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Forest_Resources BIO 350

Forest_Resources BIO 350 - Forest Resources Forests A...

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Forest Resources I Forests A Ecosystems that are dominated by trees B Structure can be viewed as vertical layers 1. Canopy formed by the tallest, oldest trees 2. Under-story of younger trees and tall shrubs 3. Floor covered in herbaceous, flowering plants 4. Soil & sub-soil filled with invertebrate animals, fungi and bacteria C Provide valuable ecological services 1. influence climate through transpiration 2. regulate atmospheric CO 2 3. produce oxygen 4. contribute to soil formation & reduce soil erosion 5. purify air & water 6. act as biodiversity reserves D Provide humans with economic resources 1. Wood a) Fuel (esp. in developing world) b) Lumber for building c) Wood pulp for paper 2. Medicines from forest plants a) Taxol (for cancer) comes from Pacific Yew tree 3. Foods (nuts, fruits, mushrooms) 4. Recreation (hunting, camping) 5. Employment for millions who provide all of the above. II Types of forests A Boreal forests 1. Forests dominated by conifer trees, located in high latitudes of the northern hemisphere (Alpine forests of mid temperate latitudes are similar) 2. Climate a) Receive less than 20 in (50 cm) precipitation per year, mostly during summer & autumn b) Water is frozen and not available during winter c) Temperatures range between 15 o C in summer to -25 o C in winter 3. Soils are acidic & mineral poor 4. Vegetation a) Dominant trees are spruces & firs b) Leaves are needle-like with small surface areas which prevents water loss c) Leaves also go dormant during the winter when sunlight is minimal and temps are low 5. Animal life a) Large mammals include caribou, moose, wolves, and bears b) Most mammals are small to mid size, including rabbits, lynx, rodents, sable & minks
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c) Most birds are abundant in summer but migrate to warmer climates for winter d) Few amphibians & reptiles B Temperate Rain Forests 1. Also coniferous forest, but range is restricted to coastal areas of the Pacific coast of North America, Southeastern Australia, and southern South America 2. Climate a) Receive high amounts of rainfall (80 – 152 in. per year) augmented by fog drip b) Proximity to coast moderates temperatures (range from 18 o C to 3 o C) 3. Soils are nutrient poor because decomposition is slow 4. Vegetation a) Dominant trees are western hemlock, Douglas fir, Sitka spruce, coast redwood b) Community is rich in epiphytes (plants that live on other plants), especially mosses. c) Forest floor is covered in ferns and perennial herbaceous plants 5. Animal life a) Large mammals include elk & deer, bears, mountain lions b) Smaller mammals include squirrels, wood rats c) Bird species are numerous and tend to be full time residents (murlettes, osprey, ) d) Many amphibians and some reptiles C Temperate Deciduous Forests 1. Forests of broad-leaf trees that drop their leaves seasonally 2. Climate a) Moderate levels of rainfall throughout the year (30 – 50 inches) b)
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