Ecosystems

5 Key excerpts on "Ecosystems"

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  eBook - ePub

  Ecosystems

  • Gordon Dickinson, Kevin Murphy(Authors)
  • 2007(Publication Date)
  • Routledge

    (Publisher)

  1 The nature of Ecosystems

  The biological world is one of great diversity and complexity. A systems approach is useful in helping us to understand the interactions between living organisms and their environment (which includes the biotic environment of other living creatures). The concept of the ecosystem provides a way in which the functioning of the biological world and its interactions with the physical environment can be understood. The ecosystem concept is useful in resource management and as a basis for predictive modelling. This chapter covers:

  • Complexity of the biological world and its physical environment
  • Development of the ecosystem concept
  • System theory, ecology and Ecosystems
  • Abiotic and biotic environment of Ecosystems

  How this book approaches the complexity of the biological world and its environment

  How can we make sense of the complex and constantly changing interactions between the living world, with its myriad species and individuals, and the multifaceted and dynamic environment which life inhabits? In this book we examine this basic question, starting from the idea of the ecosystem as the basic unit of living organisms in the environment. Understanding how Ecosystems operate, and how they support the existence of groups of organisms, is not just a question of scientific interest. At a gathering pace since the 1940s, there has been increasing concern about harmful effects caused by human actions on the planet’s life support system. Although concerns were, at first, confined to a small group of scientists and environmental activists, it is now a global issue at the top of the international political agenda. Exactly what has occurred and what may happen in the future is not clear. However, most informed people agree that at best the consequences may be uncomfortable for humankind, and at worst may be catastrophic.

  The ecosystem concept is fundamental to examination of human impacts on life on Earth. It provides a way of looking at the functional interactions between life and environment which helps us to understand the behaviour of ecological systems, and predict their response to human or natural environmental changes.

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  eBook - ePub

  Exploring Environmental Issues

  An Integrated Approach

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

    (Publisher)

  3 The Biosphere : The living environment

      After reading this chapter you should be familiar with the following concepts and terms:

  abiotic	epiphyte	pelagic ecosystem
  allelopathy	eutrophication	permafrost
  animal	eutrophic lake	photosynthesis
  azonal soil	evapotranspiration	physical weathering
  benthic ecosystem	evergreen trees	phytoplankton
  biological weathering	fire climax	plankton
  biome	food chain	plant
  biosphere	habitat	plant succession
  biotic	herbivore	podzol
  black earth (chernozem)	humus	prairie
  broad-leaved trees	hydrophyte	regolith
  brown earth	intrazonal soils	soil — classification, horizon,
  carnivore	laterite	profile, structure, texture
  chemical weathering	leaching	steppe
  climax community	mesophyte	stomata
  coniferous trees	needle-leaved trees	taiga
  cryosols	nekton	transpiration
  deciduous trees	niche	trophic level
  ecosphere	oligotrophic lake	xerophyte
  ecosystem	omnivore	zonal soil
  ecotone	osmosis	zooplankton
  ecozone	pampas

  The biosphere, or ecosphere as it is sometimes called, is the living environment. It is not a discrete entity in the way that the other spheres are, rather it is an interactive layer, incorporating elements of the lithosphere, atmosphere and hydrosphere, which combine in a variety of complex ways to maintain life in the system (Figure 2.1 ). Thus the plants and animals and other less visible constituents of the biosphere are secondary environmental elements dependent upon interaction with the primary components — lithosphere, atmosphere and hydrosphere — for their continued existence (Box 3.1

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  Toward a Unified Ecology

  • Timothy Allen, Thomas Hoekstra(Authors)
  • 2015(Publication Date)
  • Columbia University Press

    (Publisher)

  50 Huston et al. (2000) took Hector et al. to task, showing that the claims for the big science diversity studies were deeply questionable for reasons of statistical flaws. The challengers performed their own regressions, and the effects found by Hector et al. statistically disappeared. There is sufficient investment in the experimental protocol such that the political weight of diversity experiment protagonists will not let them back down on diversity increasing function. The politics of science appear notably worse in the United Kingdom compared to North America, which has its own problems.

  As we argue here, there are many reasons to question the logic and narrative of the push to ecosystem function in diversity. There is little effort to address organization because of the very conception of diversity, a static notion. By contrast, the literature on complexity and organization is much more promising, some of it coming from business management.51 It appears that the nonrandom patterns of connection are the bottom line, something ignored in the very idea of diversity. Some of the complexity literature does not play to rate-independent constraints and controls, being all too impressed with rate dependence and emergence. In chapter 4 on community, we expand on Grime’s organizing principles as he looks to strategies that plants use. His scheme dissects the types of relationships, so that he can address the functional interrelationships, a complexity issue.

  CONCLUSION

  The ecosystem criterion is very distinct from all others. Like communities, it bears a complex relationship to landscapes. For the most part, to think of an ecosystem as a place on a landscape is unworkable and certainly makes the concept depauperate. Although it is more inclusive than the community, in that Ecosystems contain meteorological and geological components, the ecosystem is not a higher level than community. They are merely alternative specifications. The reduction of an ecosystem to its functional parts does not usually lead to organisms or populations. Only by reducing to functional parts on very specific phenomena does one sometimes find plants and animals as discrete entities inside Ecosystems.

