Chapter 4 Ecology

Examples of Ecosystems:

Environmental Factors Affecting Organisms Abiotic Factors Abiotic Factors are non-living factors e.g. altitude and aspect (direction that a surface faces). High altitudes are colder, wetter and windier than lower altitudes. 2. Biotic Factors Biotic Factors are living factors. Eg. Food, competition, predation. The more food that is available the greater the number of organisms that will survive. Climatic Factors Climatic Factors refer to weather over a long period of time. E.g. temperature, rainfall etc. Higher temperatures cause faster plant growth. Edaptic Factors Edaptic Factors relate to soil. e.g. Soil type, soil pH, organic matter present. Neutral soil has a pH close to 7 and are preferred by most plants.

A grazing food chain is a sequence of organisms in which each one is eaten by the next member in the chain.

Producers: Organisms that carry out photosynthesis. e.g. oak tree. Flora: All the plants in an ecosystem. Consumers: Organisms that take in food from another organism. Fauna: All the animals in an ecosystem. Decomposers: Organisms that feed on dead organic matter. Detritus Feeders: Organisms that feed on small pieces of dead organic matter.

A trophic Level is a feeding stage in a food chain.

A food web consists of two or more interlinked food chains.

Nitrogen Fixation is the conversion of nitrogen gas into ammonia, ammonium or nitrate. Nitrification is the conversion of ammonia and ammonium compounds to nitrite then to nitrate. Denitrification is the conversion of nitrates to nitrogen gas. The nitrogen Cycle The function of the Nitrogen Cycle is to remove nitrogen from the air and make it available for use by living things. Nitrogen is needed by living things to make protein and other bio-molecules.

Steps in the Nitrogen Cycle Nitrogen gas makes up about 79% of the atmosphere. Nitrogen fixation carried out by e.g. volcanos, lightening and some bacteria removes nitrogen from the atmosphere. Symbiotic bacteria are found in the root nodules of legumes e.g. pea plants and they trap nitrogen from the atmosphere. Decomposition of dead organisms is carried out by bacteria & fungi in the soil. Nitrification is carried out by bacteria in the soil. Some nitrates formed in the soil are used by plants for growth. Dentitrification is carried out by denitrifying bacteria in the soil.

Human Impact on Ecosystems In a short time 200,000 years humans have had a huge effect on the earths resources. Three ways humans affect ecosystems: Pollution Conservation Waste Management

Control of Ozone Depletion Reduction of use of CFCs Fridges should not be dumped in landfill sites. Conservation is the wise management of the existing natural resources in an ecosystem in order to maintain a wide range of habitats and prevent the death and extinction of organisms. Conservation is a responsibility of everyone. It is important To slow down and prevent damage to ecosystems & habitats.

Fisheries (fresh water & sea water fishing) Very important industry in ireland. The main fish species caught by fishermen include herring, mackeral & cod. Problems associated with fisheries: Pollution – kills fish and some fish stocks e.g. cod will take years to regenerate Overfishing – has reduced fish stocks Small mesh nets – have reduced the numbers of young fish. Conservation in Fisheries: e.g. Size of mesh in fishing nets is very important. If the mesh size is too small very young fish are trapped as well as older fish depleting fish stocks. Waste Management Modern living creates large amounts of waste material. It is important to manage this waste material to prevent pollution.

Examples of waste Management: 1. Agriculture Many of our inland lakes have been depleted of fish e.g. due to a lack of oxygen in the water. Slurry (liquefied waste material produced by animals). When slurry enters rivers it causes increased algal growth. The addition of nutrients to fresh water is called eutrophication. When algae die they are broken down by bacteria and depletes the oxygen through respiration of the bacteria. Aquatic animals and plants die when they don’t get sufficient oxygen. 2. Fisheries Waste materials from fish e.g. heads,blood etc. can be recycled as fertilisers or pig feed.

Problems associated with waste disposal 3. Forestry Waste products in forestry include include: tops of trees, small branches, tree stumps etc. Problems associated with waste disposal Role of micro-organisms in waste management Landfill sites – most waste is disposed of in landfill sites. Bacteria & fungi in the soil break down the organic material (biodegradable).

2. Sewage – waste from toilets, bathrooms, industry & rainwater from drains. Primary sewage treatment involves physically screening or filtering waste and allowing it to settle. Secondary sewage treatment is when waste is acted on by bacteria & fungi. This biological treatment breaks down most organic waste. Tertiary sewage treatment removes mineral nutrients e.g. phosphates & nitrates. Control of Waste Production Reduce – reduce consumption of goods Reuse – re-use clothing Recycle – Collect products e.g. glass and plastic and remake into other products.