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Agroecology and Sustainable Food Systems

ISSN 2168-3565 (Print) 2168-3573 (Online) Journal homepage httpwwwtandfonlinecomloiwjsa21

The ldquoBiodiversityndashEcosystem function debaterdquoAn interdisciplinary dialogue between EcologyAgricultural Science and Agroecology

Dr Valentin Daniel Picasso

To cite this article Dr Valentin Daniel Picasso (2017) The ldquoBiodiversityndashEcosystem functiondebaterdquo An interdisciplinary dialogue between Ecology Agricultural Science and AgroecologyAgroecology and Sustainable Food Systems DOI 1010802168356520171359806

To link to this article httpdxdoiorg1010802168356520171359806

Accepted author version posted online 09Aug 2017Published online 09 Aug 2017

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The ldquoBiodiversityndashEcosystem function debaterdquo Aninterdisciplinary dialogue between Ecology AgriculturalScience and AgroecologyDr Valentin Daniel Picasso PhD

Agronomy Dept University of Wisconsin - Madison Madison Wisconsin USA

ABSTRACTThe ldquobiodiversityndashecosystem function debaterdquo is considered oneof the most heated recent scientific issues within the discipline ofEcology However it can be better understood as an interdisci-plinary dialogue between Ecology Agricultural Science andAgroecology In this article I review the interplay of these dis-ciplines on the conflict the resolution and the implications of thisdebate Agricultural Science and Agroecology challenged therelevance of nontransgressive overyielding and random assemblyexperiments provided statistical and empirical methods for rea-nalyzing the results and developed important recommendationsfor agroecosystems This exemplifies how interdisciplinaryapproaches to science can contribute to improve research qualityand relevance

KEYWORDSAgroecology EcologyAgronomy interdisciplinaryscience intercropping

Introduction

One of the most heated scientific issues in the last two decades was theldquobiodiversityndashecosystem function debaterdquo which concerned the role of bio-diversity on the productivity stability and other functions of ecosystems andits implications for the future of the ecosphere (Tilman Isbell and Cowles2014) This debate is widely viewed as evolving within the scientific disciplineof Ecology mainly a discussion between Community versus EcosystemEcology (Naeem 2002) which became entangled with issues over how eco-logical science should properly inform public policy (DeLaplante and Picasso2011) However this view may give an incomplete picture of the nature ofthe debate The biodiversityndashecosystem function debate can be better under-stood as an interdisciplinary dialogue between the disciplines of EcologyAgricultural Science and Agroecology The goal of this article is to identifythe interplay of these contrasting disciplines in key aspects of the debate sothat we can draw lessons about how interdisciplinary science can contributeto improve scientific research quality and relevance

CONTACT Valentin Daniel Picasso PhD picassorissowiscedu 1575 Linden Dr Madison Wi 53706United StatesColor versions of one or more of the figures in the article can be found online at wwwtandfonlinecomwjsa

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMShttpsdoiorg1010802168356520171359806

copy 2017 Taylor amp Francis

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The biodiversityndashecosystem function debate

The early history of this issue (Figure 1) goes back to the ldquodiversity increasesstabilityrdquo hypotheses from Odum and Elton in the 1950s contradicted later bythe modeling works of May and Pimm in the 1970s and 1980s (Mccann 2000)In the early 1990s large biodiversity experiments were established wherespecies diversity was manipulated by randomly assembling multispecies com-munities and the effects of these communities on ecosystem function (like totalbiomass productivity) were measured The three main experiments were theCedar Creek grasslands in Minnesota USA (Tilman and Downing 1994)ECOTRON multitrophic aquatic systems (Naeem et al 1994) in UK andBIODEPTH grasslands (Hector Schmid and Beierkuhnlein et al 1999) invarious sites across Europe These experiments provided empirical evidence ofa positive relationship between diversity and productivity or stability Theseresults were criticized because of two main arguments First they contradictedobservational studies where environmental conditions determined speciesdiversity (Wardle Zackrisson and Ho et al 1997) Second the design of theexperiments made their interpretation difficult or invalid in particular becauseof the ldquosampling effectrdquo (Huston 1997) ie the increase in productivity indiverse communities may be due to the higher probability of including a highlyproductive species in the mix The biodiversityndashecosystem function was aresearch program with an explicit aim to inform public policy on biodiversityconservation (Naeem Chapin and Costanza et al 1999) Probably because ofthis context generalizations were too quickly made and the debate turned intoa public ldquofull-blown warrdquo in the media (Kaiser 2000)

After a conference in Paris in December 2000 (Figure 1) a synthesisframework emerged reanalyses of experiments were carried out conceptswere redefined and conciliation was reached a large number of species arerequired to maintain ecosystem function but whether this is because more

Figure 1 Timeline of the history of the biodiversityndashecosystem function debate

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rich communities have some key species (selection) or complementaryamong various species was unknown (Hooper et al 2005 Loreau Naeemand Inchausti et al 2001) Research separating complementarity and selec-tion effects followed (Loreau and Hector 2001) A second generation ofbiodiversity experiments was developed (eg Jena Project in GermanyRoscher et al 2007) usually including all monocultures a balanced treatmentdesign to allow separating species effects (eg Picasso et al 2008) and truereplications and blocks (Figure 1) Later on a series of meta-analysis ofexperiments showed that diversity effects were positive due mainly to com-plementarity effect and transgressive overyielding (ie the diverse mixproduces more yield than the highest yielding monoculture) was foundonly in long-term experiments (Cardinale et al 2007) Recently this researchprogram has matured and expanded (Figure 1) to provide empirical andtheoretical evidence on the importance of biodiversity for ecosystem functionfor multiple trophic levels multiple functions and global scales (Maestreet al 2012 Schuman et al 2016 Tilman Isbell and Cowles 2014) A detailedreview of the historical philosophical and political context of this debate isnot the scope of this article but it can be found elsewhere (DeLaplante andPicasso 2011)