  The attributes of communities are the end products of biological evolution. Ecosystems do depend on evolved entities for some of their functions like primary production, but any one of a large number of separately evolved plants can do the job. Therefore, evolution is only tenuously connected to Ecosystems. Ecosystems are not evolved in any conventional meaning of that term. Nevertheless, some of the same principles that apply to evolution hold for ecosystem development. This is valuable, but can make for a muddled comparison. The particular Ecosystems we find take the form they do because those patterns are stable and therefore hold the material of the world in those configurations long enough for us to observe them. We find stable configurations regularly. Given a world where there is almost universal scarcity of biologically available nitrogen, Ecosystems develop organization that cycles nutrients. It is stretching Darwinian evolution too far to suggest that there is a group-selection explanation for the sharing and cycling of nutrients. We observe ecosystem functionality, not because there is selection in an evolutionary sense, but because stable patterns persist. Darwinian selection is only one way of achieving stability. Stability can arise without competition and differential survival based on genetics. The ecosystem is therefore a parallel development that is highly structured like strictly living systems, but with a different cause than natural selection in the conventional sense.

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  Human Behavior in the Social Environment

  Theories for Social Work Practice

  • Catherine N. Dulmus, Karen M. Sowers, Bruce A. Thyer(Authors)
  • 2012(Publication Date)
  • Wiley

    (Publisher)

  Like GST, ecology is a scientific discipline. The integration of GST and ecology in social work that occurs (if unevenly) in the Ecosystems perspective has not always been considered in scientific terms, however. For example, the life model of social work practice uses ecology (and in some cases Ecosystems) in an unequivocally and explicitly metaphoric manner (Gitterman & Germain, 2008). Ecological terms such as habitat, niche, adaptation, and pollution, used extensively in the life model, are understood as heuristic constructs rather than in scientific terms. Gitterman and Germain clearly recognize, however, that humans are animals living in transaction with natural, built, and social environments, and ecological concepts even when used heuristically have proven practically helpful in communicating this embeddedness to students and practitioners.

  Carol Meyer (1976, 1983, 1988, 1993, 1995), the primary architect of the Ecosystems perspective in social work, was concerned that the scientific origins of Ecosystems not be lost. She was a strong supporter of the development of research-grounded refinements of the perspective and explicitly rejected Ecosystems as primarily metaphoric (Meyer, personal communication, 1987); instead, she emphasized its use as an epistemological framework for understanding reality in its complexity. I argue later in this chapter that the epistemic utility of Ecosystems as a way of understanding phenomena of interest to social work scientifically, however, has been almost universally underemphasized.

  Ecological Theory

  Ecology, a subdiscipline of biology, is the science of adaptedness. Ecological investigations focus on mutual adaptations between the organism and the environment, with recognition that such adaptation is often (although not always) mutual. In ecological terms, in some cases organisms (including persons) simply adjust to the environment; the term “adaptation” is generally reserved for those situations where both organism and environment change in complementary and transactional ways. According to Germain and Bloom (1999, p. 12), “There is a general tendency for each party to this interaction to seek a goodness of fit or positive adaptedness vis-à-vis themselves and the other party.” Maladaptation reflects problems in this fit and is commonly regarded as the target of intervention in ecological social work.

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  The Death of Competition

  • James F. Moore(Author)
  • 2016(Publication Date)
  • Harper Paperbacks

    (Publisher)

  4 The Stages of a Business Ecosystem

  Biological communities do not spring full blown upon the earth, but rather develop over time. Life arrives only through spectacular stamina, patience, and luck. This intricate and heroic process is called biological colonization. Community development is most basic when it involves the colonization of barren land: mountainsides denuded by landslides, silt-covered fields left behind when floodwaters recede, or lava flows in Hawaii. Biologists refer to this as primary colonization, the establishment of an ecosystem literally from the ground up.

  In Hawaii, new lava comes in two textures—solid pahoehoe and rough-hewn ‘A’a. ‘A’a lava is the best base for colonization, because its innumerable small cracks collect moisture and provide some precious shade to shield early settlers. Microorganisms, lichen, and ferns are among the first to establish themselves, creating microscopic quantities of humus and primitive soil, as well as extending the awning of shade.

  Over time, the resilient ‘ōhi’a-lehua trees sprout within these small zones of habitable microclimate. The trees in turn shelter other species. Much of the initial activity is around the roots of the ‘ōhi’a-lehua trees, which tunnel through the air pockets in the hardened lava, carving out miniature underground caves where spiders, crickets, and other insects can live.

  As years and then decades pass, vegetation clothes the once-barren tract of land and the assembly of life inevitably diversifies. The local ecosystem becomes more densely structured and able to nourish a cornucopia of species. Herbivores pour in, followed by successive levels of carnivores. All these strangers rapidly make themselves at home, and a sort of communion of dependence takes hold. Given the right conditions, a richly canopied forest can establish itself within a single human lifetime. The desolate territory becomes transformed into a full-fledged forest ecosystem with a rather complex soul and destiny.

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