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P. K. Ramachandran Nair B. Mohan Kumar Vimala D. Nair An Introduction to Agroforestry Four Decades of Scientific Developments Second Edition An Introduction to Agroforestry (cid:129) P. K. Ramachandran Nair (cid:129) B. Mohan Kumar Vimala D. Nair An Introduction to Agroforestry Four Decades of Scientific Developments Second Edition P.K.RamachandranNair B.MohanKumar SchoolofForestResources ArunachalUniversityofStudies andConservation Namsai,ArunachalPradesh,India UniversityofFlorida Gainesville,FL,USA VimalaD.Nair SoilandWaterSciencesDepartment UniversityofFlorida Gainesville,FL,USA ISBN978-3-030-75357-3 ISBN978-3-030-75358-0 (eBook) https://doi.org/10.1007/978-3-030-75358-0 #SpringerNatureSwitzerlandAG1993,2021 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeor part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway, andtransmissionorinformationstorageandretrieval,electronicadaptation,computersoftware,or bysimilarordissimilarmethodologynowknownorhereafterdeveloped. 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ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface It is not an exaggeration to state that this book has been in the making for morethantwentyyears.AfewyearsafterthefirsteditionofAnIntroduction to Agroforestry was published in 1993, it became clear that it needed improvements in several areas to keep up with the increasing volumes of newresearchresultsanddevelopmentapplicationsinagroforestryintandem withthenewandemergingissuesandparadigms.Italsobecameclearoverthe years that preparing a second edition of the book would entail a thorough revision of the old version and the addition of new chapters on some major topics, such as climate change, that have become prominent since the first edition was published. I (P. K. R. Nair, the first author of this book and the sole author of its first edition) was convinced that I would not be able to undertakesuchataskuntilIcouldconcentrateexclusivelyonitforatleasta year. Such an opportunity did not arise until my formal retirement from the University of Florida in 2019. The unexpected lockdowns and travel restrictions imposed by the COVID-19 pandemic in 2020 turned out to be a sortofblessingindisguisethatallowedmetostayfocusedonthetask. About two years ago, when the project got started in earnest, I invited ProfessorsB.MohanKumarandVimalaNairtobeinvolvedasmycoauthors in this challenging task. All three of us have been close professional collaborators for decades (and Vimala andIarenearingourfiftiethwedding anniversary in 2023). The book embodies our collective efforts in pulling together and synthesizing the large body of literature that had accumulated during the nearly three decades since the first edition and presenting it in a form and format torepresent thecurrent level of understanding of the major scientificdevelopmentsinagroforestry. Thefirsteditionofthebookwasputtogetherinresponsetotheneedfeltat the time for a college-level textbook. That basic feature is retained in this editiontoo.However,agroforestryisanamalgamofseveralsubjects,andthe science of agroforestry involves a harmonious blending of both biophysical and socioeconomic sciences; dealing with the vast array of subjects in one bookwouldleadtoatoosuperficialtreatmentoftheindividualtopics.During mymanydecadesofinteractionswithstudentsandearly-careerprofessionals from different parts of the world, I have noted that the lack of a basic understandingofthebiophysicalfoundationsofagroforestry,suchasplants, v vi Preface soils, and ecology, impedes those who wish to pursue agroforestry-related careersindevelopment-orientedprofessions.Furthermore,someissues,such as climate change, soil health, biodiversity, and ecosystem services, which havecapturedtheglobalcommunity’sinquisitiveattentionoverthepastthree decades,needtobeexaminedandexplainedinmoredetailthanothers.Thus it became imperative for us to highlight the