A.S. Module 1: Unit 2 - Ecosystems

1. A.S. Module 1: Unit 2 - Ecosystems 2(a) The ecosystem as an open system involving the transfer of energy and matter

2. Ecosystem Ecology Biotic components Abiotic components Open system Tropic structure Trophic pyramids Tropic levels Autotrophs Producers Photosynthesis Heterotrophs Consumers Herbivores Carnivores Omnivores Diversivores Decomposers Detritivores Food chain Food web Soil Litter Biomass Biome Biosphere Atmosphere Hydrosphere Lithosphere Key terms to research and define.Waugh’s, An Integrated Approach,p.295 to 306 will help

3. An ecosystem is the interrelationship between living things and their environment. Ecology is the study of the interrelationships between organisms and their habitats. Biotic components are the living parts of the environment e.g. plants and animals. Abiotic components are the non-living parts of the environment e.g. rock, soil, air and water. An open system has flows of energy (sunlight) and matter (organisms, abiotic elements) across its boundaries. ECOSYSTEM ABIOTIC BIOTIC rocks plants animals air water autotroph heat heterotroph soil Definitions: self feeding depend on external nutrients Green plants Herbivores Carnivores Omnivores Detritivores

4. An Ecosystem as an Open System INPUTS PROCESSES OUTPUTS Gases Light, heat & energy from the sun Water Organic matter from: - death -excreta -brought in by wind & water -human activity e.g. fertiliser Inorganic material from rocks breaking down to form soil The delicate balance of living and non-living elements interacting with each other and the environment. Oxygen Carbon dioxide Heat energy Water: surface runoff, leaching, water vapour Matter: -movement of plants & animals -human activities: deforestation, harvesting, mining

5. A trophic pyramid is a diagram which shows the progressive loss of energy through the food chain, this reduces the biomass at each level and reduces the number of organisms that can exist at each level. A trophic level is made up of organisms which feed at the same level : 1st level is producers which include green plants capable of producing their own food by photosynthesis. 2nd level is primary consumers (herbivores) eating the producers. 3rd level is secondary consumers (smaller carnivores) eating herbivores. 4th level is tertiary consumers (larger carnivores) also known as omnivores. Trophic structure is a classification based on feeding patterns, it consists of 4 levels from producers, to herbivores, carnivores and omnivores. Loss of Fewer organisms Energy Fall in biomass Definitions: No. of organisms or amount of biomass

6. Why do the number of organism decline as you climb the pyramid? • The flow of energy decreases with each successive trophic level. • This imposes a natural limit on the total mass of living matter (biomass) and on the number of organisms that can exist at each level. • Why? • No energy transfer is 100% efficient – the transfer of light energy to food energy is only 1% efficient. • There are large losses of energy at each trophic level due to respiration, growth, reproduction and mobility.

7. Autotrophs (or producer) are organisms capable of converting sunlit energy into food energy by photosynthesis (self-feeding). These are normally green plants and can also include plankton. Photosynthesis is a process carried out by green plants where light energy is transferred into chemical energy. Light, chlorophyll, warmth, water and carbon dioxide are needed. CO2 which is absorbed through stomata in the leaves of higher plants, reacts indirectly with water taken up by the roots when temperatures are suitably high, to form carbohydrate. The energy needed for this comes from sunlight which is ‘trapped’ by chlorophyll. Oxygen is a by-product of the process. The carbohydrate is then available as food for the plant. Definitions:

8. Photosynthesis

9. Photosynthesis

10. Heterotrophs (or consumers) are organisms that feed on other organisms (dependent on external nutrients). These include: Herbivores – plant eaters Carnivores – meat eaters Omnivores (or diversivores) – plant and meat eaters Detritivores (or decomposers) - consumers such as bacteria and fungi which operate at all trophic levels. Food chains are simple linear feeding sequences. Food is passes from producer to herbivore, to carnivore. A food web shows a variety of plants and animals at each trophic level and how energy is passed through feeding patterns. Complicated food webs are more common in an ecosystem than simple food chains. FOOD WEB Definitions:

11. Soil is the top layer of the earth that is composed of disintegrated rock particles, humus, water and air. Litter is organic matter in and on the soil, it includes humus and leaf litter. Biomass is the total mass of living organisms, mainly plant tissue, per unit area. It is a store of energy and is also known as standing crop. It can be measured in 3 ways: - dry weight (kg/metre squared) - ash weight - calorific value per unit area A biome is an ecosystem found on a global scale e.g. tropical rainforest. Model of the MINERAL NUTRIENT CYCLE developed by P.F. Gersmehl in 1976 (see p.300 for labels) Definitions: biomass litter soil Store of nutrients Transfer of nutrients The size of the circles and arrows is proportional to the amount of nutrients

12. The biosphere is the part of the earth’s surface and atmosphere inhabited by living things. Reaches from the sea bed to the clouds. The atmosphere is the layers of gases surrounding the earth. The hydrosphere is the water either on the earth’s surface (oceans, lakes etc) or within porous rocks or water vapour in the atmosphere. The lithosphere is the rigid outer layer of the earth comprising the earth’s crust (rock & soil) and the solid part of the mantle. There is an exchange of energy and or matter between the biosphere and the other 3 elements. The biosphere is a global ecosystem. Relationships: HYDROSPHERE BIOSPHERE LITHOSPHERE ATMOSPHERE Definitions