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What is ecology?

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What is ecology?

Ecology is the study of the distribution and abundance of organisms, the interaction between organisms, the interaction between organisms and their environment, and structure and function of ecosystems.

British Ecological Society image of a view of a grassland delta

Why is ecology important?

Ecology helps us understand how the world works. It provides useful evidence on the interdependence between people and the natural world and, as well the consequences of human activity on the environment.

Can we conserve a habitat and its biodiversity?

Yes. Ecology provides the essential basis for nature conservation. Maintaining a mosaic of habitats ensures the survival of a rich variety of species. For instance, heathland is a valued landscape that is fast disappearing throughout much of Western Europe, but studies have helped identify how to preserve its ecological characteristic.


What is Agroecology?

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The term agroecology can be used in multiple ways, as a science, as a movement and as a practice[1]. Broadly stated, it is the study of the role of agriculture in the world. Agroecology provides an interdisciplinary framework with which to study the activity of agriculture. In this framework, agriculture does not exist as an isolated entity, but as part of an ecology of contexts. Agroecology draws upon basic ecological principles for its conceptual framework.


Ecological strategy

Agroecologists study a variety of agroecosystems, and the field of agroecology is not associated with any one particular method of farming, whether it be organic, conventional, intensive or extensive. Furthermore, it is not defined by certain management practices, such as the use of natural enemies in place of insecticides, or polyculture in place of monoculture.

Additionally, agroecologists do not unanimously oppose technology or inputs in agriculture but instead assess how, when, and if technology can be used in conjunction with natural, social and human assets[2]. Agroecology proposes a context- or site-specific manner of studying agroecosystems, and as such, it recognizes that there is no universal formula or recipe for the success and maximum well-being of an agroecosystem.


What is Ecology

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Ecology (from Greek: οἶκος, "house" or "living relations"; -λογία, "study of") is the scientific study of the distributions, abundance and relations of organisms and their interactions with the environment.[1] Ecology includes the study of plant and animal populations, plant and animal communities and ecosystems. Ecosystems describe the web or network of relations among organisms at different scales of organization. Since ecology refers to any form of biodiversity, ecologists research everything from tiny bacteria's role in nutrient recycling to the effects of tropical rain forest on the Earth's atmosphere. The discipline of ecology emerged from the natural sciences in the late 19th century. Ecology is not synonymous with environment, environmentalism, or environmental science.[1][2][3] Ecology is closely related to the disciplines of physiology, evolution, genetics and behavior.[4]

Like many of the natural sciences, a conceptual understanding of ecology is found in the broader details of study, including:

  • life processes explaining adaptations
  • distribution and abundance of organisms
  • the movement of materials and energy through living communities
  • the successional development of ecosystems, and
  • the abundance and distribution of biodiversity in context of the environment.[1][2][3]

Ecology is distinguished from natural history, which deals primarily with the descriptive study of organisms. It is a sub-discipline of biology, which is the study of life.

There are many practical applications of ecology in conservation biology, wetland management, natural resource management (agriculture, forestry, fisheries), city planning (urban ecology), community health, economics, basic & applied science and it provides a conceptual framework for understanding and researching human social interaction (human ecology).[5][6][7][8]


Ecosystem Services

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Pollination by a bumblebee, a type of ecosystem service

Humankind benefits from a multitude of resources and processes that are supplied by natural ecosystems. Collectively, these benefits are known as ecosystem services and include products like clean drinking water and processes such as the decomposition of wastes. While scientists and environmentalists have discussed ecosystem services for decades, these services were popularized and their definitions formalized by the United Nations 2004 Millennium Ecosystem Assessment (MA), a four-year study involving more than 1,300 scientists worldwide.[1] This grouped ecosystem services into four broad categories: provisioning, such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; and cultural, such as spiritual and recreational benefits.

