- “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.” .
- “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.” .
- 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.
- Carbon: Sequester carbon.
2. Agroforestry as a Regenerative System
2.1. Regenerative Characteristics of Example Agroforestry Practices
2.1.1. Alley Cropping
2.1.2. Forest Farming
2.1.3. Riparian Buffer
3. Relevant Certifications, Standards, and Guidelines
3.1. Agricultural and Forestry Certifications and Standards
- Recommend agroforestry as an option to achieve stated goals.
- Require agroforestry practices to achieve stated goals.
- Contain prescriptive criteria as to how agroforestry systems should be implemented, maintained, and measured.
3.2. Resource Conservation Guidelines
4. Approach to Standardization
4.1. Practices versus Outcomes
4.2. Organic as a Baseline Standard
5. A Standard for Regenerative Agroforestry
- Integration: 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 [57,117]. There is evidence that with more extensive and deeper root systems, perennials can appreciably decrease erosion compared with annual cropping systems . They also store carbon in their above- and below-ground biomass, which accounts for their potential to sequester carbon.
- Density: 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 . High-density plantings can increase soil-holding capacity and decrease erosion , also potentially increasing biodiversity within the agroecosystem .
- Multistory: 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) [120,121]. 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 . The abundant leaf litter and herbaceous cover of multistory agroforests create capacity to minimize erosion . Various tree/shrub heights create greater habitat for more organisms, increasing biodiversity . Finally, multistory agroforests have been shown to have a high capacity for carbon sequestration, especially in their early years [122,123].
- Multiple species: 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 [57,124]. Chisholm et al.  state, “As species richness increases, productivity and biomass of the system also increase.”
- 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).
Conflicts of Interest
- Nosowitz, D. The Real Organic Project: Disgusted with the USDA, Farmers Make Their Own Organic Label. Modern Farmer. Available online: https://modernfarmer.com/2018/03/the-real-organic-project-alternative-organic-label/ (accessed on 26 July 2018).
- Reguzzoni, A. What does the New Regenerative Organic Certification Mean for the Future of Good Food? Civil Eats. 12 March 2018. Available online: https://civileats.com/2018/03/12/what-does-the-new-regenerative-organic-certification-mean-for-the-future-of-good-food/ (accessed on 29 March 2018).
- Whoriskey, P. Analysis|“Uncertainty and Dysfunction” Have Overtaken USDA Program for Organic Foods, Key Lawmaker Says. Washington Post. Sec. Wonkblog Analysis. Available online: https://www.washingtonpost.com/news/wonk/wp/2017/07/13/uncertainty-and-dysfunction-have-overtaken-usda-program-for-organic-foods-key-lawmaker-says/ (accessed on 22 November 2017).
- Curry, L. What Could the Next Farm Bill Mean for the Organic Program? Civil Eats. Available online: https://civileats.com/2018/05/15/what-could-the-next-farm-bill-mean-for-the-organic-program/ (accessed on 24 May 2018).
- Rathke, L. Organic-Food Purists Assail the Designation for Hydroponics. AP. Available online: http://lancasteronline.com/news/national/organic-food-purists-assail-the-designation-for-hydroponics/article_6f7a0cef-f82b-5f55-8857-b4f3804e3cc2.html (accessed on 25 November 2017).
- White, A. Can You Still Trust the USDA Certified Organic Label? Rodale’s Organic Life. Available online: https://www.rodalesorganiclife.com/food/can-you-trust-organic-label (accessed on 22 November 2017).
- Regenerative Organic Alliance. Recommended Framework for Regenerative Organic Certification. Regenerative Organic Alliance. 2017. Available online: https://standards.nsf.org/apps/group_public/document.php?document_id=39305 (accessed on 1 October 2017).
- Regenerative Organic Alliance. Framework for Regenerative Organic Certification. 2018. Available online: https://regenorganic.org/wp-content/uploads/2018/03/ROC-Framework-Pilot-Ready-March-2018.pdf (accessed on 31 March 2018).
- Rodale Institute. Regenerative Organic Agriculture and Climate Change. 2014. Available online: https://rodaleinstitute.org/assets/WhitePaper.pdf (accessed on 22 May 2018).
- Regeneration Agriculture Initiative and the Carbon Underground. What is Regenerative Agriculture? Regen. Intl. Available online: http://www.regenerationinternational.org/2017/02/24/what-is-regenerative-agriculture/ (accessed on 5 March 2018).