Ecology versus Agricultural Science and Agroecology

In order to address whether this debate can be more usefully understood as aninterdisciplinary dialogue between the disciplines of Ecology AgriculturalScience and Agroecology we first must briefly address the conceptual andmethodological differences between these three disciplines All scientific disci-plines are dynamic conceptual abstractions addressing the one and complexreality from different angles or viewpoints Therefore as with any other dis-ciplines the boundaries in terms of objects of study andmethods are diffuse andchange over time However the scientific traditions the history and accumula-tion of scholarship the existence of distinct research communities and scientificjournals are enough criteria to set these three disciplines apart and identify theirunique contributions Figure 2 illustrates these three disciplines across thebroader landscape of other sciences This figure is not intended to be completeand it leaves out many scientific disciplines as well as other areas of academicpursuit like Humanities Medical sciences and Engineering

Ecology Agricultural Science and Agroecology are scientific disciplineswith different traditions and approaches although with some considerableoverlapping One main difference between Ecology and Agricultural Scienceis the object of study the first one is mainly interested with natural ecosystemswhile the second one studies human managed ecosystems with the purpose offood and fiber production (ie agroecosystems) Agroecology shares thisobject of study (agroecosystems) although it is expanded from the field and

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 3

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farm scale to the entire food system including the environmental and socio-economic dimensions (Francis et al 2003 Gliessman 2015 GliessmanRosado-May and Guadarrama-Zugasti et al 2007 Wezel et al 2009)

A second difference is the theoretical versus applied nature of the dis-ciplines Ecology is more fundamental or theoretical in nature Ecology alsohas many subdisciplines including population Community EcosystemEcology among others Although there are many applications of ecologicalscience eg in conservation biology the bulk of the Ecology work is under-standing nature On the other hand Agricultural Science is an applied fieldof science focused mainly on increasing crop and animal productivitycomprising Agronomy Breeding Soil Science among other subdisciplinesAgroecology again shares this applied focus expanding the goal toward themultiple dimensions of sustainability Agroecology comprises the subdisci-plines of fieldplot Ecology Agroecosystems Ecology and Food SystemsEcology (Wezel and Soldat 2009) Theories come second after practice inthese disciplines

Probably the most important difference for understanding the contributionsto this debate is related to the descriptive versus prescriptive criteria Ecology isdescriptive and predictive ie it is interested in describing modeling andexplaining natural variation in ecosystems In contrast Agricultural Science isnormative and prescriptive it has the goal of understanding how farmingsystems can perform in order to optimize certain functions like crop produc-tivity (Vandermeer Lawrence and Symstad 2002) Agricultural scientists areinterested in what management decisions can maximize crop yields and farmincome Considering this criteria Agroecology shares with AgriculturalScience its prescriptive nature The main difference is that Agroecology has amore explicit broader goal of agroecosystems and food systems sustainability

Figure 2 A graphical representation of Ecology Agricultural Sciences Agroecology other relatedscientific disciplines and some of their subdisciplines

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ie achieving productivity stability resilience environmental quality conser-vation social acceptability equity and economic profitability through explor-ing the benefits of increased biodiversity in farming systems and increasedfairness in the food system (Gliessman Rosado-May and Guadarrama-Zugastiet al 2007)

Contributions of Agricultural Science and Agroecology to the debate

In the following section we provide evidence of the contributions ofAgricultural Science and Agroecology to three key aspects of the debatethe conflict the resolution and the implications

First the agriculture perspective played a relevant role in creating theconflict in the debate Agricultural scientists and agroecologists confrontedecologists for initially neglecting the literature on intercropping and cropmixtures (Wardle Huston and Grime et al 2000) which had shown thatmixtures of few species usually are more productive than the average of thespecies grown in monoculture (ie mixtures show nontransgressive over-yielding) but not greater than the most productive monoculture (ie mix-tures do not show transgressive overyielding) with the exception of legumendashgrass mixtures (eg Anders Potdar and Francis 1995 Trenbath 1974) Thefocus of agricultural scientists was on transgressive overyielding to maximizecrop production and therefore ecological research results celebrating thenovelty of nontransgressive overyielding were criticized (Garnier et al1997) Ecologists argued that agroecosystems fall in the low end of thebiodiversity range and usually operate at higher nutrient concentrations(eg soil nitrogen) than natural systems therefore insisting thatAgricultural Sciences and Agroecology literature was irrelevant for under-standing natural ecosystems (Naeem 2000) This was a major contribution toarticulating the conflict

Furthermore the hottest area of debate ie the interpretation of thesampling effect as an artifact of the experimental design (Huston 1997) oras a valid biological assembly mechanism (Tilman Lehman and Thomson1997) can be interpreted also as a debate between the agricultural andecological perspectives Farmers do not plant a random assortment of cropsin their fields so experiments with species assembled at random where thesampling effect was operating had little relevance for agricultural scientistsand agroecologists In contrast extinctions in natural ecosystems could bemore random and therefore the biodiversity experiments were informativefor natural ecosystems

While much of the heat of the debate may have come from the contrastingviews of Agriculture and Ecology the interdisciplinary dialogue between thedisciplines helped resolving the debate Here Agroecology played a keyrelevant mediation role Indeed the introduction of intercropping indices

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 5

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like relative yield totals to separate transgressive versus nontransgressiveoveryielding widely used previously in agroecology research (De Wit andVan Den Bergh 1965 Vandermeer 1989) played a central role in the devel-opment of the synthesis framework in 2000 Indeed these indices are thebasis for the partitioning between selection and complementarity effects thatclarified the mechanisms behind the biodiversityndashecosystem function rela-tionships (Loreau and Hector 2001)

A second agricultural contribution to the resolution of the debate was thefocus on the principles of statistical design of experiments like using truereplications of treatments and local control of variability (blocking) whichhas been central to Agricultural Science since the early 1900s (Fisher 1960)Because of the wide range of ecological variation ecological studies not alwayshave true replications and use pseudo-replications instead (Huston 1997) Alsorelated to that ecological analyses commonly use multiple regressions andother multivariate statistical techniques which are less powerful for determin-ing causation than analysis of variance of well-replicated agronomic (oftenrandomized complete blocks) designs Understanding and addressing thesestatistical issues was key to move forward in the debate

