During the 20th century, food markets transformed significantly under the impacts of globalization, increasing urbanization, liberalization of trade, technological changes, resource scarcity combined with the growing world population, and shifts in consumption patterns ^[1][2][3][1,2,3]. The current dominant system, based on industrialized production and globalized food delivery, successfully provided a cheap and diverse supply of food to a growing population, including in low-income countries [4]. However, the dominance of multinational corporations, global integration, standardized organization, long-distance transportation, long supply chains, and the mass production features of the current dominant food supply system raised widespread concerns about its social, economic, and environmental sustainability ^[1][5][1,5]. At the center of these concerns are the pollution of soil and water, greenhouse gas (GHG) emissions, excessive land use, extensive food waste, loss of biodiversity, unfair distribution of the economic value created among supply chain members, poor working conditions for agricultural workers, and adverse impacts of food on human health ^[1][2][5][6][1,2,5,6]. Moreover, consumers are becoming increasingly concerned about the traceability, quality, and safety of food products [7], especially as conventional food supply chain systems suffer from a confidence crisis and have weak affiliated values [5].

Amidst the discontent and criticism surrounding conventional industrialized food supply systems owing to their potential to mitigate some of the sustainability issues associated with these systems, alternative food production and distribution schemes garnered interest in academia and policy-making circles in the last 20 years, including organizational models based on locally grown and distributed food involving short food supply chains (SFSCs) ^[8][9][10][8,9,10].

The most intuitive and commonly cited feature of SFSCs is that they involve some form of network, throughout which food products move from the production to the consumer point and where the number of intermediaries is reduced [11]. However, SFSCs are a multifaceted concept and there is no consensus on a unique and universally accepted definition ^[12][13][12,13]. Herein, the researchers adopt the definition articulated by the European Parliament and of the Council in regulation No 1305/2013 [14], that reflects the previously mentioned characteristics, and defines SFSC as a supply chain that has a limited number of economic operators, is committed to co-operation, local economic development, and involves close geographical and social relations between producers, processors, and consumers. Consistent with this definition, SFSCs can assume various forms, including, for example, farmers’ markets and fairs, farm shops, box delivery schemes, pick-your-own models, community-supported agriculture, consumer cooperatives, internet sales, and farmers’ direct sales to small retailers ^[1][15][16][1,15,16].

The outbreak of the coronavirus disease 2019 (COVID-19) and the consequent implementation of stringent measures by world governments in an effort to isolate cases and limit the transmission of the virus disrupted the global food supply chain, thereby exposing the vulnerabilities and revealing that some parts of the system are not resilient to disruptions outside the normal range ^{[11][14][17][18]}[11,14,17,18]. Considering the vulnerability of the global food supply system exposed by COVID-19, to strengthen the resilience of the system, some authors argue for a multichannel approach to food supply and propose complementing the dominant system with local food production and short supply chains ^{[12][14][15][17][18]}[12,14,15,17,18]. A common assumption in some of the research literature, as well as in political discourse, is that compared to conventional industrialized food supply systems, SFSCs are more economically, socially, and environmentally sustainable ^{[19][20][21][22]}[19,20,21,22]. However, to date, empirical evidence supporting the supposed sustainability of SFSCs is scarce, and this proposition needs further exploration ^{[3][14][19][20]}[3,14,19,20].

The sustainability of supply chains is one of the most explored topics in supply chain management ^[13][23][13,23]. Since Spreckley (1981) [23] articulated the “triple bottom line” framework, which attracted academic and public interest after the work of Elkington (1997) [16], sustainability in supply chains began to be interpreted in terms of the three dimensions of economic prosperity, environmental quality, and social justice. More recently, Dos Santos and Ahmad (2020) articulated an institutional dimension, which refers to the country’s level of institutional support and policies that directly or indirectly promote sustainability [24].