- LaCanne, C.E.; Lundgren, J.G. Regenerative agriculture: Merging farming and natural resource conservation profitably. PeerJ 2018, 6, E4428. [Google Scholar] [CrossRef] [PubMed]
- Grumbine, R. Edward. What is ecosystem management? Conserv. Biol. 1994, 8, 27–38. [Google Scholar] [CrossRef]
- Costanza, R. Toward an operational definition of ecosystem health. In Ecosystem Health: New Goals for Environmental Management; Costanza, R., Norton, B.G., Haskell, B.D., Eds.; Island Press: Washington, DC, USA, 1992; pp. 239–256. [Google Scholar]
- Sinclair, F.L. A general classification of agroforestry practice. Agrofor. Syst. 1999, 46, 161–180. [Google Scholar] [CrossRef]
- Torquebiau, E.F. A renewed perspective on agroforestry concepts and classification. Comptes Rendus de l’Académie Des Sciences Series III Sciences de La Vie 2000, 323, 1009–1017. [Google Scholar] [CrossRef]
- Gold, M.A.; Garrett, H.E. Agroforestry nomenclature, concepts, and practices. In North American Agroforestry: An Integrated Science and Practice, 2nd ed.; American Society of Agronomy: Madison, WI, USA, 2009; pp. 45–56. [Google Scholar]
- Leakey, R.R.B. Multifunctional Agriculture: Achieving Sustainable Development in Africa, 1st ed.; Academic Press: London, UK, 2017; ISBN 978-0-12-805356-0. [Google Scholar]
- USDA. USDA Agroforestry Strategic Framework, Fiscal Year 2011–2016; U.S. Department of Agriculture: Washington, DC, USA, 2011.
- Lovell, S.T.; Dupraz, C.; Gold, M.; Jose, S.; Revord, R.; Stanek, E.; Wolz, K.J. Temperate agroforestry research: Considering multifunctional woody polycultures and the design of long-term field trials. Agrofor. Syst. 2017, 1–19. [Google Scholar] [CrossRef]
- Nair, P.K.R. Managed multi-strata tree + crop systems: An agroecological marvel. Front. Environ. Sci. 2017, 5, 88. [Google Scholar] [CrossRef]
- Jose, S. Agroforestry for ecosystem services and environmental benefits: An overview. Agrofor. Syst. 2009, 76, 1–10. [Google Scholar] [CrossRef]
- Leakey, R.R.B. Definition of agroforestry revisited. Agrofor. Today 1996, 8, 5–7. [Google Scholar]
- King, K.F.S. The history of agroforestry. In Agroforestry: A Decade of Development; Steppler, H.A., Nair, P.K.R., Eds.; ICRAF: Nairobi, Kenya, 1987; pp. 1–11. ISBN 978-9-29-059036-1. [Google Scholar]
- Nair, P.K.R. An Introduction to Agroforestry; Springer Science & Business Media: Dordrecht, The Netherlands, 1993; ISBN 978-0-79-232134-7. [Google Scholar]
- Smith, J.R. Tree Crops: A Permanent Agriculture; Harper & Row: New York NY, USA, 1978. [Google Scholar]
- Smith, J. The History of Temperate Agroforestry; Progressive Farming Trust Limited: Newbury, UK, 2010. [Google Scholar]
- Ragone, D. Artocarpus altilis (Breadfruit). In Traditional Trees of Pacific Islands: Their Culture, Environment, and Use; Elevitch, C.R., Ed.; Permanent Agriculture Resources (PAR): Holualoa, HI, USA, 2006; pp. 85–100. [Google Scholar]
- Fownes, J.H.; Raynor, W.C. Seasonality and yield of breadfruit cultivars in the indigenous agroforestry system of Pohnpei, Federated States of Micronesia. Trop. Agric. 1993, 70, 103–109. [Google Scholar]
- Ragone, D.; Raynor, W.C. Breadfruit and its traditional cultivation and use on Pohnpei. In Ethnobotany of Pohnpei: Plants, People, and Island Culture; Balick, M.J., Ed.; University of Hawaii Press & New York Botanical Garden Press: New York, NY, USA, 2009; pp. 63–88. [Google Scholar]
- Elevitch, C.R.; Ragone, D. Breadfruit Agroforestry Guide: Planning and Implementation of Regenerative Organic Methods; Breadfruit Institute of the National Tropical Botanical Garden, Kalaheo, Hawaii and Permanent Agriculture Resources: Holualoa, HI, USA, 2018. [Google Scholar]
- Bhardwaj, D.R.; Navale, M.R.; Sharma, S. Agroforestry practices in temperate regions of the world. In Agroforestry: Anecdotal to Modern Science; Dagar, J.C., Tewari, V.P., Eds.; Springer: Singapore, 2017; pp. 163–187. [Google Scholar]
- Thevathasan, N.V.; Gordon, A.M. Ecology of tree intercropping systems in the north temperate region: Experiences from southern Ontario, Canada. In New Vistas in Agroforestry: A Compendium for 1st World Congress of Agroforestry; Nair, P.K.R., Rao, J.R., Buck, L.E., Eds.; Springer: Dordrecht, The Netherlands, 2004; pp. 257–268. [Google Scholar]
- Depommier, D. The tree behind the forest: Ecological and economic importance of traditional agroforestry systems and multiple uses of trees in India. Trop. Ecol. 2003, 44, 63–71. [Google Scholar]
- Singh, A.K.; Arunachalam, A.; Ngachan, S.V.; Mohapatra, K.P.; Dagar, J.C. From shifting cultivation to integrating farming: Experience of agroforestry development in the northeastern Himalayan region. In Agroforestry Systems in India: Livelihood Security & Ecosystem Services; Dagar, J.C., Singh, A.K., Arunachalam, A., Eds.; Springer: New Delhi, India, 2014; pp. 57–86. [Google Scholar]
- Poschen, P. An evaluation of the Acacia albida-based agroforestry practices in the Hararghe highlands of Eastern Ethiopia. Agrofor. Syst. 1986, 4, 129–143. [Google Scholar] [CrossRef]
- Mokgolodi, N.C.; Setshogo, M.P.; Shi, L.L.; Liu, Y.J.; Ma, C. Achieving food and nutritional security through agroforestry: A case of Faidherbia albida in sub-Saharan Africa. For. Stud. China 2011, 13, 123–131. [Google Scholar] [CrossRef]
- Ribeiro, N.A.; Surovy, P.; Pinheiro, A. Adaptive management on sustainability of cork oak woodlands. In Decision Support Systems in Agriculture, Food and the Environment: Trends, Applications and Advances; Manos, B., Paparrizos, K., Matsatsinis, N., Papathanasiou, J., Eds.; IGI Global: Hershey, PA, USA, 2010; pp. 437–449. [Google Scholar]
- Pinto-Correia, T.; Ribeiro, N.; Sá-Sousa, P. Introducing the montado, the cork and holm oak agroforestry system of Southern Portugal. Agrofor. Syst. 2011, 82, 99. [Google Scholar] [CrossRef]
- AGFORWARD. Available online: https://www.agforward.eu/index.php/en/ (accessed on 21 August 2018).
