names of many characteristic species. Under these cir¬ cumstances, the reader who is unacquainted with them can only be expected to follow the train of reasoning, and may pass over the names of plants unknown to him, as supplied merely to furnish more convincing evidence to those who enter more deeply into the technicalities of the subject.

It remains yet to speak of the influence of the hand of man. Important as the effects of climate are, and

INTRODUCTION.

not to be combated beyond a certain point, yet is the struggle with the elements vigorously sustained, above all in the north of Europe ; curious and striking as are the pliaenomena of the spontaneous migrations of plants, they sink into insignificance beside the operations of man’s improving hand. Barren plains are forced to yield a crop of food-plants ; bogs and marshes are drained and turned into arable lands ; vast tracts wrested from the sea and brought under the dominion of the husbandman. The bare escarpments of the rocky banks of the rivers of Germany are terraced by the patient hand of industry, and converted into smiling vineyards. The whole face of the more populous countries is changed, and a view of the vegetation of Europe would be deficient in some of its most attractive and important features, without a sketch of the distribution and characters of the culti¬ vated plants.

Not without interest either is the history of the changes which have gone on in earlier epochs of the earth’s ex¬ istence, before man trod upon its surface, and claimed dominion over the surrounding creation. Few and indi¬ stinct are the records on which this history depends, frag¬ mentary the traces of the vegetation of ancient times that remain to reward our investigations. Such as they are, they have been industriously studied, and, had we space, would claim a notice in the present volume. But in reference to this field of inquiry, we are compelled to limit our remarks to those more recent changes which have intimately affected our existing vegetation.

These are the points to be discussed in the following chapters ; the arrangement of the matter is not the least difficult portion of the task ; the plan which I have con¬ cluded to pursue is open to objections, and others have

GENERAL INFLUENCES ON VEGETATION.

suggested themselves ; but on the whole it appears the best that can be adopted in the treatment of such a mis¬ cellaneous subject, when a rigid scientific method would defeat the intention in view, and give an abstract and re¬ pelling aspect to what is designed for the instruction of general readers.

Chapter II. General Influences On The Distribution Of

VEGETATION.

In those brisk, invigorating walks, on bright, clear winter-days, which form so prominent a part of the pleasures of a Christmas in the country, it is not rare to see the humble chickweed opening imperfect flowers, while every mossy bank displays the activity of its crowd of tiny inhabitants, lifting their elegant little urns on hair-like stalks, which, tender as they look, defy the frosts of winter. Yet at this time the delicately-nur¬ tured favourites of our gardens demand the utmost care to shield them from the biting cold ; or, if more hardy, have thrown off their showy summer garb, and either cower beneath the soil, or hide their soft buds, close wrapped in many a varied form of winter covering. Through more genial seasons, too, from when the snow¬ drop and the fragrant violet announce the coming warmth, through the full blaze of summer to the time when the autumnal tints and falling leaves bear witness of the

HEAT OF CLIMATES waning year, we still must pile the constant fire to foster the rare and delicate strangers, captured from the crowd of beautiful, fantastic, or gigantic tribes that revel in full life, uncared for and in freedom, beneath the glowing heavens of the tropics.

Foremost of all the natural forces that limit or decree the general character of the vegetation of each region of our globe stands heat ; this is unquestionably the prin¬ cipal constituent of that set of conditions we call climate. As such it was recognized by the first observers in the field of geographical botany ; and if, as not unnaturally happened, even too exclusive a dominion was at first attributed to the mere proximity to the sun, still it re¬ mains the highest governing power. From the direction of the sun’s course, the gradual approach of this source of heat to the northward on the ecliptic line in summer, and the retreat to the south of the equator in our winter, were there no other modifying causes, the comparative temperatures of different places upon the globe would be clearly marked by the parallels of latitude, and these lines would connect places of equal temperature, having similar summers and winters, and the same amount of daily warmth or cold. We should then find an uniform excess of heat at the tropics, and an uniform diminution toward the poles. We might mark the daily tempera¬ ture at any place on one of these lines, and by taking the mean, or average of all the days of the year, obtain the annual temperature or amount of heat received, which would be the same at every place upon that line around the globe.

But applying to such a supposition the test of expe¬ riment, of observation, it was immediately found that places upon the same parallel by no means agree in their

HEAT OF CLIMATES.

daily temperatures. The facts most familiar to horticul¬ turists and travellers belied it, for it was known that plants will flourish perennially in the British Isles which are killed by the frosts of winter in places lying consider¬ ably to the south upon the continent ; thus the laurel, that bears our winters steadily in Ireland and the west of England, and is only affected by very severe frosts in our eastern counties, is killed by the winters of Berlin, equally fatal to the myrtle, the fuchsia, and a host of other shrubs which attain considerable age and size in the western portions of the British Isles. Again, Canada, which lies south of Paris, has the climate of Drontheim in Norway ; while at New York, lying in the latitude of Naples, the flowers open simultaneously with those of Upsala in Sweden. Moreover, it was known that those very countries suffering so severe a winter’s cold, enjoy a summer’s heat far exceeding ours, since the snow lies for months on parts of Germany which yet receive suffi¬ cient heat in summer to ripen the grape and Indian corn.

There exists then some other cause which powerfully affects the influence of the sun upon the earth, exercising an interfering power, to moderate and alter the direct in¬ fluence of the solar rays. This is the configuration of the land and sea upon the globe, giving rise, by the different action of the sun’s rays upon solid and liquid masses, to the numberless variations of condition in the atmosphere surrounding them, and by the irregularities of height of the earth’s surface to the diverse conditions of ex¬ posure of this surface to all these atmospheric con¬ ditions.

