Human Impact on Ecosystems

5 Key excerpts on "Human Impact on Ecosystems"

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  eBook - ePub

  Ecosystems

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

    (Publisher)

  9 Human impacts on ecosystems: humans as an ecological factor

  Human impacts on ecosystems are as old as the human species. However, following industrialisation, with the consequent increase in numbers of people and their ability to modify the biosphere, both the extent and consequences of human impacts on ecosystems have accelerated. Impacts resulting from human activities occur in all parts of the biosphere, and at all kinds of temporal and spatial scales. This chapter covers:

  • General nature of human impacts on ecosystems
  • Fire
  • Introduced species
  • Recreation
  • Sustainable development

  Human impacts: an old and new issue

  Human beings are part of the biosphere. In most parts of the world, humans are the dominant organisms. The previous chapters have shown that we share the biosphere with millions of other species. We also depend, as much as any other living creature, on the functioning of ecosystems in the biosphere to support our existence. Unlike all other species, people have the unique ability to affect profoundly the nature and functioning of ecosystems throughout the biosphere. This chapter is concerned with anthropogenic effects on the trophic structure and functioning of ecosystems. This is linked to functional ecology by examining the changes that take place in species composition in the affected ecosystems. In some ways humans may be considered as simply another biological species, albeit one that exists in very large numbers. But we are also the species that is capable of the most profound ecological and environmental impacts. The scale and importance of human impacts, together with the fact that (not unreasonably) humans tend to view the world from a human perspective, means that it is important to separate human roles in ecosystems from those of other species. There are now about 6,000 million individual Homo sapiens

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  Environmental Impact Assessment

  Theory and Practice

  • Anji Reddy Mareddy, Anil Shah, Naresh Davergave(Authors)
  • 2017(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  Westman, 1985 ). Ecological impact assessment can be defined as the systematic identification and evaluation of the potential impacts of proposed projects and activities relative to the biological components of the total environment. The purpose of the EIA process is to encourage the consideration of the ecosystem in planning and decision-making and to ultimately arrive at actions that are ecologically compatible. Understanding of ecosystem, biodiversity, biogeochemical cycles, and carrying capacity is necessary to understand the impacts of fauna and flora due to developments of any area. The biological environment should always be understood in terms of the above parameters.

  9.1 Biological environment

  To identify both adverse and significant impacts on biological environment, predictions of significance of such impacts, site-specific assessment of impacts and provision of mitigation measures, preparation of environmental management plan, and methods of monitoring of impacts needed to study the concepts of ecosystem and biodiversity, biogeochemical cycles, and their fundamentals and carrying capacity are very important. The quality of EIA report on ecological impacts depends on the above biological parameters, which are explained briefly in the following sections. However, the reader can refer to other books for in-depth knowledge as a number of books are available on ecology and biodiversity.

  9.1.1 Ecosystem

  An ecosystem is a stable, interacting, gathering of living organisms in their nonliving environment, which is unified by a circular flow of energy and nutrients.

  Each ecosystem is bound together by the biogeochemical cycles through which living organisms use energy from the sun to obtain or fix nonliving (inorganic) elements such as carbon, oxygen, and hydrogen from the environment and transform them into vital food, which is then used and recycled. Ecosystems are neither permanent nor unchanging. The number of organisms in a mature ecosystem and their rate of growth and lifestyle depend on the availability of energy and key chemical elements. Ecosystems do not spring full-blown, but develop in stages called as ecological succession. These stages vary in terms of altitude, climate, terrain, and mix of plants and animals. Examples of ecosystem are forest ecosystem, desert ecosystem, lake ecosystem, wetland ecosystem, pond ecosystem, fresh water ecosystem, and marine ecosystem.

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  Sustainability

  If It's Everything, Is It Nothing?

  • Heather M. Farley, Zachary A. Smith(Authors)
  • 2020(Publication Date)
  • Routledge

    (Publisher)

  Our Common Future was vague in its popular definition, there has been a wave of scholarly works related to how we identify sustainability, which, while necessary to try to define the idea, have made the concept complex and ultimately not very useful. Trying to incorporate the multitude of ideas that have emerged from the academy into a single universal definition is a daunting task. Even as we attempt to bring some philosophical and theoretical clarity to the concept, we find that once more sustainability has become everything to everyone rather than one thing that is widely understood. The objective of this chapter, therefore, is to lay out core contributions and influences from multiple disciplines that help us identify the keys to differentiating between faux sustainability and sustainable action. This chapter informs our later discussion of what a sustainability definition must entail, what must be avoided, and how it can be more useful to those who use it as a guiding principle.

  The natural sciences

  Biodiversity and resilience

  The recognition of the decline in the quality of the earth’s ecosystems and the ability of those ecosystems to adapt to human stresses was a primary motivation behind the environmental movement of the 1960s and 1970s and the subsequent international conferences held to address this decline. Today, despite efforts meant to address global adaptation to human impacts on the environment, the carrying capacity of the human population has nevertheless reached a point of overshoot; at our current global population and consumption rate, we are using resources and producing greenhouse gas emissions 44 percent faster than the earth can regenerate and reabsorb them (Global Footprint Network, 2011). A consequence of this overshoot is continuous and increasing biodiversity loss. As this section will demonstrate, biodiversity is intimately connected to ecological resilience and ecosystem equilibrium, both of which are crucial to human development and survival. Therefore, without biodiversity protection we quite simply put our own security at risk.

