Food forests: Their services and sustainability

Industrialized food systems use unsustainable practices leading to climate change, natural resource depletion, economic disparities across the value chain, and detrimental impacts on public health. In contrast, alternative food solutions such as food forests have the potential to provide healthy food, sufficient livelihoods, environmental services, and spaces for recreation, education, and community building. This study compiles evidence from more than 200 food forests worldwide, with detailed insights on 14 exemplary food forests in Europe, North America, and South America, gained through site visits and interviews. We present and illustrate the main services that food forests provide and assess their sustainability. The findings indicate that the majority of food forests perform well on social-cultural and environmental criteria by building capacity, providing food, enhancing biodiversity, and regenerating soil, among others. However, for broader impact, food forests need to go beyond the provision of social-cultural and environmental services and enhance their economic viability. There is a need for specific trainings and other measures targeting this deficit. This study appraises the current state of food forests and provides an orientation for food entrepreneurs, public officials, and activists to better understand food forests’ potential for advancing sustainable food systems.


Introduction
Large-scale industrial food system are characterized by unsustainable development, including land degradation, water contamination, climate change, negative health impacts, and unfair distribution of economic benefits (Garnett, 2011; International Assessment of Agricultural Knowledge, Science and Technology for Development [IAASTD], 2009;Swinburn et al., 2011;Tilman & Clark, 2014). Alternative food solutions such as food forests address these challenges in various local contexts. Food forests are multifunctional biodiverse agroforestry systems using several (3 to 7) plant layers of different height (strata), including trees, shrubs, and groundcover. They have the potential to provide food, livelihoods, environmental services (habitat, heat mitigation, carbon storage), and spaces for recreation, education, and community building. Many food forests exist for self-sufficiency, with little formal organization and recognition. Yet, in this study, we focus on food forests with impacts on the wider food economy.
Mimicking nature in food production is still common in indigenous and traditional agricultural production systems, especially in the tropics, and dates back 4,000 years (Belcher et al., 2005;Kumar & Nair, 2004). In Europe, the concept of 'forest gardens' emerged in the 1980s in Great Britain (Hart, 1996;Sholto Douglas & Hart, 1984). At about the same time, the permaculture movement started in Australia, with 'food forests' being a major outcome (Mollison, 1979;1981), and professionalization efforts at larger scale (Shepard, 2013). There is little distinction in research and practice between 'forest gardens' and 'food forests.' Both are defined as multi-strata ecosystems using mostly edible, perennial plants. Following definitions of what a 'forest' is (Chazdon et al., 2016; Food and Agriculture Organization of the United Nations [FAO], 2000), it seems reasonable to define the minimum size of a food forest as 1 acre (0.5ha) and at least 10% canopy cover to provide forest-like ecosystem services. However, in this study we do not apply this definition strictly and instead use the term 'food forest' as a synonym for both forest gardens and food forests, so as to not exclude interesting cases of smaller size. The practice of forest farming, i.e., growing edible or medicinal plants in existing forests or forest management for the purpose of food production, is not included in this study.
Food forests adopt basic principles of agroforestry that improve water cycle and soil formation, store carbon, regulate the microclimate, increase biodiversity, and create livelihood opportunities (Jose, 2009;Toensmeier, 2017). In Brazil, 'syntropic farming' or 'successional agroforestry' developed as a biodiverse multistrata design and management approach (Götsch, 1992) with high yield and ecological restoration potential (Schulz et al., 1994;Young, 2017).
Unlike agroforestry at large, specific research on food forests is still at a nascent stage. Recent research compiled practical knowledge on different types of food forests (Bukowski & Munsell, 2018;Remiarz, 2017), their cultural transformation (Wartman et al., 2018), their nutritional benefits (Nytofte & Henriksen, 2019), and their ecological restoration potential (Park & Higgs, 2018). Common are single case studies and a focus on the social and ecological impacts of food forests (Hammarsten et al., 2019;Knuijt, 2020;Riolo, 2019;Schafer et al., 2019). Recent research also considers urban forestry, an internationally established planning and management practice for public spaces, as a potential scaling opportunity for (community) food forests (Konijnendijk & Park;Vannozzi Brito & Borelli, 2020). Very few of these studies consider the economic dimension, which is necessary for a comprehensive sustainability solution (Schaltegger & Wagner, 2011).
A systematic knowledge base about food forests that comprehensively maps out the state of food forests is still missing. The present study intends to close this gap and open the field more widely by addressing the following research questions: This research aligns with the approach of solution-oriented sustainability research that aims at developing evidence-supported solutions to sustainability problems (Miller et al., 2014;Wiek & Lang, 2016). We used a mixed-methodology approach to answer the research questions, combining literature and document review, interviews, and site visits (data collected in 2018). We reviewed more than 200 food forests and conducted indepth case studies on a sample (14) of exemplary food forests in Europe, North America, and South America. The focus was on food forests that pursue social, environmental, and economic activities, going beyond self-sufficiency. The study might inform the work of food entrepreneurs, public officials, activists, and researchers interested in building upon current food forest practices from around the world. The insights on food forests' service diversity and sustainability can help realizing the full potential of food forests to advance sustainable food systems.

