Here is a compilation of essays on ‘Ecology’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Ecology’ especially written for school and college students.
Essay on Ecology
- Essay on Ecology: History and Relevance to Humankind
- Essay on the Levels-of-Organization Hierarchy
- Essay on the Emergent Property Principle of Ecology
- Essay on Transcending Functions and Control Processes of Ecology
- Essay on Ecological Interfacing
- Essay on Disciplinary Reductionism to Trans-Disciplinary Holism
Essay # 1. Ecology: History and Relevance to Humankind:
The word ecology is derived from the Greek oikos, meaning “household,” and logos, meaning “study.” Thus, the study of the environmental house includes all the organisms in it and all the functional processes that make the house habitable. Literally, then, ecology is the study of “life at home” with emphasis on “the totality or pattern of relations between organisms and their environment,” to cite a standard dictionary definition of the word.
The word economics is also derived from the Greek root oikos. As nomics means “management,” economics translates as “the management of the household” and, accordingly, ecology and economics should be companion disciplines. Unfortunately, many people view ecologists and economists as adversaries with antithetical visions.
Ecology was of practical interest early in human history. In primitive society, all individuals needed to know their environment—that is, to understand the forces of nature and the plants and animals around them—to survive. The beginning of civilization, in fact, coincided with the use of fire and other tools to modify the environment.
Because of technological achievements, humans seem to depend less on the natural environment for their daily needs; many of us forget our continuing dependence on nature for air, water, and indirectly, food, not to mention waste assimilation, recreation, and many other services supplied by nature. Also, economic systems, of whatever political ideology, value things made by human beings that primarily benefit the individual, but they place little monetary value on the goods and services of nature that benefit us as a society.
Until there is a crisis, humans tend to take natural goods and services for granted; we assume they are unlimited or somehow replaceable by technological innovations, even though we know that life necessities such as oxygen and water may be recyclable but not replaceable. As long as the life-support services are considered free, they have no value in current market systems.
Like all phases of learning, the science of ecology has had a gradual if spasmodic development during recorded history. The writings of Hippocrates, Aristotle, and other philosophers of ancient Greece clearly contain references to ecological topics. However, the Greeks did not have a word for ecology. The word ecology is of recent origin, having been first proposed by the German biologist Ernst Haeckel in 1869. Haeckel defined ecology as “the study of the natural environment including the relations of organisms to one another and to their surroundings”.
Before this, during a biological renaissance in the eighteenth and nineteenth centuries, many scholars had contributed to the subject, even though the word ecology was not in use. For example, in the early 1700s, Antoni van Leeuwenhoek, best known as a premier micro-scopist, also pioneered the study of food chains and population regulation, and the writings of the English botanist Richard Bradley revealed his understanding of biological productivity. All three of these subjects are important areas of modern ecology.
As a recognized, distinct field of science, ecology dates from about 1900, but only in the past few decades has the word become part of the general vocabulary. At first, the field was rather sharply divided along taxonomic lines (such as plant ecology and animal ecology), but the biotic community concept of Frederick E. Clements and Victor E. Shelford, the food chain and material cycling concepts of Raymond Linde-man and G. Evelyn Hutchinson, and the whole lake studies of Edward A. Birge and Chauncy Juday, among others, helped establish basic theory for a unified field of general ecology.
What can best be described as a worldwide environmental awareness movement burst upon the scene during two years, 1968 to 1970, as astronauts took the first photographs of Earth as seen from outer space. For the first time in human history, we were able to see Earth as a whole and to realize how alone and fragile Earth hovers in space. Suddenly, during the 1970s, almost everyone became concerned about pollution, natural areas, population growth, food and energy consumption, and biotic diversity, as indicated by the wide coverage of environmental concerns in the popular press.
The 1970s were frequently referred to as the “decade of the environment,” initiated by the first “Earth Day” on 22 April 1970. Then, in the 1980s and 1990s, environmental issues were pushed into the political background by concerns for human relations—problems such as crime, the cold war, government budgets, and welfare.
As we enter the early stages of the twenty-first century, environmental concerns are again coming to the forefront because human abuse of Earth continues to escalate. We hope that this time, to use a medical analogy, our emphasis will be on prevention rather than on treatment, and ecology can contribute a great deal to prevention technology and ecosystem health.
The increase in public attention had a profound effect on academic ecology. Before the 1970s, ecology was viewed largely as a sub-discipline of biology. Ecologists were staffed in biology departments, and ecology courses were generally found only in the biological science curricula. Although ecology remains strongly rooted in biology, it has emerged from biology as an essentially new, integrative discipline that links physical and biological processes and forms a bridge between the natural sciences and the social sciences.
Most colleges now offer campus-wide courses and have separate majors, departments, schools, centers, or institutes of ecology. While the scope of ecology is expanding, the study of how individual organisms and species interface and use resources intensifies. The multilevel approach, as outlined in the next section, brings together “evolutionary” and “systems” thinking, two approaches that have tended to divide the field in recent years.
