Ecology 15 Forests, Woodlands and Savanna Ralph Kirby.
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Transcript of Ecology 15 Forests, Woodlands and Savanna Ralph Kirby.
Ecology 15Ecology 15Forests, Woodlands and Forests, Woodlands and
SavannaSavanna
Ralph KirbyRalph Kirby
Ecosystems where trees Ecosystems where trees are dominant or codominantare dominant or codominant
Forests, Woodlands and Forests, Woodlands and SavannasSavannas
ForestsForests– Where trees form Where trees form
a closed canopya closed canopy– Most widespreadMost widespread
Requires enough Requires enough moisture to moisture to support large support large treestrees
Specific bands – Specific bands – pole to equatorpole to equator
– ConiferousConiferous
– Temperate Temperate deciduous deciduous (warm and cool(warm and cool
– TropicalTropical
Warm aseasonal Warm aseasonal environmentenvironment– Tropical ForestTropical Forest– Evergreen broadleaf Evergreen broadleaf
treestrees
SeasonalitySeasonality– Dry tropical forestDry tropical forest– DeciduousDeciduous– ConiferousConiferous
Trees get smaller Trees get smaller as seasonality as seasonality increasesincreases– Actual Actual
Evapotranspiration Evapotranspiration raterate
Productivity and Productivity and Decomposition Decomposition increase as the increase as the places get places get warmer and warmer and wetterwetter
Note differencesNote differences– LitterfallLitterfall– Forest floor Forest floor
biomassbiomass– Turnover time for Turnover time for
decompositiondecomposition
Seasonality and Tropical ForestSeasonality and Tropical Forest
Tropical Forest has been divided into various typesTropical Forest has been divided into various types– Boundary not clearBoundary not clear– Not continuousNot continuous– Broken by lack of moistureBroken by lack of moisture
Tropical Rain ForestTropical Rain Forest– Lowland (<1000 m)Lowland (<1000 m)– Mountain (>1000 m)Mountain (>1000 m)– CloudCloud
Very high altitudeVery high altitude– SwampSwamp
Wet soilsWet soils– PeatPeat
Nutrient PoorNutrient Poor
Tropical and Semi-tropical seasonal forestsTropical and Semi-tropical seasonal forests– 2 to 4 month droughts2 to 4 month droughts
Results in 30% loss of leavesResults in 30% loss of leavesFruits at the staFruits at the sta
Tropical Rain ForestTropical Rain Forest– Very high diversity of microbial, plant and animal lifeVery high diversity of microbial, plant and animal life
10 square km10 square km– 1500 species of flowering plants1500 species of flowering plants– 750 species of trees750 species of trees– Richest – Malaysia – 7900 speciesRichest – Malaysia – 7900 species
– StratificationStratificationCan be difficult to define Can be difficult to define
– Crowns of emergent treeCrowns of emergent tree– Mop top treesMop top trees– Conical top treesConical top trees– Shrubs, young trees, tall herbs and fernsShrubs, young trees, tall herbs and ferns– Tree seedlings, low herbaceous plants and low fernsTree seedlings, low herbaceous plants and low ferns
Many plants use the trees for supportMany plants use the trees for support– All shallow rootedAll shallow rooted– Mycorrhirae are importantMycorrhirae are important– EpiphytesEpiphytes
NicheNiche– StranglersStranglers
Whole treeWhole tree– ClimbersClimbers
Usually where disturbedUsually where disturbed
Continuous changesContinuous changes– Trees dieTrees die– Trees fallTrees fall– Gap appear and disappearGap appear and disappear
StratificationStratification– Supports greater diversity of animal lifeSupports greater diversity of animal life
Above canopy groupAbove canopy group– Insectivorous and carnivorous birds and batsInsectivorous and carnivorous birds and bats
Canopy groupCanopy group– Birds, fruit bats, mammals who eat leaves and fruitBirds, fruit bats, mammals who eat leaves and fruit
Below canopy groupBelow canopy group– Flying mammals, birds and batsFlying mammals, birds and bats
Middle groupMiddle group– Squirrels and such that move between group and canopySquirrels and such that move between group and canopy
Forest FloorForest Floor– Large herbivores and carnivoresLarge herbivores and carnivores
Ground GroupGround Group– Small insectivorous, herbivorous, carnivorous and omnivorous ammalsSmall insectivorous, herbivorous, carnivorous and omnivorous ammals