Research Design
First, we conducted a web-based search in English ("food forest," "forest garden") and German ("Waldgarten"), and did snowball sampling, and identified 209 food forests with activities that go beyond self-sufficiency. Networks and research initiatives in the U.S. and U.K. like the Agroforestry Research Trust and Bukowski (2015) provided larger lists of sites and contributed to 45% of the overall sample. For each food forest, we created a standardized profile with up to three main services and other relevant information, including location, size, etc. Not all relevant data were available for all food forests, e.g., size or age. For some cases with information gaps, we were able to estimate plot size through Google Maps measurements and photos of the site.
Second, we selected 14 exemplary food forests for in-depth case studies. Selection criteria included primarily age and main service (see Table 2, below) and secondarily location and access to primary data through site visits. We identified the main services by standardizing the most common activities carried out at each food forest such as generating 1 All data refer to the year 2018, if not indicated differently. Sample sizes vary due to data availability. regular income through food-forest related workshops (main service: education), hosting regular community events (main service: community building), or selling food from on-site production (main service: food production). Environmental services, especially plant biodiversity, are inherent to food forests, hence, this was only tracked for explicit major services (e.g., flood protection). In addition to a wide spectrum of services, we covered in the sample of case studies different age groups to provide insights on the diverse practices of early pioneers and later adopters. We conducted semistructured interviews and site visits that focused on the food forest's organization, management, and implementation process.
Third, each of the 14 exemplary food forest was assessed against a set of sustainability criteria (Table 1) identified from the literature on sustainability (Gibson, 2006), agroforestry and food forests (Jose, 2009;Park & Higgs, 2018), as well as expert interviews. Scorecards (see Table 3, below) indicate criteria fully (2), somewhat (1), or not (0) met.
According to the available data (n=78), the average food forest plot size is 4.7 acres (1.9 ha), with 50% of food forests being less than 1 acre (Figure 2).
While a few food forests started back in the 1970s (e.g., Langerhorst in Austria), many early adopters began in the 1990s (Figure 3). Starting in 2004, food forest start-ups steadily increased, with a peak of 19 food forests started in 2014.
Food forests offer a variety of services: they produce food (primary production, processing, nurseries), regulate and support the environment, and provide socialcultural services (community building, education, recreation). The majority of sampled food forests (n=209) focuses on education (40%), community building (32%), or food production (11%), often on larger sites ( Figure 4). Few cases (<10%) prioritize self-sufficiency (while still offering other services), recreation, food processing, or environmental services, or serve as nurseries.
In summary, the sampled food forests are predominantly located in the U.S. and in Europe, with equal distribution across rural and urban areas. They are managed mostly by nonprofit organiza-tions or run as conventional businesses. The number of annual food forest start-ups has been constant for many decades (<5), but has been increasing since the mid-2000s, with more than 10 startups in most years of the past decade. The majority of food forests focuses on providing educational or community-building services, with only about 10% of food forests prioritizing food production.  Journal of Agriculture, Food Systems, and Community Development ISSN: 2152-0801 online https://foodsystemsjournal.org

Exemplary Food Forests for Each Service
The exemplary food forests selected for in-depth analysis and showcasing (n=14; Table 2) represent all services mentioned above. Below, we provide descriptions of exemplary food forests for each service, detailing location, size, products and services, ownership, staff, and management.

