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ENV CHAPTER 6.1: WHAT IS A BIOME
There are lots of different kinds of ecosystems – ecologists group them into larger areas called biomes.Biome – large region characterized by a specific type of climate and certain types of plant and animal communities. Each biome is made of many ecosystems.
Vegetation-Biomes are described by their vegetation – b/c the plants that grow there determine the animals that can live there.-Plants in a particular biome have characteristics, special structures or adaptations that allow the plants to survive in their biome. ClimateThe main factor that determines what plants can grow is climate – the weather conditions. Temperature, precipitation, humidity, wind.-The climate is determined by average temp and precipitation.-Most organisms are adapted to survive within a particular range of temps and can’t live above or below them.-Precipitation also limits organisms – larger organisms need more water-Hotter and wetter climate – larger more dense vegetation-Colder and drier climate – vegetation is more sparse Latitude and altitudeBiomes climate and vegetation change w/ latitude (distance from the equator) and altitude (height above sea level).-when latitude and altitude increases (farther from equator and higher up) – it gets colder. -So as latitude and altitude change – the biomes change.
ENV CHAPTER 6.2: FOREST BIOMES
Forest biomes are the most widespread and most diverseTrees are big so they have to exist where temps are mild-to-hot and where there is a lot of rainfall. 3 kinds of forest biomes – tropical, temperate, coniferous.Tropical rainforestsCharacteristics:-Located in a belt around the equator. -Humid, warm, 200-450 cm rain per year, strong sunlight, maintain a constant temperature all year. -The conditions support more species than any other biome.-Nutrients: -Most nutrients are in the plants, not the soil. -Rapid decay of plants and animals by decomposers puts nutrients back into the soil – but they don’t stay there long b/c plants take them up so quick. o Some plants evolved relationships w/ decomposers so they can take the nutrients directly. o Dead organic matter is removed so efficiently that runoff from a rainforest is as pure as distilled water.-Layers:Different kinds of plants grow in different layers- emergent layer – top layer – tallest trees that get the most sun. o eagles, bats, monkeys, snakes live there- canopy – primary layer – tall trees that form a dense layer that absorbs 95% of the sun. o There’s an upper and lower canopy. o Most animals of the rainforest live in the canopy b/c of all the fruit and flowers that grow there. o Epiphytes are plants that live up there by growing on the side of other plants.- Understory – very little light – plants adapted to shade grow there Species diversity – rainforest is the biome w/ the greatest species diversity. - Most rainforest animals are specialists- Specialists use specific resources in particular ways to avoid competition
Threats:–Habitat destruction – from clearing for logging, agriculture, oil exploration. When the habitat goes so do the organisms that live there… and not just plants and animals, native people live there too.–Trading – like exotic pet trading. Temperate forestsCharacteristics:- Occurs in North America, Australia, and New Zealand. - High precipitation, high humidity, moderate temperature There’s a temperate rain forest in the pacific northwest. Temperate b/c of the cool temp, rainforest b/c of the huge amount pf precipitation. Temperate deciduous forest – trees w/ broad, flat leaves that drop them in the fall. - Can have an extreme range of temperatures due to the change of seasons. - Moist, receive 75-125 cm of rain per year. The plants of a deciduous forest grow in layers- tall trees in the canopy, small trees and shrubs cover the understory. - More light reaches the forest floor and so can support things like ferns and mosses.
Plants are also adapted to withstand and survive seasonal changes. o In the winter leaves drop and certain plants can go dormant. o When sun and precipitation increase again on the spring, things wake up. Animals in the temperate forest use the plants for food and shelter. To deal w/ the extreme temps animals can migrate away, or reduce their activity, or even hibernate Taiga/coniferous forestsCharacteristics: - northern coniferous forest – broad band across the northern hemisphere just below the artic circle. - Long winters and average temps below freezing. - Forest floor is dark w/ little vegetation. - Short growing season Plants – conifers, plants whose seeds are in cones, keep their needles through the winter, contain substances that make the soil acidic. Decomposition happens slow b/c of the cold temps and acidity of the soil.Animals – many lakes and swamps w/ birds, insects, aquatic organisms. Moose, hares, foxes.
ENV CHAPTER 6.3: GRASSLAND, DESERT AND TUNDRA BIOMES
Climates w/ less rainfall don’t have forests – instead there are the savanna, grassland, and chaperal biomes. With even less rainfall they change into dessert and tundra. In these types of biomes, there may be less species diversity (compared to forests), but there may be more individuals of each species. Savannas/tropical grsslandsGrasslands located in tropical and subtropical areas near the equator and between the rainforests and deserts. They have a wet season and a dry season.Plants – are adapted to survive long periods w/o water – grasses, scattered trees and shrubs.Animals – grazing herbivores w/ a migratory way of life to follow the rains. Predators feed on the grazers. Most have kids during the wet season when food is abundant. Temperate GrasslandsDominated by grasses/wildflowers (that are perennials – plants that survive year to year) w/ very few trees. Grazing animals (bison) and burrowers (prarie dogs) live there. Characteristics:- Hot summers and cold winters. - Moderate precipitation between 50-88 cm per year. - Has the most fertile soil of all the biomes, so many have been replaced by crops – farms and grazing areas for agriculture. Located on the interiors of continents where too little rain falls for trees to grow. Like the prairies of north America. Hot temps in the summer make them susceptible to fires. Threats – farming and overgrazing. Leads to soil erosion and loss of fertility. ChaparralCharacteristics:- Temperate woodland biome dominated by plants w/ leathery leaves – evergreen shrubs. - Located in the middle latitudes near the coast. - Warm dry summers and mild wet winters. Plants – low-lying evergreen shrubs and small trees that grow in dense patches. Leathery leaves retain water, and flammable oils promote burning. Animals – good at camouflage. Mule deer, quail, lizards, chipmunks. Threats – human development for commercial and residential use. DesertCharacteristics:- Area that receives less than 25 cm precipitation per year- has little or no vegetation- Extreme temperatures- often located by mountains since mountains block rain clouds form getting there. Plants – have adaptations for obtaining and conserving water. Can store water, go dormant, have special root systems.Animals – adaptations that prevent water loss like thick scaly skin. Nocturnal so they’re active at night when it’s cooler. TundraCharacteristics:- Biome dominated by grasses, lichens (combo of algae and fungus), and herbs.- Located north of the arctic circle. - Summers are short and only the top few inches of soil (topsoil) thaw – the rest is permafrost – permanently frozen soil.- When it thaws there are lots of swamps and bogs where swarming insects like to be Vegetation – moss and lichens which can grow w/o soil grow on the rocks. Plants that are close to the ground to stay out of the wind, and dwarf versions of some trees.Animals – migratory birds, caribou, deer, moose, rodents, wolves. Well-insulated animals Threats – oil exploration and pollution from spills. Delicate biomes that are slow to recover so any disturbance messes them up bad.Google Sites
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