1.2-a) Succession

• Ecological succession: ➞ is described as the changes in the species structure (the different types of species) in a community over time. • Succession is a process that is driven by the organisms involved, where the organisms change the habitat, making it less suitable for themselves and more suitable for other species.

• Adaptation: ➞ is any feature which makes an organism well suited to living in its environment.

• As an organism colonises a habitat, they change the habitat conditions 🐛 • As the conditions change, the organisms become less well adapted to their niche ✨ • This allows another species to outcompete the original species for the niche 🆚 • As the conditions change, the original organism makes the conditions less suitable for themselves and more suitabe for the next species on succession ➡️ ➞ (The rate of succession can be influenced by either cliamtic, biotic or edaphic factors) ➞ (The climate of region is determined by its temperature, precipitation, altitude and latitude)

• Climax community: ➞ is the final stage of ecological succession. Here a community of plants and animals remains stable and exists in balance with each other and their environment. • Key Features: 1. Stable community ➡️ 2. High biodiversity 🐛 3. Complex food webs 🕸️ 4. High biomass (big trees) 🌳

• Primary succession: ➞ is the colonisation of a new site by communities of plants and animals after an event has removed all exisitng soil (i.e. glaciation or a lava flow) • This type of succession must first wait for soil to develop sufficiently to support colonising species.

• Primary colonisers (pioneer species) are adapted to growing on bare rock (i.e. lichen and algae). • Pioneers form the first seral communtiy and will eventually form the first layer of soil. ➞ This results in them being outcompeted by vascular plants (i.e. grasses)

• A seral community: ➞ is an intermediate stage found in ecological succession that advances towards its climax community, where depending on the foundations and climate of the area, a sere can be one of many types.

• LITHOSERE: ➞ succession that begins on bare rock. They are common in Scotland due to glaciation. (Lithosere can also be seen in islands formed as a result of volcanic eruptions) 🪨 • PSAMMOSERE: ➞ succession that begins on newly exposed coastal sand (e.g. sand dunes) ⌛ • HYDROSERE: ➞ succession that occurs in areas of fresh water (e.g. ox box lakes). The open freshwater will naturally dry out and become swamp marsh and finally, woodland 🌊 • HALOSERE: ➞ succession that occurs in saline environments (e.g. salt marshes) 🧂

• SERAL STAGE 1: ➞ The pioneer community (usually lichens and algae) start to form on newly exposed bare rock. ➞ They can absorb mositure from the atmosphere and break down the rock and minerals to release nutrients. ➞ As the pioneers die and decompose, small quantities of organic matter build up. • SERAL STAGE 2: ➞ Early colonisers (i.e. grasses and mosses) take advantage of the new niches created by the pioneer species. ➞ They are adapted to survive in these conditions, so can outcompete the pioneers. For example, larger leaf area for sugar production by photosynthesis which leads to rapid growth. • SERAL STAGE 3: ➞ As soil and organic matter continues to build up, late colonisers (i.e. gorses, heather, hawthorn and bramble) outcompete the early colonisers. ➞ They have larger, animal dispersed seeds and grow much faster and taller. ➞ Their roots penetrate more deeply in the rocky substratum which causes more weathering and soil formation. • CLIMAX COMMUNITY: ➞ Trees begin to grow among the shrubs and the forest climax community forms. ➞ It will eventually grow higher than the shrubs and shade them. These shrubs are outcompeted by shade-loving plants. ➞ Leaf litter and decaying roots weather the soil further and add humus to it. ➞ An equilibrium is reached between the environment and the biotic community. The type of climax community depends upon the climate.