Food Production Services
Primary Production. Food forests in this category produce herbs, vegetables, fruits, and nuts. They sell their produce through diverse channels from community supported agriculture (CSA), food box or u-pick schemes, and onsite and market sales (B2C) to cooperation with local food businesses (B2B). Foodforest Ketelsbroek operates on 6 acres (2.4 ha) and markets its produce directly to three local businesses (gastronomy, catering service, and cider brewery) that participate in weekly harvestings. Two private owners have run the food forest in a nature-regulated approach since 2009. The design, inspired by agroforestry and food-forest pioneer Martin Crawford and farmers in Kenya, is partly "rational" in rows, partly "romantic" with high biodiversity (W. van Eck, personal communication, July 12, 2018). Input is very low, following the guideline "we must make ourselves become useless" (W. van Eck, personal communication, July 12, 2018), and consists mostly of harvesting and  1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999  Recreation, 5% Education, 40% Community, 32% Nurseries, 1% Self-sufficiency, 7% Environment, 1% Journal of Agriculture, Food Systems, and Community Development ISSN: 2152-0801 online https://foodsystemsjournal.org minimal agro-ecological interventions. Produce derives mainly from tree layers (fruits, herbal plants, edible flowers) and provides for one parttime position. According to the farmer, yield increases slowly, but the land seems more profitable than the neighboring conventional farm. Consultation and workshops are the main income source (W. van Eck, personal communication, July 12, 2018). In 2017, 1,200 visitors received a guided tour.
Ökohof Waldgarten (Eco-Farm Food Forest) operates on 12 acres (5 ha) and was started in 2006 by a private owner planting chestnuts, soon thereafter also producing annual vegetables for market sales. The farm has run a community supported agriculture (CSA) operation since 2012 that currently delivers about 120 food boxes per week (20% fruits, 80% vegetables) to its 200 members. The site includes an older 5-acre (2 ha) dome food forest, and a 7.4-acre (3 ha) vegetable garden (Demeter-certified), which successively changes into an agroforestry system. The lead gardener-owner, three gardeners, two trainees (all full-time), and two part-time staff manage the farm. In the growing seasons, the CSA members participate in coworking days.
Den Food Bosch has operated on 2.5 acres (1 ha) since 2017, with an intricate food forest design inspired by permaculture and syntropic farming to harvest on all layers. Produce is sold weekly on-site. Additional sales channels and processing options are currently under development. Den Food Bosch resulted from a student initiative, received public funding, and is steered by a foundation that contracts two managers who are responsible for generating their income. The local water authority owns the land.
Smaller food forests focusing on primary production are often part of a larger farm or network using direct-sales channels to restaurants or local markets. For example, the Rotterdam Forest Garden Network initiated 10 sites that produce food for market sales (in 2020, the network reorganized and sites are now managed by the Cooperative Ondergrond).
Processing. Food processing is rarely the main activity of food forests. It is more common as an educational activity or for catering to workshop participants. Ownership of the few food forests prioritizing processing is mostly private, the workforce is small (four employees, on average), and common distribution channels are on-site gastronomy or direct sales.
Fazenda Ouro Fino operates on 62 acres (25 ha) and processes high-value crops like açaí (puree) and cacao (fermenting) for sale at the local market and international distribution. The privately owned site produces a dozen food crops and offers educational trainings. As a neighbor and partner of agroforestry pioneer Ernst Götsch, the site contributes to the development of syntropic farming. Café Botanico (0.5 ac; 0.2 ha) and Castle Garden (0.12 ac; 0.04 ha) process specialty crops that are sold at on-site cafés. While Café Botanico builds its dishes around the on-site food and limits its sales to yield availability, Castle Garden Café adds mostly preserves and teas from the site to a broader menu. Both businesses have high staff costs and are cross-financed by the owner(s) through a second job or a second business.
Nursery. Nursery services are informally present at many sites either for a small income or to propagate plants for other sites. Some use them formally to generate an income, although mostly on a very small scale; for example, Mienbacher Waldgarten (3.7ac; 1.5ha) sells plants and seeds online. Several professional nurseries connected to food forests exist; for example, the Balkan Ecology Project in Bulgaria offers polyculture plants, exotic varieties, and multilayer packages (Remiarz, 2017), and Forest Agriculture Enterprises in the U.S. offers wholesale.

