Forest Biomes Coniferous Forests Deciduous Forests Rain Forests
Forest Biomes -Coniferous Forests -Deciduous Forests -Rain Forests
Forests • Cover 30% of Earth land surface • Contain 75% of Earth’s biomass • Rain forests are most complex and diverse biome • Rain forests cover only 6 -7% of land, but hold 50% of land biomass and has 70% of land species
Coniferous Forests • • • Coniferous means “cone-bearing” Coniferous trees, or conifers, produce seed cones The cones hold the seeds The leaf of a conifer is the needle Needles help conserve water b/c they are long, thin and covered in thick wax • Most conifers are evergreen, meaning they do not lose all their leaves at one time during the year. It happens slowly through the entire year • Pine, hemlock, fir, spruce, and cedar are common in coniferous forests • Also aspen & birch which have broad leaves
• Where • Mostly in subarctic regions of North America, Europe, and Asia • Climate • Warm summers, 2 -5 months • Long, cold, dry winters • 40 -200 cm of precipitation/yr (rain in summer, snow in winter) • Limiting factors • Must be able to survive harsh winters, soil is frozen so no moisture • Soil is poor and acidic • Ferns, lichen, sphagnum moss can grow on forest floor
• Animal adaptations • Many small herbivores are seed eaters; ex: mice, squirrels, jays, rodents, other birds • Insects are common in summer when soil is moist and poorly drained • Large herbivores feed on plants and bark; ex: moose, elk, beaver, and snowshoe hares • Many species migrate, hibernate or live under the snow • All have thick body covers to protect from cold • Logging in Coniferous Forests • Large stretches of coniferous forests in Soviet Union and North America haven’t been logged b/c of harsh climate • But the need for wood is growing • Governments of Soviet Union are selling these lands b/c they are in need of money
Deciduous Forests • Temperate zones-climates with four, well-defined seasons • Most forests in temperate zones are deciduous • Deciduous trees shed their leaves during a particular season of the year • Climate • Temps vary greatly, 30 degrees celcius in summer to -30 degrees celcius in winter • Precipitation is about 50 -300 cm/yr • Precip. is in snow or rain, and falls regularly through entire year. • Tree adaptations • Have to adapt to varying climate • Growing season is about 6 months, tree grows quickly and stores large amounts of food • During fall, tree sheds its leaves and becomes dormant. This helps conserve water during winter • Trees feed off of their stored food until spring, when grow new leaves
• • • • Deciduous examples: maple, oak, beech, ash, hickory, birch 3 layers Canopy-highest layer, made up of upper branches and leaves of tall trees The canopy captures most of sunlight, but some filters through to bottom layers Understory-under canopy, made of trees that are younger and smaller than canopy, also has shrubs Floor-mosses, ferns, and other plants that grow on ground layer Animals and organisms a deep, rich layer soil, or humus, exists b/c of falling leaves decaying quickly in moist soil Can support diverse community of animals, insects, and organisms Fungi & decomposers, insects live in leaf litter and fallen trees Birds, mice, small mammals feed on them White-tailed deer are common, Reptiles, amphibians, in warm forests
• Predators include: wolves, mountain lions, birds of prey, foxes • Human Influence • Deciduous forests used to stretch across Europe and Asia, and covered eastern US • Very little of that remains today • Replaced by farms, orchards, and urban development • Why Deciduous Forests? ? ? • rich soil makes it great for farmland if trees are removed • Deciduous trees have harder wood than conifers, so they are better for making furniture and flooring • Trees also used as fuel • Replacing Deciduous Forests • In some areas, trees have been replanted to restore the ecosystem • But this is very slow, b/c it must also bring back lost species
Rain Forest • Rain forests can be found in tropical zones-located at latitudes near the equator • Receive direct rays from sun most of the year • Climate • Avg 25 degrees celcius ALL year • Growing season last all 12 months • Precipitation is rain, except at high mountaintops • 200 -450 cm/year • ***climate does not vary or change much in the rain forest through the year • Structure • Dense canopy of evergreen, broadleaf trees supported by at least 200 cm rain /year
• trees include: cypress, balsa, teak, mahogany • Ecologists have found 700 species of trees in just 10 hectares (25 acres) of a rain forest in Borneo • Only 1% of sunlight will filter through to forest floor, plants are sparse on the floor • Dead matter does not contribute much nutrients to the soil b/c they are recycled so quickly in rain forests • This is b/c of the high moisture levels • Nutrients are quickly drawn back into the trees • Topsoil is thin and poor, usually most nutrients are in the top 5 cm • So, tree trunks are wide at the base with buttresses-ridges for support • Roots are shallow • Vines grow up trees to reach sunlight, plants can live directly on trees • These are called arboreal b/c they live in trees. Have adaptations to live in trees
• Organisms and Diversity • Rainforests are the most animal diverse biome • Two reasons: 1)diversity of plants gives high # of niches 2) wide variety of habitats in the different levels of the forest • Habitats vary in each level, each tree, and each part of the tree • Scientists don’t know how many species live in the rainforest • Wilson found 43 species of ants in one tree! • Erwin estimated over 50 million insect species • Scientists continue to find more species everytime they look for more in the rainforest
• Deforestation-destruction of forest as a result of human activity • In 1950, more than 10% of Earth’s land was rainforest • Now, down to 6% and decreasing • Destruction due to developing countries, population growth, logging, farming, mining • Animals habitats are quickly destroyed, especially since the ecosystem is vertical (goes up, not spread out) • One acre cleared will destroy millions of habitats • This (biodiversity loss) is the most serious issue with rainforest destruction
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