- AGFORWARD. Dehesa Farms in Spain. Available online: https://www.agforward.eu/index.php/en/dehesa-farms-in-spain.html (accessed on 5 September 2018).
- AGFORWARD. Montado and Mosaic Systems in Portugal. Available online: https://www.agforward.eu/index.php/en/montado-in-portugal.html (accessed on 5 September 2018).
- University of Illinois at Urbana-Champaign Institute for Sustainability, Energy, and Environment. Agroforestry for Food Project. 2018. Available online: https://sustainability.illinois.edu/research/securesustainable-agriculture/agroforestry-for-food-project/ (accessed on 5 September 2018).
- Miller, R.P.; Nair, P.K.R. Indigenous agroforestry systems in Amazonia: From prehistory to today. Agrofor. Syst. 2006, 66, 151–164. [Google Scholar] [CrossRef]
- Perfecto, I.; Vandermeer, J. The agroecological matrix as alternative to the land-sparing/agriculture intensification model. Proc. Natl. Acad. Sci. USA 2010, 107, 5786–5791. [Google Scholar] [CrossRef] [PubMed][Green Version]
- Foley, J.A.; DeFries, R.; Asner, G.P.; Barford, C.; Bonan, G.; Carpenter, S.R.; Chapin, F.S.; Coe, M.T.; Daily, G.C.; Gibbs, H.K. Global consequences of land use. Science 2005, 309, 570–574. [Google Scholar] [CrossRef] [PubMed]
- Schoeneberger, M.M.; Bentrup, G.; Patel-Weynand, T. Agroforestry: Enhancing Resiliency in U.S. Agricultural Landscapes under Changing Conditions; General Technical Report WO-96; U.S. Department of Agriculture, Forest Service: Washington, DC, USA, 2017. [Google Scholar]
- Jose, S.; Gold, M.A.; Garrett, H.E. The future of temperate agroforestry in the United States. In Agroforestry-The Future of Global Land Use; Nair, P.K.R., Garrity, D., Eds.; Springer: Dordrecht, The Netherlands, 2012; pp. 217–245. [Google Scholar] [CrossRef]
- Dagar, J.C.; Tewari, J.C. (Eds.) Agroforestry Research Developments; Nova Science Publishers: New York, NY, USA, 2016. [Google Scholar]
- Schulz, J. Imitating Natural Ecosystems through Successional Agroforestry for the Regeneration of Degraded Lands-a Case Study of Smallholder Agriculture in Northeastern Brazil; Nova Science Publishers: New York, NY, USA, 2011. [Google Scholar]
- Dosskey, M.G.; Bentrup, G.; Schoeneberger, M. A role for agroforestry in forest restoration in the lower Mississippi alluvial valley. J. For. 2012, 48–55. [Google Scholar] [CrossRef]
- Dagar, J.C. Agroforestry: Four decades of research development. Indian J. Agrofor. 2016, 18, 1–32. [Google Scholar]
- Park, H.; Turner, N.; Higgs, E. Exploring the potential of food forestry to assist in ecological restoration in North America and beyond. Restor. Ecol. 2018, 26, 284–293. [Google Scholar] [CrossRef]
- Belcher, B.; Michon, G.; Angelsen, A.; Pérez, M.R.; Asbjornsen, H. The socioeconomic conditions determining the development, persistence, and decline of forest garden systems. Econ. Bot. 2005, 59, 245–253. [Google Scholar] [CrossRef]
- Chazdon, R.L. Beyond deforestation: Restoring forests and ecosystem services on degraded lands. Science 2008, 320, 1458–1460. [Google Scholar] [CrossRef] [PubMed]
- Coelho, G. Ecosystem services in Brazilian’s southern agroforestry systems. Trop. Subtrop. Agroecosyst. 2017, 20, 475–492. [Google Scholar]
- Leakey, R.R.B.; Tchoundjeu, Z.; Schreckenberg, K.; Shackleton, S.E.; Shackleton, C.M. Agroforestry tree products (AFTPs): Targeting poverty reduction and enhanced livelihoods. Int. J. Agric. Sustain. 2005, 3, 1–23. [Google Scholar] [CrossRef]
- Stigter, C.J. Agroforestry and micro-climate change. In Tree-Crop Interactions. Agroforestry in a Changing Climate, 2nd ed.; Springer: Dordrecht, The Netherlands, 2015; pp. 119–145. [Google Scholar]