Social-Cultural Services
Community Building. Community-oriented food forests are usually located in urban areas, often on public land, and are managed through a core (member) group with support from volunteers. A prominent example is the Beacon Food Forest (7ac, 2.8ha) in Seattle, Washington, U.S. (Bukowski & Munsell, 2018). At Peace of Land (0.1ac; 0.04ha), core members from across the city meet for weekly gardening activities and offer educational workshops to educate both their core group as well as others who are interested. At The Secret Garden (0.1ac; 0.04ha), one trained volunteer maintains the site for a retirement home and a school.
Education, Consultation, Research. Educational food forests are located in urban and rural areas. They offer tours, workshops, courses, and programs from day-to year-long, about permaculture, food forestry, and related specialty topics (e.g., grafting). Educational offerings often help with the setup of a food forest through volunteer labor and provide a source of income. Mienbacher Waldgarten has specialized in self-sufficiency education since 2010. One full-time manager and other trainers use the food forest and its seminar house. The site also contributes to the food self-sufficiency of the manager's family and the property owners' families. Some food forests generate revenue by consulting on the design and management of food forests, including permaculture, regenerative agroforestry, holistic management, and syntropic farming. Only a few food forests engage in substantial research in collaboration with research organizations and universities; examples include Bec Hellouin in France, collaborating with Agro-ParisTech, the French National Agronomy Research Institute, and the Free University of Brussels (Dendoncker et al., 2017;Morel et al., 2016).
Recreation. Some food forests offer aesthetic and recreational value through their multilayered design, cool microclimate, high biodiversity, medicinal plants, and fresh food, as well as opportunities for foraging, relaxation, and discovery. Aesthetics and ecological benefits may require guidance, e.g., through signage about wildlife or insect-friendly practices. The food forest of Hotel Haferland (0.5 ac; 0.2 ha) has a seating area for relaxation, enjoyment, and contemplation. A hotel janitor manages the site, and the restaurant's chefs harvest from it. The professional design requires little maintenance. The site is too small for significant food production but offers aesthetical value. Another example is Keela Yoga Farm (2% of 46 ac; 19 ha) that offers yoga retreats combined with a tour of the food forest.

Environmental Services
Supportive. Many interviewees expressed concerns about the degraded soil and biodiversity loss associated with conventional agriculture and pointed to the regeneration of nature (and human health) as a major motivation for implementing their food forest. Foodforest Ketelsbroek limits access for visitors to reduce disturbance. The manager also regenerates soil in a slow, laissez-faire approach with a naturally occurring groundcover. Fazenda Ouro Fino does "chop-and-drop" management to increase biomass, soil building, and early yields. While Fazenda Ouro Fino manages around 20 species/ha, Foodforest Ketelsbroek manages around 200 species/ha. Plant biodiversity is often high in social-culturally focused food forests. Essgarten (6 ac; 2.5 ha) offers habitat to around 1,200 species.
Regulative. Keela Yoga Farm, for example, manages its food forest with chicken and sheep for fire protection. In semi-arid Arizona, U.S., the new food forest of W. C. L. (2.5 ac; 1 ha) aims at cooling the microclimate while producing food.

Sustainability of Food Forests
Assessing each food forest by social, environmental, and economic criteria indicates their sustainability and highlights areas for improvement (Table  3). Scores indicate that criteria are fully (2), somewhat (1), or not (0) met.
Overall, the assessment shows that food forests perform well on social-cultural and environmental criteria by offering benefits such as educational attainment, community happiness, high biodiversity, healthy soil, and resourceful water management. However, economical practices and structures tend to be unsustainable. Ownership and decision-making are often in private hands or instable due to insecure tenures. Few have business and financing plans. Young (<5 years old) food forests tend to receive a lower score due to being less developed ecologically and economically. Most food forests perform higher in the areas related to their main services.
In Table 3, we provide general insights on each assessment criterion across all 14 cases.

Social-Cultural Criteria A -Meaningful, Safe Employment and Activities with Social Purpose
All food forests in this study (14 of 14) offer work activities with meaningful outputs like ecological regeneration, quality food production, and naturebased education. Food foresters are motivated by regenerating the land and people's health. They enjoy the diversity of tasks and often develop strong emotional connections to the food forest. However, many food foresters experience high stress levels at times, due to the diverse activities, lack of qualified staff, or financial insecurity during initialization.