Finally Agricultural Science and Agroecology contributed to derive implica-tions from the results of the debate Sustainable agriculture systems must beproductive and stable control invasions of pests and diseases and recyclenutrients efficiently among other ecosystem functions Modern agriculturesystems usually have low biodiversity (both planned and associated) and theannual grain monocultures are the extreme example of this Increasing mana-ged biodiversity in agroecosystems may increase productivity and ecosystemfunctions In fact several publications out of biodiversityndashecosystem functionresearch suggested recommendations to agriculture systems particularly forgrasslands management (Minns et al 2001) forage production and grazingsystems (Sanderson et al 2004 Tracy and Faulkner 2006) dual-purpose poly-culture systems (Picasso et al 2008) and cellulosic biofuel systems (TilmanHill and Lehman 2006) Although the importance of increasing biodiversity inagricultural systems has long been proposed and it is one of the main tenants ofAgroecology (Altieri 1989 Gliessman Rosado-May and Guadarrama-Zugastiet al 2007 Jackson 2002) the conclusions and recommendations of this debateprovided more evidence and strength to this argument

Back to Charles Darwinrsquos advice

In The Origin of Species Charles Darwin (1859) refers to an English gardenexperiment from 1816 where ldquoit has been experimentally proved that if a plotof ground be sown with one species of grass and a similar plot be sown withdistinct genera of grasses a greater number of plants and a greater weight ofdry herbage can thus be raisedrdquo For this statement Darwin has been named

6 V D PICASSO

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the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

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References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

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rich communities have some key species (selection) or complementaryamong various species was unknown (Hooper et al 2005 Loreau Naeemand Inchausti et al 2001) Research separating complementarity and selec-tion effects followed (Loreau and Hector 2001) A second generation ofbiodiversity experiments was developed (eg Jena Project in GermanyRoscher et al 2007) usually including all monocultures a balanced treatmentdesign to allow separating species effects (eg Picasso et al 2008) and truereplications and blocks (Figure 1) Later on a series of meta-analysis ofexperiments showed that diversity effects were positive due mainly to com-plementarity effect and transgressive overyielding (ie the diverse mixproduces more yield than the highest yielding monoculture) was foundonly in long-term experiments (Cardinale et al 2007) Recently this researchprogram has matured and expanded (Figure 1) to provide empirical andtheoretical evidence on the importance of biodiversity for ecosystem functionfor multiple trophic levels multiple functions and global scales (Maestreet al 2012 Schuman et al 2016 Tilman Isbell and Cowles 2014) A detailedreview of the historical philosophical and political context of this debate isnot the scope of this article but it can be found elsewhere (DeLaplante andPicasso 2011)

Ecology versus Agricultural Science and Agroecology

In order to address whether this debate can be more usefully understood as aninterdisciplinary dialogue between the disciplines of Ecology AgriculturalScience and Agroecology we first must briefly address the conceptual andmethodological differences between these three disciplines All scientific disci-plines are dynamic conceptual abstractions addressing the one and complexreality from different angles or viewpoints Therefore as with any other dis-ciplines the boundaries in terms of objects of study andmethods are diffuse andchange over time However the scientific traditions the history and accumula-tion of scholarship the existence of distinct research communities and scientificjournals are enough criteria to set these three disciplines apart and identify theirunique contributions Figure 2 illustrates these three disciplines across thebroader landscape of other sciences This figure is not intended to be completeand it leaves out many scientific disciplines as well as other areas of academicpursuit like Humanities Medical sciences and Engineering

Ecology Agricultural Science and Agroecology are scientific disciplineswith different traditions and approaches although with some considerableoverlapping One main difference between Ecology and Agricultural Scienceis the object of study the first one is mainly interested with natural ecosystemswhile the second one studies human managed ecosystems with the purpose offood and fiber production (ie agroecosystems) Agroecology shares thisobject of study (agroecosystems) although it is expanded from the field and

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 3

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

farm scale to the entire food system including the environmental and socio-economic dimensions (Francis et al 2003 Gliessman 2015 GliessmanRosado-May and Guadarrama-Zugasti et al 2007 Wezel et al 2009)

A second difference is the theoretical versus applied nature of the dis-ciplines Ecology is more fundamental or theoretical in nature Ecology alsohas many subdisciplines including population Community EcosystemEcology among others Although there are many applications of ecologicalscience eg in conservation biology the bulk of the Ecology work is under-standing nature On the other hand Agricultural Science is an applied fieldof science focused mainly on increasing crop and animal productivitycomprising Agronomy Breeding Soil Science among other subdisciplinesAgroecology again shares this applied focus expanding the goal toward themultiple dimensions of sustainability Agroecology comprises the subdisci-plines of fieldplot Ecology Agroecosystems Ecology and Food SystemsEcology (Wezel and Soldat 2009) Theories come second after practice inthese disciplines

Probably the most important difference for understanding the contributionsto this debate is related to the descriptive versus prescriptive criteria Ecology isdescriptive and predictive ie it is interested in describing modeling andexplaining natural variation in ecosystems In contrast Agricultural Science isnormative and prescriptive it has the goal of understanding how farmingsystems can perform in order to optimize certain functions like crop produc-tivity (Vandermeer Lawrence and Symstad 2002) Agricultural scientists areinterested in what management decisions can maximize crop yields and farmincome Considering this criteria Agroecology shares with AgriculturalScience its prescriptive nature The main difference is that Agroecology has amore explicit broader goal of agroecosystems and food systems sustainability

Figure 2 A graphical representation of Ecology Agricultural Sciences Agroecology other relatedscientific disciplines and some of their subdisciplines

4 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

ie achieving productivity stability resilience environmental quality conser-vation social acceptability equity and economic profitability through explor-ing the benefits of increased biodiversity in farming systems and increasedfairness in the food system (Gliessman Rosado-May and Guadarrama-Zugastiet al 2007)

