There is a growing movement in the USA to develop a certification for agricultural systems that are deemed not just sustainable, but regenerative in their outcomes [1
]. This provides a unique opportunity and imperative to rethink the design and implementation of agricultural systems that not only maximize productivity, but also ecosystem and socioeconomic benefits.
Fueled by frustrations with the enforcement of the United States Department of Agriculture (USDA) organic standards [3
] and proposed changes to the National Organic Standards Board governance [4
], there has been a growing desire by many farmers and food producers in the USA to distinguish practices that “go beyond” the requirements of USDA Organic certification in terms of their beneficial impacts to the environment [5
]. In September 2017, a consortium of food producers and farming organizations released the Recommended Framework for Regenerative Organic Certification
]. While there are a handful of other efforts currently underway to certify regenerative agriculture, this paper draws upon the Regenerative Organic Certification (ROC) certification effort (the second version of which was released in March 2018 [8
There is currently no uniformly accepted definition of regenerative agriculture. In light of this, we provide three descriptions of regenerative agriculture and its associated practices to consider:
“Regenerative organic agriculture is marked by tendencies towards closed nutrient loops, greater diversity in the biological community, fewer annuals and more perennials, and greater reliance on internal rather than external resources.” [9
“Practices that: (i) contribute to generating/building soils and soil fertility and health; (ii) increase water percolation, water retention, and clean and safe water runoff; (iii) increase biodiversity and ecosystem health and resiliency; and (iv) invert the carbon emissions of our current agriculture to one of remarkably significant carbon sequestration thereby cleansing the atmosphere of legacy levels of CO2
“Unifying principles consistent across regenerative farming systems include: (1) abandoning tillage (or actively rebuilding soil communities following a tillage event); (2) eliminating spatio-temporal events of bare soil; (3) fostering plant diversity on the farm; and (4) integrating livestock and cropping operations on the land.” [11
While these three descriptions may present somewhat differing perspectives on the specific goals and supporting practices of regenerative agriculture, they highlight several universal themes. For the purpose of our analysis and proposed agroforestry standards, we summarize the broad regenerative agriculture goals as follows:
Soil: Contribute to building soils along with soil fertility and health.
Water: Increase water percolation, water retention, and clean and safe water runoff.
Biodiversity: Enhance and conserve biodiversity.
: Capacity for self-renewal and resiliency [12
Carbon: Sequester carbon.
The following section outlines the potential for agroforestry systems to achieve these regenerative goals.
2. Agroforestry as a Regenerative System
There are numerous definitions for agroforestry [14
]. The USDA definition [18
] that is frequently cited and captures many common themes of other agroforestry definitions states, “the intentional integration of trees and shrubs into crop and animal farming systems to create environmental, economic, and social benefits”. A basic agroforestry configuration is simply the integration of suitable woody perennials into an agricultural landscape [19
]. On the other end of the spectrum is the complex structure of multistory, multifunctional, agroforestry systems [17
]. In this paper, “agroforestry system” and “agroforest” are used to refer in general to systems that fall within the USDA definition of agroforestry, while “agroforestry practice” refers to specific and recognized applications of agroforestry (e.g., windbreak, alley cropping, etc., see Section 3.1
). As a “multifunctional working landscape” [21
], the promise of agroforestry is twofold: (1) a diverse, multi-layer food production system; and (2) a resource conservation and/or ecological restoration land use method.
Agroforestry is seen as a holistic food production system addressing social, ecological, and economic goals [16
], the regenerative outcomes of which have been recognized and fostered over time. While agroforestry is a relatively new term coined in the 1970s, its principles and methods have been applied for millennia throughout the world in both temperate and tropical regions [23
]. Through careful observation of natural forests, including how forests reestablish after disturbances such as fires or severe storms, and trial and error over many generations, diverse, multifunctional agroforestry was developed traditionally as a foundation for food production throughout the world. There is an indigenous/traditional body of knowledge that substantiates the promise and potential of agroforestry as a regenerative strategy [23
A testament to agroforests’ ability to sustain themselves over generations is the indigenous cultivation of breadfruit (Artocarpus altilis
), which has taken place over millennia and up to the present day in highly biodiverse multistory perennial agroforests in the Pacific Islands. The breadfruit is a signature tree of traditional agroforestry systems (Figure 1
) throughout Oceania, on volcanic islands as well as low-lying coral atolls [27
]. The landscape coverage, complexity, and diversity of plants grown together with breadfruit can be impressive. Breadfruit agroforests on the island of Pohnpei, Federated States of Micronesia, epitomize these systems by incorporating more than 120 useful species, as well as 50 cultivars of breadfruit [28
]. Up until very recently, breadfruit has exclusively been grown in traditional agroforestry systems as diverse multistory polycultures [30
]. The cultivation of breadfruit in commercial monocultures began approximately 10 years ago and appears to be rapidly expanding on a large scale in the Pacific Islands, the Caribbean, and to a lesser extent in Central America and West Africa. These commercial breadfruit monocultures lack the regenerative characteristics of the traditional multistory agroforest and underscore a need to understand how to measure and support agroforestry systems and practices that yield regenerative outcomes.