- Jat, M.L.; Dagar, J.C.; Sapkota, T.B.; Govaerts, B.; Ridaura, S.L.; Saharawat, Y.S.; Sharma, R.K.; Tetarwal, J.P.; Jat, R.K.; Hobbs, H.; et al. Chapter Three—Climate change and agriculture: Adaptation strategies and mitigation opportunities for food security in South Asia and Latin America. In Advances in Agron; Sparks, D.L., Ed.; Academic Press: Cambridge, MA, USA, 2016; Volume 137, pp. 127–235. [Google Scholar]
- Hillbrand, A.; Borelli, S.; Conigliaro, M.; Olivier, A. Agroforestry for Landscape Restoration: Exploring the Potential of Agroforestry to Enhance the Sustainability and Resilience of Degraded Landscapes; Food and Agriculture Organization of the United Nations: Rome, Italy, 2017. [Google Scholar]
- Den Herder, M.; Moreno, G.; Mosquera-Losada, M.R.; Palma, J.; Sidiropoulou, A.; Santiago Freijanes, J.J.; Crous-Duran, J.; Paulo, J.; Tomé, M.; Pantera, A. Current Extent and Trends of Agroforestry in the EU27: Deliverable report 1.2 for EU FP7 Research Project. AGFORWARD 613520. 2016. Available online: https://www.agforward.eu/index.php/es/current-extent-and-trends-of-agroforestry-in-the-eu27.html (accessed on 31 May 2018).
- USDA NAC. Agroforestry Practices. 2018. Available online: https://www.fs.usda.gov/nac/practices/index.shtml (accessed on 17 March 2018).
- Quinkenstein, A.; Wöllecke, J.; Böhm, C.; Grünewald, H.; Freese, D.; Schneider, B.U.; Hüttl, R.F. Ecological benefits of the alley cropping agroforestry system in sensitive regions of Europe. Environ. Sci. Policy 2009, 12, 1112–1121. [Google Scholar] [CrossRef]
- Tsonkova, P.; Böhm, C.; Quinkenstein, A.; Freese, D. Ecological benefits provided by alley cropping systems for production of woody biomass in the temperate region: A review. Agrofor. Syst. 2012, 85, 133–152. [Google Scholar] [CrossRef]
- MacFarland, K. Alley Cropping: An Agroforestry Practice. USDA National Agroforestry Center; 2017. Available online: https://www.fs.usda.gov/nac/documents/agroforestrynotes/an12ac01.pdf (accessed on 15 June 2018).
- Wilson, M.H.; Lovell, S.T. Agroforestry—The next step in sustainable and resilient agriculture. Sustainability 2016, 8, 574. [Google Scholar] [CrossRef]
- Van der Werf, W.; Keesman, K.; Burgess, P.; Graves, A.; Pilbeam, D.; Incoll, L.D.; Dupraz, C. Yield-SAFE: A parameter-sparse, process-based dynamic model for predicting resource capture, growth, and production in agroforestry systems. Ecol. Eng. 2007, 29, 419–433. [Google Scholar] [CrossRef][Green Version]
- Garrett, H.E.; McGraw, R.L.; Walter, W.D. Alley cropping practices. Am. Soc. Agron. 2009. [Google Scholar] [CrossRef]
- Dix, M.E.; Hill, D.B.; Buck, L.E.; Rietveld, W.J. Forest Farming: An Agroforestry Practice—Agroforestry Notes, 7. USDA National Agroforestry Center; 1997. Available online: https://www.fs.usda.gov/nac/documents/agroforestrynotes/an07ff01.pdf (accessed on 15 June 2018).
- Mudge, K.; Gabriel, S. Farming the Woods: An Integrated Permaculture Approach to Growing Food and Medicinals in Temperate Forests; Chelsea Green Publishing: Hartford, VT, USA, 2014; ISBN 978-1-60-358507-1. [Google Scholar]
- USDA NAC. What is Forest Farming?—Working Trees. USDA National Agroforestry Center; 2012. Available online: https://www.fs.usda.gov/nac/documents/workingtrees/infosheets/WT_Info_forest_farming.pdf (accessed on 30 May 2018).
- Chamberlain, J.L.; Mitchell, D.; Brigham, T.; Hobby, T.; Zabek, L.; Davis, J.; Gene Garrett, H.E. Forest farming practices. ACSESS Publications. Am. Soc. Agron. 2009. [Google Scholar] [CrossRef]
- Bentrup, G. Conservation Buffers—Design Guidelines for Buffers, Corridors, and Greenways; Gen. Tech. Rep. SRS–109; U.S. Department of Agriculture, Forest Service, Southern Research Station: Asheville, NC, USA, 2008; Volume 110, p. 109.
- Johnson, C.W.; Buffler, S. Riparian Buffer Design Guidelines for Water Quality and Wildlife Habitat Functions on Agricultural Landscapes in the Intermountain West; Gen. Tech. Rep. RMRS-GTR-203; US Department of Agriculture, Forest Service; Rocky Mountain Research Station: Fort Collins, CO, USA, 2008.
