Ecosystems: Ecological Succession and Climatic Climax

Ecosystems: Change and Challenge The Structure of Ecosystems Ecosystem: a dynamic, stable system characterised by the interaction of plants and animals with each other and with the non-living components of the environment The components of an ecosystem are categorised as either biotic and abiotic Biotic means the living environment, components include: i). Vegetation (living and decomposing) ii). Mammals, insects, birds and microorganisms Biomass-the mass of material in the bodies of animals and plants (total mass of living matter) Abiotic means the non-living, chemical and physical components of the ecosystem and includes: i). Climate- in particular the seasonal pattern of temperature and precipitation ii). Soil characteristics iii). Underlying parent rock iv). Relief of the land v). Drainage characteristics Ecosystems are open systems because energy and living matter can both enter and leave the system: * Inputs-Energy from the sun, which drives photosynthesis-enabling the plants to grow, water transported into the ecosystem from precipitation and animals that arrive from elsewhere * Outputs-nutrients are transferred out of the system by: animals can physically move out, water can leave through evapotranspiration, groundwater flow and throughflow * Flows-nutrients can be transferred from one store to another e.g. capillary uptake * Stores- stores of nutrients: vegetation, plant litter and soils Energy Flows and nutrient cycling Energy flows- is the flow of energy through a food chain * Energy flows flow through an ecosystem from one stage to another. * Through photosynthesis plants are able to capture light energy from the sun to make carbohydrates from carbon dioxide and water to grow and increase their biomass * Within all ecosystems, nutrients are required for plant growth and are recycled from one store to another e.g. leaves fall from tree-> when they decompose nutrients are returned