The Web of Life: Ecosystems
An ecosystem is a biological community of interacting organisms and their physical environment.
Biotic Factors: The living or once-living components of an ecosystem. Examples: plants, animals, fungi, bacteria.
Abiotic Factors: The non-living chemical and physical parts of the environment that affect living organisms. Examples: sunlight, temperature, soil composition, water, pH.
Energy Flow in Ecosystems
Energy flows through an ecosystem in one direction.
1.Producers (or Autotrophs): Organisms that produce their own food, usually through photosynthesis. They form the base of the food web. Examples: plants, algae.
2.Consumers (or Heterotrophs): Organisms that obtain energy by feeding on other organisms.
Primary Consumers (Herbivores): Eat producers (e.g., rabbits).
Secondary Consumers (Carnivores/Omnivores): Eat primary consumers (e.g., foxes).
Tertiary Consumers: Eat secondary consumers (e.g., eagles).
3.Decomposers: Organisms that break down dead organic matter, returning essential nutrients to the soil. Examples: bacteria, fungi.
Only about 10% of the energy from one trophic level is transferred to the next. The rest is lost as heat.
Global Life Zones: Biomes
A biome is a large community of vegetation and wildlife adapted to a specific climate. The major terrestrial biomes are classified based on their dominant vegetation, which is determined by temperature and precipitation.
Major Terrestrial Biomes:
Tropical Rainforest: Found near the equator. Characterized by high temperatures, high rainfall, and extremely high biodiversity.
Desert: Characterized by very low rainfall (less than 25 cm per year). Can be hot or cold. Organisms have adaptations to conserve water.
Grassland (Savanna/Prairie): Dominated by grasses rather than large shrubs or trees. Characterized by seasonal rainfall, with wet and dry seasons.
Temperate Deciduous Forest: Has four distinct seasons. Characterized by trees that lose their leaves in the fall (e.g., oak, maple).
Taiga (Boreal Forest): The largest terrestrial biome. Characterized by long, cold winters and coniferous (cone-bearing) trees like pine and spruce.
Tundra: Characterized by extremely cold temperatures, a short growing season, and a layer of permanently frozen soil called permafrost. Vegetation consists of low-growing shrubs, mosses, and lichens.