Figure 3 shows a food web made up of many levels. The first, the producer, absorbs the most energy from the sun (around 10% of sun’s total energy output- this is the highest amount of energy received in the whole chain). Without the producers energy would not be obtained and the whole web would terminate. The second trophic level consists of primary consumers. These can only be herbivores, such as rabbits and worms, they will only eat the plants. Trophic level 3 of the food web comprises of secondary consumers, which stereotypically consume other animals. An example of this is the owls, which consume small birds. In figure 3 the final trophic level is the tertiary consumers, which consists of the top predators that often prey upon most of the other animals in the food chain, figure 3 shows how an owl will prey on both beetles and larger animals such as mice and voles. At each trophic level, 10% of the energy consumed by the predecessor is passed on, meaning that animal must consume lots of food in order to gain the correct amounts of energy for basic functions such as respiration, digestion and excretion. Dead organic matter is highest near the bottom of the food web as the nutrients released from the decomposing plants and animals releases lots of nutrients which helps the plant to grow. This is resulting from decomposers such as bacteria and algae.

Studland bay in Dorset contains a classic psammosere (dynamic vegetation succession, which characteristically increases inland). The first stage, known as the embryo dune, contains a significant lack of vegetation due to the hostile conditions faced. Strong sea winds remove moisture in the air and the salty water inhibits any other plant than halophytes and xerophytes to occur. Due to this, dune height is just less than 1 meter and there is only an average of 20% vegetation occurrence. In addition to the abiotic factors inhibiting much plant growth, biotic factors such as humus and moisture content levels, which is minimal due to lack of vegetation to be decomposed and created the optimum conditions. Fore/yellow dunes are the next level of the psammosere where vegetation cover is around 75% and the height is round five times that of the embryo dune. Marram grass is a typical plant to be found here due to their adaptations such as long roots to obtain as much water as available and sunken stomata to retain the water. The height of this stage of the dune is vital as it provides protection from the wind and sand so that the next stage (the grey dunes) are sheltered. This, and the now higher humus and moisture content of the soil, creates a more optimum environment and so species such as heather and gorse are able to grow, allowing a vegetation cover of over 80%. With each stage the level of vegetation increases, mainly due to decomposition and release of nutrients, thus increasing humus levels. In time, soil begins to from due to the dead organic matter creating a steady and nutrient sufficient environment for the species on the next dune to grow.

Biodiversity is the variety of living organisms (plants and animals) specifying on either a general term, such as globally, or in a particular place, habitat. There are many different benefits that come from maintaining a high biodiversity such as resources. With a rising population, there is a higher demand for specific resources such as food, fuel and medicine. Concerns from this include overhunting- draining that resource to extinction leaving the people with less sufficient supplies. Particularly, in the case of food supply, if one species becomes extinct it could massively disrupt the food chain as their predators no longer have food and so will too become extinct and so on. This could cause a global starvation. In addition to food loss, with the removal of trees and plants for biofuels, the possibility of new medicines being discovered is diminishing daily. Biofuels provide over half of the energy in developing countries such as Burkino Faso and in others it accounts for over eighty percent of total energy consumption. In countries such as Nigeria, overexploitation of wood fuel leaves areas with a high population density without access to alternative affordable energy resources. Although in Burkino Faso new stoves have been created to be as efficient as possible, some countries may not have access to these. In addition to overexploitation of trees and plants, the oceans have had major losses of biodiversity. Overfishing has increased 18% since 2004 and the global fleet is 2-3 times larger than the ocean can support. Depleting fish stocks has not just removed species, but has also caused the collapse of jobs. In 2005 40,000 people were made redundant due to a lack of availability to be provided with a steady income. To conclude, biodiversity provides sustainability and with rapid decrease in levels of biodiversity, people will no longer be able to sustain a steady livelihood and the future of the Earth’s sustainability as at major risk.