2. Sustainability Impacts of the COVID-19 Pandemic

The multiple dimensions of sustainability are not always complementary. The lockdowns and consequent movement restrictions, as well as the closure of open markets, both of which caused serious difficulties for SFSCs, potentially produced positive marginal effects on environmental sustainability and stimulated some level of technology adoption by SFSC producers; however, they implicated a series of negative impacts on SDGs related to social sustainability, including SDG 1 (no poverty) SDG2 (zero hunger), SDG3 (good health and well-being), SD5 (gender equality), SDG 8 (decent work and economic growth), and SDG10 (reduced inequalities) and SDG11 (sustainable cities and communities). The pandemic crisis affected businesses in SFSCs, causing cash flow shortages and diminishing operating capacities with negative effects on employment and small producers’ income. There may be a trade-off between supply chain sustainability and resilience. The small-scale operations, non-intensive production systems, and the use of organic inputs, which are often the argumentation basis for SFSC sustainability advantages, limit the capacity of SFSCs to constitute a real alternative to the conventional supply system. The pandemic underlined the importance of a resilient food supply system that functions during extreme events and is able to rapidly adjust to market shocks. However, evidence on the comparative resilience of SFSCs in relation to conventional supply chains under the pandemic is largely anecdotal [4]. Small chains suffer from a series of intrinsic limitations. These limitations were evident during the pandemic and constitute the main challenges for the future development of SFSCs. Short chains involve small farmers with limited capabilities in terms of access to financing, logistic infrastructure, technology, knowledge, and innovation capacity, and they require specific resources to address these liabilities. Furthermore, SFSCs were severely conditioned by public policies to combat COVID-19. Notwithstanding the above-mentioned limitations, from a resource-based perspective, SFSCs also present some competitive advantages in a crisis context, such as the current pandemic. Small producers in short chains are often dimensioned according to the available local labor force, so they are not so dependent on immigrant wage workers, and some are able to produce a significant proportion of input resources needed for operation [25]. In addition, the decentralized structure of SFSCs allows the spread of risk among many producers ^[26][46]. SFSCs are not capable of replacing the conventional globalized food supply because of their insufficient productive capacity to offer cheap food in volumes that meet demand. However, it is important to note that the dichotomy between long-chain industrialized supply systems and local short chains is not so clear and there is some level of integration in the system. Small producers often sell their produce in both long and short chains, and small operators tend to specialize in certain types of products not offered by large companies. SFSCs integrated into a system that is predominantly based on production-intensive units increase the resilience of the system by serving as a safety net in the event of any type of major disturbance.

