Editing IPCC:AR6/WGII/Chapter-5 (section)

==== 5.4.4.4 Integrated approach to enhance agroecosystem resilience ====

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Diversifying agricultural systems is an adaptation strategy that can strengthen resilience to climate change, with socioeconomic and environmental co-benefits, but trade-offs and benefits vary by socio-ecological context ( ''high confidence'' ) (Table 5.6, [[#M’Kaibi--2015|M’Kaibi et al., 2015]] ; [[#Bellon--2016|Bellon et al., 2016]] ; [[#Jones--2017b|Jones, 2017b]] ; [[#Schulte--2017|Schulte et al., 2017]] ; [[#Jarecki--2018|Jarecki et al., 2018]] ; [[#Jones--2018|Jones et al., 2018]] ; [[#Luna-Gonzalez--2018|Luna-Gonzalez and Sorensen, 2018]] ; [[#Sibhatu--2018|Sibhatu and Qaim, 2018]] ; [[#Renard--2019|Renard and Tilman, 2019]] ; [[#Rosa-Schleich--2019|Rosa-Schleich et al., 2019]] ; [[#Bozzola--2020|Bozzola and Smale, 2020]] ; [[#Mulwa--2020|Mulwa and Visser, 2020]] ). Crop diversification alongside livestock, fish and other species can be applied at various scales in a range of systems, from rainfed or irrigated to urban and home gardens in multiple spatial and temporal arrangements such as mixed planting, intercrops, crop rotation, diversified management of field margins, agroforestry ( [[#5.10.1.3|Section 5.10.1.3]] ) and integrated crop livestock systems ( [[#5.10.1.1|Section 5.10.1.1]] , [[#Isbell--2017|Isbell et al., 2017]] ; [[#Kremen--2018|Kremen and Merenlender, 2018]] ; [[#Dainese--2019|Dainese et al., 2019]] ; [[#Rosa-Schleich--2019|Rosa-Schleich et al., 2019]] ; [[#Hussain--2020|Hussain et al., 2020]] ; [[#Renwick--2020|Renwick et al., 2020]] ; [[#Tamburini--2020|Tamburini et al., 2020]] ; [[#Snapp--2021|Snapp et al., 2021]] ; see [[#5.1|Section 5.1]] 4 and Cross-Chapter Box NATURAL in Chapter 2).

'''Table 5.6 |''' Agroecosystem diversification practices, climate change adaptation mechanisms, trade-offs, co-benefits and constraints to implementation.

{| class="wikitable"
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! '''Agroecosystem diversification practice and'''

'''mechanism for climate change adaptation'''

! '''Benefits, trade-offs and constraints to implementation with examples'''

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| '''''Crop diversification'''''

* Diversifying revenue streams and food supply (portfolio effect).
* Can impact multiple plant and soil biological and physicochemical properties associated with building SOM, improving soil structure and water conservation.

| * Crop diversification reduces cereal crop sensitivity to '''precipitation variability''' , yield losses and crop insurance payouts under '''drought''' ( ''high confidence'' ) ( [[#McDaniel--2014|McDaniel et al., 2014]] ; [[#Williams--2016|Williams et al., 2016]] ; [[#Iizumi--2019|Iizumi and Wagai, 2019]] ; [[#Renwick--2020|Renwick et al., 2020]] ; [[#Huang--2021|Huang et al., 2021]] ; [[#Kane--2021|Kane et al., 2021]] ).
* For example, a study in Canada comparing diversified rotations and monoculture corn found significant positive yield impacts, yield stability and increased SOC under both RCP4.5 and RCP8.5 by 2100 ( [[#Jarecki--2018|Jarecki et al., 2018]] ).
* Diverse agroecosystems with a range of native, neglected and introduced species, often maintained through Indigenous knowledge and farmer seed systems, offer adaptation opportunities in some regions ( ''medium evidence'' , ''high agreement'' ) ( [[#Bezner%20Kerr--2014|Bezner Kerr, 2014]] ; Westengen and Brysting, 2014; [[#Camacho-Henriquez--2015|Camacho-Henriquez et al., 2015]] ; [[#Ghosh-Jerath--2015|Ghosh-Jerath et al., 2015]] ; [[#Adhikari--2017|Adhikari et al., 2017]] ; Li and Siddique, 2018; [[#Scurrah--2019|Scurrah et al., 2019]] ).
* Diversified landscapes can also enhance CES, by supporting cultural heritage crops, recreational and aesthetic experiences ( ''medium confidence'' ) ( [[#Novikova--2017|Novikova et al., 2017]] ; [[#Martínez-Paz--2019|Martínez-Paz et al., 2019]] ; [[#Alcon--2020|Alcon et al., 2020]] ).
* Diversified cropping systems often require new knowledge, equipment access to inputs and viable markets for new products ( [[#van%20Zonneveld--2020|van Zonneveld et al., 2020]] ). Barriers to diversification, or those which support agroecosystem simplification, include environmental constraints such as elevation or soil type, along with institutional constraints such as low research investment, limited policy support, subsidies that encourage monocrops, poor market access, market instability and limited access to seeds ( [[#Kaushal--2015|Kaushal and Muchomba, 2015]] ; [[#DeLonge--2016|DeLonge et al., 2016]] ; [[#Burchfield--2018|Burchfield and de la Poterie, 2018]] ).

