Transcript Ecology
Ecology Organisms Organisms Niche • It is an organisms role in the community. It includes: – what it eats – What eats it – What and how much resources it uses • Can you think of an example? Limits on population size • The maximum number of individuals of a species that an area can support is called carrying capacity • Limiting factors are factors that limit a populations size – Factors can be abiotic or biotic Population growth 2,000 Population size (N) dN 1.0N dt 1,500 Exponential growth K 1,500 Logistic growth 1,000 dN 1.0N dt 1,500 N 1,500 500 0 0 5 10 Number of generations 15 Limiting factors • Examples of abiotic include: – Oxygen in a pond, – amount of sunlight – Temperature • Examples of biotic factors include: – Predators – Competition Figure 53.10 Examples of terrestrial and marine food chains Figure 53.11 An antarctic marine food web Other feeding relationships • Decomposers break down dead plants and animals. – This recycles the materials • Scavengers are consumers that eat dead organisms • Parasites attack living organisms Figure 54.2 Fungi decomposing a log Figure 54.11 An idealized pyramid of net production • Materials are recycled but energy is NOT • Ecosystems need a constant source of energy from the sun. Figure 54.17 The carbon cycle Biodiversity • Is the measure of how many different species there are in an area • Ecosystems that have a high biodiversity are more stable • It is valuable to humans because it can be a source of medicine. • What other benefits are there? • Name a human activity that can lead to the loss of biodiversity Loss of Biodiversity • Direct Harvesting • Habitat destruction – Deforestation • Imported Species Water Pollution • Sewage and animal wastes add nutrients to the water • This causes algae to grow more and die more • Decomposers suck oxygen out of the water • If too much oxygen is removed, the fish begin to die Toxic Wastes • Chemicals that are added to lakes and rivers can kill off many kinds of organisms • An example is DDT • Biological control Burning fossil fuels • Burning oil and coal releases CO2 and sulfur into the air • Sulfur in the air will lead to acid rain that can damage or kill plants and animals – Can cause some lakes to be so acidic that nothing can live there • CO2 is a greenhouse gas and can lead to global warming – Ice caps can melt causing a rise in sea level and loss of coastline Ozone Depletion • Ozone is found in the upper atmosphere • It absorbs much of the harmful radiation from the sun • Depletion of the ozone will allow more harmful radiation to hit the Earth • This can lead to higher mutation and cancer rates.