The global spectrum of agroforestry systems and practices is important to note. Climatic, physiographic, and socioeconomic variations influence the types of agroforestry practices used and systems yielded across the world [24
]. For example, agroforestry is prevalent in traditional land use systems across India. Agroforestry systems of Erythrina indica
trees shading coffee (Coffea
spp.) and acting as a support tree for black pepper (Piper nigra
) vines are common in the Western Ghats of Kerala, India [33
]. In the northeastern Himalayan region of India, another common system is the highly productive and widely practiced intercropping of pineapple (Ananas comosus
) and black pepper beneath the areca nut palm (Areca catechu
]. In the Hararghe highlands of Eastern Ethiopia and other areas across sub-Saharan Africa, Faidherbia albida
(formerly Acacia albida
) has traditionally been grown as a permanent tree crop with cereals, vegetables, and coffee underneath [35
Though less diverse and widespread than the tropical agroforestry systems of lower latitudes, there is also a long tradition of agroforestry in temperate zones [32
], with practices that are largely informed by the distinct seasonality of temperate climates and the existing natural systems [24
]. In Europe, the traditional dehesa systems of Spain and montado systems of Portugal are closely related examples of temperate multifunctional agroforestry systems on the Iberian Peninsula. The Portuguese montado is internationally recognized for its agro-silvopastral system of cork, holm oak, and livestock, producing a global majority of cork [37
Furthermore, the scope of and interest in temperate agroforestry continues to expand [19
]. The European initiative AGFORWARD (AGroFORestry that Will Advance Rural Development [39
]) conducts research on these systems and convenes stakeholders from both of these countries and systems to understand producers’ needs [40
]. In an example from the temperate regions of the USA, the University of Illinois created a long-term temperate multistory agroforestry trial, “Agroforestry for Food,” inspired by the original oak savanna and prairie of the Central Illinois landscape [19
]. This trial is testing the performance of multifunctional woody polyculture configurations to understand their potential as “an alternative option for agriculture in the Midwest” [42
Another consideration is the wide range of regional differences within regions that also have an extensive range of latitudes (e.g., Europe, United States, India). Complex agroforestry is more common in tropical regions than in temperate regions due to distinctions in seasonality, socioeconomic conditions, cultural influences, and agricultural development histories. Global and regional differences necessitate a flexible framework for considering and measuring regenerative agroforestry systems and the practices that yield such systems.
In addition to their ubiquity, agroforestry systems around the world are recognized for their high biological and natural resources conservation values [43
] and are increasingly considered an innovative response to today’s agricultural challenges including increasing weather extremes, soil and water degradation, and declining biodiversity [45
]. A recent USDA Forest Service study [46
] with over 50 contributors from around the USA documents the ability of agroforestry systems to “enhance agricultural production; protect soil, air, and water quality; provide wildlife habitat; and allow for diversified income.” Recent review papers on agroforestry [47
] confirm a list of benefits in alignment with regenerative agriculture goals: soil enrichment; water quality enhancement; biodiversity enhancement and conservation; ecosystem services; and carbon sequestration. This alignment suggests that agroforestry systems—when appropriately designed, implemented, and managed—are regenerative in their outcomes.
Agroforestry practices also have the potential to repair degraded and deforested land [49
] and restore or enhance the multifunctionality of landscapes [52
]. Agroforestry can significantly improve ecosystem services and enhance biodiversity conservation on degraded agricultural land and deforested areas [54
]. Agroforestry promises myriad of other significant benefits, including cultural and social [56
]. For example, regeneration of degraded lands through agroforestry offers the added benefit of producing food within communities and supporting rural economies and subsistence livelihoods [54
]. While recognizing the importance of the sociocultural benefits, in this paper we focus on the environmental and agroecological benefits of agroforestry as they relate to regenerative agriculture and standardization efforts.