significant benefits and services that agroforestry offers in meeting the targets set out in the United Nations Sustainable Development Goals (SDGs) 2030 (https://sdgs.un.org/goals). We decided to drop the short chapters on experimental designs and farming system methodology, from the first edition, and focus on explaining the principlesthatunderliethescience-basedpracticesinplant,soil,andecosys- tem management in agroforestry. Over the decades, we have also been convincedthateveninthefifthdecadeofagroforestrydevelopmentdifferent groups of professionals entertain divergent, even vague, perceptions on the subject.Inthehopes ofaddressingthis problem, we haveincluded,with the splendidcooperationofnumerouscolleaguesfromvariouspartsoftheworld, pictorialpresentationsofthediversityofagroforestrysystemsinavarietyof ecologicalandgeographicalregions. The book is organized into five sections spanning twenty-four chapters. Chapters1–3intheintroductorysection(essentiallythesameasitwasinthe first edition) trace the historical developments leading to the emergence of agroforestry,anarrativeofthedefinitionandconcepts,andtheclassification of agroforestry systems based on various criteria. Section II summarizes in eight chapters the major agroforestry systems in the world, with ample photographicillustrations,asindicatedabove.Thebiophysicalfoundationsof agroforestry are explained in two sections – Section III (Plant Productivity) andSectionIV(Soils).Someoftheecosystemservicesrelatedtosoilfertility management and soil conservation are also included in Section IV. Other major ecosystem services, such as carbon sequestration for climate change mitigation and biodiversity conservation, are the main themes described in Section V. Finally, the concluding section (Section VI) has two chapters, Chapter23discussingtheroleofagroforestryinattainingtheSDGsingeneral and food security in particular, and Chapter 24 provides a broad outlook on agroforestryandlandmanagementintothefuture. Wehavetriedtoreducetheuseofscientificjargontotheextentpossibleto makethebookmoreaccessibletothosewhoarerelativelylessproficientwith thescientific literature. Forexample,we usethecommonly understood term ton (“t”) instead of Mg (1,000 kg) as the unit of mass for expressing crop yieldsandsoilcarbonstocksexceptinsomesituations.Similarly,theauthor (authority) names attached to the Latin names of plants are generally not mentionedtoavoidtheclumsinessofastringofsuchnamesappendedtothe Latinnamesofsomeunderexploitedplants.Allotherinternationallyaccepted scientificnorms,terms,andunitsareused. Preface vii Althoughasinglevolumemaynotsatisfyeveryoneinterestedinacomplex subjectlikeagroforestry,wehopethereaderswillfindthisbookuseful. Gainesville,FL,USA P.K.R.Nair Vellanikkara,Kerala,India B.MohanKumar Gainesville,FL,USA VimalaD.Nair December2020 Acknowledgments Duringthepastmorethantwodecades,therehavebeeninnumerablerequests andpersuasionsfromcolleaguesaroundtheworldforarevisedversionofthe firsteditionofthisbook.Theensuinginteractionsanddiscussionswithawide spectrum of graduate students, trainees, professionals, and administrators from different countries have influenced our decisions on the scope and content of this book. We are grateful to all those agroforestry enthusiasts at largefortheirunfailingsupportandencouragementovertheyears. Sincetheworkonthebookstartedinearnestabouttwoyearsago,wehave been blessed with the outpouring of help and support from numerous individualswhomwe contacted withspecificrequests.Therequestscovered avarietyofsubjectssuchasphotographsofdifferentagroforestrysystemsand components,copiesofpublications,discussionandclarificationontechnical points,reviewofsectionsofthemanuscript,etc.Althoughthesourcesofsuch inputs and resources used in the book have been duly cited, we wish to mention (in no specific order) the names of some such colleagues and acknowledge their help: Ravi Prabhu, Ramni Jamnadass, Roeland