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| '''Legume diversification''' can be effective for both mitigation and adaptation, by reducing '''use of nitrogen derived from fossil fuels''' , and meat consumption, and providing ecosystem services through '''nutrient cycling, increasing soil biological activity and erosion control''' ( [[#Snapp--2019|Snapp et al., 2019]] ).

| * Can increase food security and nutrition by increasing cereal productivity and stability in intercropped systems, diversify diets and increase income in crop sales ( ''high agreement, medium evidence'' ) ( [[#Snapp--2019|Snapp et al., 2019]] ; [[#Steward--2019|Steward et al., 2019]] ; [[#Renwick--2020|Renwick et al., 2020]] ), but legume production may be constrained by pest, disease, limited access to genetic material, market access and food preferences ( [[#Anders--2020|Anders et al., 2020]] ).

|-
| '''Organic amendments, no/low tillage or crop residue retention''' may increase diversity in soil biological organisms, which might be important in building resilience to multiple stresses such as '''drought and pest pressure''' ( [[#Furze--2017|Furze et al., 2017]] ; [[#Blundell--2020|Blundell et al., 2020]] ; [[#de%20Vries--2020|de Vries et al., 2020]] ; [[#Stefan--2021|Stefan et al., 2021]] ; [[#Yang--2021|Yang et al., 2021]] ).

| * Higher organic matter does not consistently improve soil hydraulic properties ( [[#Minasny--2018|Minasny and McBratney, 2018]] ; [[#Basche--2019|Basche and DeLonge, 2019]] ).
* Can decrease '''yield variability under dry conditions''' and increase rainfed annual crop yield productivity ( ''high agreement'' ) ( [[#Pittelkow--2014|Pittelkow et al., 2014]] ; [[#Williams--2016|Williams et al., 2016]] ; [[#Williams--2018|Williams et al., 2018]] ; [[#Degani--2019|Degani et al., 2019]] ; [[#Steward--2019|Steward et al., 2019]] ; [[#Bowles--2020|Bowles et al., 2020]] ; [[#Marini--2020|Marini et al., 2020]] ; [[#Sanford--2021|Sanford et al., 2021]] ).

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| '''Livestock integration''' . Inclusion of legumes and other forage into crop rotation allows mixed crop and livestock operations to '''mitigate farm-level risk and ecosystem buffering''' .

| * Benefits to productivity and stability of annual crop yields in some contexts (see [[#5.10.3|Section 5.10.3]] , ''high agreement'' , ''medium evidence'' ) ( [[#Stark--2018|Stark et al., 2018]] ; [[#Peterson--2020|Peterson et al., 2020]] ; [[#de%20Albuquerque%20Nunes--2021|de Albuquerque Nunes et al., 2021]] ).

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| Traditional and locally adapted '''mixed cropping and agroforestry practices''' which include leguminous trees can improve soil fertility and microclimate ( [[#Sida--2018|Sida et al., 2018]] ; [[#Amadu--2020|Amadu et al., 2020]] ).

| Benefits: resilience to extreme events such as hurricanes can be promoted by supporting ecosystem functions to mitigate impacts and accelerate recovery ( ''high agreement'' , ''medium evidence'' ) ( [[#Altieri--2015|Altieri et al., 2015]] ; [[#Simelton--2015|Simelton et al., 2015]] ; [[#Sida--2018|Sida et al., 2018]] ; [[#Perfecto--2019|Perfecto et al., 2019]] ).

