Ecosystem

“ Even the recent ice ages did not result in a diminution of species.
The Biosphere of our earth is Eco Island on a global scale, made up of an almost infinite number of sub-systems: as a natural ecosystem, the Biosphere is a Viable Ecosystem.
3.9 REAL ECOLOGY: HUMAN SOCIETY
The Natural Ecosystem defines the natural environment; that is, the described environment without human society. But in reality, as we have already made clear, human society has to be added to the ecological equation. ”

“ It is difficult to analyse natural Ecosystems as total and self-contained entities, in order to understand the dynamics of the natural relationships that are the subject matter of ecology. In reality Ecosystems consist of many inter-related cycles that link one with another, so that in the end there is only one Ecosystem, and that is the Biosphere. ”

“ Thus the present state of the ecological resources and land-uses of any country or region are best understood in terms of:
the natural ecosystems; human economic impact; society; and the resulting human landscape.
3.4 LANDSCAPES ARE ALIVE
Ecology recognises that landscapes are alive. There is a dynamic relationship between their components, so that the landscape is always changing: not for one minute does it stay the same. Thus in ecology, landscapes are classified not just in terms of the components we have described, but in terms of life. ”

“ Principle 2 The natural resources of the earth, including the air, water, land, flora and fauna and especially representative samples of natural ecosystems, must be safeguarded for the benefit of present and future generations through careful planning or management, as appropriate. ”

“ The landscapes that we see around us today are the visible manifestations of human ecosystems: the concepts of 'wild landscapes' or 'natural landscapes' that imply some sort of landscape that has evolved without the aid of people is nonsense.
For the greater part of our history, people have lived in ecological balance with the environment. We lived as viable people exploiting the ecosystems of which we were part in a sustainable manner. Thus our ecosystems remained healthy and were able to continue to supply the resources that we required from them. ”

“ Larger ecosystems or combinations of ecosystems, which occur in similar climates and share a similar character and arrangement of vegetation, are biomes. The Arctic tundra, prairie grasslands, and the desert are examples. ”

“ Ecology is the science of the intricate web of relationships between living organisms and their living and nonliving surroundings. These interdependent living and nonliving parts make up ecosystems. Forests, lakes, and estuaries are examples. ”

“ Where the bigger trees have been removed, where some of the populations of the larger animals are reduced or extinct, and where other forest products are exploited to some degree, these are forest ecosystems which operate much as natural forests. ”

“ Associated with these various land forms is a progression of ecosystems representing a continuum of communities from the boreal spruce forest and riparian shrub thickets in the south to the arctic tussock tundra in the north. These communities of plants and undisturbed animals offer excellent opportunities for study of natural interaction of the species. ”

“ The cutting down and washing of the [Pg 28] lands, the draining and filling of depressions, the flooding of the lands, the destruction (or succession) of plant and animal associations (including crop rotation) , are processes brought about or practiced by other organisms or animal agencies. An ecological standpoint gives us a consistent, comprehensive orientation of all these natural and “artificial” activities and processes, and shows the unity in all organic responses to the environment. Man’s influence in the main consists of hastening or retarding “natural processes.” ”

“ 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. ”

“ This home economy of plants, or how they meet the environment and each other, is called Plant Ecology, a phase of botany now much studied, for it tells us more directly than most other plant research what the actual response to various factors of the environment may be. Just as plant distribution is the reflection of many, usually widely operating forces, so ecology narrows down to individual plants or groups of them the impact of the immediately surrounding conditions upon vegetation. ”

“ With such an understanding of the general rules of the game we may turn to the application or art of ecology, to indicate its relation to general problems. With a grounding in the general principles of organic response to the total environment, one is able to see that the disturbances due to man are a problem in the adjustment of the highest type of animal, as a member of an animal association, to its complete environment. The “control of nature” for which men strive is the process of making the environments and associations to order. ”

“ The vegetation form of the invading species is often of the greatest importance in determining whether it will become established. The vegetation form represents those modifications which, produced in the original home by competition, i. e., the struggle for existence, are primarily of value in securing and maintaining a foothold. These comprise all structures by means of which the plant occupies a definite space in the air, through which the necessary light and heat reach it, and in the soil, from which it draws its food supply. ”

“ Where any one of these conditions is not supplied, the existence of life, whether animal or vegetable, becomes impossible; where it is insufficiently supplied, life is {256} proportionally enfeebled or repressed. But, to limit our consideration to the vegetable kingdom, it may be observed, that where a loose and deep soil affords an abundant supply of food, where a genial climate diffuses warmth in an adequate degree, and where a favourable exposure allows a competent access of light (for air, being fully and universally given, may be thrown out of the case) ”

“ 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. ”

“ We walk to the water's edge and here he shows me Green scum, or stalks, or sedges, grasses, shrubs, That yield to trees beyond the levels, where The beech and oak have triumph; for along This gradual growth from algae, reeds and grasses, That builds the soil against the water's hands, All things are fierce for place and garner life From weaker things. And then he shows me root stocks, And Alpine willow, growths that sneak and crawl Beneath the soil. ”

