Biology 3A – Ecosystems – background

Terminology Pyramids Food chains Food webs Field work Sustainability Diversity Flexibility Matter cycles Energy flows Interdependence Relationships Global issues Human impact Conservation Management Applications & implications Key concepts Tools Ecosystem concepts you need to be able to use What you need to be able to discuss for 3A What is ecology?

Ecological systems Biosphere Atmosphere Lithosphere Hydrosphere Ecosphere

Biodiversity Biodiversity = many living things ecosystem biodiversity – a range of different habitats and complex ecosystems are available around the world or within an area species biodiversity – different species exist within each ecosystem genetic biodiversity – variations exist within a species within an ecosystem

Ecosystems Habitat Particular area in which a population lives Abiotic factor Non living factors eg temperature, rainfall Population All the organisms from one species in an ecosystem Community All the organisms in an ecosystem Environment All the abiotic factors Biotic factor Living factors eg predation, competition Ecosystem is a term that describes ecological systems consisting of interacting organisms and their physical environment

Biomes Ecosystems with similar abiotic factors

Biomes 2 Canada Australia Dry aridTemperate forestTemperate reef

Niche Description of an organisms role and or location within an ecosystem Eg the fox can be described as 2 nd order consumer or forest floor dweller

Ecological terms Autotroph makes own food (either by photosynthesis or chemosynthesis) = producer Heterotroph eats other organisms Producer makes own food (either by photosynthesis or chemosynthesis) = autotroph Consumer eats other organisms Decomposer feeds of wastes or dead animals = detrivore Detrivore feeds of wastes or dead animals = decomposer Detritus wastes or dead matter First order consumer eats producers Second order consumer eats 1 st order consumers Respiration manufacture of energy by burning organic compounds eg glucose Photosynthesis manufacture of organic compounds eg glucose using the energy of the sun Chemical energy Energy gained from chemical reactions eg respiration Thermal energy Heat energy Solar energy Energy from the sun Trophic level location on food chain eg producer

Matter and energy In most natural ecosystems, matter cycles and is re-used Energy flows and is lost At each trophic level most of the energy is lost in respiration

Food chains show energy movement Arrows show movement of energy The direction of the arrow is from organism being eaten to the organism doing the eating

Food webs show feeding relationships Arrows show movement of energy The direction of the arrow is from organism being eaten to the organism doing the eating

Energy flows in ecosystems Energy available from previous level Energy leaving as waste heat Energy used for new growth Respiration Energy lost in wastes

Measuring energy flow Sun outputs ~ kJ per day kJ per day is reflected and not used 2 000kJ per day is used by plants Heat energy lost due to respiration 1200 kJ 220 kJ 32 kJ Energy used for growth and thus available to next level 320 kJ40 kJ 480 kJ 60 kJ8 kJ 548 kJ Energy in dead matter and wastes

Measuring energy flow Productivity - rate at which an ecosystem accumulates mass or energy – biomass/unit area/time period (eg kg/m 2 /day) or energy/unit area/time period (eg kJ/m 2 /day) Biomass – dry weight of organisms found in a trophic level - mass/unit area (eg kg/m 2 ) or energy/unit area (eg kJ/m 2 ) Gross primary productivity – how much solar energy is fixed as chemical energy by producers (ie measure of energy trapped by photosynthesis Net primary productivity – amount of energy available once respiration has occurred

Pyramids These show numbers of organisms, or energy/mass available at each trophic level The 4 types are numbers, size, biomass and productivity

Drawing pyramids Trophic status OrganismNumber of organisms Size of organismBiomass (g Carbon/m 2 )New tissue produced (g/day) Producer15 m1506 1st order consumer 5005mm158 2nd order consumer 420 cm rd order consumer 401 mm number size biomass productivity producer 1 st order consumer 2 nd order consumer 3 rd order consumer 1 st order consumer producer 2 nd order consumer 3 rd order consumer <5000 mm <500 mm <50 mm <5 mm <1 mm

Types of ecosystem Natural – relatively unaffected by humans eg forest, reserves, parks Agricultural – farming ecosystems Urban – human ecosystems eg towns and cities Aquatic – ecosystems in water eg rivers, seas Terrestrial –ecosystems found on land eg forests, deserts

Measures of stability Stability ability to cope with change. The more stable an ecosystem, the better it can cope. Stable systems usually have high biodiversity, complexity and amount of recycling Biodiversity number of species present. The greater the number, the higher the biodiversity Complexity how many relationships can be seen, size of food web. The more complex the ecosystem the larger the food web, and the more relationships that can be seen Recycling amount of matter that is lost from the system. The greater the recycling, the less matter is lost to other ecosystem

Different ecosystems CriteriaNaturalAgriculturalUrban InputsLow – energy, water & nutrients Migratory animals or flow from rivers or leeching from soil High – energy & matter (+ possibly water – irrigation) Stock & seedlings, fertilizers & pesticides High – energy, water & matter Raw materials and goods OutputsLow – energy, water & nutrients Migratory animals or flow from rivers or leeching from soil High – energy & matter Crops & animal products & wastes High – energy & matter Wastes & sewerage, manufactured goods Ecological complexity Biodiversity Trophic levels Stability Recycling of matter High High (usually 5+) High Low Low – crops Low (1- 2) Low Low - moderate Very low Low (1- 2) Low Low - none Effects on neighbouring ecosystems LowHigh – feral species, algal blooms, erosion, salinity, biological magnification High – feral species, pollution, greenhouse, desertification, ozone depletion, algal blooms

Comparing natural, urban & agricultural ecosystems Biotic Abiotic Natural ecosystem Agricultural Urban Heat Solar energy Chemical energy Recycling Matter Feed, fertiliser pesticides Seed, stock Less recycling Very little recycling Produce Waste, produce Heat, electricity Wastes Raw material, manufactured goods Rubbish, sewerage manufactured goods