Contributions of Agricultural Science and Agroecology to the debate

In the following section we provide evidence of the contributions ofAgricultural Science and Agroecology to three key aspects of the debatethe conflict the resolution and the implications

First the agriculture perspective played a relevant role in creating theconflict in the debate Agricultural scientists and agroecologists confrontedecologists for initially neglecting the literature on intercropping and cropmixtures (Wardle Huston and Grime et al 2000) which had shown thatmixtures of few species usually are more productive than the average of thespecies grown in monoculture (ie mixtures show nontransgressive over-yielding) but not greater than the most productive monoculture (ie mix-tures do not show transgressive overyielding) with the exception of legumendashgrass mixtures (eg Anders Potdar and Francis 1995 Trenbath 1974) Thefocus of agricultural scientists was on transgressive overyielding to maximizecrop production and therefore ecological research results celebrating thenovelty of nontransgressive overyielding were criticized (Garnier et al1997) Ecologists argued that agroecosystems fall in the low end of thebiodiversity range and usually operate at higher nutrient concentrations(eg soil nitrogen) than natural systems therefore insisting thatAgricultural Sciences and Agroecology literature was irrelevant for under-standing natural ecosystems (Naeem 2000) This was a major contribution toarticulating the conflict

Furthermore the hottest area of debate ie the interpretation of thesampling effect as an artifact of the experimental design (Huston 1997) oras a valid biological assembly mechanism (Tilman Lehman and Thomson1997) can be interpreted also as a debate between the agricultural andecological perspectives Farmers do not plant a random assortment of cropsin their fields so experiments with species assembled at random where thesampling effect was operating had little relevance for agricultural scientistsand agroecologists In contrast extinctions in natural ecosystems could bemore random and therefore the biodiversity experiments were informativefor natural ecosystems

While much of the heat of the debate may have come from the contrastingviews of Agriculture and Ecology the interdisciplinary dialogue between thedisciplines helped resolving the debate Here Agroecology played a keyrelevant mediation role Indeed the introduction of intercropping indices

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 5

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

like relative yield totals to separate transgressive versus nontransgressiveoveryielding widely used previously in agroecology research (De Wit andVan Den Bergh 1965 Vandermeer 1989) played a central role in the devel-opment of the synthesis framework in 2000 Indeed these indices are thebasis for the partitioning between selection and complementarity effects thatclarified the mechanisms behind the biodiversityndashecosystem function rela-tionships (Loreau and Hector 2001)

A second agricultural contribution to the resolution of the debate was thefocus on the principles of statistical design of experiments like using truereplications of treatments and local control of variability (blocking) whichhas been central to Agricultural Science since the early 1900s (Fisher 1960)Because of the wide range of ecological variation ecological studies not alwayshave true replications and use pseudo-replications instead (Huston 1997) Alsorelated to that ecological analyses commonly use multiple regressions andother multivariate statistical techniques which are less powerful for determin-ing causation than analysis of variance of well-replicated agronomic (oftenrandomized complete blocks) designs Understanding and addressing thesestatistical issues was key to move forward in the debate

Finally Agricultural Science and Agroecology contributed to derive implica-tions from the results of the debate Sustainable agriculture systems must beproductive and stable control invasions of pests and diseases and recyclenutrients efficiently among other ecosystem functions Modern agriculturesystems usually have low biodiversity (both planned and associated) and theannual grain monocultures are the extreme example of this Increasing mana-ged biodiversity in agroecosystems may increase productivity and ecosystemfunctions In fact several publications out of biodiversityndashecosystem functionresearch suggested recommendations to agriculture systems particularly forgrasslands management (Minns et al 2001) forage production and grazingsystems (Sanderson et al 2004 Tracy and Faulkner 2006) dual-purpose poly-culture systems (Picasso et al 2008) and cellulosic biofuel systems (TilmanHill and Lehman 2006) Although the importance of increasing biodiversity inagricultural systems has long been proposed and it is one of the main tenants ofAgroecology (Altieri 1989 Gliessman Rosado-May and Guadarrama-Zugastiet al 2007 Jackson 2002) the conclusions and recommendations of this debateprovided more evidence and strength to this argument

Back to Charles Darwinrsquos advice

In The Origin of Species Charles Darwin (1859) refers to an English gardenexperiment from 1816 where ldquoit has been experimentally proved that if a plotof ground be sown with one species of grass and a similar plot be sown withdistinct genera of grasses a greater number of plants and a greater weight ofdry herbage can thus be raisedrdquo For this statement Darwin has been named

6 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 7

Dow

nloa

ded

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3]

at 1

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07

Sept

embe

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17

References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

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17

farm scale to the entire food system including the environmental and socio-economic dimensions (Francis et al 2003 Gliessman 2015 GliessmanRosado-May and Guadarrama-Zugasti et al 2007 Wezel et al 2009)

A second difference is the theoretical versus applied nature of the dis-ciplines Ecology is more fundamental or theoretical in nature Ecology alsohas many subdisciplines including population Community EcosystemEcology among others Although there are many applications of ecologicalscience eg in conservation biology the bulk of the Ecology work is under-standing nature On the other hand Agricultural Science is an applied fieldof science focused mainly on increasing crop and animal productivitycomprising Agronomy Breeding Soil Science among other subdisciplinesAgroecology again shares this applied focus expanding the goal toward themultiple dimensions of sustainability Agroecology comprises the subdisci-plines of fieldplot Ecology Agroecosystems Ecology and Food SystemsEcology (Wezel and Soldat 2009) Theories come second after practice inthese disciplines

Probably the most important difference for understanding the contributionsto this debate is related to the descriptive versus prescriptive criteria Ecology isdescriptive and predictive ie it is interested in describing modeling andexplaining natural variation in ecosystems In contrast Agricultural Science isnormative and prescriptive it has the goal of understanding how farmingsystems can perform in order to optimize certain functions like crop produc-tivity (Vandermeer Lawrence and Symstad 2002) Agricultural scientists areinterested in what management decisions can maximize crop yields and farmincome Considering this criteria Agroecology shares with AgriculturalScience its prescriptive nature The main difference is that Agroecology has amore explicit broader goal of agroecosystems and food systems sustainability

