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Chapter 13 – Biomes and Ecosystems Lesson 1 – Land Biomes Biome: a geographic area on Earth that contains ecosystems with similar biotic and abiotic features. Deserts: biomes that receive very little rain. Often hot during day, cold at night Rainwater drains away quickly Plants grow slowly Grassland: areas where grasses are the dominant plants. Have wet and dry season Deep fertile soil Tropical Rain Forest Biome: Forests that receive large amounts of rain and have dense growths of tall, leafy trees. Weather is warm and wet year-round. Soil is shallow and easily washed away by rain Less than 1% of the sunlight that reaches the top of the forest trees also reaches the forest floor. Temperate Rain Forest Biome: Regions of Earth between the tropics and the polar circles. Winters are mild and rainy. Summers are cool and foggy. Soil is rich and moist. Temperate Deciduous Forest Biome: Winter temperatures are often below freezing. Snow is common. Summers are hot and humid. Soil is rich in nutrients. Taiga Biome: A forest biome consisting mostly of cone-bearing evergreen trees. Winters are long, cold, and snowy, Summers are short, warm, and moist. Soil is thin and acidic. Tundra Biome: Cold, dry, and treeless. Winters are long, dark, freezing; summers are short and cool. Growing season is only 50-60 days. Permafrost – a layer of permanently frozen soil-prevents deep root growth. Lesson 2 – Aquatic Ecosystems Important ABIOTIC factors in aquatic ecosystems include temperature, sunlight, and dissolved oxygen gas. Salinity: the amount of salt dissolved in water. Freshwater: Streams and Rivers Streams forms from underground sources of water, such as springs or from runoff from rain and melting snow. Often clear and quickly washes away soil particles Oxygen levels in streams are high in fast moving streams Slow moving streams are high in nutrients but lower in dissolved oxygen when compared to fast-moving water. Freshwater: Ponds and Lakes Ponds are shallow and warm. Sunlight reaches the bottom of most ponds. Pond water is often high in nutrients. Lakes are larger and deeper than ponds. Sunlight penetrates into the top few feed of lake water. Wetlands: Aquatic ecosystems that have a thin layer of water covering soil that is wet most of the time. Wetlands contain freshwater, salt water, or both. Freshwater wetlands from at the edges of lakes and ponds and in low areas on land. Saltwater wetlands form along ocean coasts. Nutrient levels and biodiversity are high. Wetlands trap sediments and purify water. Plants and microscopic organisms filter out pollution and waste materials. Estuaries: Regions along coastlines where streams and rivers flow into a body of salt water. Salinity depends on rainfall, the amount of freshwater flowing from land, and the amount of salt water pushed in by tides. Estuaries help protect coastal land from flooding and erosion. Purifies water and filters out pollution. Nutrient levels and biodiversity are high. Oceans: Covers most of the earth and has high salinity. Photosynthesis can take place only in the uppermost, or sunlit zone. Very little sunlight reaches the twilight zone. None reaches the deepest water, known as the dark zone. Decaying matter and nutrients float down from the sunlit zone, through the twilight and dark zones, to the seafloor. Oceans: Coastal Oceans Intertidal Zone: the ocean shore between the lowest low tide and the highest high tide. Sunlight reaches the bottom of shallow coastal ecosystems. Nutrients washed in from rivers and streams contribute to high biodiversity. Ocean: Coral Reefs Coral reef: an underwater structure made from outside skeletons of tiny, soft-bodied animals called coral. Most coral reefs form in shallow tropical oceans. Coral reefs protect coastlines from storm damage and erosion. Lesson 3: How Ecosystems Change Ecological Succession – the process of one ecological community gradually changing into another. Climax Community – A stable community that no longer goes through major ecological changes. Usually stable over hundreds of years. Primary Succession – The first species that colonize new or undisturbed land. Secondary Succession – Areas where existing ecosystems have been disturbed or destroyed. Aquatic Succession – Like land ecosystems, water ecosystems change over time in natural, predictable processes. Eutrophication: The process of a body of water becoming nutrient-rich.