Ecology

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Ecology is the branch of science that studies habitats and the interactions between living things and the environment. The term was coined in 1866 by the darwinist German biologist Ernst Haeckel from the Greek oikos meaning "house" and logos meaning "science"). The environment includes both the abiotic environment -- non-living things like climate and geology -- and the biotic environment -- living things like plants and animals. Much of ecological research is concerned with the distribution and abundance of organisms and how these are influenced by characteristics and properties of the environment: organisms influence their environment and the environment influences organisms.

Usage of the term

A quite frequent definition, particularly used in human ecology defines ecology as the study of the following triangular relationship:

the relationship between individuals of a species -- for example, the study of a single rabbit, and how it relates to other rabbits, such as a high reproductive rate resulting in an increasing number of rabbits;
the organized activity of a species -- for example, the effect that increased food consumption by rabbits has on their environment, so that rabbits consume so much of the food supply that there is not enough food to sustain the population;
and the environment of this activity -- for example, the consequences of the environmental change on the rabbit, so that rabbits die out due to the above conditions -- thus the environment is at the same time the product and the condition of this activity and thus of the survival of the species.

The term ecology may mean different things depending on who is using it. For many scientists, ecology belongs to the basic biological sciences. However, most ecologists would argue that ecology is a scientific field of its own. For most non-scientsts, ecology is first and foremost the protection of nature and the environment from humans and our activities, with the sense that on one side are humans and on the other a virgin "Nature" to protect. A smaller number of people view ecology as more than biology as studied by science -- to them it is a certain vision of the world, which would consist in living in harmony with the other living beings, and in not seing the other organisms which surrounds us as mere objects to be used, but rather as organisations, entities belonging to a larger coherent system.

History of ecology

One of the first ecologists may have been Aristotle who was interested in many species of animals. He was followed by numerous naturalists such as Buffon and Linné, whose work is usually considered the origin of modern ecology.

Botanical geography and Alexander von Humbolt

Throughout the 18th and the beginning of the 19th century, the great maritime powers such as France and Germany, launched many world exploratory expeditions to develop maritime commerce with other countries, and to discover new natural resources, as well as to catalog them. At the beginning of the 18th century, about twenty thousand plant species were known, versus forty thousand at the beginning of the 19th, and almost 400,000 today.

These expeditions were joined by many scientists, including botanists, such as the German explorer Alexander von Humboldt. Humboldt is often considered the true father of ecology. He was the first to take on the study of the relationship between organisms and their environment. He exposed the existing relationships between observed plant species and climate, and described vegetation zones using latitude and altitude, a discipline now known as geobotany.

In 1804, for example, he reported an impressive number of species, particularly plants, for which he sought to explain their geographic distribution with respect to geological data. One of Humboldt's famous works was "Idea for a Plant Geography" (1805).

Other important botanists include Aimé Bonpland and Eugenius Warming.

The notion of biocenose: Darwin and Wallace

Towards 1850 there was a breakthrough in the field with the publishing of the work of Charles Darwin on The Origin of Species: Ecology passed from a repetitive, mechanical model to a biological, organic, and hence evolutionary model.

Alfred Russel Wallace, contemporary and competitor to Darwin, was first to propose a "geography" of animal species. Several authors recognized at the time that species were not independent of each other, and grouped them into plant species, animal species, and later into communities of living beings or biocenose. This term was coined in 1877 by Karl Möbius.

The biosphere - Eduard Suess and Vernadsky

By the 19th century, ecology blossomed due to new discoveries in chemistry by Lavoisier and de Saussure, notably the nitrogen cycle. After observing the fact that life developed only within strict limits of each compartment that makes up the atmosphere, hydrosphere, and lithosphere, the Austrian geologist Eduard Suess proposed the term biosphere in 1875. Suess proposed the name biosphere for the conditions promoting life, such as those found on Earth, which includes flora, fauna, minerals, matter cycles, et cetera.

In the 1920s Vladimir Ivanovitch Vernadsky, a Russian geologist who had defected to France, detailed the idea of the biosphere in his work "The biosphere" (1926), and described the fundamental principles of the biogeochemical cycles. He thus redefined the biosphere as the sum of all ecosystems.

First ecological damages were reported in the 18th century, as the multiplication of colonies caused deforestation. Since the 19th century, with the industrial revolution, more and more pressing concerns have grown about the impact of human activity on the environment. The term ecologist has been in use since the end of the 19th century.

The ecosystem concept and Arthur Tansley

Over the 19th century, botanical geography and zoogeography combined to form the basis of biogeography.
Biogeography, which deals with habitats of species, is often confused with ecology; it seeks to explain the reasons for the presence of certain species in a given location.

It was in 1935 that Arthur Tansley, the british ecologist, coined the term ecosystem, the interactive system established between the biocenose (the group of living creatures), and their biotope, the environment in which they live. Ecology thus became the science of ecosystems.

James Lovelock and the Gaia hypothesis

Main article: Gaia theory

Since the Second World War, the subdiscipline of human ecology, dealing with the place and role of humanity on the Earth, has dealt with the new challenges of the dangers and problems associated with nuclear energy, industrialization, the consequences of pollution, the exhaustion of natural resources by industrialized nations and the exponential population growth of many third world countries.

