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