7 Key excerpts on "Ecological Terms"

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  eBook - ePub

  Exploring Environmental Issues

  An Integrated Approach

  • David D. Kemp(Author)
  • 2004(Publication Date)
  • Routledge

    (Publisher)

  The relationships among the vegetation and animals in a food chain are only part of a much more comprehensive group of interactions that take place among the biotic (living) and abiotic (non-living) elements that make up the environment. The interrelationships are complex, but they lead to the formation of characteristic communities of organisms that interact with each other and with the abiotic elements of their environment. Such groupings of organisms and the physical environment they inhabit are known as ecosystems. Ecosystems are dynamic entities, driven by the flow of energy within and through them, and being dynamic they can respond to a considerable degree of change while retaining sufficient equilibrium that the basic characteristics of the system are maintained. Despite this, major or prolonged environmental disruption, such as that caused by climate change or fire, may alter a specific ecosystem irreversibly, and bring about its replacement by a system with different characteristics. Human interference has become the most common cause of this type of change.

  Ecosystems are commonly divided into terrestrial and aquatic groups (Enger and Smith 2002). Terrestrial ecosystems incorporate continental flora and fauna and the land surface that they occupy, whereas aquatic ecosystems include salt-water and freshwater communities plus those in coastal and interior wetlands. Within any ecosystem, in theory, organisms occupy areas in which the physical conditions best meet their needs, although in practice they are often forced to tolerate conditions that may not be optimal. These areas are called habitats. Although the term may be linked with a particular species — the habitat best suited to elephants, for example — a specific habitat will be shared by a variety of organisms that have requirements in common. The nature of any habitat is determined by a large number of variables, but most can be grouped into climatic, topographic, edaphic and biotic categories. Of these, the climatic factors — light, heat, moisture and wind — are generally considered to be of most importance. The position of an organism within a habitat, defined by its role in the habitat, is its niche. Niche includes not only physical location, but also the functional role of the organism in its community as determined by its needs and its interrelationships with other components of the ecosystem. In occupying a specific niche an organism is making use of the set of conditions that are best suited to its survival. Any change in these conditions, or the conditions in the wider habitat, may threaten the survival of the organism, and through it the integrity of the ecosystem.

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  The Routledge Handbook of Landscape Ecology

  • Robert A. Francis, James D.A. Millington, George L.W. Perry, Emily S. Minor, Robert A. Francis, James D.A. Millington, George L.W. Perry, Emily S. Minor(Authors)
  • 2021(Publication Date)
  • Routledge

    (Publisher)

  An ecotope is the (smallest) tangible spatial building block of the landscape. These are sometimes referred to as landscape ‘components’ or ‘elements’. Examples include a patch of woodland, a park, a pond, or a hedgerow, though they do not have to include a biotic community (for example, a building may represent an ecotope). A ‘landscape’ may ultimately be considered an ecosystem composed of many ecotopes.

  Habitat

  The terms ‘ecosystem’ and ‘habitat’ are sometimes used almost as synonyms, and the two concepts are conflated to an extent. ‘Habitat’ may be defined in various ways, and different measures of what habitat is and how species use it have led to some confusion in ecology and difficulty in comparing and contrasting studies. Essentially, habitat may be defined as ‘the resources and conditions present in an area that produce occupancy – including survival and reproduction – by a given organism’ (Hall et al., 1997). Importantly, habitat may only be defined by reference to a particular organism; though ‘woodland’ may in general act as a habitat for many species, it is more accurate to say that it is an ecosystem, while the conditions found within the woodland (and perhaps elsewhere) form the habitat for a given species. For example, the habitat for barn owls (Tyto alba) in the United Kingdom will include the resources provided by many different ecosystems at different spatial scales, some of which are interchangeable: farmland and grassland for hunting; woodland, individual trees, and buildings for nesting; and so on (Taylor, 1994). It is also essential to note that habitat ‘selection’ (remember that this is not always a conscious or even semi-conscious process for many species) takes place over a hierarchy of scale, beginning at the broader scales of resource distribution (such as climatic conditions, soil and vegetation types, etc.) and becoming finer as species select for localized food or environmental resources (e.g. choice of tree for foraging/nesting, germination of seeds in soil patches with sufficient moisture or nutrients). Typically in landscape ecology, patches and corridors are defined as ‘favorable habitat’ for a given species, while ‘unfavorable habitat’ would be considered as the matrix (see Chapter 2

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  Biomes and Ecosystems

  • Britannica Educational Publishing, John P Rafferty(Authors)
  • 2010(Publication Date)
  • Britannica Educational Publishing