- Stutter, M.I.; Chardon, W.J.; Kronvang, B. Riparian buffer strips as a multifunctional management tool in agricultural landscapes: Introduction. J. Environ. Qual. 2012, 41, 297–303. [Google Scholar] [CrossRef] [PubMed]
- MacFarland, K.; Straight, R.; Dosskey, M. Riparian Forest Buffers: An Agroforestry Practice. USDA National Agroforestry Center; 2017. Available online: https://www.fs.usda.gov/nac/documents/agroforestrynotes/an49rfb01.pdf (accessed on 29 May 2018).
- Sharrow, S.H.; Brauer, D.; Clason, T.R.; Gene Garrett, H.E. Silvopastoral Practices. ACSESS Publications. Am. Soc. Agron. 2009. [Google Scholar] [CrossRef]
- Klopfenstein, N.B.; Rietveld, W.J.; Carman, R.C.; Clason, T.R.; Sharrow, S.H.; Garrett, G.; Anderson, B.E. Silvopasture: An Agroforestry Practice—Agroforestry Notes, 8. USDA National Agroforestry Center; 1997. Available online: https://www.fs.usda.gov/nac/documents/agroforestrynotes/an08s01.pdf (accessed on 29 May 2018).
- Drawdown. Silvopasture. Available online: https://www.drawdown.org/solutions/food/silvopasture (accessed on 7 February 2018).
- Goodrich, N. Can Windbreaks Benefit Your Soil Health Management System?—Working Trees. USDA National Agroforestry Center; 2017. Available online: https://www.fs.usda.gov/nac/documents/workingtrees/infosheets/WTInfoSheet-WBSoilHealth.pdf (accessed on 30 May 2018).
- University of Missouri Center for Agroforestry. Chapter 6: Windbreaks. In Training Manual for Applied Agroforestry Practices; University of Missouri Center for Agroforestry: Columbia, MO, USA, 2015; pp. 92–113. [Google Scholar]
- Cleugh, H.A.; Miller, J.M.; Böhm, M. Direct mechanical effects of wind on crops. Agrofor. Syst. 1998, 41, 85–112. [Google Scholar] [CrossRef]
- Nuberg, I.K. Effect of shelter on temperate crops: A review to define research for Australian conditions. Agrofor. Syst. 1998, 41, 3–34. [Google Scholar] [CrossRef]
- Wight, B.; Stuhr, K. Windbreaks: An Agroforestry Practice—Agroforestry Notes. USDA National Agroforestry Center; 2002. Available online: https://www.fs.usda.gov/nac/documents/agroforestrynotes/an25w01.pdf (accessed on 30 May 2018).
- Alemu, M.M. Ecological benefits of trees as windbreaks and shelterbelts. Int. J. Ecosyst. 2016, 6, 10–13. [Google Scholar] [CrossRef]
- USDA NAC. What is a Windbreak?—Working Trees. USDA National Agroforestry Center; 2012. Available online: https://www.fs.usda.gov/nac/documents/workingtrees/infosheets/wb_info_050712v8.pdf (accessed on 30 May 2018).
- USDA NAC. Working Trees for Pollinators. 2016. Available online: https://www.fs.usda.gov/nac/documents/workingtrees/brochures/WTPollinators.pdf (accessed on 19 August 2018).
- Smithsonian Migratory Bird Center. Bird Friendly Farm Criteria. Smithsonian’s National Zoo & Conservation Biology Institute. Available online: https://nationalzoo.si.edu/migratory-birds/bird-friendly-farm-criteria (accessed on 2 February 2017).
- Smithsonian Migratory Bird Center. Shade Management Criteria. Smithsonian’s National Zoo & Conservation Biology Institute. Available online: https://nationalzoo.si.edu/migratory-birds/bird-friendly-coffee-criteria (accessed on 2 February 2017).
- Certified Naturally Grown Produce Standards. Certified Naturally Grown: Brooklyn, N.Y. Available online: https://certified.naturallygrown.org/documents/Produce_Standards.pdf (accessed on 12 March 2018).
- Demeter-International. Production Standards: For the Use of Demeter, Biodynamic® and Related Trademarks; Demeter-International: Darmstadt, Germany, 2017. [Google Scholar]
- International Analog Forestry Network. Standard for Forest Garden Products (FGP); International Analog Forestry Network: San José, Costa Rica, 2014. [Google Scholar]
- GLOBALG.A.P. Integrated Farm Assurance: All Farm Base—Crops Base—Fruit and Vegetable. Control Points and Compliance Criteria, Version 5.1; GLOBALG.A.P: Cologne, Germany, 2017. [Google Scholar]
- IFOAM-Organics International. The IFOAM NORMS for Organic Production and Processing; IFOAM-Organics International: Bonn, Germany, 2014. [Google Scholar]
- PCO. PCO Forest Grown Verification Program Manual; Pennsylvania Certified Organic: Spring Mills, PA, USA, 2014. [Google Scholar]
- Sustainable Agriculture Network. Sustainable Agriculture Standard (Version 1.2). Available online: https://www.sustainableagriculture.eco/blog/2017/11/9/is-saving-water-enough-5tss3 (accessed on 9 November 2017).