2.1. Regenerative Characteristics of Example Agroforestry Practices
A wide range of agroforestry practices can be integrated into existing agricultural systems. Recognized agroforestry practices include alley cropping, contour hedgerow, forest farming, living fence, multistory cropping, riparian forest buffer, silvoarable systems, silvopasture, and windbreak [15
]. The five most common agroforestry practices implemented in the USA are alley cropping, forest farming, riparian buffers, silvopasture, and windbreaks [47
], which are briefly described below. For their wide applicability and well-developed knowledge base, we will focus on these five practices and their role and relationship with respect to regenerative agriculture. Our discussion of a regenerative agroforestry standard in Section 5
, however, is applicable to all recognized agroforestry systems beyond those explored here.
2.1.1. Alley Cropping
Alley cropping, also known as intercropping and closely related to silvoarable agroforestry, is the practice of planting single or multiple rows of trees with cultivated crops in the “alleys” between the tree rows [16
]. There is strong evidence that alley cropping systems can reduce runoff and soil erosion by water, improve nutrient use efficiency, sequester carbon, and increase biodiversity [62
]. Alley cropping systems can be oriented to increase potential benefits. For example, planting tree rows along the contour of the land can reduce soil erosion [64
]. A diverse crop portfolio and the mix of perennial and annual crops also diversifies revenue streams over time, providing short-term and long-term income generation [65
]. Alley cropping can also be leveraged to transition from monocultures and/or row crop farms to perennial agricultural systems. Beneficial interactions occur between complementary plant species and plant types when grown together; these interactions can result in yields exceeding those in monoculture or plantation stands [66
2.1.2. Forest Farming
Forest farming is the practice of cultivating high-value, shade-tolerant specialty crops under the protection of a forest managed to provide a favorable microclimate for understory crops such as mushrooms and medicinal herbs [68
]. A forest farming system is established by selectively thinning an existing woodland or plantation to manage the conditions for understory crops or by adding a new layer to the structure of an existing system [70
]. Products produced from forest farming are typically referred to as non-timber forest products (NTFPs), and include four categories of products: food, botanicals, decoratives, and handicrafts. While people have been informally managing forests for NTFPs for generations, forest farming has become popular in North America as “a way for landowners to diversify income opportunities, improve management of forest resources, and increase biological diversity” [71
]. In addition to providing valuable ecosystem services, forest farming can help protect forests from clearing for other uses and NTFP populations from being over harvested.
2.1.3. Riparian Buffer
As defined by Gold and Garrett [16
], riparian buffers are “strips of permanent vegetation consisting of trees, shrubs, herbs, and grasses that are planted and managed together” adjacent to waterways and water bodies. These planted zones buffer water bodies from potential negative impacts of surrounding cropland or pasture by reducing soil erosion and runoff of sediment and nutrients, stabilizing banks, improving water quality, and increasing biodiversity [72
]. While riparian systems are typically implemented for their conservation benefits, they can also provide perennial crops and thus another source of revenue for a farmer or rancher [75
]. The conservation benefits and crop production potential, combined with utilization of riparian areas that are not considered for production, afford this multifunctional agroforestry practice great potential to meet regenerative goals.
Silvopasture is an agroforestry practice that “combines trees with forage (pasture) and livestock production” [47
]. There are two approaches to the establishment of silvopasture: (1) the planting of tree species on pastureland; or (2) the thinning and management of existing forestland to establish forage crops and accommodate grazing of livestock, sometimes referred to as forest grazing [16
]. Through either approach, trees and pasture are managed as a single integrated system that is actively used to graze livestock [77
]. Converting pasture to silvopasture diversifies a rancher’s sources of revenue and can provide the security of mid- to long-term revenue from tree crops, such as fruit, nuts, and/or timber [76
]. The trees in silvopasture systems can also shade livestock from direct sunlight, as well as abate winds to provide livestock with limited protection from cold weather [77
]. Of the five categories of agroforestry practices, Jose et al. [47
] found silvopasture to have the largest potential available area for expansion, suggesting that the adoption of silvopasture practices on existing pasture lands holds great potential as a regenerative system in the USA, while Project Drawdown identified silvopasture in the top 10 potential solutions for reversing carbon emissions [78
Windbreaks, also known as shelterbelts, are the intentional planting of trees and/or shrubs as barriers to decrease the speed and impact from winds to protect a specific area downwind, thereby creating a different microclimate [79
]. Windbreaks can be planted on existing crop or pastureland. On cropland, field windbreaks can reduce wind erosion of soils, improve growth and yield performance, protect plants directly from wind damage, increase the availability of water by reducing evaporation [63
]. On pastureland, windbreaks can help reduce animal stress or even mortality due to extreme heat and cold; visual impacts; and odors [83
]. By reducing wind speed, windbreaks can control blowing and drifting snow [85
]. With appropriate species selection and design, windbreaks can also produce food, fodder, fiber, timber, and pollinator and predatory insect habitat [86
] as key secondary products or functions.