“ Soils and climate determine vegetation, but clearly, also, vegetation influences the soil: change the vegetation from forest to plantation and you will thereby change the nature of the soil. The climate, hydrology and vegetation are able to determine what sort of aquatic and terrestrial animal communities live in an area.
Animals also influence vegetation by their eating habits. They influence the soil by the deposition of their waste products on to it, by burrowing into it and, at death, by becoming part of it. ”

“ First a reef is formed; seeds are wafted to it, vegetation springs up, a verdant island exists; then man takes possession, and a colony is formed.
Dig down into the earth, and from a hundred yards deep, throw up a portion of soil—cover it so that no communication can take place between that earth and the surrounding air. Soon you will observe vegetation springing up—perhaps new plants, altogether unlike any thing heretofore grown in that neighborhood. During how many thousands of years has the vitality of these seeds been preserved deep in the earth's bosom! ”

“ Organic Changes as affecting Distribution.—We have now briefly touched on some of the direct effects of changes in physical geography, climate, and vegetation, on the distribution of animals; but the indirect effects of such changes are probably of quite equal, if not of greater importance. Every change becomes the centre of an ever-widening circle of effects. The different members of the organic world are so bound together by complex relations, that any one change generally involves numerous other changes, often of the most unexpected kind. ”

“ On the plants the animals feed, and so this vast assemblage of organisms is maintained. Not only does the land life maintain itself on the soil, and give much to the sea, but it serves in various ways to protect this detrital coating from too rapid destruction, and to improve its quality. To see the nature of this work we should visit a region where primeval forests still lie upon the slopes of a hilly region. ”

“ 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 ”

“ In any long-settled, long-cultivated tract of country, the modification which has been brought about by human agency is, of necessity, very considerable. Around the place where man fixes his dwelling swamps, moors, and woods disappear to make way for cultivated fields, roads, and gardens: the bog, heath, and shade-loving plants are restricted in their range or altogether exterminated; and the places which these occupied are filled up by the species which man grows for food or other purposes and the weeds which these bring in their train. ”

“ A goldfish placed in a small glass jar with no food or no green water plants soon seeks the surface of the water, and if the water is not changed frequently so as to supply air the fish will die. Again the artificial environment lacks something that the fish needs. Each plant and animal is limited to a certain environment because of certain individual needs which make the surroundings fit for it to live in.
Changes in Environment.—Most plants and animals do not change their environment. ”

“ In contrast with this is the method of artificial habitats, in which the habitat itself is definitely modified, or a group of species actually transferred to a different habitat. Many problems of vegetation can be attacked with greater success under control than in the field. This is particularly true of competition, in which results can be obtained most readily by means of the method of control habitats, as carried on in the plant house. ”

“ For, as species spread themselves gradually over the globe, they are exposed from time to time to variations in climate, and to changes in the quantity and quality of their food; they meet with new plants and animals which 575 assist or retard their development, by supplying them with nutriment, or destroying their foes. The nature, also, of each locality, is in itself fluctuating; so that, even if the relation of other animals and plants were invariable, the habits and organization of species would be modified by the influence of local revolutions. ”

“ Or, as in the slow development of a forest, the growth of the trees themselves can change the environment, the maturity of one species whose seedlings require sunlight contributing to the growth of those better adapted to shade. If you should watch an old abandoned pasture over a period of many years, you could see environment gradually altered. First there are the mosses and grasses that create a fertile soil. ”

“ Making all due allowance for the astonishing influence exercised by winds, waves, and the migration of animals over the diffusion of vegetable species, yet the means of transport by the ocean or by currents of water is confined within narrow limits, and under the most favourable conditions is limited to the very few plants which can maintain their powers of reproduction uninjured by immersion in water, and those on the other hand which, on being transported to a strange shore, find there the means of existence and increase. ”

“ It seemed to him incredible that the well-defined and practically so important distinctions based on natural vegetation, everywhere recognized and continually acted upon by farmers and settlers, should not be traceable to definite physical and chemical differences in the respective lands, by competent, comprehensively-trained scientific observers, whose field of vision should be broad enough to embrace concurrently the several points of view—geological, physical, chemical and botanical—that must be conjointly considered in forming one’s judgment of land. ”

“ Everywhere and at all times multiplication of species was promoted by facilities for expansion. The great limestones of our continents, full of corals and shells of new species, belong to times when the ocean spread itself over the continental plateaus, affording wide, untenanted areas of warm and shallow water. The introduction of new faunas and floras on the land belongs to times when vast supplies of food for plants and animals and favourable conditions of existence were afforded by the emergence of new lands possessing fertile soils and abundantly supplied with light, heat, and moisture. ”

“ We have seen, that, with this system of animal and vegetable economy, which depends on soil and climate, there is also a system of moving water, poured upon the surface of the earth30, in the most beneficial manner possible for the use of vegetation, and the preservation of our soil ”