Figure 2 A graphical representation of Ecology Agricultural Sciences Agroecology other relatedscientific disciplines and some of their subdisciplines

4 V D PICASSO

Dow

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ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

ie achieving productivity stability resilience environmental quality conser-vation social acceptability equity and economic profitability through explor-ing the benefits of increased biodiversity in farming systems and increasedfairness in the food system (Gliessman Rosado-May and Guadarrama-Zugastiet al 2007)

Contributions of Agricultural Science and Agroecology to the debate

In the following section we provide evidence of the contributions ofAgricultural Science and Agroecology to three key aspects of the debatethe conflict the resolution and the implications

First the agriculture perspective played a relevant role in creating theconflict in the debate Agricultural scientists and agroecologists confrontedecologists for initially neglecting the literature on intercropping and cropmixtures (Wardle Huston and Grime et al 2000) which had shown thatmixtures of few species usually are more productive than the average of thespecies grown in monoculture (ie mixtures show nontransgressive over-yielding) but not greater than the most productive monoculture (ie mix-tures do not show transgressive overyielding) with the exception of legumendashgrass mixtures (eg Anders Potdar and Francis 1995 Trenbath 1974) Thefocus of agricultural scientists was on transgressive overyielding to maximizecrop production and therefore ecological research results celebrating thenovelty of nontransgressive overyielding were criticized (Garnier et al1997) Ecologists argued that agroecosystems fall in the low end of thebiodiversity range and usually operate at higher nutrient concentrations(eg soil nitrogen) than natural systems therefore insisting thatAgricultural Sciences and Agroecology literature was irrelevant for under-standing natural ecosystems (Naeem 2000) This was a major contribution toarticulating the conflict

Furthermore the hottest area of debate ie the interpretation of thesampling effect as an artifact of the experimental design (Huston 1997) oras a valid biological assembly mechanism (Tilman Lehman and Thomson1997) can be interpreted also as a debate between the agricultural andecological perspectives Farmers do not plant a random assortment of cropsin their fields so experiments with species assembled at random where thesampling effect was operating had little relevance for agricultural scientistsand agroecologists In contrast extinctions in natural ecosystems could bemore random and therefore the biodiversity experiments were informativefor natural ecosystems

While much of the heat of the debate may have come from the contrastingviews of Agriculture and Ecology the interdisciplinary dialogue between thedisciplines helped resolving the debate Here Agroecology played a keyrelevant mediation role Indeed the introduction of intercropping indices

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 5

Dow

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ded

by [

473

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3]

at 1

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07

Sept

embe

r 20

17

like relative yield totals to separate transgressive versus nontransgressiveoveryielding widely used previously in agroecology research (De Wit andVan Den Bergh 1965 Vandermeer 1989) played a central role in the devel-opment of the synthesis framework in 2000 Indeed these indices are thebasis for the partitioning between selection and complementarity effects thatclarified the mechanisms behind the biodiversityndashecosystem function rela-tionships (Loreau and Hector 2001)

A second agricultural contribution to the resolution of the debate was thefocus on the principles of statistical design of experiments like using truereplications of treatments and local control of variability (blocking) whichhas been central to Agricultural Science since the early 1900s (Fisher 1960)Because of the wide range of ecological variation ecological studies not alwayshave true replications and use pseudo-replications instead (Huston 1997) Alsorelated to that ecological analyses commonly use multiple regressions andother multivariate statistical techniques which are less powerful for determin-ing causation than analysis of variance of well-replicated agronomic (oftenrandomized complete blocks) designs Understanding and addressing thesestatistical issues was key to move forward in the debate

Finally Agricultural Science and Agroecology contributed to derive implica-tions from the results of the debate Sustainable agriculture systems must beproductive and stable control invasions of pests and diseases and recyclenutrients efficiently among other ecosystem functions Modern agriculturesystems usually have low biodiversity (both planned and associated) and theannual grain monocultures are the extreme example of this Increasing mana-ged biodiversity in agroecosystems may increase productivity and ecosystemfunctions In fact several publications out of biodiversityndashecosystem functionresearch suggested recommendations to agriculture systems particularly forgrasslands management (Minns et al 2001) forage production and grazingsystems (Sanderson et al 2004 Tracy and Faulkner 2006) dual-purpose poly-culture systems (Picasso et al 2008) and cellulosic biofuel systems (TilmanHill and Lehman 2006) Although the importance of increasing biodiversity inagricultural systems has long been proposed and it is one of the main tenants ofAgroecology (Altieri 1989 Gliessman Rosado-May and Guadarrama-Zugastiet al 2007 Jackson 2002) the conclusions and recommendations of this debateprovided more evidence and strength to this argument

Back to Charles Darwinrsquos advice

In The Origin of Species Charles Darwin (1859) refers to an English gardenexperiment from 1816 where ldquoit has been experimentally proved that if a plotof ground be sown with one species of grass and a similar plot be sown withdistinct genera of grasses a greater number of plants and a greater weight ofdry herbage can thus be raisedrdquo For this statement Darwin has been named

6 V D PICASSO

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ded

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473

411

3]

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07

Sept

embe

r 20

17

the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 7

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

ie achieving productivity stability resilience environmental quality conser-vation social acceptability equity and economic profitability through explor-ing the benefits of increased biodiversity in farming systems and increasedfairness in the food system (Gliessman Rosado-May and Guadarrama-Zugastiet al 2007)

Contributions of Agricultural Science and Agroecology to the debate

In the following section we provide evidence of the contributions ofAgricultural Science and Agroecology to three key aspects of the debatethe conflict the resolution and the implications

