Ecohydrology of Water-Controlled Ecosystems: Soil Moisture and Plant Dynamics

478 Pages·2005·7.81 MB·English

by  Ignacio Rodríguez-Iturbe

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Ecohydrology of Water-Controlled Ecosystems
Soil Moisture and Plant Dynamics
Understandingofthesystemsthatcontrolthecirculationofwaterbetween
atmosphere, soil, and plant life is clearly important for a general under-
standing ofthehydrologic cycleandtheway thatecosystems operate and
survive. Ecohydrology of Water-Controlled Ecosystems: Soil Moisture and
PlantDynamicsaddressestheconnectionsbetweenthehydrologiccycleand
plantecosystems,withspecialemphasisonaridandsemi-aridclimates.
Thisbook presentsaquantitativeunderstandingoftheimpactsofsoil
moisture on ecosystem dynamics using a probabilistic framework. It
investigates thevegetation response to water stress (drought),thehydro-
logiccontrolofcyclesofsoilnutrients,andthedynamicsofplantcompeti-
tionforwater.Thebookalsooffersinsightsintoprocessescloselyrelated
tosoilmoisturedynamics,suchassoil–atmosphereinteractionandsoilgas
emissions.Thismodernandimportanttopicistreatedbybuildingsuitable
mathematical models of the physics involved and then applying them to
study the ecosystem structure and its response to rainfall and climate
forcing in different parts of the world, including savannas, grasslands,
andforests.
Thebookwillappealtoadvancedstudentsandresearchersfromalarge
rangeofdisciplines,includingenvironmentalscience,hydrology,ecology,
earthscience,civilandenvironmentalengineering,agriculture,andatmo-
sphericscience.
IGNACIO RODR(cid:1)IGUEZ-ITURBE is Theodora Shelton Pitney Professor of
Environmental Sciences and Professor of Civil and Environmental
Engineering at Princeton University. Professor Rodr(cid:1)iguez-Iturbe is the
author of over 200 research papers and several books, including Fractal
River Basins: Chance and Self-Organization with Andrea Rinaldo
(Cambridge, 1997). A member of the US National Academy of
Engineers,andmanyotheracademiesthroughouttheworld,heisthewinner
of numerous national and international awards including the Stockholm
Water Prize, the Horton and Macelwane Medals of the American
Geophysical Union, the Langbein Lecture (also AGU), the Huber Prize
and V. T. Chow Award (American Society of Civil Engineering), the
Horton Lecture (American Meteorological Society), the Premio Mexico,
andthePremioNacionaldeCienciasdeVenezuela.
AMILCARE PORPORATO is Associate Professor of Civil and Environmental
EngineeringatDukeUniversity.Heistheauthorofmorethan50research
papers. He received the Arturo Parisatti International Prize, awarded by
the Istituto Veneto di Scienze, Lettere e Arti. He has been a research
associate in the Civil Engineering, Environmental and Water Resources
DivisionatTexasA&MUniversityandtheDepartmentofCivilEngineering
at Princeton University. He was chairman of the last two Ecohydrology
sessionsoftheAmericanGeophysicalUnionSpringMeeting.
Ecohydrology of
Water-Controlled Ecosystems
Soil Moisture and Plant Dynamics
IgnacioRodr(cid:1)iguez-Iturbe
PrincetonUniversity,NewJersey,USA
AmilcarePorporato
DukeUniversity,NorthCarolina,USA
  
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge  , UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521819435
© I. Rodríguez-Iturbe and A. Porporato 2004
This book is in copyright. Subject to statutory exception and to the provision of
relevant collective licensing agreements, no reproduction of any part may take place
without the written permission of Cambridge University Press.
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ASandra
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Contents
Foreword,GabrielKatul xi
Preface xv
1 Introduction 1
1.1 Ecohydrologyofwater-controlledecosystems 2
1.2 Simplifyingassumptions 4
1.3 Levelsofdescription 6
1.4 Temporalscales 8
1.5 Spatialdimensions 10
1.6 Soilmoistureandthecyclesofsoilnutrients 11
1.7 Soilmoisturedynamicsandecosystemstructure 12
2 Stochasticsoilmoisturedynamicsandwaterbalance 15
2.1 Soilwaterbalanceat apoint 15
2.2 Probabilisticevolutionofthesoilmoistureprocess 33
2.3 Steady-stateprobabilitydistributionofsoilmoisture 36
2.4 Waterbalance 41
2.5 Comparisonwithfielddata 46
2.6 Simplermodelsofsoilmoisturedynamics 47
2.7 AppendixA.Soilmoisturecumulativeprobability
distribution 57
3 Crossingpropertiesofsoilmoisturedynamics 59
3.1 Meanfirstpassagetimesofprocessesdrivenbywhite
shotnoise 59
3.2 Crossingpropertiesofthesoilmoistureprocess 66
3.3 Durationofexcursionsbetweentwodifferentlevelsof
soilmoisture 74
3.4 MFPT’sforminimalisticmodelsofsoilmoisture 76
3.5 AppendixB.Backwarddifferentialequationandcrossing
properties 82
vii
viii Contents
4 Plantwaterstress 86
4.1 Soil-waterdeficitandplantwaterstress 86
4.2 Probabilisticdescriptionofstaticwaterstress 101
4.3 Dynamicwaterstress 107
4.4 Impactofenvironmentalconditionsondynamic
waterstress 110
4.5 Optimalplantconditions 114
5 Applicationstonaturalecosystems 117
5.1 TheroleofvegetationintheNylsvleysavanna 119
5.2 SensitivitytoclimatefluctuationsinasouthernTexas
savanna 129
5.3 TheroleofsoiltextureintheColoradoshortgrasssteppe 140
5.4 VegetationpatternsalongtheKalahariprecipitation
gradient 149
5.5 TreecanopyeffectsinsouthernAfricansavannas 164
5.6 SoilmoisturebalanceandwaterstressinaMediterranean
oaksavanna 173
6 Coupleddynamicsofphotosynthesis,transpirationandsoil
waterbalance:fromhourlytogrowing-seasontimescale 179
6.1 Transpirationandsoilwaterbalanceat the
hourlytimescale 180
6.2 Stomatalfunction 186
6.3 Leafcarbonassimilationandphotosynthesis 189
6.4 Hourlydynamics 194
6.5 Comparisonwithdata 198
6.6 Dailytimescaledynamics 200
6.7 Physicalinterpretationof theparameters 203
6.8 Probabilisticdynamicsof carbonassimilation 204
6.9 Meancarbonassimilationandplantwaterstress 207
7 Plantstrategiesandwateruse 212
7.1 Extensiveandintensiveusersofsoilmoisture 213
7.2 TheinversetextureeffectinthesouthernTexassavanna 218
7.3 Stochasticwateravailabilityandadaptationof
transpirationcharacteristics 227
8 Seasonalandinterannualfluctuationsinsoilmoisture
dynamics 236
8.1 Seasonalmeansoilmoisturedynamics 237
8.2 Interannualrainfallfluctuationsandsoil
moisturedynamics 250
8.3 AppendixC 266