Chapter 4: Ecosystems and Communities Section 4.1 Climate
What is Weather? Weather can change on a day to day basis
What is climate? Defined by year after year patterns
What is a microclimate? When Environmental conditions change over small distances
What shapes climate? Solar energy trapped in the biosphere Latitude Transport of heat by winds and ocean currents
What is the relationship between Solar energy and the greenhouse effect?
How does latitude affect amount of solar energy hitting Earth? At the poles solar energy is spread over a larger area due to the Earth s curvature Earth s surface can be divided into 3 zones Polar Temperate Tropical Amount of solar energy varies throughout the year
How does Heat transport in the Biosphere relate to winds? Winds are caused the rising and cooling of air Warm air is less dense and rises Cold air is denser and sinks Winds transport heat from warm to cold air Earth s rotation leads to general west to east movement over temperate zone
How do Ocean current effect heat transport in the Biosphere? Surface waters are moved by winds Currents transport large amounts of heat Affect weather of nearby landmasses Depp ocean currents cause by sinking in polar regions, This water rises in upwellings in warmer areas
Niches and community interactions Section 4.2
What is a niche? Each species has a range of conditions under which it can grow and reproduce Help define where and how an organism can live
What does tolerance mean in Biology? Every species has it s own tolerance range A species tolerance for environmental conditions helps define it s habitat Example environmental conditions are temperature, amount of sunlight
How do you define a niche? A niche describes not only what an organism does, but how it interacts with biotic and abiotic factors in the environment A niche is: The range of physical and biological conditions in which a species lives & the way the species obtains what it need to survive and reproduce Understanding a nice is important to understanding how organisms interact to form a community
What is a resource? Can refer to anything necessary for life Examples are: Water Nutrients Light Food Space Shelter Places to feed
Physical aspects of niches Part of an organisms niche involves abiotic factors that are required for survival Amphibians loose and absorb water through their skin They must live somewhere moist If too hot and dry, or too cold most won t survive for long
Biological aspects of niches Part of an organism's niche involve biotic factors required for survival When/how it reproduces Food source How it obtains food Example, birds on Christmas Island in Indian ocean live in harmony, but prey on different fish
When do organisms compete against each other? When organisms attempt to use the same limited ecological resource Can occur within the same species - intraspecific Can occur between different species interspecific Basis of survival of the fittest!
What is the competition exclusion principle? No two species can occupy exactly the same niche in exactly the same habitat One species will always be better at competing for limited resources It is very rare for natural resources to overlap
Are organisms any good at sharing? Species often divide resources rather than compete for them North American warblers all live harmoniously in the same tree Resources for each species are similar but different Competition helps determine the number and kinds of species in a community, and the niche each species occupies
What is the relationship between Predator and Prey populations? Predators can affect the size of the prey population in an ecosystem Predators can determine places prey can live and feed
Do you see a similar relationship between herbivores and plants? Just as important as predator prey relationships Herbivores can affect the size and distribution of plant populations Can determine the places that certain plants can live
What is a Keystone species? Changes in the amount of a single species can cause dramatic change Off pacific coast of USA Sea otters eat urchins Urchins are herbivores and eat kelp (a type of giant algae) When otters were nearly eliminated by hunting the kelp forest nearly disappeared Too many urchins devoured all the kelp Other organisms which lived on kelp died When otters given protected status, everything started to return to normal, but now otter numbers are falling again Wolves in Yellowstone national park another perfect example of keystone species
What does Symbioses mean? Any relationship where two creatures live closely together 3 types of symbiotic relationships Mutualism Parasitism Commensalism
What is mutualism? Nile crocodile and Egyptian plover bird The bird will clean the crocodile's mouth as it basks in the sun There is a clear benefit to both organisms Both consent to the relationship
What is Parasitism? Where one organism lives inside or on another organism Often weakens but not does kill the host Obtain all or part of their nutritional needs from the host
Is the giraffe and the tickbird an example of parasitism or mutualism?