Essay # 2. Levels-of-Organization Hierarchy:
Perhaps the best way to delimit modern ecology is to consider the concept of levels of organization, visualized as an ecological spectrum (Fig. 1-2) and as an extended ecological hierarchy (Fig. 1-3). Hierarchy means “an arrangement into a graded series”. Interaction with the physical environment (energy and matter) at each level produces characteristic functional systems.
A system, according to a standard definition, consists of “regularly interacting and interdependent components forming a unified whole”. Systems containing living (biotic) and nonliving (abiotic) components constitute bio-systems, ranging from genetic systems to ecological systems.
This spectrum may be conceived of or studied at any level, as illustrated in Figure 1-2, or at any intermediate position convenient or practical for analysis. For example, host-parasite systems or a two-species system of mutually linked organisms (such as the fungi-algae partnership that constitutes the lichen) are intermediate levels between population and community.
Ecology is largely, but not entirely, concerned with the system levels beyond that of the organism. In ecology, the term population, originally coined to denote a group of people, is broadened to include groups of individuals of any one kind of organism. Likewise, community, in the ecological sense (sometimes designated as “biotic community”), includes all the populations occupying a given area.
The community and the nonliving environment function together as an ecological system or ecosystem. Biocoenosis and biogeocoenosis (literally, “life and Earth functioning together”), terms frequently used in European and Russian literature, are roughly equivalent to community and ecosystem, respectively.
Referring again to Figure 1-3, the next level in the ecological hierarchy is the landscape, a term originally referring to a painting and defined as “an expanse of scenery seen by the eye as one view”. In ecology, landscape is defined as a “heterogonous area composed of a cluster of interacting ecosystems that are repeated in a similar manner throughout”.
A watershed is a convenient landscape-level unit for large-scale study and management because it usually has identifiable natural boundaries. Biome is a term in wide use for a large regional or sub-continental system characterized by a major vegetation type or other identifying landscape aspect, as, for example, the Temperate Deciduous Forest biome or the Continental Shelf Ocean biome. A region is a large geological or political area that may contain more than one biome—for example, the regions of the Midwest, the Appalachian Mountains, or the Pacific Coast.
The largest and most nearly self-sufficient biological system is often designated as the ecosphere, which includes all the living organisms of Earth interacting with the physical environment as a whole to maintain a self-adjusting, loosely controlled pulsing state.
Hierarchical theory provides a convenient framework for subdividing and examining complex situations or extensive gradients, but it is more than just a useful rank-order classification. It is a holistic approach to understanding and dealing with complex situations, and is an alternative to the reductionist approach of seeking answers by reducing problems to lower-level analysis.
More than 50 years ago, Novikoff (1945) pointed out that there is both continuity and discontinuity in the evolution of the universe. Development may be viewed as continuous because it involves never-ending change, but it is also discontinuous because it passes through a series of different levels of organization.
Thus, dividing a graded series, or hierarchy, into components is in many cases arbitrary, but sometimes subdivisions can be based on natural discontinuities. Because each level in the levels-of-organization spectrum is “integrated” or interdependent with other levels, there can be no sharp lines or breaks in a functional sense, not even between organism and population.
The individual organism, for example, cannot survive for long without its population, any more than the organ would be able to survive for long as a self-perpetuating unit without its organism. Similarly, the community cannot exist without the cycling of materials and the flow of energy in the ecosystem. This argument is applicable to the previously discussed mistaken notion that human civilization can exist separately from the natural world.
It is very important to emphasize that hierarchies in nature are nested—that is, each level is made up of groups of lower-level units (populations are composed of groups of organisms, for example). In sharp contrast, human-organized hierarchies in governments, co-operations, universities, or the military are no nested (sergeants are not composed of groups of privates, for example). Accordingly, human-organized hierarchies tend to be more rigid and more sharply separated as compared to natural levels of organization. For more on hierarchical theory, see T. F. H. Allen and Starr (1982), O’Neill et al. (1986), and Ahl and Allen (1996).
Essay # 3. The Emergent Property Principle of Ecology:
An important consequence of hierarchical organization is that as components, or subsets, are combined to produce larger functional wholes, new properties emerge that were not present at the level below. Accordingly, an emergent property of an ecological level or unit cannot be predicted from the study of the components of that level or unit.
Another way to express the same concept is non-reducible property— that is, a property of the whole not reducible to the sum of the properties of the parts. Though findings at any one level aid in the study of the next level, they never completely explain the phenomena occurring at the next level, which must itself be studied to complete the picture.
Two examples, one from the physical realm and one from the ecological realm, will suffice to illustrate emergent properties. When hydrogen and oxygen are combined in a certain molecular configuration, water is formed—a liquid with properties utterly different from those of its gaseous components.
