Habitat

“ In fact the whole work of the introduction and diffusion of valuable food-animals in territory not naturally included in the habitat of the species is based on our knowledge that the habitat of a species is often determined by physical barriers rather than by exclusive fitness of environment. Within the natural habitat the environment is fit for the species' existence, outside of it the environment may be fit. ”

“ The factors of a habitat are water-content, humidity, light, temperature, soil, wind, precipitation, pressure, altitude, exposure, slope, surface (cover) , and animals. To these should be added gravity and polarity, which are practically uniform for all habitats, and may, in consequence, be ignored in this treatise. Length of season, while it plays an important part in vegetation, is clearly a complex and is to be treated under its constituents. Of the factors given, all are regularly found in each habitat, though some are not constantly present. ”

“ Ecology and Physiology.—Whilst our knowledge of the nature and effect of habitat is still in a very rudimentary condition, much progress has been made in recent years in the study of plant communities, but even here the questions involved in relating the facts of the distribution of plant communities to the factors of the habitat are very imperfectly understood. ”

“ What seabird cliffs, islands, lagoons, wetlands, river mouths, and other habitat features are of first importance for breeding or for maintaining the populations? Some small areas of habitat are critical for the survival of some species during periods of stress. Those habitats need official recognition. Steps are needed to ensure that the habitats are maintained.
2. What physical expressions of economic development are of little, modest, or serious impact on wildlife and its habitat? ”

“ A society is in entire correspondence with the physical factors of its area, and the same is true of the vegetation of a province. Nevertheless, many societies usually occur in a single habitat, and a province contains many habitats. The final test of a habitat is an efficient difference in one or more of the direct factors, water-content, humidity, and light, by virtue of which the plant covering differs in structure and in species from the areas contiguous to it. ”

“ This spectrum of interconnected vegetation types provides essential habitat for wildlife, ranging from large, charismatic animals to less visible and less familiar forms of life, such as fungi and insects. ”

“ This necessarily presupposes a certain preliminary acquaintance with the habitat to be investigated, as it is imperative that the station for making readings be located well within the formation, in order to avoid transition conditions. In vegetation, there are as many habitats as formations, and in addition a large number of new and denuded habitats upon which successions have not yet started; a knowledge of each formation or succession must rest ultimately upon the factors of its particular habitat. ”

“ Its habitat is in a land where plums grow with the stones outside, where aboriginal dogs have never been heard to bark, where birds are found covered with hair, and where mammals jump about like frogs! ”

“ Methods. All field experiments in evolution are based upon a change of habitat. The latter is accomplished by the modification of the habitat itself, or by the transfer of the species to one or more different habitats, or to different areas of the same habitat. ”

“ The physiographic factors of a definite habitat are altitude, exposure, slope, and surface. In addition, topography is a general though less tangible factor of regions, while the dynamic forces of weathering, 81erosion and sedimentation play a fundamental role in the change of habitats. ”

“ Modification of habitat. As the final factors in ecesis and competition, water, light, and temperature control the grouping of plants into vegetation. An efficient change in one of these, or in all of them, brings about a visible adjustment in the structure of the plant group concerned. Modifications 308of water-content and light are readily produced in the field by drainage, irrigation, shading, clearing, etc. In fact, all the changes of habitat indicated under experimental evolution serve equally well to initiate experiments in experimental vegetation ”

“ As time went on, through the constant changes that the surface of the globe is undergoing, one variety would be isolated from another, and in such an isolation the differences would increase. And the more a species27 varied, the more fitted it might become for some habitat, from which it was completely cut off by a chain of mountains, a rapid river, or a deep sea. ”

“ A few undoubted examples of adaptation of groups to special environment are of birds to aërial habitat, of fishes to water, of rodents to hard foods, and of squirrels to arboreal seeds with hard coverings. ”

“ But where is that favoured land?—It is in that great continent to whose distant shores Europe has sent forth her adventurous sons, to wrest for themselves a habitation from the wild inhabitants of the forest, and to convert the neglected soil into fields of exuberant fertility. ”

“ Professor H. F. Osborn points out that mammals may seek any one of the twelve different habitat-zones, and that in each of these there may be six quite different kinds of food. Living creatures penetrate everywhere like the overflowing waters of a great river in flood. ”

“ Such factors are not themselves susceptible of exact measurement, but their influence upon the habitat is usually measurable in terms of the physical factors affected. In the case 87of biotic factors, it must be distinctly understood that these are not properly factors of the habitat as a physical complex, but that they are rather to be considered as reactions exerted by the effect, or formation, upon the cause or habitat. This is most especially true of plants.
129. Animals. The activities of man fall into two classes: (1) those that destroy vegetation, and (2) those that modify it. ”

“ Abundant nourishment and good weather favour the increase of all animals, and affect that of a few plant-eating mammals to such an extraordinary degree, that, even under propitious conditions, their habitat must be extended. ”

“ Some walk upright, others crawl upon the ground; others burrow into the earth, and form their habitation under the surface; others fly aloft, and traverse the air in every direction; others swim in the waters. Throughout the whole of creation, every part is the habitation of some animal, or reptile, or insect. Even in the woods, among the leaves of the trees, in the fruits they bear, in the earth from whence they grow, nay, even among the stones, there are some living things. ”

“ The route which they follow is a succession of habitats, in which they linger and domicile themselves for a while, though not long enough to lose wholly the habits of life and thought acquired in their previous dwelling place. ”

“ Upon the whole then we are driven to the conclusion, that if the special creation theory is true, the various plants and animals have not been placed in the various habitats which they occupy with any reference to the suitability of these habitats to the organisations of these particular plants and animals. ”

