Chapter 19 Outline

Chapter 19 Outline - Chapter 19: Ecosystem Essentials...

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Chapter 19: Ecosystem Essentials Introduction Orgm diversity on earth response to interaxn of atmos, hydrosphere, lithosphere; thr evol tied to that of interplay, coevol of living orgms + Earth’s phys, chem. sys’s; this interaxn=>variety of conditions w/in which exists biosphere - sphere of life, organic activity, extends ocean floor 8 km alt in atmos Incl many ecosystem s- self-sustaining assn of living plants, animals & thr nonliving phys envt; ntrl ecosys’ open sys’ for solar energy, matter; bndrys= non-sharp transition zones; distinct ecosys’ eg seas, forests, islands=>lrgr whole; ecology Ecosys’ in biosphere; biogeography - study of distribution of plants, animals, diverse spatial patterns they create, phys/bio processes tht=>earth’s species richness; humans= earth’s most influential biotic (living) agents; 6 major extinctions since Earth life began, 5 th -dinosaurs 65 mil yrs ago, 6 th occurring present decades-only one of biotic origin due mainly to humans Ecosystem Components and Cycles Ecosys incl biotic/abiotic components; ~all depend on direct input of solar energy, few limited ones on chem. rxns (chemosynthesis); ecosys’ divided into subsystems : biotic = producers (plants), consumers (animals), detritus feeders (bacteria, fungi etc); abiotic = gaseous, hydrologic, mineral cycs Communities Biotic subdiv in ecosys; formed by interaxns among pops of living animals, plants at particular time; eg cmmty on forest floor vs. another in canopy above; cmmty identified by: phys appearance, species present/abundance o feach, complex patterns of thr interdependence, trophic (feeding) structure Impt concepts: habitat - type of envt where orgms resides/biologically adapted to live; most species have specific reqs; niche - fxn/occupation of life form w/in given cmmty; way orgm obtains/sustains phys, chem., bio’l factors needed to survive; svrl facets: habitat, trophic, or reproductive niche Stable cmmty, no niche unfilled; competitive exclusion principle - no 2 species can occupy same niche (food/space) successfully in stable cmmty; each species works to reduce competition, maximize own reproduction rate; =>species shift, adapt to fill each niche=>more diversity Some species symbiotic - 2(+) species exist together in overlapping relationship; mutualism - each orgm benefits, is sustained over extended per by relation eg lichen- algae/fungi; parasitic relationship (unsustainable) can kill host, destroying parasite’s own niche/habitat; question if human society & earth’s phys sys’= global-scale mutualism or parasitic symbiotic relationship Plants: The Essential Biotic Component Plants=critical biotic link btwn solar energy/biosphere; all depend on thr ability to turn sunlight food; vascular plants have conductive tissues, true roots for internal transport of fluid, nutrients; most current known plant species vascular; many unidentified plants= grt untapped resource base
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Chapter 19 Outline - Chapter 19: Ecosystem Essentials...

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