The vision of "Gaïa" is a sign of the times, proposed by James Lovelock, in his work The Earth is Alive, which compares the Earth to a single living macro-organism. Though controversial, the Gaia Hypothesis increased concern about ecology to the general public. Some of the public adopted the view that their Earth-mother, Gaia, was "becoming sick from humans and their activities". From a scientific point of view, this hypothesis is consistent with the new notion of the ecology as being a global vision of the biosphere and of biodiversity.

Human ecology

Human ecology began in the 1920s, through the study of changes in vegetation succession in the city of Chicago. It became a distinct field of study in the 1970s. This marked the first recognition that humans, who had colonized all of the Earth's continents, were a major ecological factor. Humans greatly modify the environment through the development of the habitat (in particular urban planning), by intensive fishing, and through agricultural and industrial activities. Human ecology began as a field of study with the participation of anthropologists, architects, biologists, demographers, ecologists, ergonomicists, ethnologists, urban planners and doctors.

Human ecology is the branch of ecology which studies humankind, the organized activity of this species, and its environment. In addition, environmentalism -- a philosophy resulting from ecology and applicable to human societies -- developed. Finally, political ecology also appeared in the 1920s. It consists of applying ecological science to the policy and the management of the city (see also List of planned cities).

Global ecology

In 1971, UNESCO launched a research program called Man and Biosphere, with the objective of increasing knowledge about the mutual relationship between humans and nature. A few years later it defined the concept of Biosphere Reserve.

In 1972, the United Nations held the first international conference on the human environment in Stockholm, prepared by René Dubos and other experts. This conference was the origin of the phrase "Think Globally, Act Locally". The next major events in ecology were the development of the concept of biosphere and the appearance of terms "biological diversity" -- or now more commonly biodiversity -- in the 1980s. These terms were developed during the Earth Summit in Rio de Janeiro in 1992, where the concept of the biosphere was recognized by the major international organizations, and risks associated with reductions in biodiversity were publicly acknowledged.

Then, in 1997, the dangers the biosphere was facing were recognized from an international point of view at the Kyoto conference. In particular, this conference highlighted the increasing dangers of the greenhouse effect -- related to the increasing concentration of greenhouse gases in the atmosphere, leading to global changes in climate. In Kyoto, most of the world's nations recognized the importance of looking at ecology from a global point of view, on a worldwide scale, and to take into account the impact of humans on the Earth's environment.

Fundamental principles of ecology

Disciplines of ecology

For many ecology belongs to the science of biology which relates to living beings. In biology, various levels of organization exist, such as molecular biology (which includes nucleic acids), cellular biology, the biology of organisms (on the individual level and organism level), the study of populations, the study of communities, and the study of ecosystems and the biosphere.

The field of ecology would include the last categories of these. Indeed, it is a holistic science which studies not only each element's relationship with other elements, but also the evolution of these reports according to modifications' which undergo it in the animal and plants populations. These types are described from the smallest to the largest level. Some of these other disciplines are:

Ecophysiology (or autoecology), which studies the relations between a type of organism and the factors of its environment;
Population ecology, which studies the relations between a population of individuals of the same species and its environment;
Synecology, which studies the relations between ones community, in addition to individuals of different species within his environment;
The study of ecosystems;
Global ecology, which studies ecology on the scale of the ecosphere or biosphere (the totality of the space occupied by alive beings).

What is called ecology is thus actually a unit of science, known as ecological sciences. Disciplines within the ecological sciences include geology, biochemistry, geography, pedology, and physical science.

The concept of an ecosystem

The first principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. An ecosystem can be defined as any situation where there is interaction between organisms and their environment.

The ecosystem is composed of two entities, the entirety of life (called the biocenose) and the medium that life exists in (the biotope). Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves and with their environment.

The concept of an ecosystem can apply to units of variable size, a pond, a field, or a piece of deadwood. A unit of smaller size is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. A mesoecosystem could be a forest, and a macroecosystem a whole ecoregion, with its watershed.

The environment includes both the abiotic environment &#151 non-living things like climate and geology &#151 and the biotic environment &#151 living things like plants and animals. Much of ecological research is concerned with the distribution and abundance of organisms and how distributions are influenced by characteristics of the environment. Organisms influence their environment and the environment influences organisms.

From an ecological point of view, the Earth consists of a hydrosphere, a lithosphere, a geosphere and a biosphere. An assemblage of natural communities and species, within areas of ecological potential based on soil, climate and topography parameters are called ecoregions, and constitute a basic element in ecology.

Ecological crisis

The Nuclear meltdown at Chernobyl in 1986 caused the death of many people and animals from cancer, and caused mutations in a large number of animals and people. The area around the plant is now abandoned because of the large amount of radiation generated by the meltdown.

Political ecology

Main articles : Political ecology, environmentalism

In recent years, as a result of the deteriorating environment, there has been an emergence of ecological movements such as the Green Party. It is important to understand the fundamental differences between politics, ideology, and the science of ecology.

Related fields

Ecology includes many sub-disciplines including:

Agroecology - Applied ecology - Animal ecology - Aquatic ecology - Behavioral ecology - Chemical ecology - Community ecology - Conservation ecology - Ecoevolution - Ecological anthropology - Ecosystems ecology - Ecotoxicology - Human ecology - Industrial ecology - Landscape ecology - Macroecology - Microbial ecology - Molecular ecology - Paleoecology - Plant ecology - Population ecology - Restoration ecology - Social ecology - Soil ecology - Systems ecology - Theoretical ecology - Tropical ecology - Urban ecology

Ecology also plays important roles in the inter-disciplinary fields of ecological economics, ecological health, ecological design and ecological engineering.