3. Possible Routes to Improve the Sustainability of SFSCs

In the wake of this health crisis, the importance of encouraging local food production and SFSCs to supplement the traditional food supply system and strengthen food supply resilience was reinforced. However, to contribute to the long-term goals of food system resilience, the ability of SFSCs to deliver food in a sustainable way should also be enhanced ^[26][46]. Possible routes to improve the sustainability of SFSCs may involve ecological technology and innovation, as well as clear, tailor-made, well-targeted development strategies and policies that support SFSC actors and are aligned with sustainable goals. These aspects are related because policy development can build the basis for sustainable innovation and can help SFSC actors to overcome intrinsic and contextual constraints to innovation adoption. In terms of technology and innovation, some authors argue that catastrophic global events, such as the COVID-19 pandemic, can trigger complete paradigm shifts, with the introduction of disruptive technologies ^[27][28][75,83]. Notwithstanding the possibility of introducing disruptive technology, sustaining innovation, which entails improving and adapting existing technologies, may be a more pragmatic and short-term solution. Existing technology solutions that are commonly used by long chains can be adapted to fit the low-scale characteristics of SFSCs. Sustainable efficiency-enhancing production and logistics technologies can improve the economic and environmental sustainability of SFSCs. These technologies include e-procurement solutions, intelligent decision support systems and artificial intelligence technology, automation (of production, processing and delivery), outsourced transportation, new farming precise systems that are climate-smart, technologies to reduce carbon emissions and improve input use, biofertilizers, expansion of sustainable micro-agriculture models (e.g., vertical hydroponic farming, rooftop agriculture, as well as office and school gardens), biodynamic cultivation methods, and on-farm production of renewable energy. Traceability and quality certification technology can contribute to the economic sustainability of SFSCs. These technologies facilitate food traceability, uncover food piracy, and contribute to the social sustainability of SFSCs by safeguarding public health. Traceability and quality certification technology includes technologies based on genomics and bioinformatics to trace and access the genetic authenticity of food products, such as DNA barcoding or DNA genotyping methods. In addition, the digitalization of business activities favors the economic development of SFSCs. This pathway includes the implementation of scale-appropriate innovations, such as biosensor technologies, satellite navigation systems and positioning technologies, the Internet of Things, radio frequency identification technology, electronic food placement, non-cash payment solutions, and big data. Producers in SFSCs can also improve the sustainability and traceability of the system by improving green supplier selection and related methods and approaches ^[28][29][58,83]. Institutional and governance innovation is also important for the sustainable development of SFSCs. Institutional innovation may involve partnerships linking various actors (small local producers, larger companies, academic institutions, nonprofit organizations, government, and consumers), collaborative ventures for innovation, horizontal collaboration involving coopetition arrangements, cooperative organizations to improve access to markets and to gain scale, landbanks and conservation easements, community land trusts, centers of research excellence linked to enterprise and education, or international networks involving farmers. SFSCs can innovate by exploring new market niches and marketing channels. For example, small farmers can develop new marketing channels by diversifying production through crop rotation or intercropping, enabling harvesting throughout the year, exploring market niches (e.g., organic food and vegan consumers), expanding e-commerce, adopting mobile apps for selling purposes, associating with big e-platforms, as well as complementing agriculture with ecotourism, gastrotourism, and handicrafts. Innovative marketing strategies can facilitate SFSC farmers to better reach consumers, and social marketing studies and programs can help in better understanding consumers’ attitudes, perceptions, and the barriers that influence behavior, while also setting the stage for behavior change toward the type of healthy products usually offered by SFSCs. Regarding public policies to support the sustainable development of SFSCs, the literature emphasizes the importance of incentives for technology adoption and innovation, including financial incentives and knowledge diffusion programs ^[30][31][84,85]. Technology adaptation requires investments and appropriate education for farmers, who are often less experienced in handling such technologies [20]. Another possible government strategy to tackle the economic liabilities of small producers is to provide financial assistance. Financial assistance can assume various forms, including targeted subsidies to support input costs (fuel and other energy sources, transit and parking fees, wholesale market fees, etc.), reimbursement of operational costs, policies that facilitate access to credit (e.g., guaranteed loan programs, interest-free loans, specialized credit services), tax reductions, and tax exemptions. Governments can also invest in providing operational and support infrastructure. This option refers to investment in market structures and infrastructure, such as market facilities and related infrastructures, warehousing facilities, cooling equipment, refrigerated transport vehicles, and the provision of other assets to decrease operational costs. In addition to tangible assets, governments can assist SFSC producers by offering specific services, such as providing market- and environment-related studies and information. The provision of market-related information to SFSC actors can support business decisions. The information provided may include data concerning climatic conditions, input and output market prices, information about labor availability, market demand, or information concerning operators’ environmental performance. Related to the COVID-19 pandemic, and future events of this nature, the researchers highlight the importance of lifting commerce barriers, such as the restrictions imposed on open markets, which constituted a real source of discrimination against supermarkets and other big commerce outlets. In addition to alleviating trade restrictions, it is also important to reduce bureaucratic barriers to ensure easier access to markets and policies that enhance equity and fairness within the supply chain by stimulating fair trade practices. The lack of adequate labor during the pandemic also highlights the importance of employment policies, which may involve financial incentives for new employment, providing personal protective equipment, green channels for immigrant workers in the sector, welfare schemes, disease testing and treatment, the redirection of unemployment in the sector, education about the transmission routes, and information about pandemic prevention. Finally, the researchers emphasize the relevance of governance policies, such as the formation of new institutions for governance, state-supported collaboration between public institutions, SFSC actors, and non-governmental entities toward enhancing sustainability; the creation of public institutions to measure, monitor, and guide sustainable agriculture; and the implementation of certification schemes. SFSCs are very diverse in terms of their organization, structure, and types of actors involved, and policy measures to support these chains need to consider the specificities of each particular chain that is being targeted. However, emerging economies, especially developing countries, are more constrained in their investment options; thus, supranational organizations also have key roles to play, such as by providing liquidity injections or facilitating technology transfer and knowledge acquisition.