5. A Standard for Regenerative Agroforestry
We suggest that any interest in certifying agroforestry be channeled into the development of a robust standard describing measurable criteria of regenerative agroforestry systems. While there is potential for agroforestry systems to advance regenerative goals, their ability to do so lies in how they are implemented and managed. As such, the development of a single set of regenerative standards for the many diverse agroforestry practices is a challenging exercise. We maintain that meaningful agroforestry standards require some degree of prescriptivism (what to do, rather than only what not to do), while also allowing for virtually unlimited configurations. To this end, we have proposed detailed criteria and corresponding measurements or thresholds for each criterion to guide the development of such an agroforestry standard based upon a synthesis of criteria from existing efforts (Table 2
and Table 3
Because of the complexity of agroforestry systems as compared to monocultures, as well as the wide range of potential applications in various environments and farm sites, we first identify four interrelated characteristics of regenerative agroforests, which can be achieved through a variety of agroforestry practices. By our definition a regenerative agroforestry system should be highly integrated, densely planted, multistoried, and contain multiple species. We propose these characteristics as the core criteria of a regenerative agroforestry standard.
: The first of these characteristics is the integration of trees, shrubs, and other perennials within the cropping system, which is a fundamental feature of agroforestry, as stated in all agroforestry definitions. Perennials are more resilient to weather extremes and other environmental variations, imparting increased resiliency compared with annual crops [57
]. There is evidence that with more extensive and deeper root systems, perennials can appreciably decrease erosion compared with annual cropping systems [118
]. They also store carbon in their above- and below-ground biomass, which accounts for their potential to sequester carbon.
The second important characteristic of agroforestry systems is the density of plants growing together in a stacked or multistory configuration. When optimized for a given environment and species mix, higher density plantings confer multiple regenerative benefits. High plant density builds soil by increasing organic matter production, which through leaf drop, root senescence, and pruning/cutting management can be left in place to add organic matter and mulch cover for the soil [59
]. High-density plantings can increase soil-holding capacity and decrease erosion [118
], also potentially increasing biodiversity within the agroecosystem [119
The third characteristic is a multistory configuration, which is a result of integrating many species. Multistory agroforests have a higher total light interception than single-layer canopies, and therefore have higher total primary production of biomass (higher photosynthetic conversion) [120
]. The multistory aboveground structure of agroforests with diverse species composition are paralleled by root systems that occupy various soil depths and together form a network that efficiently captures nutrients before they can be carried away by water [19
]. The abundant leaf litter and herbaceous cover of multistory agroforests create capacity to minimize erosion [59
]. Various tree/shrub heights create greater habitat for more organisms, increasing biodiversity [119
]. Finally, multistory agroforests have been shown to have a high capacity for carbon sequestration, especially in their early years [122
The fourth characteristic is the inclusion of multiple species and varieties, which is related to plant density and multistory structure. Increased species diversity increases overall biodiversity of the system. Having a large number of species also confers resiliency by ensuring that ecological niches are occupied even after weather extremes and other disturbances [57
]. Chisholm et al. [125
] state, “As species richness increases, productivity and biomass of the system also increase.”
Realizing the potential benefits of agroforestry within a certification framework necessitates quantifiable measures for each standard criterion (Figure 2
). Of these four characteristics of regenerative agroforests, by definition, only the first is inherent to all agroforests. The other three can be implemented to various degrees, suggesting minimum measures be developed for plant density, number of layers (Figure 2
), and plant diversity. We propose measuring the regenerative agroforestry standard criteria as follows:
Integration: Presence of trees, shrubs, and perennials integrated into a farming system.
Density: Plants per unit area (horizontal structure).
Multistory: Strata represented in the layered structure and root systems (vertical structure).
