OCR A Level Biology

Revision Notes

6.6.4 Managing Ecosystems Sustainably

Managing Ecosystems Sustainably

  • Sustainability is the ability of an ecosystem to maintain (or ideally increase) its biodiversity whilst simultaneously providing humans with the resources they need over a long period of time
  • Humans, in the way that they set up and manage an ecosystem, are in control of whether that ecosystem is sustainable or not
    • The resource must be allowed sufficient time to replenish before being harvested so that it does not run out
    • No harm should be done to the ecosystem, its surrounding areas, or to species living within it
    • Practices that boost biodiversity are promoted
    • The long-term future of the ecosystem must be guaranteed
  • Two examples of managed ecosystems for sustainability are commercial fishing and timber production

Commercial fishing

  • The human appetite for fish and seafood is very high, and growing fast as the human population rises
  • Fish is a lean and healthy meat source with good protein levels for growth
  • Modern fishing fleets have technologically advanced systems that could if used irresponsibly, strip the oceans bare of the most desirable fish species in a matter of months
  • Sustainable fishing means:
    • Leaving enough fish in the ocean
    • Protecting habitats and marine food webs that fish rely on
    • Human communities that catch and process fish can maintain their livelihoods
  • Governmental regulation can be enforced by:
    • Establishing fishing quotas
    • Agreeing areas of the ocean where fishing is banned (eg. spawning grounds) and permitted (eg. within a country’s territorial waters)
    • Regulating mesh size of nets (to allow undersized/juvenile fish to escape)
    • Limiting the size of the fishing fleet by issuing licenses
    • Inspecting the catch as a fishing boat returns to port
    • Banning certain practices eg. gillnets (static nets that catch anything that swims by, and the fish struggle and die in distress)
    • Promoting sustainable practices such as trolling (different to trawling) that reduces bycatch
  • Nevertheless, a lot of commercial fishing is carried out illegally
    • There is a very wide area of ocean for the authorities to patrol
    • High demand and profit potential has made poachers more daring and willing to break the law

Sustainable fishing 1, downloadable AS Level & A Level Biology revision notes Sustainable fishing 2, downloadable AS Level & A Level Biology revision notes
Measures to make commercial fishing more sustainable.

Trolling, downloadable AS Level & A Level Biology revision notes
Trolling uses hook-and-line and reduces bycatch and damage to the seabed

Timber Production

  • Human demand for wood and timber products fluctuates
    • In the mid-20th century, UK forests were reduced to 5% of the land area; today it’s back up to around 12% through afforestation efforts
  • Alternative materials are being used (eg. uPVC window frames)
  • New uses of timber products exist eg. as a fuel for power stations to replace non-renewable coal
  • Timber remains an important resource in today’s society, with many uses
  • There is pressure on natural woodland to be felled and used as grazing land or for crop production, particularly in developing countries
  • There are 2 main groups of tree crops used in commercial logging
    • Fast-growing conifers eg. spruce, pine, fir, larch
    • Slower-growing broad-leaf trees eg. oak, beech, hazel

Fast-growing coniferous plantations

  • Conifers are the fastest-growing trees in the northern hemisphere used as a strategic reserve of timber
  • Low-grade agricultural land is used to grow these trees, creating an effective monoculture
    • Densely planted forests, deep shade, and needle litter at floor level all contribute to low biodiversity
  • Work has been done to try and increase biodiversity in these areas
    • The use of felling methods other than clear-felling introduces pockets of variety into a plantation
    • Creation of firebreaks, clearings, selective felling, strip felling, coppicing, edge habitat creation and in-situ leaving of naturally dead trees all attract other species and boost biodiversity
    • Genomic research has identified suitable sub-species eg. spp of Sitka spruce that can grow faster and shorten the tree breeding process
    • Recreation and public education projects now form part of the remit of forestry authorities

Woodland Management 1, downloadable AS Level & A Level Biology revision notes Woodland Management 2, downloadable AS Level & A Level Biology revision notes Woodland Management 3, downloadable AS Level & A Level Biology revision notes Woodland Management 4, downloadable AS Level & A Level Biology revision notes Woodland Management 5, downloadable AS Level & A Level Biology revision notes Woodland Management 6, downloadable AS Level & A Level Biology revision notes
Examples of woodland management techniques to make commercial forestry more sustainable

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