Chapter 9Review and IntroductionNatural VegetationHuman Influences on VegetationNatural Vegetation of North AmericaNatural Vegetation of the WorldWhat Environmental Factors Influence Vegetation?Structure and Life-form of PlantsLife-forms by Size and ShapeStructure and Life-form of Plants (cont’d)Forest vs. WoodlandEcosystemsTerrestrial EcosystemsForest BiomeForest BiomesSavanna BiomeSavanna BiomesGrassland BiomeSlide 19Desert BiomeSlide 21Tundra BiomeSlide 23Elevation and VegetationNatural Vegetation, Altitude Zonation, and Life Zones in ArizonaClimate and VegetationA Final Word on Changes in VegetationChapter 9Global BiogeographyReview and IntroductionChapter 8 reviewLooked at processes involved in ecological and historical biogeographyFood web, photosynthesis, respiration, factors influencing biogeography (climate, geomorphic, soil), succession, spatial and temporal distribution patternsNow, turning to general patterns of vegetation cover over Earth and their relation to climateNatural VegetationWhat is natural vegetation?Plant cover that develops or grows in a region without (or with very little) influence of humans, or what grows somewhere with no or little interruption by humansOpposite of human-influenced vegetation – plant cover that results from human interference, introduction, or modification – might be “invasive species”Human Influences on VegetationIntensive agricultureDomesticationGrazing by domesticated animalsUrbanization – expansion and new developmentFighting fires – why?Introducing new/non-native plant speciesCareless/reckless recreational activitiesGreenhouse gas emissionsGenetic engineering (gene splicing, selective cross-breeding)Natural Vegetation of North AmericaFrom http://www.uwsp.edu/geo/faculty/ritter/geog101/modules/natural_vegetation_of_north_america_map.htmlNatural Vegetation of the WorldWhat Environmental Factors Influence Vegetation?Climatic, geomorphic, and edaphic factorsMore specifically amount of soil water, type and amount of nutrients in soil, and temperatureEach factor affects plant cover structure and outward appearanceTherefore, we see different vegetation in different regions (compare SE AZ with over areas of U.S.)Structure and Life-form of PlantsBotanists focus more on species where biogeographers tend to focus on overall plant cover and life-formLife-form – physical structure, size, and shape of plantsLooking at size and shape: trees (large woody plants with branching usually farther away from ground, ex. Ponderosa pine), shrubs (woody plants with branching near ground, ex. creosote), lianas (woody vines supported by trees and shrubs, ex. poison ivy), herbs (small tender plants, ex. grasses), lichens (structure formed by combination of algae and/or fungi, ex. moss)Life-forms by Size and ShapeTreeShrubs and LianasHerb LichensStructure and Life-form of Plants (cont’d)Types of life-form by life spanAnnuals – live only for one season or year, many grasses and flowersPerennials – survive for many seasons or years, trees and shrubsTypes by overall structureForest – trees grow close together with crowns in contact, ex. NE US (Fig. 9.14), Amazon (background of figure on p. 321)Woodland – trees farther apart (crowns not in contact), ex. southern India (Fig. 9.9), Tanzania (Fig. 7.15), portions of California (bottom figure on p. 252)Forest vs. WoodlandForestWoodlandEcosystemsDefinition (from Ch. 8): group of organisms and the environment with which they interactTwo major groupsAquatic – marine (saltwater) and freshwater environmentsTerrestrial – land environments; solid part of continentsEven though these are considered separate ecosystems, there is actually some interaction.Terrestrial EcosystemsSubdivisionsBiome – largest recognizable subdivision; total of plant cover and animal speciesFormation – subdivision of biome based on vegetation structure, size, and shapeExample: Jungle (rainforest) in Brazil and forests in Catalina Mountains are in same biome (forest), but are in different formationsFive main biomes: forest, savanna, grassland, desert, and tundraForest BiomeOverall structure is forest (trees grow close together with crowns in contact)Canopy closed or nearly closed at least part of yearAbundant soil moisture, and therefore precip, is necessary (lose leaves in dry season)Requires either warm temps year-round or at least a warm season (lose leaves in cold season)Range from low to high latitudes (0° - 35°S, 0° - 70°N)Forest BiomesTropical deciduous forest ↑ ↑ Coniferous forestTemperate deciduous forest Savanna BiomeOverall structure is woodland (tree widely spaced and crowns not in contact)Combination of trees, grasses, and herbsTransition zone between forest and grassland biomesOccurs in regions with distinct wet and dry seasonsTemps tend to be warm much of yearMainly in low latitudes (between 30°S and 30°N)Savanna BiomesAustraliaAfricaGrassland BiomeMainly grasses; few, if any, treesOccurs in regions with fairly lengthy dry season (semi-arid)Distinct warm and cool/cold seasons; temps must be warm enough for portion of year to support a growing seasonMainly in middle latitudes (30° - 40°S, 30° - 50°N)Grassland BiomeDesert BiomeCombination of some trees, shrubs, and grassesTransition from savanna and grassland to little/no vegetationPrecipitation is rare (moderate to severe drought conditions), maybe a short wet seasonLarge temp range: cool to very hotRange from low to middle latitudes (0° - 50°S, 0° - 50°N)Desert BiomeTundra BiomeCombination of some trees, some shrubs, grasses, and lichensPrecipitation is mainly snowTemps cold most of year, maybe short periods warmer than 0°C (32°F)Mainly in high latitudes (60° - 80°N) and high elevationsTundra BiomeElevation and VegetationCan see changes in vegetation with elevationThink of driving up Mt. Lemmon Highway Due to changes in temp and precip with elevationChange in climate factors with elevation results in systematic changes in vegetation cover – vegetation (or altitude) zonationLife zones – series of vegetation zones describing vegetation type seen with increasing elevation (Fig. 9.25)May also hear term sky island, which refers to forest areas in locations where type of vegetation is not expected or common (e.g., mountains in
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