First the agriculture perspective played a relevant role in creating theconflict in the debate Agricultural scientists and agroecologists confrontedecologists for initially neglecting the literature on intercropping and cropmixtures (Wardle Huston and Grime et al 2000) which had shown thatmixtures of few species usually are more productive than the average of thespecies grown in monoculture (ie mixtures show nontransgressive over-yielding) but not greater than the most productive monoculture (ie mix-tures do not show transgressive overyielding) with the exception of legumendashgrass mixtures (eg Anders Potdar and Francis 1995 Trenbath 1974) Thefocus of agricultural scientists was on transgressive overyielding to maximizecrop production and therefore ecological research results celebrating thenovelty of nontransgressive overyielding were criticized (Garnier et al1997) Ecologists argued that agroecosystems fall in the low end of thebiodiversity range and usually operate at higher nutrient concentrations(eg soil nitrogen) than natural systems therefore insisting thatAgricultural Sciences and Agroecology literature was irrelevant for under-standing natural ecosystems (Naeem 2000) This was a major contribution toarticulating the conflict

Furthermore the hottest area of debate ie the interpretation of thesampling effect as an artifact of the experimental design (Huston 1997) oras a valid biological assembly mechanism (Tilman Lehman and Thomson1997) can be interpreted also as a debate between the agricultural andecological perspectives Farmers do not plant a random assortment of cropsin their fields so experiments with species assembled at random where thesampling effect was operating had little relevance for agricultural scientistsand agroecologists In contrast extinctions in natural ecosystems could bemore random and therefore the biodiversity experiments were informativefor natural ecosystems

While much of the heat of the debate may have come from the contrastingviews of Agriculture and Ecology the interdisciplinary dialogue between thedisciplines helped resolving the debate Here Agroecology played a keyrelevant mediation role Indeed the introduction of intercropping indices

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 5

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

like relative yield totals to separate transgressive versus nontransgressiveoveryielding widely used previously in agroecology research (De Wit andVan Den Bergh 1965 Vandermeer 1989) played a central role in the devel-opment of the synthesis framework in 2000 Indeed these indices are thebasis for the partitioning between selection and complementarity effects thatclarified the mechanisms behind the biodiversityndashecosystem function rela-tionships (Loreau and Hector 2001)

A second agricultural contribution to the resolution of the debate was thefocus on the principles of statistical design of experiments like using truereplications of treatments and local control of variability (blocking) whichhas been central to Agricultural Science since the early 1900s (Fisher 1960)Because of the wide range of ecological variation ecological studies not alwayshave true replications and use pseudo-replications instead (Huston 1997) Alsorelated to that ecological analyses commonly use multiple regressions andother multivariate statistical techniques which are less powerful for determin-ing causation than analysis of variance of well-replicated agronomic (oftenrandomized complete blocks) designs Understanding and addressing thesestatistical issues was key to move forward in the debate

Finally Agricultural Science and Agroecology contributed to derive implica-tions from the results of the debate Sustainable agriculture systems must beproductive and stable control invasions of pests and diseases and recyclenutrients efficiently among other ecosystem functions Modern agriculturesystems usually have low biodiversity (both planned and associated) and theannual grain monocultures are the extreme example of this Increasing mana-ged biodiversity in agroecosystems may increase productivity and ecosystemfunctions In fact several publications out of biodiversityndashecosystem functionresearch suggested recommendations to agriculture systems particularly forgrasslands management (Minns et al 2001) forage production and grazingsystems (Sanderson et al 2004 Tracy and Faulkner 2006) dual-purpose poly-culture systems (Picasso et al 2008) and cellulosic biofuel systems (TilmanHill and Lehman 2006) Although the importance of increasing biodiversity inagricultural systems has long been proposed and it is one of the main tenants ofAgroecology (Altieri 1989 Gliessman Rosado-May and Guadarrama-Zugastiet al 2007 Jackson 2002) the conclusions and recommendations of this debateprovided more evidence and strength to this argument

Back to Charles Darwinrsquos advice

In The Origin of Species Charles Darwin (1859) refers to an English gardenexperiment from 1816 where ldquoit has been experimentally proved that if a plotof ground be sown with one species of grass and a similar plot be sown withdistinct genera of grasses a greater number of plants and a greater weight ofdry herbage can thus be raisedrdquo For this statement Darwin has been named

6 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 7

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

like relative yield totals to separate transgressive versus nontransgressiveoveryielding widely used previously in agroecology research (De Wit andVan Den Bergh 1965 Vandermeer 1989) played a central role in the devel-opment of the synthesis framework in 2000 Indeed these indices are thebasis for the partitioning between selection and complementarity effects thatclarified the mechanisms behind the biodiversityndashecosystem function rela-tionships (Loreau and Hector 2001)

A second agricultural contribution to the resolution of the debate was thefocus on the principles of statistical design of experiments like using truereplications of treatments and local control of variability (blocking) whichhas been central to Agricultural Science since the early 1900s (Fisher 1960)Because of the wide range of ecological variation ecological studies not alwayshave true replications and use pseudo-replications instead (Huston 1997) Alsorelated to that ecological analyses commonly use multiple regressions andother multivariate statistical techniques which are less powerful for determin-ing causation than analysis of variance of well-replicated agronomic (oftenrandomized complete blocks) designs Understanding and addressing thesestatistical issues was key to move forward in the debate

Finally Agricultural Science and Agroecology contributed to derive implica-tions from the results of the debate Sustainable agriculture systems must beproductive and stable control invasions of pests and diseases and recyclenutrients efficiently among other ecosystem functions Modern agriculturesystems usually have low biodiversity (both planned and associated) and theannual grain monocultures are the extreme example of this Increasing mana-ged biodiversity in agroecosystems may increase productivity and ecosystemfunctions In fact several publications out of biodiversityndashecosystem functionresearch suggested recommendations to agriculture systems particularly forgrasslands management (Minns et al 2001) forage production and grazingsystems (Sanderson et al 2004 Tracy and Faulkner 2006) dual-purpose poly-culture systems (Picasso et al 2008) and cellulosic biofuel systems (TilmanHill and Lehman 2006) Although the importance of increasing biodiversity inagricultural systems has long been proposed and it is one of the main tenants ofAgroecology (Altieri 1989 Gliessman Rosado-May and Guadarrama-Zugastiet al 2007 Jackson 2002) the conclusions and recommendations of this debateprovided more evidence and strength to this argument