- USDA NOP. The Program Handbook: Guidance and Instructions for Accredited Certifying Agents and Certified Operations. USDA National Organic Program; 2007. Available online: https://www.ams.usda.gov/rules-regulations/organic/handbook (accessed on 26 July 2018).
- UTZ. Individual Core Code of Conduct 1.1; UTZ: Amsterdam, The Netherlands, 2015; Available online: https://utz.org/wp-content/uploads/2015/12/EN_UTZ_Core-Code-Individual-v1.1_2015.pdf (accessed on 18 December 2017).
- American Forest Foundation. Standards & Guidance 2015–2020. American Forest Foundation. 2015. Available online: https://www.treefarmsystem.org/stuff/contentmgr/files/2/b0872a8dc122128baacea886ebf468f1/pdf/final_standards_guidance_7.9.15_links.pdf (accessed on 26 July 2018).
- Forest Stewardship Council. FSC Forest Stewardship Standard for the United States of America; Forest Stewardship Council: Bonn, Germany, 2010. [Google Scholar]
- Forest Stewardship Council. FSC® International Standard: FSC Principles and Criteria for Forest Stewardship (FSC-STD-01-001 V5-2 EN); Forest Stewardship Council: Bonn, Germany, 2015. [Google Scholar]
- Sustainable Forestry Initiative. SFI 2015-2019 Forest Management Standard. Sustainable Forestry Initiative. 2015. Available online: http://www.sfiprogram.org/files/pdf/2015-2019-standardsandrules-section-2-pdf/ (accessed on 21 March 2018).
- Millard, E. Incorporating agroforestry approaches into commodity value chains. Environ. Manag. 2011, 48, 365–377. [Google Scholar] [CrossRef] [PubMed]
- Forest Stewardship Council. Ecosystem Services Procedure: Impact Demonstration and Market Tools; Forest Stewardship Council: Washington, DC, USA, 2017. [Google Scholar]
- PEFC. Endorsed National Forest Certification Systems—United States. 2018. Available online: https://pefc.org/standards/national-standards/endorsed-national-standards/8-United%20States (accessed on 26 July 2018).
- PEFC. Sustainable Forest Management—Requirements (PEFC ST 1003:201x); PEFC International: Switzerland, Geneva, 2018. [Google Scholar]
- USDA NRCS. Forestry/Agroforestry Technical Note No. 11: Mixed Agroforest Specification; USDA NRCS Pacific Islands Area: Honolulu, HI, USA, 2017.
- USDA NRCS. Riparian Forest Buffer (Code 391) Conservation Practice Standard. Illinois. 2014. Available online: https://efotg.sc.egov.usda.gov/references/public/IL/IL391_2014.pdf (accessed on 2 July 2018).
- USDA NRCS. Silvopasture (Code 381) Conservation Practice Standard. Kentucky. 2016. Available online: https://efotg.sc.egov.usda.gov/references/public/KY/KY381SilvopastureOct2017.pdf (accessed on 2 July 2018).
- Tscharntke, T.; Milder, J.C.; Schroth, G.; Clough, Y.; DeClerck, F.; Waldron, A.; Rice, R.; Ghazoul, J. Conserving biodiversity through certification of tropical agroforestry crops at local and landscape scales. Conserv. Lett. 2015, 8, 14–23. [Google Scholar] [CrossRef]
- Dankers, C.; Liu, P. Environmental and Social Standards, Certification and Labeling for Cash Crops; Food and Agriculture Organization of the United Nations: Rome, Italy, 2003. [Google Scholar]
- Tipraqsa, P.; Craswell, E.T.; Noble, A.D.; Schmidt-Vogt, D. Resource integration for multiple benefits: Multifunctionality of integrated farming systems in northeast Thailand. Agric. Syst. 2007, 94, 694–703. [Google Scholar] [CrossRef]
- Burkhart, E.P.; Pennsylvania State University, State College, PA, USA. Personal communication, 2018.