As human populations grow, so do the resource demands imposed on ecosystems and the impacts of our global footprint. Natural resources are not invulnerable and infinitely available. The environmental impacts of anthropogenic actions, which are processes or materials derived from human activities, are becoming more apparent – air and water quality are increasingly compromised, oceans are being overfished, pests and diseases are extending beyond their historical boundaries, and deforestation is exacerbating flooding downstream. It has been reported that approximately 40-50% of Earth’s ice-free land surface has been heavily transformed or degraded by anthropogenic activities, 66% of marine fisheries are either overexploited or at their limit, atmospheric CO2 has increased more than 30% since the advent of industrialization, and nearly 25% of Earth’s bird species have gone extinct in the last two thousand years [2]. Society is increasingly becoming aware that ecosystem services are not only limited, but also that they are threatened by human activities. The need to better consider long-term ecosystem health and its role in enabling human habitation and economic activity is urgent. To help inform decision-makers, many ecosystem services are being assigned economic values, often based on the cost of replacement with anthropogenic alternatives. The ongoing challenge of prescribing economic value to nature, for example through biodiversity banking, is prompting transdisciplinary shifts in how we recognize and manage the environment, social responsibility, business opportunities, and our future as a species.


A brief history

The simple notion of human dependence on Earth’s ecosystems probably reaches to the start of our species’ existence, when we benefited from the products of nature to nourish our bodies and for shelter from harsh climates. Recognition of how ecosystems could provide more complex services to mankind date back to at least Plato (c. 400 BC) who understood that deforestation could lead to soil erosion and the drying of springs [3]. However, modern ideas of ecosystem services probably began with Marsh in 1864 [4] when he challenged the idea that Earth’s natural resources are not infinite by pointing out changes in soil fertility in the Mediterranean. Unfortunately, his observations and cautions passed largely unnoticed at the time and it was not until the late 1940s that society’s attention was again brought to the matter. During this era, three key authors – Osborn [5], Vogt [6], and Leopold [7] – awakened and promoted recognition of human dependence on the environment with the idea of ‘natural capital’. In 1956, Sears [8] drew attention to the critical role of the ecosystem in processing wastes and recycling nutrients. An environmental science textbook [9] called attention to “the most subtle and dangerous threat to man’s existence… the potential destruction, by man’s own activities, of those ecological systems upon which the very existence of the human species depends”. The term ‘environmental services’ was finally introduced in a report of the Study of Critical Environmental Problems [10], which listed services including insect pollination, fisheries, climate regulation and flood control. In following years, variations of the term were used, but eventually ‘ecosystem services’ became the standard in scientific literature.[11]

Modern expansions of the ecosystem services concept include socio-economic and conservation objectives, which are discussed below. For a more complete history of the concepts and terminology of ecosystem services, see Daily (1997)[3].


Restoration Ecology

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Restoration ecology
is the study of renewing a degraded, damaged, or destroyed ecosystem through active human intervention. Restoration ecology specifically refers to the scientific study that has evolved as recently as the 1980s. Land managers, laypeople, and stewards have been practicing restoration for many hundreds, if not thousands of years (Anderson 2005), yet the scientific field of "restoration ecology" was first identified and coined in the late 1980s by John Aber and William Jordan. The study of restoration ecology has only become a robust and independent scientific discipline over the last two decades (Young et al. 2005).

The Society for Ecological Restoration defines ecological restoration as an “intentional activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity and sustainability” (SER 2004). The practice of ecological restoration includes wide scope of projects including: erosion control, reforestation, removal of non-native species and weeds, revegetation of disturbed areas, daylighting streams, reintroduction of native species, as well as habitat and range improvement for targeted species. The term "ecological restoration" refers to the practice of the discipline of "restoration ecology".

In the view of biologist E. O. Wilson, "Here is the means to end the great extinction spasm. The next century will, I believe, be the era of restoration in ecology.".