Deciduous ForestDeciduous Forest
Once covered most of Europe, China, North and Once covered most of Europe, China, North and South AmericaSouth AmericaLargely cleared by humansLargely cleared by humansRemaining only semi natural with few exceptionsRemaining only semi natural with few exceptionsTwo TypesTwo Types– Beech-Oak-HornbeamBeech-Oak-Hornbeam– Oak-HornbeamOak-Hornbeam
More acid soilsMore acid soils
Temperate Evergreen Forests in Subtropical areasTemperate Evergreen Forests in Subtropical areas– AustraliaAustralia– New ZealandNew Zealand– PatagoniaPatagonia
Temperate Deciduous ForestTemperate Deciduous Forest– Four strata in uneven aged standsFour strata in uneven aged stands– Even aged stands show poor separationEven aged stands show poor separation
Canopy of dominant and codominant treesCanopy of dominant and codominant treesLower Tree CanopyLower Tree CanopyShrub LayerShrub LayerGround layerGround layer
– Animals inhabit various layers but less diversity than tropical forestAnimals inhabit various layers but less diversity than tropical forest– Light intensity in different areas varies with seasonLight intensity in different areas varies with season
Spring gives most light to groundSpring gives most light to groundDarkest for ground in midsummerDarkest for ground in midsummer
– Microclimate variationMicroclimate variationHighest temperatures in canopyHighest temperatures in canopy
– Humidity varies with seasonHumidity varies with seasonHighest in summerHighest in summerHigher during night than dayHigher during night than day
Coniferous ForestsConiferous ForestsWide variety of Wide variety of environemntsenvironemnts
– MountainsMountains– Cool Temperate RegionsCool Temperate Regions
Simple Vertical StructuresSimple Vertical Structures– Three types of crownThree types of crown
Straight cylindrical trunks Straight cylindrical trunks with varying crown densitywith varying crown density
– Scots pineScots pine
Spiral shapedSpiral shaped– Douglas firDouglas fir– CedarsCedars
Deciduous conifers with Deciduous conifers with pyramidal open crownspyramidal open crowns
– LarchLarch
Little vertical structureLittle vertical structure– Sharp reduction in lightSharp reduction in light– Does not changeDoes not change– Some stratification for birdsSome stratification for birds
Temperature variationTemperature variation– Changes with type of forestChanges with type of forest
Dominant in northern Dominant in northern latitudeslatitudes
Boreal ForestBoreal ForestConiferous Forest that dominates northern latitudesConiferous Forest that dominates northern latitudes– 11% of terrestial surface11% of terrestial surface– Highly influenced by seasonal freezing and thawingHighly influenced by seasonal freezing and thawing
Permafrost in northPermafrost in northWet in summer due to thawingWet in summer due to thawing
– Tundra southwardsTundra southwardsForest-TundraForest-TundraOpen borealOpen borealMain borealMain borealBoreal-mixed forestBoreal-mixed forest
– Simple StructureSimple StructureSpiral spruces and firsSpiral spruces and firsOpen pinesOpen pinesLarchLarchShallow rootsShallow rootsFire importantFire important
– Unique but simple animal communityUnique but simple animal communityLarge herbivoresLarge herbivoresGround birdsGround birdsSome large carnvioresSome large carnvioresHerbivorous insectsHerbivorous insectsNesting ground of many neotropical and tropical birdsNesting ground of many neotropical and tropical birds
Changes in Environment affect Changes in Environment affect ForestsForests
High results in change from deciduous to High results in change from deciduous to coniferousconiferousReduced soil moisture gives rise to woodlands in Reduced soil moisture gives rise to woodlands in temperate regionstemperate regions– Increased diversity of habitats and speciesIncreased diversity of habitats and species
Reduced soil moistures gives rise to savannas in Reduced soil moistures gives rise to savannas in tropicstropics– High biomass of grassesHigh biomass of grasses– Still lots of trees but spread outStill lots of trees but spread out– Driven by seasonalityDriven by seasonality– Unique herbivores Unique herbivores