Kindt, SusanOnyanko,andRobertFinlaysonofICRAF/WorldAgroforestry;former ICRAFcolleaguesDennisGarrity,RogerLeakey,ChinOng,andMeinevan Noordwijk;CraigElevitchoftheAgroforestryNet,Hawaii;KaoruIchikawa, formerlywiththeUNU/IAS,Tokyo;severalcolleaguesfromBrazilincluding Charles Clement and his associates at INPA, Steel Vasconselas of EMBRAPA, and Robert Miller, Brasilia; Rosa Mosquera-Losada and colleagues of the University of Santiago de Compostela, Spain; Dan Cartledge,Guangzhou,China;PaulBurgessandalltheEuropeancolleagues associated with the AGFORWARD project; Shibu Jose, University of Missouri; Gary Bentrup, USDA/National Agroforestry Center; Eric ToensmeierandFlorenciaMontagnini,YaleUniversity;Canadiancolleagues includingNareshThevathasanoftheUniversityofGuelph,ScottChangofthe University ofAlberta, and Malcolm Cairns;Emmanuel Torquebiau,CIRAD and Christian Dupraz, INRA, France; Pablo Piri, UNPA, Argentina; Francis Dube, Concepción, Chile; A. Arunachalam, Jhansi, India; and Tim Martin, SFRC/IFAS,UniversityofFlorida(UF).Wealsowishtoexpressourspecial appreciationfortheefficientprofessionalhelpfromRaghuConsbruck,Eight Eyes,forthegraphicdesign,drawings,photoconversions,andrelatedworks. B.M.Kumargreatlyappreciatestheconstantsupportandencouragement ofhiswifeSheenuNair.Duringthetermofthisproject,hewassupportedby ix x Acknowledgments theIndianCouncilofAgriculturalResearch(ICAR)asanEmeritusScientist attachedtotheKeralaAgriculturalUniversity(KAU),Thrissur,India.Healso acknowledgesthehelpofhisdaughterManeeshaMohan(LincolnUniversity, NewZealand)andR.Abhijith(KAU)fortheirhelpintheliteraturesearch. Vimala Nair is grateful to Matt Whiles, Chair, Soil and Water Sciences Department,UF,forhisencouragement.P.K.Nairacknowledgesthesupport and cooperation of Terrell (“Red”) Baker, Director, School of Forest Resources and Conservation, and other UF colleagues, to complete this work. Vimala andP. K.also greatlyappreciate thelovingencouragement of theirdaughtersBindu,Deepa,andRekha,andtheirfamilies. P.K.R.Nair B.MohanKumar VimalaD.Nair Contents SectionI Introduction 1 HistoricalDevelopments:TheComingofAge ofAgroforestry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 CultivatingTreesandCropsTogether: AnAge-OldPractice. . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 DevelopmentsintheAgricultureSector. . . . . . . . . . . . . . 5 1.3.1 TheGreenRevolution. . . . . . . . . . . . . . . . . . . . 6 1.3.2 TheInternationalAgriculturalResearch Centers(IARCs). . . . . . . . . . . . . . . . . . . . . . . . 6 1.4 DevelopmentsintheForestrySector. . . . . . . . . . . . . . . . 6 1.4.1 TheGeneralPatternofForestResource UtilizationOverTime. . . . . . . . . . . . . . . . . . . . 6 1.4.2 MajorForestryResearchandDevelopment InitiativesSincethe1950s. . . . . . . . . . . . . . . . . 9 1.4.3 Deforestation. . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.4.4 People-OrientedForestryPrograms. . . . . . . . . . 13 1.5 FormationofICRAFandtheInstitutionalizationof Agroforestry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 References. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . 19 2 DefinitionandConceptsofAgroforestry. . . . . . . . . . . . . . . . 21 2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.2 EvolutionofDefinitionsofAgroforestry. . . . . . . . . . . . . 22 2.3 DefinitionsGalore. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.4 Concepts,Principles,andAttributesofAgroforestry. . . . . 23 2.5 OtherAgroforestry-RelatedLand-UseSystems. . . . . . . . 26 References. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . 27 3 ClassificationofAgroforestrySystems. . . . . . . . . . . . . . . . . . 29 3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2 EarlyEffortsinClassification. . . . . . . . . . . . . . . . . . . . . 30 3.3 ClassificationBasedontheStructureoftheSystem. . . . . 31 3.3.1 NatureofComponents. . . . . . . . . . . . . . . . . . . . 31 3.3.2 ArrangementofComponents. . . . . . . . . . . . . . . 33 xi