Chapter 20 Outline

Chapter 20 Outline - Chapter 20: Terrestrial Biomes...

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Chapter 20: Terrestrial Biomes Biogeographic Realms Biogeographic realm - geog’ic reg where grp of plant, animal species evolved; ~correspond to continents; main separating barrier= ocean; species migrate according to niche reqs/reproductive success/competition w/other species but limited by climatic/topographic barriers: The realms= thr collective effort to do this; botanical (plant), zoological (animal) realms diff than othrs b/c have many distinct ecosystems; Australian realm=>450 species Eucalyptus , 125 species marsupials; unique flora, fauna due to its early isolation fr other continents since Pangaea breakup Transition Zones Alfred Wallace 1 st zoogeography scholar; bndry btwn Oriental /Australian realms (see Fig. 20.1 )= wide transition zone where one reg grades into other; bndries btwn ntrl sys’s=zones of shared traits - mixed composition; ecotone - bndry transition zone btwn adjoining ecosys regs; defined by diff phys factors Thus vary in width; climatic ecotones usu more gradl than phys ones- diffs in soil/topography can=> abrupt bndrys; ecotone area of tension- competition for resource base; thse bndry, edge areas=>bio- diversity as adaptation, ntrl selection favor pop w/reproductive success Coevolution poss whre interacting pops in tension zone can=>genetic changes in each pop (microevol) Terrestrial Ecosystems Terrestrial ecosystem - self-sustaining assn of land-based plants, animals/thr abiotic envt, char’d by specific plnt frmtn classes; plants=mst visible in biotic landscape/key mbrs of terrestrial ecosys’s; interactng pops of plants/animals in area= community ; habitat -area plants/animals bio’ly suited to live Ecosystem = interplay btwn cmmty of plants/animals/thr abiotic phys envt; in habitat, perform basic operational fxn- niche ; biome - lg, stable terrestrial ecosys w/specific plant/animal cmmtys; each usu named for dominant vegetation b/c most easily identified; 6 broad biomes : Forest, savanna, grassland, shrubland, desert, tundra; also aquatic ecosys’: polar seas, temperate seas, trop seas, seafloor, shoreline, coral reef; plant life-form designations based on outward phys properties of indv plants/general form/structure; incl: o Trees - lg woody trunk, perennial, 3-10+ ft tall o Lianas - woody climbers, vines o Shrubs - smlr woody plants, stems branching at ground o Herbs - sml plants w/o woody stems; incl grasses, nonwoody vascular plants o Bryophytes - nonflowering, spore-producing plants eg mosses o Epiphytes - plants growing above ground on other plants, using thm for support o Thallophytes - lack true leaves/stems/roots; incl bacteria, fungi, algae, lichens These divided into more specific vegetation units- formation classes - refer to structure, appearance of dominant plants in terrestrial ecosys Earth’s Major Terrestrial Biomes Few ntrl cmmtys of plants/animals left; ntrl vegetation reflects ideal potential mature veg given envtl chars in reg; US/CAN, type of transition community, btwn grasslands/forest- artificial stage due to lg-
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This note was uploaded on 06/24/2008 for the course GEOG 1 taught by Professor Okin during the Fall '06 term at UCLA.

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Chapter 20 Outline - Chapter 20: Terrestrial Biomes...

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