  Biological scientists define biodiversity as the variety of life forms found on the planet. Biodiversity is used as a measure of variety at the genetic, species, and ecosystem levels for both animal and plant life forms. Jeffrey McNeely et al. (1990) explain that biodiversity is not simply a count of genetic codes or species numbers, but also the variation found among and within habitats, biotic communities, and ecological processes. The Living Planet Index has estimated that bird, mammalian, amphibian, reptilian, and fish species declined by 28 percent between 1970 and 2008 (WWF, 2012). Over the course of less than 40 years, human demand for resources has slashed biodiversity by nearly one-third globally, and by 60 percent in tropical regions. Biodiversity loss has long been a research concern for biologists, ecologists, and other scholars in the natural sciences, and it was this community who ensured that the relationship between biodiversity and sustainability was clearly understood and incorporated during the sustainable development conferences and international meetings of the past four decades.

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  The Green Marble

  Earth System Science and Global Sustainability

  • David Turner(Author)
  • 2018(Publication Date)
  • Columbia University Press

    (Publisher)

  That mental flexibility and capacity for transmitting information has given humans the ability to colonize almost the complete range of climatic zones on Earth. Even as hunter-gatherers, we adapted to everything from Arctic tundra to tropical rain forests. With the development of the technosphere by way of cultural evolution, we have not retreated from anywhere, and our population density has increased everywhere. Thus, the scale of our impacts on the environment has extended from the local to the global level.

  Efforts to assess human-mediated impacts on the biosphere, such as the United Nations–sponsored Millennium Ecosystem Assessment (MEA, 2005) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES, 2017), have attempted to integrate social science along with indigenous or traditional knowledge to a greater degree than efforts to assess human impacts on climate (e.g., the Intergovernmental Panel on Climate Change [IPCC]). This more transdisciplinary approach creates a tension about what constitutes knowledge, and how best to approach adaptation to global environmental change (Obermeister, 2017). The globally valid knowledge base of biophysical science is increasingly augmented with the local knowledge involving specific people and places (Escobar, 2001).

  LAND COVER AND LAND USE CHANGE

  Human impacts on the land surface include changes in land cover type, e.g., from forestland to agricultural land, as well as changes in land use, e.g., primary (native) forestland to plantation forestland (Lambin, Geist, and Rindfuss, 2006). As discussed in chapter 4 , these changes influence the local hydrologic cycle (DeFries and Eshleman, 2004), regional climate (Pielke et al., 2011), and the global carbon cycle (Houghton et al., 2012). They also determine the geographic distribution of many wild and domesticated plant and animal species.

  The importance of human-induced land surface change has inspired sustained attention from the Earth system science research community (B. L. Turner et al., 1993), notably by the Land Use and Land Cover Change Project of the International Geosphere-Biosphere Programme (Lambin et al., 2006). Ambiguities in classifying land cover have made it difficult to rigorously track global changes in land cover and land use over long time periods. For example, the global area of pastureland reported by Ramankutty and colleagues (2008) was 18 percent lower than a standard estimate from the United Nations Food and Agriculture Organization because the latter included grazed forestland and semiarid land. However, application of satellite remote sensing, and increasing investments in national level surveys of natural resources, are rapidly improving monitoring capability.

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  Human Ecology

  The Story of Our Place in Nature from Prehistory to the Present

  • Bernard Campbell(Author)
  • 2017(Publication Date)
  • Routledge

    (Publisher)

  11 The Human Ecosystem: Past, Present, and Future

  ‘Population, when unchecked, increases in geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second.

  By that law of our nature which makes food necessary to the life of man, the effects of these two unequal powers must be kept equal.

  This implies a strong and constantly operating check on population from the difficulty of subsistence. This difficulty must fall some where and must necessarily be severely felt by a large portion of mankind.’

  An Essay on the Principle of Population, 1798 T. R. Malthus. 1766-1834.

  THE EVOLUTION OF THE ECOSYSTEM

  In the preceding chapters we have seen how the hominids evolved from a tropical, arboreal species into a terrestrial, bipedal form that colonized every major biome of the world. In the course of radiating from the tropics, humankind has exerted an increasingly profound influence on the environment inhabited, especially in the last few thousand years when technological proficiency has so rapidly increased. When human numbers were small and population densities were low, humankind adapted both biologically and behaviourally to existing ecosystems without extensive modification of the system’s structure. Thus, for the major portion of human prehistory, it has been possible to delineate distinct kinds of adaptations to the different ecosystems in which the human species participated; tropical, temperate woodland, grassland, boreal forest, and so on. Today, however, because of the present level of technological development and its associated enormous increase in human population, the boundaries between the various systems have become less significant, and today humankind can be seen to participate in what is essentially a single worldwide ecosystem: the biosphere. Our survival as a species is dependent upon our recognition of this fact.

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