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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.