Grassland, Shrubland, Grassland, Shrubland, Desert and TundraDesert and Tundra
Decrease in available Decrease in available water changes Forest to water changes Forest to Grassland in Temperate Grassland in Temperate zoneszones– 250mm to 800mm of 250mm to 800mm of
rainrainNote difference between Note difference between created and natural created and natural grasslandsgrasslands– Europe – stableEurope – stable– America – revert to America – revert to
forestforestGrasslands varyGrasslands vary
Tallgrass prairieTallgrass prairie– Near forestNear forest
Shortgrass prairieShortgrass prairie– Great plains of USGreat plains of US
Desert grasslandDesert grassland– 300-400 mm rain300-400 mm rain
SteppeSteppe– AsiaAsia– 500-600 mm rain500-600 mm rain
PampasPampas– South AmericaSouth America– 450-900 mm rain450-900 mm rain
VeldVeld– Southern AfricaSouthern Africa– 1500-2000 metres1500-2000 metres
Vertical structure of Vertical structure of grassland changes grassland changes with seasonwith seasonVarious layers Various layers containing different containing different plantsplantsAs plants grow out As plants grow out of winterof winter– At the groundAt the ground
Light Light decreasesdecreasesTemperature Temperature decreasesdecreasesHumidity Humidity increasesincreasesWind Wind decreasesdecreases
Thatch Thatch accumulatesaccumulates– Slow Slow
decompositiondecomposition3 to 4 years3 to 4 years
Burning importantBurning important– Removes thatch Removes thatch
and mulchand mulch– As does grazingAs does grazing
Complex root Complex root systemssystems– Half plant below Half plant below
groundground
Natural and domestic Natural and domestic grassland support a very grassland support a very wide diversity of lifewide diversity of life– Large ungulatesLarge ungulates
Example: bison in USExample: bison in US
Eurasian too originallyEurasian too originally
Africa: Zebra, Rhino, etcAfrica: Zebra, Rhino, etc
Productivity and nutrient Productivity and nutrient cycling controlled by cycling controlled by droughtdrought– Best >800mm rain and Best >800mm rain and
>15>15ooCC
All grassland have evolved All grassland have evolved under grazing pressure under grazing pressure together with droughttogether with drought
ShrublandShrublandDifficult to characterizeDifficult to characterize– Created by manCreated by man– Created by disturbanceCreated by disturbance– Part of arid gradientPart of arid gradient
Shrubs have an advantage over trees in arid areasShrubs have an advantage over trees in arid areas– Invest less energy above groundInvest less energy above ground– Better moisture collectionBetter moisture collection– Faster growthFaster growth
Mediterranean ShrublandMediterranean Shrubland– Winter rainfallWinter rainfall
Broad leaf shrubsBroad leaf shrubsDwarfed treesDwarfed trees
HeathlandHeathland– Cold type shrublandCold type shrubland– Nutriant poor, especially nitrogen and phosphorusNutriant poor, especially nitrogen and phosphorus– Usually high altitudeUsually high altitude– Dry TypeDry Type
Seasonal droughtSeasonal drought– Wet TypeWet Type
Seasonal waterloggingSeasonal waterlogging
Animal CommunityAnimal Community– Small animals and ground birdsSmall animals and ground birds– Distinct to regionDistinct to region
DesertDesert
Diverse set of ecosystemDiverse set of ecosystemWhere evaporation exceeds rainfallWhere evaporation exceeds rainfallSemi desertsSemi deserts– 150 to 300 mm rain150 to 300 mm rain
True desertsTrue deserts– 70 to 150 mm rain70 to 150 mm rain
Extreme desertsExtreme deserts– <70 mm rain<70 mm rain
Simple physical structureSimple physical structureMoisture limits productionMoisture limits productionPlants and animals adapt to aridityPlants and animals adapt to aridityLimited plant and animal diversityLimited plant and animal diversity
TundraTundraLow precipitationLow precipitationLow temperatureLow temperaturePermafrostPermafrost100% cover and moist100% cover and moistSimple structureSimple structure
– Low diversity of plants and animalsLow diversity of plants and animals– Animals and plants well adaptedAnimals and plants well adapted– Simple structureSimple structure
ProductivityProductivity– Low temperatureLow temperature– Extreme seasonalityExtreme seasonality
Also polar desertAlso polar desert