    (Publisher)

  IOMES AND ECOSYSTEMS

  T he largest of Earth’s ecological communities are biomes and biogeographic regions. Each one of these vast systems possesses a unique set of species and climatic conditions. However, noticeable patterns emerge. Deserts around the world are characterized by high atmospheric pressure and low moisture, whereas tropical rainforests on different continents have ample moisture and warm temperatures. These climatic conditions contribute to the dominant vegetation type found in each area. (Deserts are characterized by sparse, shrubby vegetation, whereas tropical forests are made up of a rich diversity of thick-canopied tall trees.) This chapter is devoted to describing the unique characteristics of different biomes and biogeographic regions, as well as the features some share with others.

  A biogeographic region is an area of animal and plant distribution having similar or shared characteristics throughout. It is a matter of general experience that the plants and animals of the land and inland waters differ to a greater or lesser degree from one part of the world to another. Why should this be? Why should the same species not exist wherever suitable environmental conditions for them prevail?

  Geographic regions around the world that have similar environmental conditions are capable of harbouring the same type of biota. This situation effectively separates the biosphere into biomes—ecological communities that have the same climatic conditions and geologic features and that support species with similar life strategies and adaptations. A biome is frequently described as a major community of plants and animals with similar life-forms and environmental conditions. It includes various communities and is named for the dominant type of vegetation, such as grassland or coniferous forest. Several similar biomes constitute a biome type—for example, the temperate deciduous forest biome type includes the deciduous forest biomes of Asia, Europe, and North America. “Major life zone” is the European phrase for the North American biome concept.

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  The Ecological and Societal Consequences of Biodiversity Loss

  • Michel Loreau, Andy Hector, Forest Isbell(Authors)
  • 2022(Publication Date)
  • Wiley-ISTE

    (Publisher)

  IntroductionThe Ecological and Societal Consequences of Biodiversity Loss Michel LOREAU1 , Andy HECTOR2 , and Forest ISBELL3 1 Theoretical and Experimental Ecology Station, CNRS, Moulis, France 2 University of Oxford, UK 3 University of Minnesota, St. Paul, USA

  One of the distinctive and fascinating features of ecological systems is their extraordinary complexity. An ecosystem is often composed of thousands of different species that interact in myriad ways at the scale of a single hectare. Each species is composed of many individuals that vary due to differences in their genetics and their particular experience of their local environment. These complex local systems are strongly connected to each other, and aggregate into larger and larger entities, from the landscape scale to that of the entire biosphere, where it becomes evident that they exert a major influence on the physical and chemical properties of our planet. How can such enormously complex systems be studied?

  During the second half of the 20th century, two increasingly divergent approaches to ecological systems developed within ecology, which have gradually led to two largely distinct disciplines, community ecology and ecosystem ecology. A community is defined broadly as a set of species that live together in some place. The focus in community ecology has traditionally been on species diversity: what exogenous and endogenous forces lead to more or less diverse communities? How do species interactions constrain the number of species that can coexist? What patterns emerge from these interactions? An ecosystem is the entire system of biotic and abiotic components that interact in some place. The ecosystem concept is broader than the community concept because it includes a wide range of biological, physical, and chemical processes that connect organisms and their environment. But the focus in ecosystem ecology has traditionally been on the overall functioning of ecosystems as distinct entities: how is energy captured, transferred, and ultimately dissipated in different ecosystems? How are limiting nutrients recycled, thereby ensuring the renewal of the material elements necessary for growth? What factors and processes control energy and material flows, from local to global scales?

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  Foundations of Ecology

  Classic Papers with Commentaries

  • Leslie A. Real, James H. Brown(Authors)
  • 2012(Publication Date)
  • University of Chicago Press

    (Publisher)

  plus its abiotic environment. The concept of the ecosystem is believed by the writer to be of fundamental importance in interpreting the data of dynamic ecology.

  TROPHIC DYNAMICS Qualitative food-cycle relationships

  Although certain aspects of food relations have been known for centuries, many processes within ecosystems are still very incompletely understood. The basic process in trophic dynamics is the transfer of energy from one part of the ecosystem to another. All function, and indeed all life, within an ecosystem depends upon the utilization of an external source of energy, solar radiation. A portion of this incident energy is transformed by the process of photosynthesis into the structure of living organisms. In the language of community economics introduced by Thienemann (’26), auto-trophic plants are producer organisms, employing the energy obtained by photosynthesis to synthesize complex organic substances from simple inorganic substances. Although plants again release a portion of this potential energy in catabolic processes, a great surplus of organic substance is accumulated. Animals and heterotrophic plants, as consumer organisms, feed upon this surplus of potential energy, oxidizing a considerable portion of the consumed substance to release kinetic energy for metabolism, but transforming the remainder into the complex chemical substances of their own bodies. Following death, every organism is a potential source of energy for saprophagous organisms (feeding directly on dead tissues), which again may act as energy sources for successive categories of consumers. Heterotrophic bacteria and fungi, representing the most important saprophagous consumption of energy, may be conveniently differentiated from animal consumers as specialized decomposers 3 of organic substance. Waksman (’41) has suggested that certain of these bacteria be further differentiated as transformers

