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Chapter 10- Forest Ecosystems.docx

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Monika Havelka

Chapter 10- Forest Ecosystems  Forest ecosystems cover 30% of earth’s land surface  Contain 90% of terrestrial biodiversity  25% of world’s natural forest is in Canada  To grow a forest:  Temperature  Air (carbon dioxide, hydrogen, oxygen, nitrogen)  Light (photosynthesis)  Water  Soil  (N,P,K,C,Mg,S)  (Fe,Mn, B,Z,Cu,Mb,CI)  Forests create, store and mobilize nutrients and water  Photosynthesis  Mycorrhizal associations  Soil interactions: nutrients, transpiration stream  Fungal symbiosis: mycorrhizae  Symbiotic relationship between plants and fungi  Plant gets increased surface area for nutrient absorption; fungus get carbohydrates  Mycorrhizae critical to plant success’ productivity  Endomycorrhizae  Fungus penetrates root cells  Fungus forms a sheath around root  Animals are important in dispersing fungal spores in many forest ecosystems  Soils supply water and nutrients to trees  Transpiration stream  To transport water, water must be lost  Capillary action= moves water 2-3m  Rest= evaporation  Redwood: evaporates 160 gal./d  Mature forests are complex ecosystems  Trees provide many ecological services  Crucial link in nutrient and water cycles  Stabilize soil and prevents erosion  Slow runoff and lessen flooding  Store carbon, release oxygen, moderate climate  Forests are economically valuable  Benefits: fuel, shelter, transportation (ships), paper  Softwood= timber harvested from coniferous trees  Hardwood= timber harvested from deciduous trees  NTFPs= non timber forest products such as medical, herbal, decorative, and edible products  Forests are home to 300 million people  >1.6 billion people depend on forests for their livelihoods  60 million indigenous people are dependent on forests  1.2 billion people rely on agroforestry to sustain agricultural productivity and generate income  Three major types of forest biome  Boreal o Fairly dry (50cm precipitation/year) o Cold winters o Soil: shallow, acidic o Vegetation: conifers, mosses o Closed canopy o Conifers; cold tolerant o Low light penetration; understory limited o Heavily dependent on mycorrhizae o Acidic peat bogs, fens, and marches  Tropical rainforest o Only 9% of land but >50% of species o 40% gone; mostly in last 50 years o Relatively constant temperature (25 degrees C mean) o No freezing temperatures o Annual rainfall > 1m; often 2-3 m o Extremely high productivity o Variation in degree of seasonality o Canopy: multilayered, continuous; little light penetration o Intense competition for light o Vines, epiphytes, bromeliads o Soil: nutrient poor, acidic o Rapid decomposition; rapid leaving (laterite soils) o <1% nutrients penetrate > 5cm; most nutrients are in biota o Buttress roots o Since most primary production is in canopy, most species are canopy specialists unlike in other biomes, most mammal herbivores are arboreal in these forests  Temperate forest o Temperate deciduous forest  Mid latitude forests in Europe, eastern China, eastern North America  Deciduous trees- lose their leaves each fall and remain dormant during winter  Temperate: -30% to +30% 
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