When certain algae and coelenterate animals evolve together to produce a coral, an efficient nutrient cycling mechanism is created that enables the combined system to maintain a high rate of productivity in waters with a very low nutrient content. Thus, the fabulous productivity and diversity of coral reefs are emergent properties only at the level of the reef community.
Salt (1979) suggested that a distinction be made between emergent properties, as defined previously, and collective properties, which are summations of the behavior of components. Both are properties of the whole, but the collective properties do not involve new or unique characteristics resulting from the functioning of the whole unit. Birth rate is an example of a population level collective property, as it is merely a sum of the individual births in a designated time period, expressed as a fraction or percent of the total number of individuals in the population.
New properties emerge because the components interact, not because the basic nature of the components is changed. Parts are not “melted down,” as it were, but integrated to produce unique new properties. It can be demonstrated mathematically that integrative hierarchies evolve more rapidly from their constituents than nonhierarchical systems with the same number of elements; they are also more resilient in response to disturbance. Theoretically, when hierarchies are decomposed to their various levels of subsystems, the latter can still interact and reorganize to achieve a higher level of complexity.
Some attributes, obviously, become more complex and variable as one proceeds to higher levels of organization, but often other attributes become less complex and less variable as one goes from the smaller to the larger unit. Because feedback mechanisms (checks and balances, forces and counterforces) operate throughout, the amplitude of oscillations tends to be reduced as smaller units function within larger units.
Statistically, the variance of the whole-system level property is less than the sum of the variance of the parts. For example, the rate of photosynthesis of a forest community is less variable than that of individual leaves or trees within the community, because when one component slows down, another component may speed up to compensate. When one considers both the emergent properties and the increasing homeostasis that develop at each level, not all component parts must be known before the whole can be understood.
This is an important point, because some contend that it is useless to try to work on complex populations and communities when the smaller units are not yet fully understood. Quite the contrary, one may begin study at any point in the spectrum, provided that adjacent levels, as well as the level in question, are considered, some attributes are predictable from parts (collective properties), but others are not (emergent properties). Ideally, a system-level study is itself a threefold hierarchy-system, sub-system (next level below), and supra system (next level above). For more on emergent properties, see T. F. H. Allen and Starr (1982), T. F. H. Allen and Hoekstra (1992), and Ahl and Allen (1996).
Each bio-system level has emergent properties and reduced variance as well as a summation of attributes of its subsystem components. The folk wisdom about the forest being more than just a collection of trees is, indeed, a first working principle of ecology. Although the philosophy of science has always been holistic in seeking to understand phenomena as a whole, in recent years the practice of science has become increasingly reductionist in seeking to understand phenomena by detailed study of smaller and smaller components.
Laszlo and Margenau (1972) described within the history of science an alternation of reductionist and holistic thinking (reductionism- constructionism and atomism-holism are other pairs of words used to contrast these philosophical approaches). The law of diminishing returns may very well be involved here, as excessive effort in any one direction eventually necessitates taking the other (or another) direction.
The reductionist approach that has dominated science and technology since Isaac Newton has made major contributions. For example, research at the cellular and molecular levels has established a firm basis for the future cure and prevention of cancers at the level of the organism. However, cell-level science will contribute very little to the well-being or survival of human civilization if we understand the higher levels of organization so inadequately that we can find no solutions to population overgrowth, pollution, and other forms of societal and environmental disorders.
Both holism and reductionism must be accorded equal value—and simultaneously, not alternatively. Ecology seeks synthesis, not separation. The revival of the holistic disciplines may be due at least partly to citizen dissatisfaction with the specialized scientist who cannot respond to the large-scale problems that need urgent attention. (Historian Lynn White’s 1980 essay “The Ecology of Our Science” is recommended reading on this viewpoint.)
Accordingly, we shall discuss ecological principles at the ecosystem level, with appropriate attention to organism, population, and community subsets and to landscape, biome, and ecosphere supra- sets.
Fortunately, in the past 10 years, technological advances have allowed humans to deal quantitatively with large, complex systems such as ecosystems and landscapes. Tracer methodology, mass chemistry (spectrometry, colorimetry, and chromatography), remote sensing, automatic monitoring, mathematic modeling, geographical information systems (GIS), and computer technology are providing the tools. Technology is, of course, a double-edged sword; it can be the means of understanding the wholeness of humans and nature or of destroying it.
Essay # 4. Transcending Functions and Control Processes of Ecology:
Whereas each level in the ecological hierarchy can be expected to have unique emergent and collective properties, there are basic functions that operate at all levels. Examples of such transcending functions are behavior, development, diversity, energetics, evolution, integration, and regulation (see Fig. 1-3 for details). Some of these (energetics, for example) operate the same throughout the hierarchy, but others differ in modus operandi at different levels. Natural selection evolution, for example, involves mutations and other direct genetic interactions at the organism level but indirect co-evolutionary and group selection processes at higher levels.