* Can increase food security, livelihoods and productivity, but local context and resource availability must be considered to optimise species arrangement and benefits and can have considerable implementation barriers and costs ( ''high confidence'' ) (see Sections 5.10.3, 5.14 and Cross-Chapter Box NATURAL in Chapter 2). ( [[#Altieri--2015|Altieri et al., 2015]] ; [[#Simelton--2015|Simelton et al., 2015]] ; [[#Sida--2018|Sida et al., 2018]] ; [[#Perfecto--2019|Perfecto et al., 2019]] ).

|}

Diversification improves regulating and supporting ecosystem services such as pest control, soil fertility and health, pollination, nutrient cycling, water regulation and buffering of temperature extremes ( ''high confidence'' ) ( [[#Barral--2015|Barral et al., 2015]] ; [[#Prieto--2015|Prieto et al., 2015]] ; [[#Tiemann--2015|Tiemann et al., 2015]] ; [[#Schulte--2017|Schulte et al., 2017]] ; [[#Beillouin--2019a|Beillouin et al., 2019a]] ; [[#Dainese--2019|Dainese et al., 2019]] ; [[#Kuyah--2019|Kuyah et al., 2019]] ; [[#Tamburini--2020|Tamburini et al., 2020]] ), which can in turn mediate yield stability and reduced risk of crop loss according to socio-ecological contexts and time since adoption ( ''high confidence'' ) ( [[#Prieto--2015|Prieto et al., 2015]] ; [[#Roesch-McNally--2018|Roesch-McNally et al., 2018]] ; [[#Sida--2018|Sida et al., 2018]] ; [[#Williams--2018|Williams et al., 2018]] ; [[#Birthal--2019|Birthal and Hazrana, 2019]] ; [[#Degani--2019|Degani et al., 2019]] ; [[#Amadu--2020|Amadu et al., 2020]] ; [[#Bowles--2020|Bowles et al., 2020]] ; [[#Li--2020|Li et al., 2020]] ; [[#Sanford--2021|Sanford et al., 2021]] ).

Agroecosystem diversification often has variable impacts depending on crop combination, agro-ecological zone and soil types, and rigorous assessments of adaptive gains with traditional and locally diversified systems and potential trade-offs still need to be conducted across socio-ecological contexts. The quantitative upstanding will assist in enhancing multiple benefits of diversification tailored for each condition (Table 5.6). Progress is also needed via breeding and/or agronomy to adapt underutilised as well as major food crops to diversified agroecosystems and optimise management of nutrients, pest and disease pressure and other socio-ecological constraints ( [[#Araújo--2015|Araújo et al., 2015]] ; [[#Foyer--2016|Foyer et al., 2016]] ; [[#Adams--2018|Adams et al., 2018]] ; [[#Pang--2018|Pang et al., 2018]] ).

Managing for diversity and flexibility at multiple scales is central to developing adaptive capacity. Policies to support diversification include shifting subsidies towards diversified systems, public procurement for diverse foods for schools and other public institutions, investment in shorter value chains, lower insurance premiums and payments for ecosystem services that include diversification ( [[#Sorensen--2015|Sorensen et al., 2015]] ; [[#Guerra--2017|Guerra et al., 2017]] ; [[#Nehring--2017|Nehring et al., 2017]] ; [[#Valencia--2019|Valencia et al., 2019]] ). Integrated landscape approaches involving multiple stakeholders ( [[#Reed--2016|Reed et al., 2016]] ) including urban governments can support diversification at a regional scale through public and private sector investment in extension services, regional supply chains, agritourism and other incentives for diversified landscapes ( [[#Milder--2014|Milder et al., 2014]] ; [[#Münke--2015|Münke et al., 2015]] ; [[#Sorensen--2015|Sorensen et al., 2015]] ; [[#Pérez-Marin--2017|Pérez-Marin et al., 2017]] ; [[#Caron--2018|Caron et al., 2018]] ; 5.14.1.5).

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