  • 1 Rationale for restoration
  • 2 Conservation biology and restoration ecology
    • 2.1 Approaches
    • 2.2 Focuses
    • 2.3 Modes of inquiry
  • 3 Theoretical foundations
    • 3.1 Disturbance
    • 3.2 Succession
    • 3.3 Fragmentation
    • 3.4 Ecosystem function
  • 4 Emerging concepts
    • 4.1 Local Genetics
    • 4.2 Time frame, Performance standards
    • 4.3 Societal reasonable amounts of money for projects
    • 4.4 Inventing successful restoration technologies, especially for non-riparian projects
    • 4.5 Assembly
      • 4.5.1 Stable states
    • 4.6 Ontogeny
    • 4.7 Restoration Ecology as a basis for a new world religion
  • 5 Application of theory
    • 5.1 Soil heterogeneity effects on community heterogeneity
    • 5.2 Invasion, competitive dominance and resource use
    • 5.3 Successional trajectories
  • 6 Ethical considerations
    • 6.1 Restoration is "faking it"
    • 6.2 Mitigation’s black eye
    • 6.3 Ultimate complexity versus limited knowledge
    • 6.4 Where's the target?
  • 7 References
  • 8 See also
  • 9 Bibliography
  • 10 External links
    • 10.1 Societies and journals
    • 10.2 Educational opportunities
    • 10.3 Ecological restoration internships and non-profit organizations

Rationale for restoration

There is consensus in the scientific community that the current environmental degradation and destruction of many of the Earth's biota is considerable, and is taking place on a “catastrophically short timescale” (Novacek & Cleland 2001). In fact, estimates of the current extinction rate are 1000 to 10,000 times the normal rate (Wilson 1988). For many people biological diversity (biodiversity) has an intrinsic value; humans have a responsibility toward other living things, and obligations to future generations.

On a more anthropocentric level, natural ecosystems provide human society with food, fuel and timber. More fundamentally, ecosystem services involve the purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and pollination of crops. Such processes have been estimated to be worth trillions of dollars annually (Daily et al. 1997).

Habitat loss is the leading cause of both species extinctions (Wilson 1988) and ecosystem service decline (Daily et al. 1997). There are two ways to reverse this trend of habitat loss: conservation of currently viable habitat and restoration of degraded habitats.



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Ecology is the study of environmental systems, or as it is sometimes called, the economy of nature. "Environmental" usually means relating to the natural, versus human-made world; the "systems" means that ecology is, by its very nature, not interested in just the components of nature individually but especially in how the parts interact. Ecology is technically an academic discipline, such as mathematics or physics, although in public or media use, it is often used to connote some sort of normative or evaluative issue as in something is “ecologically bad” or is or is not “good for the ecology”. More properly ecology is used only in the sense that it is an academic discipline, no more evaluative than mathematics or physics. When a normative or evaluative term is needed then it is more proper to use the term “environmental”, i.e., environmental quality or “environmentally degrading”. Most professional ecologists are not terribly unhappy when ecology is used in the normative sense, preferring the wider public awareness of environmental issues today compared to the widespread ignorance of three decades ago. 

The subject matter of ecology is normally divided onto four broad categories: physiological ecology, having to do with the response of single species to environmental conditions such as temperature or light; population ecology, usually focusing on the abundance and distribution of individual species and the factors that cause such distribution; community ecology, having to do with the number of species found at given location and their interactions; and ecosystems ecology, having to do with the structure and function of the entire suite of microbes, plants, and animals, and their abiotic environment, and how the parts interact to generate the whole. This branch of ecology often focuses on the energy and nutrient flows of ecosystems, and when this approach is combined with computer analysis and simulation we often call it systems ecology. Evolutionary ecology, which may operate at any of these levels but most commonly at the physiological or population level, is a rich and dynamic area of ecology focusing on attempting to understand how natural selection developed the structure and function of the organisms and ecosystems at any of these levels.  

Levels of organization of Ecology

Levels of organization of Ecology

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