Multiple species: Number of plant families, genera, species, and varieties over time (temporal succession).
presents the proposed regenerative agroforestry standard, including suggested means of measuring each criterion and thresholds by which to measure adherence to each criterion (as illustrated in Figure 3
). The standard as proposed applies to an agroforest itself, rather than the whole farm or other issues related to certification. Tree/shrub cover percentage is given as a minimum based upon the standards and specification recommendations that list specific cover percentages in Table 2
and Table 3
. As there will be an establishment period for an agroforest, the minimum cover percentage applies after an appropriate transition period, depending on location. Upon reaching a mature phase, cover percentage is the minimum achieved after pruning. The woody perennial density criteria are based upon 500 stems per ha (200/ac), the median of the criteria provided by the standards and criteria we explored. In terms of structural layers, two and three are mentioned as minimum values in the Smithsonian Migratory Bird Center’s Bird Friendly Coffee (Table 2
), and Mixed Agroforest specification (Table 3
), respectively. The threshold for multiple species reflects the median of those specified in Table 2
and Table 3
. Despite the basis of the criteria threshold numbers in Table 4
in existing certifications and NRCS specifications, the numbers themselves should be seen as initial values to be subject to further evaluation and research.
We have suggested a standard that is outcomes-oriented, rather than recommending or requiring the application of specific agroforestry practices (alley cropping, windbreak, etc.). In other words, in theory, any practice that yields an agroforestry system that meets the standard criteria and corresponding thresholds would meet the proposed standard.
The development of a regenerative agroforestry standard alongside current efforts to certify regenerative agriculture offers an opportunity to leverage the common goals and potential strengths of each field/domain. To this end, we have proposed a framework and measurable criteria for a regenerative agroforestry standard with the aim of advancing dialogue around (1) the content of the proposed standard itself; and (2) the role of regenerative agroforestry to advance the goals of regenerative agriculture.
In reviewing existing certification programs and standards we conclude that, while there is demonstrated interest and current efforts to certify agroforestry, there is also a lack of robust standards and measurable criteria available to closely guide agroforestry production, particularly in temperate locations. The sparse inclusion of prescriptive agroforestry criteria in existing certification programs also demonstrates a scarcity of guidance materials that detail quantifiable agroforestry metrics for meeting desired outcomes.
In proposing an agroforestry standard, we have suggested a subtle shift in thinking in order to maximize the regenerative benefits of agroforestry. We recommend orienting the concept of standardization around specific measures generalizable to any agroforestry system rather than requiring the use of specific agroforestry practices, of which there are many promising and site-specific variations. Additionally, we have attempted to create a baseline of quantitative measures for agroforests that translate into the desired outcomes of regenerative agriculture. In order to move beyond this preliminary exploration of a regenerative agroforestry standard, additional research and discussion within the agroforestry and eco-certification community are necessary to refine the thresholds behind each measurable criterion. This further development will likely include discussion within the contexts of individual certification programs, such as the Regenerative Organic Certification, and regional differences such as temperate versus tropical agroforestry systems.
While the implementation of a new standard itself may prove challenging or even infeasible, the exploration of measurable agroforestry criteria may help focus a dialogue on the regenerative outcomes of agroforestry and position agroforestry within the regenerative agriculture narrative. Such an exercise may prove valuable to the regenerative agriculture field itself as it works to codify its broader goals and understand potential intersections with existing efforts or methodologies (in this case, agroforestry).
As compelling as agroforestry is to meet regenerative goals, further exploration is necessary to understand how an agroforestry standard could be implemented through the mechanisms of certification. This includes understanding the barriers to the adoption and promotion of agroforestry, and necessary policy implications related to adoption and promotion; the limitations of eco-certification; and the underlying economic influences that are crucial to the success of market-based certification programs. To this end, the production of breadfruit may offer a promising case study to apply the proposed regenerative agroforestry standards and provide guidelines for the commercial production of breadfruit in agroforestry systems [30
]. Additionally, further exploration of the proposed standards should be considered in the context of a changing climate, including examination as to how agroforests can be designed to be both resilient to and mitigate major disturbances (e.g., wildfires, floods, and pest outbreaks).
Lastly, to realize the paper’s aim of stimulating dialogue, outreach must be conducted to ensure that stakeholders at all levels are included. Of particular importance is the intentional inclusion of rural stakeholders, such as those represented by the European initiative AGFORWARD [39
], and small-scale agroecological farmers, such as those represented by international non-profit organization La Via Campesina [126
]. Further development of the proposed standards for regenerative agroforestry systems should be informed by existing models of participatory agricultural research, of which Drinkwater et al. [127
] provide numerous examples.