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Chapter 19 “Ecosystem Essentials”. Geosystems 6e An Introduction to Physical Geography. Robert W. Christopherson Charles E. Thomsen. Ecology. Study of relationships between organisms and their abiotic environment Can be studies at several levels: Population Community Ecosystem
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Chapter 19 “Ecosystem Essentials” Geosystems 6e An Introduction to Physical Geography Robert W. Christopherson Charles E. Thomsen
Ecology • Study of relationships between organisms and their abiotic environment • Can be studies at several levels: • Population • Community • Ecosystem • Biosphere Fig 1.8
Communities Fig. 19.3
Community Terms • Habitat • Type of environment where an organism resides • Niche • Function of a life form within a community • In stable community, no niche is left unfilled • Competitive Exclusion Principle applies: • No two species occupy same niche at same time
Interactions in communities • Competition • Negative for both species (–/–) • Symbiotic/Mutualistic (+/+) • Both species benefit • lichen (fungi and algae) • Predation (+/–) • One benefits, one loses
Ecosystem Figure 19.2
Plants (Vegetation) • Critical biotic link between solar energy and the biosphere • Base of vast majority of food webs • About 20 species of plants provide 90% of the human food supply • Wheat, corn (maize), and rice are half • Convert carbon dioxide to oxygen • Transpiration elevates atmospheric humidity
Photosynthesis and Respiration Figure 19.5
Distribution of Vegetation • Five major factors: • Climate (temperature and precipitation) • Topography (elevation, slope) • Soils (nutrients, minerals) • Biotic Influences (dispersal mechanisms) • Disturbance (natural or anthropogenic)
Climate Figure 19.8
Life Zones Figure 19.9
Climate Change Figure 19.23
What’s limiting these distributions? Figure 19.12
Soils – nutrients, minerals Serpentine http://www.cfr.washington.edu/Classes.esc.520B/ImagesNorthFork/Serpentine6SM.jpg http://www.krisweb.com/krisnavarro/krisdb/ac/dscn2166_sm.jpg http://nrs.ucdavis.edu/mclaughlin/images/plants/Seep.jpg
Dispersal Mechanisms – Fruit and Seed http://www.cas.vanderbilt.edu/bioimages/pages/fruit-seed-dispersal.htm
What about this fruit? • Osage orange (Hedge apple) • These huge fruits ooze sticky, white latex when bruised. • They are large and hard - what would want, or be able to eat them? Probably were once dispersed by extinct megafauna (large mammals) that died out soon after humans arrived in North America. http://www.cas.vanderbilt.edu/bioimages/pages/fruit-seed-dispersal.htm
Extinct Megafauna Mammoth Tooth Gomphothere http://sscl.berkeley.edu/~anth122/mammoth.gif http://www.intersurf.com/~chalcedony/gomp.jpg http://mishilo.image.pbase.com/u36/zidar/upload/23675731.pbtooth1.jpg
Disturbance • Natural • Water, wind, volcano, fire… • Anthropogenic (human-caused) • Deforestation, fire, development…
Succession • Ecological succession – when newer communities replace older communities of plants and animals • Primary succession – an area of bare rock or disturbed site with no previous community • Secondary succession – some aspects pf a previously functioning community are present
End Chapter 19 Geosystems 6e An Introduction to Physical Geography Robert W. Christopherson Charles E. Thomsen