“ These, though slow, must be universal—must affect the habitats of stationary organisms as well as those of locomotive ones. For if, during an astronomic era, there is going on at any limit to a plant's habitat, a diminution of the winter's cold or summer's heat, which {501}had before stopped its spread at that limit; then, though the individual plants are fixed, yet the species will move: the seeds of plants living at the limit, will produce individuals which survive beyond the limit. ”

“ In such habitats exist animals having, in various degrees, the power to live in both media, consequent on various phases of transitional organization. Near akin to these animals, there are some that, after passing their early lives in the water, acquire more completely the structures fitting them to live on land, to which they then migrate. ”

“ Now just as the yearly changes in the amounts of light and heat falling on each locality, yearly extend and restrict the habitats of many organisms which are able to move about with some rapidity; so must the alterations of temperate and intemperate climates produce extensions and restrictions of habitats. ”

“ For though every environment on the Earth's surface undergoes changes; and though usually the organisms which each environment contains, cannot escape certain resulting new influences; yet occasionally such new influences are escaped, by the survival of species in the unchanged parts of their habitats, or by their spread into neighbouring habitats which the change has rendered like their original habitats, or by both. Any alteration in the temperature of a climate or its degree of humidity, is unlikely to affect simultaneously the whole area occupied by a species ”

“ The animal ecology of a particular region can only be properly investigated after the habitats and plant formations have been carefully studied. Here, as in floristics, a great deal can be done in the way of listing the fauna, or studying the life habits of its species, without any knowledge of plant ecology; but an adequate study must be based upon a knowledge of the vegetation. Although animal formations are often poorly defined, there can be no doubt of their existence. Frequently they coincide with plant formations, and then have very definite limits. ”

“ On the other hand, we have areas remote from each other in latitude, and contrasted in soil as well as climate, which are occupied by closely-allied Faunas." Whence it was inferred that "as like organisms are not universally, or even generally, found in like habitats; nor very unlike organisms, in very unlike habitats; there is no manifest pre-determined adaptation of the organisms to the habitats." ”

“ What is said of the dissemination of fish, shells, and reptiles may be consistently said of vegetation.
The earth is filled with the seed of every plant and tree and shrub that ever sprang into life in any place, clime or time. Dig to whatever depth [76] you will, the substance you throw out, whether earth or stone, when exposed to the air, will produce some growth of vegetation. Frequently something entirely new and different from the surrounding vegetation. ”

“ Such are the elements of the scenery, but it is a hopeless attempt to paint the general effect. Learned naturalists describe these scenes of the tropics by naming a multitude of objects, and mentioning some characteristic feature of each. To a learned traveller this possibly may communicate some definite ideas: but who else from seeing a plant in an herbarium can imagine its appearance when growing in its native soil? Who from seeing choice plants in a hothouse, can magnify some into the dimensions of forest trees, and crowd others into an entangled jungle? ”

“ Section II.—On Fowls. Number of Species — Superiority and peculiar Construction — Skill in building their Nests — Power and season of Propagation — Dexterity in providing Food — Instinct — Migrations — Insects — Religious Improvement.
Not any part of nature is destitute of inhabitants. The woods, the waters, the depths of the earth, have their respective tenants; while the transparent and elastic air, and those regions where man can never soar, but with much art and at considerable risk, are occupied with the most beautiful creatures. Every order of animals is fitted for its situation in life ”

“ Let us consider, in the first place, the chances for the preservation of remains of the present fauna and flora of a country. The surface of the land may be densely clothed with forest and abundantly peopled with animal life. But the trees die and moulder into soil. The animals, too, disappear, generation after generation, and leave few or no perceptible traces of their existence. ”

“ Give these plants the least bit of fair play as regards environment—a sheltered glen, or the shores of a loch or firth, where there is sufficient moisture, plenty of sun, and good soil enriched by the water running down from the wonderful bird cliffs inhabited by hundreds of thousands if not millions of birds, or by the droppings of reindeer, musk-oxen, and other animals, and a veritable paradise of verdure is produced. ”

“ The specific identity, to any extent, of the flora and fauna of one area with those of another, depends on both areas forming, or having formed, part of the same specific centre, or on their having derived their animal and vegetable population by transmission, through migration, over continuous or closely contiguous land, aided, in the case of alpine floras, by transportation on floating masses of ice. ”

“ To understand rightly the daily accumulating stores of organic reliquiæ, requires more than a slight knowledge of existing nature,—more even than an acquaintance with animal and vegetable forms. The philosophy of their existence must be considered—the variations of their structure, with respiration in air or in water—life in fresh or salt water—in trees or on the ground—carnivorous or herbivorous food—their geographical distribution dependence—on climate and atmospheric conditions. ”

“ Apart from botany, the physical side of ecology is largely a question of soil physics, and of physiography. On the other hand, vegetation is coming more and more to be regarded as a fundamental factor in zoogeography and in sociology. Furthermore, with respect to the latter, it will be pointed out below that the principles of association which have been determined for plants, viz., invasion, succession, zonation, and alternation, apply with almost equal force to man. ”

“ This facies depends on combinations of colour, sculpture, texture, and often minute and insignificant characters, when regarded separately, but when presented in coordination, becoming of importance through their constancy and their influence in determining the leading features of a fauna or flora, or both combined. Even when comparatively few of the characteristic animal and vegetable types of a province are brought together, within a limited space, some notion may thus be conveyed to the spectator of the facies, or aspect of life in that region. ”