Succession from pioneer species to climax community. At each stage in succession, certain species may be recognised which change the environment so that it becomes more suitable for other species. The changes in the abiotic environment result in a less hostile environment and changing diversity. Conservation of habitats frequently involves management of succession. Candidates should be able to • use their knowledge and understanding to present scientific arguments and ideas relating to the conservation of species and habitats • evaluate evidence and data concerning issues relating to the conservation of species and habitats and consider conflicting evidence • explain how conservation relies on science to inform decision-making.

Succession is the idea of the sorts of plants and animals in a habitat changing over time. There are two types: primary succession occurs when there is a totally bare piece of land, like a rock or somewhere that has been wiped out by a volcanic eruption.

Pioneer species are the first living things to grow on the land, they are renowned for being able to withstand tough and extreme conditions that other plants cannot live in. Often they get there because they have spores or windblown seeds which are easily transported from other communities. Once there they reproduce rapidly, as this is often a feature of pioneer species. The plants will photosynthesise to produce energy, they may also produce nitrogen by bacteria on their root nodules as there will be little existing nutrient in the soil.

When the plants from the pioneer species die and decompose, they leave deposits of nutrients; the beginnings of soil. This soil is rich in humus (organic matter) which other plants need to survive, this means that other species can begin to grow. These plants then decompose in turn increasing the humus even further, and the depth of soil, so new species can move in that are less hardy and have bigger roots. This cycle continues: often the original species are out competed by newer ones; at some point when there are enough plants animals will join the system.

Secondary succession is when a minor disturbance kills off plants, but leaves soil and possibly seeds behind. Here the same process of succession will happen, but as the conditions are less hospitable it does not need a pioneer species to start it off.

The further into succession, the higher the biodiversity as conditions become less hostile and are more friendly to live in for more organisms. Not only is this caused by an improvement in soil, but things like also a decrease in wind, changes in soil acidity and a greater variety of habitats.

We have the idea of a climax community which is the sorts of plants and animals that will grow in an area once it has reached equilibrium. For example, in England, due to the climate, most areas stop changing the species when there is deciduous oak woodland.

Because different plants and animals are suited to different stages of succession, if conservationists are trying to increase the population of a plant or animal, they will control succession to be at the stage that that organism is successful at.