- Verchot, L.V.; Noordwijk, M.V.; Kandji, S.; Tomich, T.; Ong, C.; lain Albrecht, A.; Mackensen, J.; Bantilan, C.; Anupama, K.V.; Palm, C. Climate Change: Linking Adaptation and Mitigation through Agroforestry. Mitig. Adapt. Strateg. Glob. Chang. 2007, 12, 901–918. [Google Scholar] [CrossRef]
- Van Noordwijk, M.; Hoang, M.H.; Neufeldt, H.; Öborn, I.; Yatich, T. How Trees and People Can Co-Adapt to Climate Change: Reducing Vulnerability through Multifunctional Agroforestry Landscapes; World Agroforestry Centre (ICRAF): Nairobi, Kenya, 2011. [Google Scholar]
- Stavi, I.; Lal, R. Agroforestry and biochar to offset climate change: A Review. Agron. Sustain. Dev. 2013, 33, 81–96. [Google Scholar] [CrossRef]
- Lasco, R.D.; Rafaela Jane, P. Delfino, R.P.D.; Espaldon, J.L.O. Agroforestry Systems: Helping smallholders adapt to climate risks while mitigating climate change. Wiley Interdiscip. Rev. Clim. Chang. 2014, 5, 825–833. [Google Scholar] [CrossRef]
- Prabhu, R.; Barrios, E.; Bayala, J.; Diby, L.; Donovan, J.; Gyau, A.; Graudal, L.; Jamnadass, R.; Kahia, J.; Kehlenbeck, K.; et al. Agroforestry: Realizing the Promise of an Agroecological Approach. In Agroecology for Food Security and Nutrition, Proceedings of the FAO International Symposium, Rome, Italy, 18–19 September 2014; Biodiversity & Ecosystem Services in Agricultural Production Systems, Food and Agriculture Organization: Rome, Italy, 2015; pp. 201–224. [Google Scholar]
- Young, A. Agroforestry for Soil Conservation; CAB International: Wallingford, UK, 1989. [Google Scholar]
- Schroth, G.; da Fonseca, G.A.B.; Harvey, C.A.; Gascon, C.; Vasconcelos, H.L.; Izac, A.-M.N. (Eds.) Agroforestry and Biodiversity Conservation in Tropical Landscapes; Island Press: Washington, DC, USA, 2004. [Google Scholar]
- Monteith, J.L. Solar radiation and productivity in tropical ecosystems. J. App. Ecol. 1972, 9, 747–766. [Google Scholar] [CrossRef]
- Goudriaan, J. Light distribution. In Canopy Photosynthesis: From Basics to Applications; Springer: Dordrecht, The Netherlands, 2016; pp. 3–22. [Google Scholar]
- Kumar, B.M.; Nair, P.K.R. Carbon Sequestration Potential of Agroforestry Systems: Opportunities and Challenges; Springer Science & Business Media: Dordrecht, The Netherlands, 2011; Volume 8. [Google Scholar]
- Toensmeier, E. The Carbon Farming Solution: A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security; Chelsea Green Publishing: Hartford, VT, USA, 2016. [Google Scholar]
- Ewel, J.J. Natural systems as models for the design of sustainable systems of land use. Agrofor. Syst. 1999, 45, 1–21. [Google Scholar] [CrossRef]
- Chisholm, R.A.; Muller-Landau, H.C.; Rahman, K.A.; Bebber, D.P.; Bin, Y.; Bohlman, S.A.; Bourg, N.A.; Brinks, J.; Bunyavejchewin, S.; Butt, N.; et al. Scale-dependent relationships between tree species richness and ecosystem function in forests. J. Ecol. 2013, 101, 1214–1224. [Google Scholar] [CrossRef]
- Via Campesina—Globalizing Hope, Globalizing the Struggle! Available online: https://viacampesina.org/en/ (accessed on 21 August 2018).
- Drinkwater, L.; Friedman, D.; Buck, L.E. Systems Research for Agriculture: Innovative Solutions to Complex Challenges; Sustainable Agriculture Research and Education (SARE): College Park, MD, USA, 2016. [Google Scholar]
|Certification/Standard 1 (Standard Owner)||Scope||Recommends Agroforestry||Requires Agroforestry Practices||Contains Prescriptive Agroforestry Criteria|
|Bird-Friendly Coffee (Smithsonian Migratory Bird Center) [87,88]||Int’l||Y||Y||Y|
|Certified Naturally Grown (Certified Naturally Grown) ||U.S.||N||N||N|
|Demeter Biodynamic® Production Standards (Demeter-International) ||Int’l||Y||N||N|
|Forest Garden Products (International Analog Forestry Network) ||Int’l||Y||Y||N|
|GLOBALG.A.P. (GLOBALG.A.P.) ||Int’l||N||N||N|
|IFOAM Standard (IFOAM-Organics International) ||Int’l||N||N||N|
|PCO Verified Forest Grown (Pennsylvania Certified Organic) ||U.S.||Y||Y||N|
|Regenerative Organic Certification (Regenerative Organic Alliance) ||U.S.||Y||N||N|
|Rainforest Alliance Sustainable Agriculture Standard (Rainforest Alliance) ||Int’l||Y||N||Y|
|USDA Organic (USDA National Organic Program) ||U.S.||N||N||N|
|UTZ Standard (UTZ) ||Int’l||Y||N||N|
|Forest Management Certifications|
|American Tree Farm System (American Forest Foundation) ||U.S.||N||N||N|
|Forest Stewardship Council Forest Management Certification (Forest Stewardship Council) [99,100]||Int’l and U.S.||N||N||N|
|Sustainable Forestry Initiative North American Program (Sustainable Forestry Initiative) ||U.S. and Canada||N||N||N|
|Criteria Measurement||Smithsonian Migratory Bird Center’s Bird Friendly Coffee [87,88]||Rainforest Alliance Sustainable Agriculture Standard |
|1. Presence of trees, shrubs, and perennials||≥10 woody species (in addition to the predominant shade trees or “backbone” species). At least 10 of these should represent 1% or more of all individuals sampled and be dispersed throughout. Backbone species must be native. ||Incorporation of native trees as border plantings and barriers around housing and infrastructure (e.g., live fences, shade trees, and permanent agroforestry systems).|
|2. Plants per unit area||≥40% tree/shrub cover, measured during dry season after pruning.||Minimum total canopy cover of 20–40%, depending on geographic region.|
|3. Layers represented in the tree/shrub structure||≥12 m (40 ft) height of the backbone species. Preferably three layers or strata : |
a. The layer formed by the backbone species and other trees of that size;
b. The taller emergent species comprised of native trees of the natural forest;
c. Understory made up of shrubs and small trees or plants.