Back to Charles Darwinrsquos advice

In The Origin of Species Charles Darwin (1859) refers to an English gardenexperiment from 1816 where ldquoit has been experimentally proved that if a plotof ground be sown with one species of grass and a similar plot be sown withdistinct genera of grasses a greater number of plants and a greater weight ofdry herbage can thus be raisedrdquo For this statement Darwin has been named

6 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 7

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References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

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07

Sept

embe

r 20

17

the father of the biodiversityndashecosystem function debate (Hector and Hooper2002) Interestingly enough Darwin pointed to a ldquosownrdquo plot rather than anatural grassland Furthermore in the next line Darwin continues ldquoThesame has been found to hold good when first one variety and then severalmixed varieties of wheat have been sown on equal spaces of groundrdquo Darwinwas referring to an agriculture situation rather than a natural situation moreprecisely to an intercropping wheat field As he did throughout his bookstarting with ldquovariation under domesticationrdquo and then moving to ldquovariationunder naturerdquo Darwin drew many examples from familiar agriculture situa-tions to help explain natural phenomena In Darwinrsquos time the disciplinaryboundaries that may seem so thick today between Evolutionary BiologyEcology Agroecology and Agronomy did not exist Therefore learningfrom both ldquonaturerdquo and ldquodomestic productionsrdquo was not only allowed butencouraged as a proper way to understand reality ldquoAs has always been mypractice let us seek light on this head from our domestic productions We shallhere find something analogousrdquo (Darwin 1859) This interdisciplinary learn-ing going from ecosystems to agroecosystems and back is one of theessential features of Agroecology and for this Charles Darwin should alsobe considered the great grandfather of Agroecology Hopefully Darwinrsquosadvice will provide insight today in this much needed interdisciplinarydialogue between Ecology Agricultural Science and Agroecology

Lessons for interdisciplinary science

Scientific progress can occur by focusing on clarifying definitions andassumptions which is the first step in an interdisciplinary dialogue Indeedone of the benefits of interdisciplinary science is that it allows for explicitlyacknowledging each individual disciplinersquos ignorance of whatrsquos outside theirown domain Acknowledging ignorance is the first step for learning andunderstanding new phenomena Explaining our definitions and assumptionsto colleagues outside our own discipline is useful for revisiting these assump-tions A second step in the interdisciplinary dialogue is to acknowledgedifferent methods and approaches and realizing their usefulness and limita-tions In rare successful occasions the integration of different methods canbe achieved and a new understanding emerges This was the case of thebiodiversityndashecosystem function debate And that is why this debate madesubstantial contributions both in the scientific understanding of the eco-sphere and in suggesting management and policy decisions in biodiversityconservation and agricultural sustainability

ORCID

Valentin Daniel Picasso httporcidorg0000-0002-4989-6317

AGROECOLOGY AND SUSTAINABLE FOOD SYSTEMS 7

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

Dow

nloa

ded

by [

473

411

3]

at 1

619

07

Sept

embe

r 20

17

References

Altieri M A 1989 Agroecology A new research and development paradigm for worldagriculture Agriculture Ecosystems and Environment 2737ndash46 doi1010160167-8809(89)90070-4

Anders M M M V Potdar and C S Francis 1995 Significance of intercropping incropping systems Series on International Agricultural Research 31-8

Cardinale B J J P Wright M W Cadotte I T Carroll A Hector D S Srivastava MLoreau and J J Weis 2007 Impacts of plant diversity on biomass production increasethrough time because of species complementarity Proceedings of the Natural Academy ofScience 10418123ndash28 doi101073pnas0709069104

Darwin C 1859 On the origin of species by natural selection London MurrayDe Wit C and J Van Den Bergh 1965 Competition between herbage plants Netherlands

Journal of Agricultural Science 13212ndash21DeLaplante K and V D Picasso 2011 The biodiversityndashecosystem function debate in

ecology In Handbook of philosophy of ecology ed K DeLaplante B Brown and P KaElsevier BV North Holland Hardcover ISBN 9780444516732 httpswwwelseviercombooksphilosophy-of-ecologybrown978-0-444-51673-2

Fisher R A 1960 The design of experiments Edinburgh Oliver and BoydFrancis C G Lieblein S R Gliessman T A Breland N Creamer R Harwood L

Salomonsson J Helenius D Rickerl R Salvador M Wiedenhoeft S Simmons PAllen M Altieri C Flora and R Poincelot 2003 Agroecology The ecology of foodsystems Journal of Sustainable Agriculture 2299ndash118 doi101300J064v22n03_10

Garnier E M Navas M Austin J Lilley and R Gifford 1997 A problem for biodiversity-productivity studies How to compare the productivity of multispecific plant mixtures tothat of monocultures Acta Oecologica 18657ndash70 doi101016S1146-609X(97)80049-5

Gliessman S R 2015 Agroecology The ecology of sustainable food systems 3rd ed BocaRaton FL CRC Press

Gliessman S R F J Rosado-May C Guadarrama-Zugasti et al 2007 AgroecologiacuteaPromoviendo una transicioacuten hacia la sostenibilidad Ecosistemas 11ndash3

Hector A and R Hooper 2002 Darwin and the first ecological experiment Science295639ndash40 doi101126science1064815

Hector A B Schmid C Beierkuhnlein et al 1999 Plant diversity and productivityexperiments in European grasslands Science 2861123ndash27 doi101126science28654421123

Hooper D U F S Chapin J J Ewel A Hector P Inchausti S Lavorel J H Lawton D MLodge M Loreau S Naeem B Schmid H Setaumllauml A J Symstad J Vandermeer and D AWardle 2005 Effects of biodiversity on ecosystem functioning A consensus of currentknowledge Ecological Monographs 753ndash35 doi10189004-0922

