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Ecosystem and Sustainability
Module 3 Ecosystem and Sustainability
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Glossary Ecosystem Biotic Factor Abiotic Factor Producer Consumer
All the living organisms and non living components in a specific habitat, and their interactions Biotic Factor Living organisms in an ecosystem that can effect each other e.g. food supply, predation and disease Abiotic Factor Effects of non-living components of an ecosystem e.g. pH, temperature, soil type Producer Autotrophic organisms that convert light energy into chemical energy Consumer Living organisms that feed on other living organisms Decomposer Organisms that feed on dead organic matter, make molecules, minerals and energy available to other organisms
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Glossary Trophic Level Carrying Capacity Interspecific Competition
The level at which an organism feeds in a food chain Carrying Capacity The maximum population size that can be maintained over a period of time in a particular habitat Interspecific Competition Between individuals of different species Intraspecific Competition Between individuals of the same species Conservation Maintenance of biodiversity, including diversity between species, genetic diversity within species and variety of habitats Preservation Protecting areas of land yet untouched by human
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Ecosystems Are DYNAMIC
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Energy Energy is transferred through ecosystems by feeding
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Energy Transfers Energy transfers between trophic levels can be measured Pyramid of number Each bar proportional to the number of individuals Pyramid of biomass Each bar proportional to the dry mass of individuals in that trophic level Often wet mass is used and dry mass calculated from previous data Pyramid of energy How much energy is released from a species individual per unit mass Burn individual in a calorimeter, but is considered too destructive Productivity Rate of energy flow: productivity Gross primary productivity: rate at which plants convert light into chemical energy Not just a snapshot, take into accounts fluctuations over time
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Human activities Human activities can manipulate the flow of energy through the ecosystem More light Plant crops early Grow under light banks More water Irrigating crops Lack of nutrients Fertiliser, crop rotation Pests remove biomass Pesticides, gm pest resistance Competition for light Use herbicides to kill weeds Human activities can manipulate the flow of energy through the ecosystem Young animals use energy to grow more than adults Kill animals before adulthood Steroids Pathogens slow growth Antibiotics Use energy for heat and moving instead of growth Pen animals Keep indoors
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Example of Primary Succession
Directional change in a community over time Primary Succession From bare rock Pioneer community First organisms to live on bare rock Climax community Final stable community Example Sea Rocket: tolerate salt, lack of fresh water and unstable sand Sand builds up around them, when they die they add nutrients Sea Couch Grass: Under ground stems that help stabilise the sand Marram Grass: More sand builds up around it Bird’s foot trefoil Legume: adds nitrate Sand Fescue Stabilises ground further Woodland or Grassland
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Measuring distribution and abundance of organisms
Transects Look for change across habitat Line transect: Look at what is touching the tape at regular intervals Belt transect Place quadrat at regular intervals Quadrats Point quadrats Look at what is touching the needles
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Role of Decomposers Decomposition of organic material Saprotrophic
Secrete enzymes onto dead material Digests the material into smaller molecules which are then absorbed
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Nitrogen Cycle Microorganisms recycle nitrogen within the ecosystem
Nitrosomonas Oxidises ammonia to nitrite Nitrobacter Oxidises nitrite to nitrate Rhizobium Nitrogen fixing bacteria Live in root nodules of legumes Turns nitrogen into nitrate
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Limiting Factors Determine the final size of a population
Availability of resources E.g. food, water, light, oxygen, nesting sites, shelter# Effects of other species E.g. parasites, predators, competition of resources from individuals of the same or different species Carrying capacity Upper limit these factors place on the population
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Predator-Prey Relationships
More predators more prey eaten Prey population gets smaller less food for predators Less food less predators survive Less predators fewer prey eaten so their population increases More prey predator population increases
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Sustainable Management of Resources
Timber production in a temperate country Sustainable: similar quantities of timber can be harvested year on year Trees not planted too close together Prevent young trees from being grazed Plant fast growing plant Clear felling not done as causes soil erosion Selective felling Strip felling Coppicing/pollarding
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Conservation A dynamic process involving management and reclamation
Raise carrying capacity by providing extra food Add individuals Restrict dispersal Control predators Vaccinate against disease
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Conservation of Biological Resources
Economic Valuable food source Natural predators/pests can act as control agents Pollinators Social Potential beneficial resources e.g. drugs Ethical Species has values in their own right
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Galapagos Islands Effects of human activities on the animal and plant populations Habitat disturbance, fragmentation Use of resources Increased pollution Over exploitation Giant tortoises taken for food Over fishing for exotic species Introduced species e.g. goats, cats, insects Out compete native species e.g. goats outcompete tortoises Eat native species Bring diseases
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