The emergent and understory strata each should account for 20% of the total foliage volume present. The remaining 60% of the foliage volume should be the principal canopy. 
|Not explicitly given.|
|4. Number of woody perennial (trees, shrubs, palms, etc.) families, genera, species, and varieties||Requirement same as noted in criteria area #1. The total floristic diversity is the sum of all woody and herbaceous species counted in the sampling. ||The tree community consists of 5–12 native species per hectare (per 2.5 acres) on average, depending on the shade-tolerant crop being grown.|
|5. Additional criteria||Leaf litter should be present; no minimum percentage required, which, together with living ground cover, keeps the soil covered . Weeds/herbs/forbs should be present. Living fences and buffer zones along waterways should be present. Should qualify at least for the category “traditional polyculture” (the more diverse category of the polyculture systems). Must have current organic certification by a USDA-accredited certification agency. ||The farm must use and expand its use of vegetative ground cover to reduce erosion and improve soil fertility; structure and organic material content, as well as minimize the use of herbicides.|
|Criteria Measurement||Mixed Agroforest Specification (Pacific Islands Area) ||Riparian Forest Buffer (Illinois) ||Silvopasture (Kentucky) |
|1. Presence of trees, shrubs, and perennials||“Mixed Agroforests” are described as small-scale tree and shrub plantings.||Trees and/or shrubs located adjacent to and up-gradient from watercourses or water bodies.||Use trees and forages (shrubs where desired) that are adapted to the climate, soil, and biological conditions of the site and compatible with its planned use and management.|
|2. Plants per unit area||Tree/shrub counts must be ≥1050/ha (≥425/ac), including ≥62/ha (25/ac) tall stature trees. The balance must be short-stature trees or shrubs. Specific guidelines are given in tabular form for minimum number of species and structural diversity.||The location, layout and density of the buffer should complement natural features, and mimic natural riparian forests. Initial plant densities for trees and shrubs should be based on their potential height, crown characteristics and growth form, in addition to planting objectives.||Tree density at planting should be approximately 500–1000/ha (200–400/acre) for conifers, or 250/ha (100/acre) for black walnut, black locust, or pecan. Throughout the rotation, trees will be thinned in order to maintain understory-overstory balance that accommodates the producer’s goals.|
|3. Layers represented in the tree/shrub structure||High diversity in the planting arrangement of different genera and structure (height) at maturity, and may include tree, shrub, and vine. A minimum of two layers (tall and short stature trees/shrubs) are required.||Manage the dominant tree canopy to maintain maximum vigor of overstory and understory species. Periodic thinning and/or prescribed burning may be necessary to allow adequate light to reach the forest floor to maintain a good cover of grasses and forbs.||Manage trees, forages, and shrubs as needed to provide appropriate light conditions for forages, and shade/shelter conditions for livestock. Pruning needed to achieve the desired canopy type for production of fruits, nuts, and timber.|
|4. Number of woody perennial (trees, shrubs, palms, etc.) families, genera, species, and varieties||a. 6 woody plant genera or more depending on field size;|
b. ≤50% that produce non-timber forest products—any number of timber-producing trees are allowed;
c. A minimum of 20% as native species (may be timber producing).
Limitations: Individual plant genera that produce non-timber forest products may be planted in pure or contiguous clumps not to exceed five trees or 20 shrubs/vines. Different clumps of the same genera shall be separated by the maximum space feasible given overall species selection and land area of a given agroforest.
|No single species will make up more than 50% of the total number of species planted. Favor tree and shrub species that have multiple values such as those suited for timber, nuts, fruit, florals, browse, nesting, and aesthetics.||None specified.|
|Standard Criteria||Criteria Measurement||Description of Measure||Criteria Threshold|
|1. Integration||Presence of trees, shrubs, and other woody perennials.||Annuals have an essential early successional role to play in agroforestry, while the long-term structure of the system emphasizes both woody and herbaceous perennials.||≥40% cover by trees/shrubs, allowing transition time from open field. Individual practices (e.g., windbreak) may require higher cover for acceptable resource conservation functionality.|
|2. Density||Woody perennials per unit area.||This measure ensures continuous soil cover for erosion control, capture of nutrients, and weed suppression.||≥5 woody perennials per 100 m2 (1080 ft2), plus herbaceous cover and mulch.|
|3. Multistory||Layers occupied in the agroforest structure and root systems.||Based upon five potential vegetation layers (emergent, upper canopy, lower canopy layer or understory, shrub, and herbaceous) occupied per unit area.||≥2 woody perennial layers per 200 m2 (2160 ft2), plus the herbaceous layer and mulch.|
|4. Multiple species||Number of woody perennial (tree, shrub, palm, etc.) families, genera, species, and varieties.||A measure of biodiversity intentionally planted or protected in the agroforest.||≥8 plant families, genera, species, and/or varieties of woody perennials per 100 m2 (1080 ft2) present throughout the life of the agroforest. Pure or contiguous clumps not to exceed 3 trees or 10 shrubs/vines of a single species. Different clumps of the same species to be separated by minimum 3 times their maximum canopy diameter.|
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