It is especially important to emphasize that although positive and negative feedback controls are universal, from the organism down, control is set point, in that it involves very exacting genetic, hormonal, and neural controls on growth and development, leading to what is often called homeostasis.
The term homeorhesis, from the Greek meaning “maintaining the flow,” has been suggested for this pulsing control. In other words, there are no equilibriums at the ecosystem and ecosphere levels, but there are pulsing balances, such as between production and respiration or between oxygen and carbon dioxide in the atmosphere. Failure to recognize this difference in cybernetics (the science dealing with mechanisms of control or regulation) has resulted in much confusion about the realities of the so-called “balance of nature.”
Essay # 5. Ecological Interfacing:
Because ecology is a broad, multilevel discipline, it interfaces well with traditional disciplines that tend to have more narrow focus. During the past decade, there has been a rapid rise of interface fields of study accompanied by new societies, journals, symposium volumes, books—and new careers. Others that are receiving a great deal of attention, especially in resource management, are agro-ecology, biodiversity, conservation ecology, ecological engineering, ecosystem health, ecotoxicology, environmental ethics, and restoration ecology.
In the beginning, an interface effort enriches the disciplines being interfaced. Lines of communication are established, and the expertise of narrowly trained “experts” in each field is expanded. However, for an interface field to become a new discipline, something new has to emerge, such as a new concept or technology. The concept of nonmarket goods and services, for example, was a new concept that emerged in ecological economics, but that initially neither traditional ecologists nor economists would put in their textbooks.
Natural capital is defined as the benefits and services supplied to human societies by natural ecosystems, or provided “free of cost” by unmanaged natural systems. These benefits and services include purification of water and air by natural processes, decomposition of wastes, maintenance of biodiversity, control of insect pests, pollination of crops, mitigation of floods, and provision of natural beauty and recreation, among others.
Economic capital is defined as the goods and services provided by humankind, or the human workforce, typically expressed as the gross national product (GNP). Gross national product is the total monetary value of all goods and services provided in a country during one year. Natural capital is typically quantified and expressed in units of energy, whereas economic capital is expressed in monetary units.
Only in recent years has there been an attempt to value the world’s ecosystem services and natural capital in monetary terms. Costanza, d’Arge, et al. (1997) estimated this value to be in the range of 16 to 54 trillion U.S. dollars per year for the entire biosphere, with an average of 33 trillion U.S. dollars per year. Thus it is wise to protect natural ecosystems, both ecologically and economically, because of the benefits and services they provide to human societies.
Essay # 6. Disciplinary Reductionism to Trans-Disciplinary Holism:
In a paper entitled “The Emergence of Ecology as a New Integrative Discipline,” E. P. Odum (1977) noted that ecology had become a new holistic discipline, having roots in the biological, physical, and social sciences, rather than just a sub-discipline of biology. Thus, a goal of ecology is to link the natural and social sciences. It should be noted that most disciplines and disciplinary approaches are based on increased specialization in isolation. The early evolution and development of ecology was frequently based on multidisciplinary approaches (multi = “many”), especially during the 1960s and 1970s.
Unfortunately, the multi-disciplinary approaches lacked cooperation or focus. To achieve cooperation and define goals, institutes or centers were established on campuses throughout the world, such as the Institute of Ecology located on the campus of the University of Georgia. These cross-disciplinary approaches frequently resulted in polarization toward a specific mono-disciplinary concept, a poorly funded administrative unit, or a narrow mission.
A cross-disciplinary approach also frequently resulted in polarized faculty reward systems. Institutions of higher learning, traditionally built on disciplinary structures, have difficulties in administering programs and addressing environmental problems as well as taking advantage of opportunities at greater temporal and spatial scales.
To address the dilemma, interdisciplinary approaches (inter = “among”) were employed, resulting in cooperation on a higher-level concept, problem, or question. For example, the process and study of natural ecological succession provided a higher-level concept resulting in the success of the Savannah River Ecological Laboratory (SREL) during its conception.
Researchers theorized that new system properties emerge during the course of ecosystem development and that it is these properties that largely account for species and growth form changes that occur. Today, interdisciplinary approaches are common when addressing problems at ecosystem, landscape, and global levels.
Much remains to be done, however, there is an increased need to solve problems, promote environmental literacy, and manage resources in a trans-disciplinary manner. This multilevel, large-scale approach involves entire education and innovation systems. This integrative approach to the need for unlocking cause-and- effect explanations across and among disciplines (achieving a trans-disciplinary understanding) has been termed consilience, sustainability science, and integrative science.
Actually, the continued development of the science of ecology (the “study of the household” or “place where we live”) will likely evolve into that much-needed integrative science of the future.