An Introduction to Agroforestry: Four Decades of Scientific Developments

670 Pages·2022·38.382 MB·English

by  P. K. Ramachandran Nair, B. Mohan Kumar, Vimala D. Nair

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
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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