Ecology 14Ecology 14Biogeography & BiodiversityBiogeography & Biodiversity

Ralph KirbyRalph Kirby

Diversity of plant communitiesDiversity of plant communitiesSimilar climates support similar communitiesSimilar climates support similar communitiesThus vegetation is correlated to climateThus vegetation is correlated to climateThis is BiogeographyThis is Biogeography– Aim is to understand the patternsAim is to understand the patterns

HistoricalHistorical– Origin, dispersal and extinction of groupsOrigin, dispersal and extinction of groups

EcologicalEcological– Distribution and interaction of contemporary organisms Distribution and interaction of contemporary organisms

Why do these patterns existWhy do these patterns exist

CandolleCandolle– Temperature and available waterTemperature and available water

KKööppenppen– Fixed on climateFixed on climate

MerriamMerriam– Elevation importantElevation important

Northward – average temperatureNorthward – average temperatureSouthward – Heat toleranceSouthward – Heat tolerance

Clements & ShelfordClements & Shelford– Animal and Plants together as single unitAnimal and Plants together as single unit

BiomeBiome

WhittakerWhittaker– Minimum of 9 terrestial biomesMinimum of 9 terrestial biomes– Specific patternSpecific pattern

Mean annual temperatureMean annual temperatureMean annual precipitationMean annual precipitation

KKööppen Systemppen System

Clements & ShelfordClements & Shelford

Major Biomes of the WorldMajor Biomes of the World

WhittakerWhittaker– Precipitation versus TemperaturePrecipitation versus Temperature

HoldridgeHoldridge– Life ZonesLife Zones

Average daily temperatureAverage daily temperatureAnnual precipitationAnnual precipitationPotential evapotranspiration ratioPotential evapotranspiration ratioBiotemperatureBiotemperature

Terrestial Ecosystems are reflected in their dominant plantsTerrestial Ecosystems are reflected in their dominant plants

Three general plant life formsThree general plant life forms– TreesTrees– ShrubsShrubs– GrassesGrasses

Ratio decides ecosystemRatio decides ecosystem– ForestForest

Closed canopy of treesClosed canopy of trees– Woodland/SavannaWoodland/Savanna

Codominance of trees and grassCodominance of trees and grassRatio variesRatio varies

– ShrublandShrublandShrubsShrubs

– GrasslandGrasslandGrassGrass

– DesertDesertAbsence of plant coverAbsence of plant cover

Caused by advantages and disadvantages of each type of plant in a particular Caused by advantages and disadvantages of each type of plant in a particular environmentenvironment– GrassesGrasses

Higher ratio of photosynthetic tissueHigher ratio of photosynthetic tissueLess supportive tissueLess supportive tissue

– TreesTreesHigher ratio of supportive tissueHigher ratio of supportive tissueLess photosynthetic tissueLess photosynthetic tissueHeight advantageHeight advantage

– ShrubsShrubsIntermediate but better in more extreme climatesIntermediate but better in more extreme climates

LeavesLeavesBased on cost to plant versus climate/sunlightBased on cost to plant versus climate/sunlightSee Figure 24.4See Figure 24.4– DeciduousDeciduous

Distinct growing seasonDistinct growing season– Winter deciduousWinter deciduous

Temperate regions with low temperature dormancyTemperate regions with low temperature dormancyLeaves shed during winterLeaves shed during winter

– Drought deciduousDrought deciduousSeasonal rainfall areas of tropics and subtropicsSeasonal rainfall areas of tropics and subtropicsLeaves shed during dry seasonLeaves shed during dry season

– EvergreenEvergreenNeedleleaf TypeNeedleleaf Type

– Very short growing seasonVery short growing season– Or very nutrient limited environmentOr very nutrient limited environment

Broadleaf TypeBroadleaf Type– No distinct growing seasonNo distinct growing season

WallaceWallace– Based on Based on

biodistributionbiodistributionDriven by Driven by continental continental movement over movement over timetime

– Six regionsSix regionsPalearcticPalearcticNearcticNearcticNeotropicalNeotropicalEthiopianEthiopianOrientalOrientalAustralianAustralian

– Or three regionsOr three regionsNeogeaNeogea

– NeotropicalNeotropical

NotogeaNotogea– AustralianAustralian

MetageaMetagea– ArcticArctic– EthiopeanEthiopean– OrientalOriental

Aquatic systemsAquatic systemsBased on physical Based on physical environmentenvironment– FreshwaterFreshwater

DepthDepthFlow of waterFlow of waterSeparate intoSeparate into

– Streams & riversStreams & rivers– Ponds, lakes & Ponds, lakes &

wetlandswetlands

– SalineSalineCoastalCoastal

– Transition zoneTransition zoneEstuaries etcEstuaries etc

– Diversity of Diversity of ecosystemsecosystems

OpenOpen– VerticalVertical– HorizontalHorizontal

All are linkedAll are linked

Species based on major taxonomic groups vary in Species based on major taxonomic groups vary in greatlygreatly– Note microorganismsNote microorganisms

Wrong estimateWrong estimate

Distribution of species not evenDistribution of species not even– Variation in species richnessVariation in species richness

Terrestrial decreases from equator to poleTerrestrial decreases from equator to pole– Age of communityAge of community

Ice AgesIce Ages– Heterogeneity of environmentHeterogeneity of environment– Climate stabilityClimate stability– Ecosystem productivityEcosystem productivity

This supports This supports decrease from decrease from equator to pole for equator to pole for North AmericaNorth America

Effectively related to Effectively related to a number of factors a number of factors seen beforeseen before– Annual temperatureAnnual temperature– Solar radiationSolar radiation– PrecipitationPrecipitation

Best correlate Best correlate actual actual evapotranspiration evapotranspiration raterate

Plots of North American species Plots of North American species richness with latitude northrichness with latitude north

Plots for Evapotranspiration Plots for Evapotranspiration rate and species richness in rate and species richness in North AmericaNorth America

Terrestrial systemsTerrestrial systems– Basically water and temperatureBasically water and temperature– Thus altitude is also importantThus altitude is also important

Marine environmentsMarine environments– Latitude similarLatitude similar– Inverse to productivityInverse to productivity– Importance of seasonalityImportance of seasonality

UpwellingUpwellingMixingMixing

However species diversity operates at many different However species diversity operates at many different scalesscales– From communitiesFrom communities– To biomesTo biomes

Hard to measure when time is taken into accountHard to measure when time is taken into account– Migration etcMigration etc

Need to plot to manage Need to plot to manage resourcesresourcesLandLand– Tends to splittingTends to splitting

SeaSea– BroadBroad

Usually as followsUsually as follows– Eco-regionsEco-regions

DomainsDomains– DivisionsDivisions

ProvincesProvinces

Can use pollen to look at Can use pollen to look at ecosystems historyecosystems historyPredict effect of climate Predict effect of climate changeschanges