IndividualsWater RelationsIndividualsWATERRELATIONSX
Individuals Water Relations WATER RELATIONS Individuals
IndividualsWater RelationsBalancinglosswatertothewithenvironmentintake is callthewater"water relations
Individuals Water Relations Balancing water loss to the environment with water intake is call the “water relations
IndividualsWater RelationsA cicada(Diceroproctaapache)'story:Eric Toolson and his studentsSonoran Desert46°C(shade)~70°C(ground surface)Diceroprocta apache福
Individuals Water Relations A cicada(Diceroprocta apache)’ story: Eric Toolson and his students Sonoran Desert 46ºC(shade)~70ºC(ground surface) Diceroprocta apache
IndividualsWaterRelationsEric Toolson' questions:How could this species be active in apparently lethal airtemperatures?[Our questionsto Toolson:Howdid he maintaina bodytemperatureof37°Cinthis desertheat?Did the cicada keep cool by using small, shadymicroclimates in the mesquit tree?Did the cicada somehow manage to evaporatively cool?..How did it avoid desiccating in the desert heat?-HowDiceroproctaapachecan regulatethetemperature and water content of its body whilelivingin such an extreme enviornment
Individuals Water Relations Eric Toolson’ questions: How could this species be active in apparently lethal air temperatures? [Our questions to Toolson:How did he maintain a body temperature of 37ºC in this desert heat?] Did the cicada keep cool by using small, shady microclimates in the mesquit tree ? Did the cicada somehow manage to evaporatively cool? .How did it avoid desiccating in the desert heat? -How Diceroprocta apache can regulate the temperature and water content of its body while living in such an extreme enviornment
IndividualsWater RelationsFallingtothegroundwithatemperatureofAirtemperunreora6ec70°c wouldbe certainishigherthanlethaldeath tor the cicadnmaximumrorthecicadaHow does the cicada remainactixewhenenviroumentultemperatures exceedits lethalmaxmumn?FIGURE5.1Aneeologicalpztle
Individuals Water Relations
IndividualsWater RelationsXTheof watermovementdown concentration gradientsinandterrestrialaquatictheenvironmentsdeterminesoftoavailabilitywaterorganisms
Individuals Water Relations ❖ The movement of water down concentration gradients in terrestrial and aquatic environments determines the availability of water to organisms
IndividualsWater RelationsWater Content of Air
Individuals Water Relations ➢ Water Content of Air
IndividualsWater RelationsA steep gradient of water concentration produces a highrateof evaporationWater vapor densityX100RelativehumiditySaturation watervapor densityWatervaporpressureSaturation watervaporpressuredeficit.Vaporpressure
Individuals Water Relations •A steep gradient of water concentration produces a high rate of evaporation. •Relative humidity = 100 •Water vapor pressure • Saturation water vapor pressure •Vapor pressure deficit Water vapor density Saturation water vapor density
IndividualsWater RelationsWatervapor in aircan beorbythepressuremeasured eitheras grams ofexertedbythevaporpercubicmeterofairwatervaporinair40D5nsoo3020210--00102030Temperature (C)Arlowtemperatures,airisAstemperatureincreases,thesaturated by low quantitiesamountofwaterairholdsatofwatervaporand watersaturation and saturation watervaporpressure is low.vaporpressureincreaseFIGURE5.2The relationshipbenwveenair temperature and rwo mea-suresofwatervaporsaturationofair
Individuals Water Relations
IndiidualsWater RelationsThevaporpressuredeficit(ypd)indicatesthe gradientinwaterconcentration from aterrestrial organismto theairA highervpd indicatesa steeperconcentrationgradient.AhighvpdindicatesthattheAlowvpdindicatesthatthewatervaporcontentofairiswatervaporcontentofairiswellbelowsaturation.near saturation,EvaporationEvaporationWhere the vpd ishigh,theWherethevpd is low.therate of evaporative waterrate of evaporative waterlossbyorganisms is higher.lossbyorganismsis lower.FIGUREVaporpresuredefiandevaporativewaerlossbyrresrialoganism
Individuals Water Relations