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  Fundamentals of Biogeography

  • Richard John Huggett(Author)
  • 2004(Publication Date)
  • Routledge

    (Publisher)

  PART I

  INTRODUCING BIOGEOGRAPHY

  Passage contains an image

  1

  WHAT IS BIOGEOGRAPHY?

  Biogeographers study the geography, ecology, and evolution of living things. This chapter covers:

  •  ecology – environmental constraints on living •  history and geography – time and space constraints on living

  Biogeographers address a misleadingly simple question: why do organisms live where they do? Why does the speckled rangeland grasshopper live only in short-grass prairie and forest or brush-land clearings containing small patches of bare ground? Why does the ring ouzel live in Norway, Sweden, the British Isles, and mountainous parts of central Europe, Turkey, and southwest Asia, but not in the intervening regions? Why do tapirs live only in South America and southeast Asia? Why do the nestor parrots – the kea and the kaka – live only in New Zealand?

  Two groups of reasons are given in answer to such questions as these – ecological reasons and historical-cum-geographical reasons.

  ECOLOGY

  Ecological explanations for the distribution of organisms involve several interrelated ideas. First is the idea of populations , which is the subject of analytical biogeography . Each species has a characteristic life history, reproduction rate, behaviour , means of dispersion, and so on. These traits affect a population’s response to the environment in which it lives. The second idea concerns this biological response to the environment and is the subject of ecological biogeography . A population responds to its physical surroundings (abiotic environment) and its living surroundings (biotic environment). Factors in the abiotic environment include such physical factors as temperature, light, soil

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  The Global Casino

  An Introduction to Environmental Issues

  • Nick Middleton(Author)
  • 2018(Publication Date)
  • Routledge

    (Publisher)

  CHAPTER 1 The physical environment

  Learning Outcomes At the end of this chapter you should:

  • Appreciate some of the key ways we classify the natural world by identifying units, such as biomes.
  • Understand how the natural world works through the recognition of cycles, such as the hydrological cycle.
  • Appreciate the importance of scale (both time and space).
  • Recognize that the state of our knowledge of the natural world is imperfect.
  • Understand that our sources of data include direct and indirect methods of measurement.
  • Appreciate that a scientific approach to environmental change is dominant but it is by no means the only kind of knowledge about how our planet works.

  Key Concepts

  productivity, biome, food chain, biogeochemical cycle, regime shift, feedback, threshold, timelag, resistance, resilience, equilibrium, linear/non-linear system, proxy methods, palaeoenvironmental indicator

  The term environment is used in many ways. This book is about issues that arise from the physical environment, which is made up of the living (biotic) and non-living (abiotic) things and conditions that characterize the world around us. While this is the central theme, the main reason for the topicality of the issues covered here is the way in which people interact with the physical environment. Hence, it is pertinent also to refer to the social, economic and political environments to describe those human conditions characteristic of certain places at particular times, and to explain why conflict has arisen between human activity and the natural world. This chapter looks at some of the basic features of the physical environment, while Chapter 2 is concerned with the human factors that affect the ways in which the human race interacts with the physical world.

  Classifying the Natural World

  Geography, like other academic disciplines, classifies things in its attempt to understand how they work. The physical environment can be classified in numerous ways, but one of the most commonly used classifications is that which breaks it down into four interrelated spheres: the lithosphere, the atmosphere, the biosphere and the hydrosphere. These four basic elements of the natural world can be further subdivided. The lithosphere, for example, is made up of rocks that are typically classified according to their modes of formation (igneous, metamorphic and sedimentary); these rock types are further subdivided according to the processes that formed them and other factors such as their chemical composition. Similarly, the workings of the atmosphere are manifested at the Earth’s surface by a typical distribution of climates; the biosphere is made up of many types of flora and fauna; and the hydrosphere can be subdivided according to its chemical constituents (fresh water and saline, for example), or the condition or phase of the water: solid ice, liquid water or gaseous vapour.

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