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Assignment
Two students have produced an essay plan for the following title: ‘Discuss the
relationship between biodiversity, ecosystem processes and sustainability’.
Read the following two essay plans and answer the following questions.
1. Which essay plan do you think is better?
2. Explain your answer, providing specific examples of the differences between
the two plans, specifying the features that indicate poorer or better quality.
3. What specific advice would you give to the student who wrote to the poorer
plan to improve it?
4. What general advice would you give to the student who produced the poorer
essay plan, so that they could improve any essay plans that they write in the
future?
5. Based on these essays, which one of these students do you think would be
most suited to doing scientific research? Explain your answer.
Essay Plan I
Provide definition/explanation of biodiversity; describe and discuss biodiversity levels
(genetic, subspecies, species, habitats, ecosystems biomes); briefly mention problems in
determining number of species, current estimates of number of species and threats to
biodiversity
Explain ecosystem processes with examples e.g. productivity, decomposition and
biogeochemical cycling: describe how ecosystem processes provide benefits to humanity
e.g. maintenance of soil fertility, food and materials, regulation of atmosphere, hydrosphere
and hydrology, pest control, pollination, decomposition of wastes, detoxification of
pollutants (Costanza et al. 1997)
Define sustainability: There are several definitions, but most common is "Sustainable
development is development that meets the needs of the present without compromising the
needs of future generations to meet their own needs" (Brundtland 1987). Sustainable
systems are those that can indefinitely meet human requirements at socially acceptable,
economical and environmental costs. Most discussions of sustainability centre about the
judicious use of resources. Economics may be used to value resources and modes of
resource consumption, thus facilitating judicious choice of consumption mode (although
such economic methods may not incorporate indirect, non-use values). In practice,
sustainability is difficult to define, but typically involves integration of natural biological
cycles and controls, and protects and renews soil fertility and the natural resource base.
Across several scales, sustainability is intimately reliant on ecosystem processes, and the
provision of human services from these processes. At the level of the biosphere, the
processes that result in atmospheric quality and regulation, for example, need to be
maintained at, or near, current levels to meet the current needs of humanity and its
descendants. At ecosystem levels, natural regimes of hydrologic regulation are important for
e.g. the prevention of flooding, maintenance of a steady supply of water flow (Likens et al.),
purification of water. At smaller levels, habitats rely on the complimentary processes of
decomposition and primary production for the efficient cycling of nutrients, with minimal
loss from the system, as well as support biomass at different trophic levels. In agricultural
systems, production, decomposition, pollination, soil fertility and water quality are essential
to maintain food production (arguably one of the most important elements of sustainability).
Thus, having established how sustainability has to consider, and is reliant upon, ecosystem
processes, the relationship with biodiversity is shown. Recent research has considered the
idea that ecosystem process rates may be regulated by biodiversity. Ecosystem process are
typically achieved by the activities of microbes, plants and animals (e.g. decomposition of
wastes, detox. of pollutants, production, carbon storage etc.) The question arises: if
ecosystem process rates are dependent on the activities of species, then how might
ecosystem process rates be affected by the loss of species? Conceptual hypotheses to deal
with this include redundant, null, idiosyncratic and rivet. (Describe and discuss these, with a
diagram). If depauperate communities generally result in lowered ecosystem process rates,
then the current threats to biodiversity may threaten sustainability.
Recent experiments have addressed this question. (BIODEPTH, Hector et a11999; Tilman;
Vitousek and Hooper; and Insurance Hypothesis). The majority of research has focused on
production in plant assemblages of different diversity. Although there are some exceptions,
most studies shoe an increase in plant biomass or productivity as local species (or functional
group) richness increases. However, if this research is to be more generally applicable, there
is a need to investigate other organism groups and processes e.g. soil microbes and
decomposition, soil invertebrates and soil structure and fertility etc.
Conclude by reiterating the relationship between sustainability and ecosystem processes, and
how these may be regulated by species diversity. Conservation efforts and legislation may
need to reconsider not just the conservation of species, populations and habitats, but also the
conservation of ecosystem process rates.
Essay Plan 2
Introduce by talking about how important it is to maintain biodiversity, ecosystem processes
and sustainability, because these affect all of us.
Explain biodiversity and discuss species richness and biodiversity hotspots; briefly mention
current estimates of number of species and elaborate on threats to biodiversity.
Explain ecosystem processes with examples e.g. productivity, decomposition and
biogeochemical cycling: describe how ecosystem processes provide benefits to humanity
e.g. maintenance of soil fertility, food and materials, regulation of atmosphere, hydrosphere
and hydrology, pest control, pollination, decomposition of wastes, detoxification of
pollutants.
There are several definitions of sustainability "Sustainable development is development that
meets the needs of the present without compromising the needs of future generations to meet
their own needs" or "Sustainable agriculture is a system that can evolve indefinitely toward
greater human utility, greater efficiency of resource use and a balance with the environment
which is which is favourable to humans and most other species" or "Sustainable systems are
those that can indefinitely meet human requirements at socially acceptable, economical and
environmental costs." Discuss some methods to promote sustainable agriculture (elaborate
on lecture notes on this topic).
Sustainability is intimately reliant on ecosystem processes, and the provision of human
services from these processes. Humanity depends on a lot of the processes that ecosystems
produce: atmospheric quality and weather regulation, the prevention of flooding, purification
of water, decomposition, primary production, pollination, soil fertility and pest control. This
shows why we need biodiversity. In addition, for the future to be sustainable we need the
medicines from plants etc. that may hold the cure for cancer (from lecture notes).
Recent research has shown that ecosystem process rates are increase when biodiversity is
greatest. Ecosystem process are typically achieved by the activities of microbes, plants and
animals (e.g. decomposition of wastes, detox. of pollutants, production, carbon storage etc.)
The question arises: if ecosystem process rates are dependent on the activities of species,
then how might ecosystem process rates be affected by the loss of species? Conceptual
hypotheses to deal with this include redundant, null, idiosyncratic and rivet. (Provide a
diagram). We would expect depauperate communities to have lowered ecosystem process
rates, so that species extinctions will have an effect on ecosystem processes, and thus on
sustainability. .
Recent experiments have addressed this question. Several researchers have proven that
increases in biodiversity result in an increase in plant productivity. The BIODEPTH
experiment by Hector and co- workers showed that plant diversity and functional group
diversity caused an increase in productivity These experiments prove that species extinctions
will have detrimental effects on the ecosystem processes that are so important for
sustainability.
Thus, we need to maintain our efforts to conserve as many species as possible, with a sound
knowledge of the causes of extinction e.g. habitat fragmentation and destruction, pollution.
We also need to do more research on how to save species and restore habitats.