Huston M A 1997 Hidden treatments in ecological experiments Re-evaluating the ecosys-tem function of biodiversity Oecologia 110449ndash60 doi101007s004420050180

Jackson W 2002 Natural systems agriculture A truly radical alternative AgricultureEcosystems and Environment 88111ndash17 doi101016S0167-8809(01)00247-X

Kaiser J 2000 Rift over biodiversity divides ecologists Science 2891282ndash83 doi101126science28954831282

Loreau M and A Hector 2001 Partitioning selection and complementarity in biodiversityexperiments Nature 41272ndash76 doi10103835083573

Loreau M S Naeem P Inchausti et al 2001 Biodiversity and ecosystem functioningCurrent knowledge and future challenges Science 294804ndash08 doi101126science1064088

8 V D PICASSO

Dow

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ded

by [

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411

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at 1

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Sept

embe

r 20

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Maestre F T J L Quero N J Gotelli A Escudero V Ochoa M Delgado-Baquerizo MGarcia-Gomez M A Bowker S Soliveres C Escolar P Garcia-Palacios M Berdugo EValencia B Gozalo A Gallardo L Aguilera T Arredondo J Blones B Boeken D BranA A Conceicao O Cabrera M Chaieb M Derak D J Eldridge C I Espinosa AFlorentino J Gaitan M G Gatica W Ghiloufi S Gomez-Gonzalez J R Gutierrez R MHernandez X Huang E Huber-Sannwald M Jankju M Miriti J Monerris R L Mau EMorici K Naseri A Ospina V Polo A Prina E Pucheta D A Ramirez-Collantes RRomao M Tighe C Torres-Diaz J Val J P Veiga D Wang and E Zaady 2012 Plantspecies richness and ecosystem multifunctionality in global drylands Science 335214ndash18doi101126science1215442

Mccann K S 2000 The diversityndashstability debate Nature 405228ndash33 doi10103835012234Minns A J Finn A Hector M Caldeira J Joshi C Palmborg B Schmid M Scherer-

Lorenzen and E Spehn 2001 The functioning of European grassland ecosystemsPotential benefits of biodiversity to agriculture Outlook on Agriculture 30179ndash85doi105367000000001101293634

Naeem S 2000 Reply to Wardle et al ESA Bulletin 81241ndash46Naeem S 2002 Ecosystem consequences of biodiversity loss The evolution of a paradigm

Ecology 831537ndash52 doi1018900012-9658(2002)083[1537ECOBLT]20CO2Naeem S F S Chapin P Costanza III et al 1999 Biodiversity and Ecosystem functioning

Maintaining life support processes Issues in Ecology 41ndash12Naeem S L J Thompson S P Lawler J H Lawton and R M Woodfin 1994 Declining

biodiversity can alter the performance of ecosystems Nature 368734ndash37 doi101038368734a0

Picasso V D E C Brummer M Liebman P M Dixon and B J Wilsey 2008 Crop speciesdiversity affects productivity and weed suppression in perennial polycultures under twomanagement strategies Crop Science 48331ndash42 doi102135cropsci2007040225

Roscher C J Schumacher W Weisser B Schmid and E-D Schulze 2007 Detecting therole of individual species for overyielding in experimental grassland communities com-posed of potentially dominant species Oecologia 154535ndash49 doi101007s00442-007-0846-4

Sanderson M A R H Skinner D J Barker G R Edwards B F Tracy and D A Wedin2004 Plant species diversity and management of temperate forage and grazing landecosystems Crop Science 441132ndash44 doi102135cropsci20041132

Schuman M C N M Van Dam F F Beran and W S Harpole 2016 How does plantchemical diversity contribute to biodiversity at higher trophic levels Current Opinion inInsect Science 1446ndash55 doi101016jcois201601003

Tilman D and J Downing 1994 Biodiversity and stability in grasslands Nature 367363ndash65doi101038367363a0

Tilman D J Hill and C Lehman 2006 Carbon-negative biofuels from low-input high-diversity grassland biomass Science 3141598ndash600 doi101126science1133306

Tilman D F Isbell and J M Cowles 2014 Biodiversity and ecosystem functioning AnnualReview of Ecology Evolution and Systematics 45471ndash93 doi101146annurev-ecolsys-120213-091917

Tilman D C L Lehman and K T Thomson 1997 Plant diversity and ecosystem produc-tivity Theoretical considerations PNAS 941857ndash61 doi101073pnas9451857

Tracy B F and D B Faulkner 2006 Pasture and cattle responses in rotationally stockedgrazing systems sown with differing levels of species richness Crop Science 462062ndash68doi102135cropsci2005120473

Trenbath B 1974 Biomass productivity of mixtures Advances in Agronomy 26177ndash210

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Vandermeer J 1989 The ecology of intercropping Cambridge University Press doiorg101017CBO9780511623523

Vandermeer J D Lawrence and A Symstad 2002 Effect of biodiversity on ecosystemfunctioning in managed ecosystems In Biodiversity and ecosystem functioning Synthesisand perspectives eds M Loreau S Naeem P Inchausti et al Oxford University Presshttpsglobaloupcomacademicproductbiodiversity-and-ecosystem-functioning-9780198515715cc=usamplang=enamp

Wardle D A M A Huston J P Grime et al 2000 Biodiversity and ecosystem functionAn issue in ecology Ecological Society of America Bulletin 81235ndash39

Wardle D A O Zackrisson G Ho et al 1997 The influence of island area on ecosystemproperties Science 2771296ndash99 doi101126science27753301296

Wezel A S Bellon T Doreacute C Francis D Vallod and C David 2009 Agroecology as ascience a movement and a practice A review Agronomy for Sustainable Development29503ndash15 doi101051agro2009004

Wezel A and V Soldat 2009 A quantitative and qualitative historical analysis of thescientific discipline of agroecology International Journal of Agricultural Sustainability73ndash18 doi103763ijas20090400

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