Presentation on theme: "P AGE 93 1. List 4 biotic and 4 abiotic factors in: (a) a freshwater ecosystem, such as a lake biotic: fish, snails, frogs, dragonfly larvae, water lilies,"— Presentation transcript:
P AGE List 4 biotic and 4 abiotic factors in: (a) a freshwater ecosystem, such as a lake biotic: fish, snails, frogs, dragonfly larvae, water lilies, phytoplankton abiotic: water, rocks, sand, dissolved oxygen, minerals (b) a terrestrial ecosystem, such as a forest biotic: maples, trilliums, bracket fungus, squirrels, red fox, earthworms abiotic: rocks, soil, sunlight, wind, temperature, rain 2. Predict whether you would find more species in a forest, an open field, or the forest-grassland ecotone between them. Explain your prediction More species are found in ecotones that border two ecosystems because the organisms from both ecosystems are found in the ecotone.
P AGE Figure 10 shows changes in the size of the populations of paramecia (single-celled organisms) placed in 3 different beakers. (a) Compare the growth of Species 1 in Beaker A with the growth of Species 2 in Beaker B The population of Species 1 in beaker A grows until it reaches a “steady state” or constant level. The population of Species 2 in beaker B takes a little longer to begin to increase, but once it does, the population reaches a higher number than Species 1 before reaching a steady state and then starts to decline. (b) What evidence suggests that the populations of paramecia affect each other? An increase in the population of paramecium 1 corresponds to a decrease in the population of paramecium 2. This suggests that paramecium 1 has a negative effect on paramecium 2. Perhaps they compete for the same food source.
P AGE 93 (c) Suggest a conclusion that can be drawn from the population changes in Beaker C In Beaker C, Species 2 increases in number before Species 1 begins to increase in number. Species 2 begins to decrease in number, whereas Species 1 continues to increase beyond the level of Species 2 and then levels off. One could conclude that the presence of Species 1 has a negative effect on Species 2. (Remember that answers such as “Species 1 feeds on Species 2” or “Species 1 is able to compete for food more successfully than Species 2” are inferences that cannot be supported without further study.)
P AGE In your own words, define the term ecological niche. A student’s answer should include an understanding of the “role” or “occupation” of an organism within a food chain or web, along with the other abiotic and biotic factors it requires.
5. Give examples illustrating the problems that can be created when a new species is introduced into an ecosystem. Exotic species often have no natural predators when they enter a new habitat. This allows populations of exotic species to increase so quickly that they crowd out native species. When a population is unchecked by predators or disease, it has an advantage over the native (indigenous) populations and can increase very quickly. Native species might not be able to compete successfully for space, food, or reproductive sites. If the introduced species is a predator, prey organisms may not have defence mechanisms against it. Examples include the starling, the Canada thistle, and purple loosestrife.
7. Human interference often causes ecosystems to change (a) Provide an example of how human interference has caused an increase in the population of a species. In the 1890s, a misguided fan of Shakespeare brought all the birds mentioned in his plays from the United Kingdom and released them in Central Park in New York City. One of the birds was the starling. A single pair burgeoned into one of the most abundant and widespread birds in North America. (b) Provide an example of how human interference has caused a decrease in the population of a species In Alberta, starlings settle in prime nesting sites long before the mountain bluebird returns from the south. Starlings even evict swallows and mountain bluebirds from their nesting sites. The indigenous bluebird is unable to secure nesting sites from the starling, and its population has declined. (c) Provide an example of how the rapid increase in a species has affected another species. Purple loosestrife entered North America accidentally, when it was mixed in contaminated grain seeds. Purple loosestrife spread so quickly and is so common that early settlers believed it was an indigenous (native) plant. Since it is well suited for marshes, purple loosestrife has choked out many species of native plants in wetlands.
U NIT B S ECTION 4.2 Terrestrial and Aquatic Ecosystems
B IOMES Biome – large geographical area with a specific range of temperatures and precipitation, and the organisms that are adapted to that climate (average temp and precip. of a region) Have dominant species that are characteristic of that region Biomes contain many different ecosystems with their own characteristic biotic and abiotic factors Canada: 4 major terrestrial biomes, 2 aquatic (salt and freshwater) biomes
A LBERTA B IOMES 2 major biomes: Taiga Grassland There are many ecosystems within these biomes
T AIGA B IOME A.K.A-Boreal Forest Northern Alberta & Rocky Mountains Dominant Species: Conifers (cone-bearing trees with needles) Warm, moist summers and Cold, dry winters Many different ecosystems Variable sunlight: High sunlight in the forest canopy (upper layer of vegetation) Good for mature conifers (spruce, pine) and for birds, squirrels, etc. Low sunlight on the forest floor Good for shade-loving plants (shrubs, mosses, ferns) and the animals that eat them (moose, white-tailed deer, etc.)
There is a large range of climates in the taiga which results in many different ecosystems Areas with warmer ground temps, there is more decomposition of organics which means better soil Muskeg Ecosystem Permafrost (permanently frozen soil) results from cold climate Muskeg is the soil above the permafrost that is swampy in the summer because rain and melted snow cannot drain Decomposition is very slow - hard to form soil Fragile ecosystem Muskeg has very different organisms than a conifer forest ecosystem Plants have low roots: lichens, mosses, grasses, small shrubs, stunted conifers Animals: lots of aqueous breeding grounds for black flies and mosquitoes
G RASSLAND B IOME Very fertile black soil Large biomass for decomposition Warm temperatures = high decay = rich layer of humus Only one layer to support biotic community (opposite to forests) This limits the number/diversity of organisms Plants: rough fescue, wheat grass, spear grass Animals: Deer, squirrels, rabbits, birds, snakes The edges of the grassland (prior to entering taiga) are dominated by trees
D ECIDUOUS F OREST E COSYSTEM Trees: aspen, balsam poplar, birch Require lower amounts of water Spring gives warmer temp, more precipitation, and humus (dead leaves in fall) provide rich soil because of high levels of decay (most sunlight will reach forest floor and understorey) In the summer only 6% of sunlight reaches understorey (below canopy layer – shrubs, small trees) Animals: insects & insect-eating birds and mammals (fly-catchers, shrews), deer, moose, birds, etc. Check out Table 1 (pg 97) for Alberta’ terrestrial ecosystems