Heated water is lighter than cold; therefore the surface of the ocean, warmed by the sun, remains comparatively unchanged, and being a bad conductor, the heat is but

] 4

HEAT OF CLIMATES.

slowly transmitted to the lower parts ; but the agita¬ tion of the waves tends to ecpialize the heat over larger surfaces, and evaporation contributes much to check the increase of the temperature ; the mass of water is thus but slowly heated. At night, when the sun leaves the sea, the heat radiating from its surface renders this cooler, the cooled particles descend and give place to warmer particles rising from below, so that a continued source of warmth is exposed to the air in contact with the surface, while the bad conducting power of the aqueous vapour also retards the cooling; therefore neither in day nor night is there great excess of temperature.

With the land it is different. The solid surface ab¬ sorbing readily, growrs hotter and hotter beneath the sun’s rays, since no motion takes place to equalize the distri¬ bution of the heat. At night the radiation or cooling is equally rapid, and the clearer the atmosphere, the less moisture present in it, the more freely does this go on, since the heated air rises uninterruptedly from the surface, to be replaced by the cold bright air from above, or cooler neighbouring regions. The atmosphere of the sea then has a more equable condition of heat than that of the land, and it should follow from this that the two extremes must lie on the open ocean and in the interior of large continents, and that we ought to find gradations between the conditions according to the intermediate position of points at which we make our observations. And we are in possession of abundant facts disclosing a striking con¬ trast between the continental and maritime climates, and explaining some of the most remarkable contradictions to the first supposition, that the temperature would be proportionate to the distance from the sun, the primary source of heat.

HEAT OF CLIMATES.

In these investigations, however, the interfering causes prove to be so numerous, that the observation of existing temperatures is only a first step toward a much wider field of research ; and the apparent anomalies require a very extended examination of the physical phenomena of the globe in order even to their partial elucidation. Some of them it will be necessary to examine before we can acquire any satisfactory understanding of the climate of Europe, but in the first place we will take the facts of the existing temperatures.

The phenomena of heat upon the globe have been greatly studied, and, aided by the developments of those principles laid down by Humboldt, which have occupied so much of the attention of meteorologists and naturalists of late years, we are able to obtain a very satisfactory view of the absolute and relative climates of different parts of Europe without much difficulty.

The observations of temperature obtained by the ther¬ mometer, and continued over long series of years, afford the data for characterizing the heat of the climate ; but in their condition of long catalogues of facts, indicated by figures, they are but the crude, though indispensable materials for simpler and more general statements. The first process to be applied to them is that of obtaining averages or means ; that is to say, of extracting from a set of observations of thermometric degrees an inter¬ mediate figure by which the combined or ultimate result of the whole is expressed. Thus to obtain the mean temperature of a day, say by hourly observation, the degrees marked at each hour are added together and divided by twenty-four, the quotient of which indicates the average amount received, since all the figures above that number are regarded as balancing or neutralizing

ANNUAL TEMPERATURES.

those below it. It is found, in practice, that a suffi¬ ciently accurate mean temperature for the day can be obtained by an observation of the highest and the lowest degrees indicated by the thermometer in the twenty-four hours ; the intermediate number derived from these two is near enough to the average of observations carried on through the twenty-four hours.

The first attempt to establish a systematic comparison between the temperatures of different climates was made by Humboldt, who obtained for this purpose a number of annual mean temperatures, deduced in a similar way from daily observations carried on through a series of years. In order to demonstrate the relations of these clearly, he proceeded to lay down upon a map lines con¬ necting all those places together which have the same mean annual temperature ; these he called isothermal lines, or lines of equal heat, and, as is seen by a glance at the map, they at once declared themselves to be under the most evident influence of the distribution of land and water, and in a great degree independent of the parallels of latitude in the northern hemisphere, an independence however most marked as they approach the pole, and becoming less and less observable toward the neighbour¬ hood of the equator ; yet even there bearing witness of the greater influence of the absorbing and radiating power of solid matter, by the advance of the thermal equator, or line of greatest annual heat on the globe, almost wholly to the north side of the terrestrial equator.

The line indicating the points where the cold is so intense that the ground is permanently frozen, leaves the eastern coast of Labrador at about 54° N.L. and runs up to a point more than 6° further north, near the south coast of Greenland. Thence extending obliquely toward

ANNUAL TEMPERATURES.

the pole, skirting Iceland, it strikes the north coast of Lapland beyond 70° N.L., more than 16° nearer the pole than the point where it left the American continent. It then goes south again more than 15° as it gradually sweeps across Lapland and Siberia, whence it extends up north, reaching the western coast of N. America, there again to be deflected. According to the researches of Prof. Dove, the region of the greatest cold upon the earth, in January, is a tongue-shaped strip extending down from the pole to below Yakutsk in Siberia, within which the temperature has a mean of 44° below zero, Fahr., in that month.

It is unnecessary, however, to travel so far north to acquire striking instances of the irregularities of the curves of mean annual temperature. The isotherms of Canada pass through Iceland, across about the middle of Norway and Sweden, St. Petersburg and Kamtscliatka. Those of New York through the north of Ireland and En¬ gland, 12° further north, N. and Cent. Germany, and the Crimea. That which leaves the United States at about 36° N.L., crosses Southern Europe from the north of Spain to the Adriatic in a tolerably straight line, some 8° further north, and then falls south again, where the influence of the north-east polar current is more felt, in Greece and Turkey.

But if we depend upon these annual means for our ideas of the climates of different regions, we derive very erroneous impressions of their true nature. I have already spoken of the discrepancies between the coast and con¬ tinental climates, arising from the constancy of the one and the excessive character of the other. And annual means are most directly open to this error ; for suppo¬ sing that any place had a daily mean of 60° all the year