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Transcript
Introduction to Ecosystems Aims • To understand what an ecosystem is. • To learn about a small scale ecosystem (a pond ecosystem) Definition Ecosystems are the interaction between the living and the nonliving environment. Ecosystems are the interaction between plants, animals or people and things such as local relief (shape of the land), climate, soils and vegetation (plants and trees). Ecosystems can be identified at different scales. A local ecosystem may be as small as a pond or a hedge. Larger ecosystems include lakes or woodlands. Ecosystems found on a global scale (also called biomes) include tropical rainforests and deciduous woodlands. Global ecosystems are known as biomes. The dominant type of vegetation cover usually defines a biome. There are many different ecosystems in the world. We are going to study 3: • Temperate Deciduous Woodlands • Tropical Rainforests • Hot deserts The main factor that influences the distribution (where they are found) of each ecosystem is climate. Each ecosystem has a different soil depending on the climate and vegetation. The Climate of the World’s Major Ecosystems Ecosystem Climate description Temps winter + summer Rainfall winter + summer TRF Hot and wet all year. 27–30oC. Wet all year. TAP = 20003000mm. Hot Desert Very hot most of the year. Above 30oC. TAP below 250mm. Summers about 25oC. Winters about 10oC. Dry in summer. Wet in winter. TAP = 750mm. Mediterranean Hot summers. Mild/warm winters. Temperate Deciduous Woodland Warm summers. Mild/cold winters. Summer about 18oC. Winter about 5oC. Precipitation all year. TAP = 1000mm. Coniferous Woodland Warm summers. Very cold winters. Summer 16-20oC. Winter = below freezing. Mainly in summer. TAP = low (below 500mm). Savanna Grasslands Hot all year. 25-35oC. Variable rainfall totals but always a drought period. TAP =500-1000mm. Location of the global ecosystems A Food Chain A food chain is a line of linkages between producers and consumers. It always begins with a plant. A Freshwater Pond Food Chain Consumers Heron Fish Great Diving Beetle Producer Midge Lava Detritus (decaying leaves) A Food Web A food web is more complex than a food chain. It is a diagram that shows the linkages between producers and consumers in an ecosystem. Food chains and food webs both show the transfer of energy through an ecosystem. A Freshwater Pond Food Web Kingfisher Heron Fish Great diving beetle Midge larva Stonefly Caddis Dragonfly Blackfly Mayfly Worms Detritus Algae and microscopic plants The Impact of Change on the Freshwater Pond Ecosystem The number and the types of species in an ecosystem can change over time and these changes often have impacts in other parts of the ecosystem. Changes can be caused by natural or human factors. Natural Factors • Changes in the environment may occur through floods, fires and drought. Human Factors • Changes in drainage basins • Depletion of fish stocks • Deforestation • Increased human use for timber and land for settlements and farmland (e.g. in the Tropical Rainforests).
