Ecosystem and Sustainability Module 3 Ecosystem and Sustainability

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

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

Ecosystems Are DYNAMIC

Energy Energy is transferred through ecosystems by feeding

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

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

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

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

Role of Decomposers Decomposition of organic material Saprotrophic Secrete enzymes onto dead material Digests the material into smaller molecules which are then absorbed

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

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

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

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

Conservation A dynamic process involving management and reclamation Raise carrying capacity by providing extra food Add individuals Restrict dispersal Control predators Vaccinate against disease

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

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