Social-Cultural Criteria B -Contributing to Community Wellbeing
Almost all food forests (13 of 14) offer affordable food products or educational services. For example, Mienbacher Waldgarten provides food education in a rural neighborhood to adults and children, donates food surplus, and is engaged in setting up a community garden in the nearby town. Young food forests attract specific user communities and struggle with wider uptake. For example, the Rotterdam Forest Garden Network aims at connecting a school and a retirement home at The Secret Garden. With little activity from the partners, a volunteer maintains the site for the retirement home. The site acts as an investment for plant propagation, food sales, and display.

Social-Cultural Criteria C -Capacity Building
Almost all food forests (13 of 14) offer various learning activities on food production and ecology to guests, students, and co-workers. Offerings depend on the land management approach (naturevs. human-regulated). The depth and quality of the offerings depend on the length of stay, expertise of the trainer, and content focus; for example, tours facilitate basic understanding of food forests, while workshops facilitate experiential learning and skill development. Structured educational programs vary significantly in duration, ranging from the more common 1 to 2 weeks (e.g., Mienbacher Waldgarten) or, less often, 1 month (Keela Yoga Farm) to, exceptionally, 2 years (Fazenda Ouro Fino).

Environmental D -Water Conservation and Soil Formation
Mulching is a common management practice at all food forests to build soil and conserve water. Several food forests irrigate lightly, and some integrate rainwater harvesting. Only one site with major annual vegetable production has high irrigation needs Journal of Agriculture, Food Systems, and Community Development ISSN: 2152-0801 online https://foodsystemsjournal.org

Environmental E -Cool Micro-Climate
The majority of food forests (10 of 14) are very small or too young to yield significant cooling effects. Ten food forests are large, mature sites or connect to other green infrastructure. Due to dense canopy covers, they contribute to cooler microclimates.

Environmental F -High Biodiversity
The majority of food forests (9 of 14) shows a very high plant species diversity. In addition to traditional species, most food forests include diverse rare and specialty crops, often from other regions with similar climatic conditions. Climate change resilience and curiosity about specialty foods motivates these plant choices. Some food forests support high genetic diversity and have areas reserved for wildlife only.

Economic G -Economic Viability
The weak point of many food forests (8 of 14) is economic viability. While many food forests develop site plans, very few use financing plans and business plans due to a lack of experience or interest, or resistance to conventional business practices. For example, Ökohof Waldgarten, while envisioned as a food forest business, was implemented without a business plan or training (e.g., planted seeds for chestnut trees that do not carry edible fruits), and now generates most of its income from annual vegetables. For many, idealism acts like an alternative currency: a natural lifestyle and resistance to conventional food production compensate for economic burdens. Common income sources are fees (tours, workshops and consultation) and grants, especially for young sites. Small food forests with on-site gastronomy primarily provide an aesthetic service, and their owners subsidize them. Large and mature food forests are economically viable with diversified income sources or a few high-selling products or services (e.g., Essgarten, Foodforest Ketelsbroek, and Fazenda Ouro Fino).

Economic H -Formalized Organization
Almost all food forests (13 of 14) are run through a registered association or a business. Few practitioners, however, track yields and do full bookkeeping. Younger food forests design a site plan. Design and management techniques differ, building on British forest gardening, Australian permaculture, Swiss-Brazilian syntropic farming, farming practices from Kenya, and Indigenous food systems in Brazil. Apart from Permaculture Design Certificate and Permaculture Teacher Certificate for general design principles, there is no certified food forest education. Accordingly, food foresters have diverse educational backgrounds, often in creative or social professions. The managers of four food forestsall focused on food services-have professional backgrounds in agriculture, forestry, or landscape architecture.

Economic I -Shared Ownership and Decision-Making
The majority of food forests (9 of 14) are in private ownership. Often, one person manages the site and has exclusive decision-making power. A few food forests, like Den Food Bosch or Castle Garden, formed a foundation or employee-owned business with a board for collective decision-making. About half of the food forests face lease insecurity, with short-term leases on private or public land.