What is Commensalism? A relationship in which one organism benefits and another is neither helped nor harmed
Succession Section 4.3
What happened at Krakatau? In 1883, an explosive eruption destroyed the island of krakatau Within 2 years grasses were growing Within 14 years there were 49 plant species By 1929 there were 300 plant species Now there is a forest!
What is Ecological Succession? A series of predictable changes that occur over time Over the course of succession the number of species will increase Causes volcanic eruption, glacier retreating
What do these plants have in common? Pioneer species the first to colonize an area of land Simple structure Often get crowded out over time
Secondary succession Pre existing soil speeds up the development process
Why does succession occur? Organisms change the environment they live in As organic matter begins to accumulate it becomes easier for more complex plants to grow Trees for example will provide shade and cooler temperatures for other species Roots will help soil build up Help organisms to find their niche
What is a climax community? End stage of succession Not always stable and uniform Succession doesn t always follow the same path
Succession after natural disasters In a healthy ecosystem secondary succession will return the land to the original climax community Example Coral reef or tropical rainforest recovering from a storm Often climax communities are not stable Patchwork of different areas in different stages of secondary succession
Do Human s disrupt the sequence of succession? Ecosystems may or may not recover from human disturbances Microclimate and soil can be changed so much that the original community cannot return
Patterns of succession. We learn from experience Identify predictable stages based on our experiences For example compare what happened with Mt St Helens with records of Krakatau
Writing exercise What effect do pioneer species have on an environment undergoing primary succession
Biomes Section 4.4
Why do Oregon, Montana and Vermont have different climates Proximity to oceans, & Mountain ranges will affect regional climate
How do mountains affect amount of rain on land? Could be Oregon, could be North West England Same process
Biomes At least 10 groups of regional climate communities Biomes Biomes can be described in terms of abiotic factors like climate and soil type, and biotic factors such as plant and animal life Examples are Tropical rain forest Grassland/savana Desert Temperate grassland Temperate woodland Temperate forest Tundra
Climate diagrams what kind of environment do these two graphs correspond to? Left = temperate forest Right = desert
Biomes of the world
Comparing biomes What is the difference between desert and tundra? Where do you find each of them in the world? What is the difference between tropical rain forests and tropical dry forests? Where do you find each of them in the world? What is the difference between temperate grassland and temperate forest? Where do you find each of them
Section 4.5 Aquatic Ecosystems
What factors affect life in aquatic ecosystems? Water depth Temperature Flow Amount of dissolved nutrients
What is the photic zone? The sunlit region near the surface in which photosynthesis can occur Can range in depth from 200m to a few meters Phytoplankton (photosynthetic algae) live in the photic zone Zooplankton eat phytoplankton Aphotic zone - where photosynthesis can not occur Benthic zone - sediments at rocks at base of water Highly variable depending on water depth
How do temperature and nutrient availability affect life in aquatic ecosystems? Aquatic habitats are warmer near the equator can colder near the poles Temperature also varies with depth Currents can have large effects on ocean temperature; drastically changing typical water temperatures for a given place Nutrients are often scarce, and availibility will have large effects on ecosystem
What are the three main types of freshwater ecosystems? Rivers/Streams: Often lots of oxygen but little plant life near source Lakes/Ponds: Food webs based around plants and algae Freshwater Wetlands: Water either covers soil or present near the surface part of the year Help purify water, and prevent flooding Examples: Bogs, marheses and swamps
What is an estuary? Why are they so important? A special kind of wetland where a river meets the sea Therefore they are a mixture of freshwater and seawater Also affected by tides Shallow - photosynthetic benthic zone Large amount of biomass Acts as spawning/nursery ground for ecologicall and comerically important fish Key examples - salt marsh and mangrove swamp
How is the ocean classified? The ocean is divided into zones based on the depth and distance from the shore
How do creatures live in such extreme environments? Total darkness, High pressure and frigid temperatures lead to some weird adaptations Life revolves around chemosynthesis and hydrothermal vents rather than photosynthetic organisms