Services of Food Forests
Food forests are often part of multifunctional spaces and organizational hybrids with diverse services, products, and other income sources. Apart from producing food, all of them offer socialcultural and/or environmental services. The large majority of the food forests in the full sample (n=209) are small and focus on education and community building (70%), while only a few pursue food production on a substantive level (11%). Still fewer cases (<5%) prioritize food processing or serving as a nursery. The focus on social-cultural services reflects the community gardening trend (Bukowski & Munsell, 2018) and the social-cultural background of many food forest initiators. For developing food forests as food businesses, practi-tioners often have insufficient farming or market gardening experience, specialty crop knowledge, and entrepreneurial training. Guidance on efficient design and management techniques like syntropic farming or restoration agriculture was not widely available (in English) until recently (Giezen, 2018;Shepard, 2013). To harness the food production potential of food forests and contribute to wider food system change, specific training and research on food forests should to be offered and conducted more broadly.

Sustainability of Food Forests
Food forests contribute to a diverse food system with perennial crops and experiential educational and recreational offerings around food and ecology. Many perform well on social-ecological criteria but display weaknesses on economic criteria. As 30% of the food forests studied in-depth are young (<5 years), their economic viability may still be developing. They could learn from mature food forests that diversified their product range or focused on a few main products or services. Weak economic viability-common in many permaculture farms-may also be overcome by monetarizing the value of ecosystem services and receiving adequate compensation (Fiebrig et al., 2020). However, such compensation policies to date focus on agro-industrial sites; this poses a structural barrier to the economic viability of agro-ecological solutions such as food forests (Fernandez et al., 2013;Smith et al., 2012).
Generally, the pursuit of cooperative ownership models may address several sustainability challenges, such as work overload, high land prices, limited start-up funds, and late return on investment. Initiated collectively, a group (and community) could invest into setup and management, share specialty knowledge, value individual net benefits, and promote self-governing practices (Bukowski & Munsell, 2018;Poteete et al., 2010). Collective ownership models such as cooperatives, land trusts, or foundations may also help accessing larger land parcels to increase food production potential. Generally, for wider agroforestry uptake, a "cognitive unlocking process" might help with adopting holistic agro-ecological practices rather than following the dominant reductionist paradigm towards agriculture . This calls again for specific training and research to be offered in vocational schools, colleges, and universities. Interestingly, for all sustainability gaps identified at individual food forests, we found solutions at other sites-which points to an even larger cooperation potential.

Study Limitations
The presented findings cannot simply be extended to all food forests worldwide due to a number of factors. First, while the overall pool of 209 food forests analyzed is large (the most extensive pool analyzed to date), it is somewhat biased. First, the pool (and subsequently the sample of 14 exemplary food forests) draws mostly on sites in Europe, North America, and South America. This regional bias is due to the search language (English), the general search engines used (DuckDuckGo, Google), and the researchers consulted (inventories). For example, few Australian and New Zealand food forests came up in the general online search, although the permaculture movement that contributed to food forest designs started there (Mollison, 1979(Mollison, , 1981 and country-specific online searches yielded a number of sites. Additionally, a search in Portuguese and Spanish yielded some potentially relevant cases. Finally, some renowned food forests did not respond to our interview request. Beyond the sampling, the study displays other limitations. There were some relevant data gaps for many food forests due to a lack of data collection capacity or due to nondisclosure of data. In addition, the presented assessment offers initial results for a moderately sized sample (n=14) with a broad criteria set, which could be further specified for indepth research. For a full assessment, longer monitoring periods of outputs and outcomes at each site are necessary (Park & Higgs, 2018). And for higher validity, more cases would need to be studied in detail and included in comparative studies.

Conclusions
Food forests differ in what main services they offer and how sustainable they are. For the main services, there is a focus on social-cultural services (education, community building) and less on food Journal of Agriculture, Food Systems, and Community Development ISSN: 2152-0801 online https://foodsystemsjournal.org Advance online publication 13 production. Food forests often perform well on social-cultural and environmental criteria, while displaying weaknesses in economic ones, especially regarding economic viability and sustainable business model innovation. Yet, best practices can be found across the cases, e.g., for inclusive ownership through cooperative, land trust, and foundation models. Advances in specific food forest education (farming, business practices) and the transfer of best practices across food forests are necessary to harness the full potential of this multifunctional sustainability solution. While this study offers a broad exploratory overview, there are several limitations calling for additional research to validate these findings and allow for wider applicability.