Results are structured along the four dimensions of our conceptual framework (Fig. 1) and show actors’ contributions and barriers to FD. At an individual level, regime and niche actors may contribute to FD by adopting self-transcendent sustainability approaches, adopting different strategies towards efficacy with respect to food system sustainability and/or creating different kinds of knowledge. Intra and across levels, actors may also share the created knowledge and/or collaborate towards sustainability and thus contribute to FD. Actors may also be confronted with barriers to FD along the four dimensions, which are either inherent to the internal dynamics of the actors or the dynamics of the current food system (Table 3).
Orientation towards the community good
Among the interviewees, most niche actors and a few regime actors take a self-transcending approach of universalism and benevolence towards food system sustainability. They seem to be oriented towards the community good and prioritize practices going beyond their organizations' interests. Niche actors (N1, N4, N7), as well as interest groups (R12, R33, R34) and NGOs (R21, R22, R32) at the regime level, tackle the promotion of an environmentally sustainable food provision (e.g., increasing biodiversity, the share of organic food or reducing food waste). Some actors have a solidary approach towards the food system. At the niche level, interest groups try to integrate and empower socially disadvantaged citizens, such as immigrants and low-income persons (N9, N10). At the regime level, food banks provide free food to the people in need (R21, R22). About 20.0000 people in poverty get access to food from the largest local food bank. They are supplied with food donations or food (e.g., by retailers, bakeries) by local volunteers, which would have been thrown away otherwise (R22). Finally, niche actors of the resource subsystem (N1, N4, N8) aim to increase economic sustainability by orienting towards a fair price policy for food provision and consumption.
Apart from these self-transcending approaches, most interviewees conduct various practices towards the community good, next to other individualistic orientations –i.e., several niche and regime interviewees across different subsystems (N1, N2, N5-N9, R12, R20, R25, R26, R28, R29) increase citizens' food literacy through knowledge provision (e.g., on cooking skills, food production and origin). Furthermore, actors, mainly at the regime level (N1, N7, R12, R13, R17, R20, R23, R24, R25, R28, R30, R31), promote the re-localization of food provision (e.g., by preserving urban agricultural land (R28, R30) and increasing Vienna's food self-sufficiency (R22, R24, R31). While some niche interviewees (N2, N7, N7, N10) aim to develop large-scale approaches for their innovations, several interviewed regime actors have already implemented large-scale measures to promote, mainly, environmental sustainability. For example, municipal authorities, together with an organic farming association (R12, R14, R28, R31), among others, developed a program for integrating organic food and reducing food waste in public food procurement. Furthermore, retail chains promote organic food and other environmental measures (e.g., food packaging reduction) (R16, R17). An interest group points to the low orientation towards specific citizen-consumers' consumption behaviors (e.g., Halal food) within VUFS (N9) in terms of social sustainability. According to the Austrian trade association, ethnic minorities, such as the Turkish community, seem to consume more vegetables and buy food, often in greater quantities, preferably in specialized grocery shops or at food markets (R18). Interviewees rarely reported about their individualistic orientations. Only a few regime actors of the retail and distribution subsystems highlighted their orientation towards the self-enhancement value of power by increasing their market dominance in Vienna (R16), and of achievement by expanding their product range (R18). According to niche actors (N1, N2, N4), some regime actors (e.g., politicians, mainstream farmers, and retailers) lack an orientation towards social and environmental sustainability.
Efficacy with respect to food and the food system
Interviewees (N2, N6, R21) notice a growing number of niche innovations popping up in Vienna. Actors of the resource subsystem (N4, N7, R11, R14) perceive that these innovations could serve as lighthouse projects for others to follow (e.g., zero-waste packaging in retail). Several niche interviewees try to professionalize their innovations by optimizing niche internal structural processes (e.g., logistical organization of distribution, division of work, and responsibilities) (N1, N2, N5, N7-N9) and by tackling challenges within VUFS, such as legal frameworks change in favor of their innovation (N1, N2, N7). Moreover, niche interviewees (N2, N3, N5-N8) strive for efficacy to out-scale and/or up-scale by continually developing and experimenting with their innovation, expanding on it, and seeking funding for it.
Interviewees mentioned that powerful regime actors might be springboards for niche innovations and could leverage the niches' up-scaling (e.g., creation of laws favoring niches; adaption of niche innovations by the retail chain) (N2, N3, N6, R26, R32). Niche interviewees of the resource subsystem perceived that regime actors supported them in developing efficacy towards the food system (N2, N6). Regime actors of the resource and governance subsystems highlighted the integration of niche innovations into their organizations (R17) or their support for niche development (R11, R18, R22, R32). Furthermore, interviewees (N2, N3, N4, N7-N9, R12) perceive that municipal authorities and the local government can take the lead in contributing to food system sustainability. They may introduce local regulations and measures in favor of niche innovations (e.g., subsidies for sustainability measures) and food system sustainability (e.g., preservation of urban agricultural areas). Yet, municipal authorities (R28) highlight the dependence on national authorities when implementing regulations. Nevertheless, several interviewees of the governance subsystem (N10, R11, R14, R19, R22, R31) already see Vienna's municipal authorities as change agents who take specific sustainability measures, such as increasing the share of organic food and reducing food waste in public food procurement.
A niche interviewee (N10) perceived that niche actors seem to lack efficacy, appreciation, and visibility within the urban food system. They face difficulties finding interested collaboration partners (N2, N7) and suitable financial support (N1-N4, N7-N9) for their innovations. Internal organizational challenges (e.g., logistics, personnel management) seem to prevent niche interviewees from achieving desired outcomes towards food system sustainability (N1-3, N6, N7, N10). Furthermore, niche actors (N1, N2, N7-N9) seem to face restrictions on flexible and free experimentation due to limited financial resources. Niche interviewees perceive that, as soon as their organizations would out- and/or up-scale, they would reach structural, ideological, and financial limits (N1, N6, N7). Besides, most niche interviewees (N1-N3, N5-N8, N10) mention the existence of external barriers of societal (e.g., lack of societal acceptance for innovations), political (e.g., conservative policy, legal restrictions of innovation), and spatial nature (e.g., high rental costs for the limited space) within the VUFS.
Interviewees (N1, N4, N5, N8, N10, R14) perceive that farmers at the niche and the regime level depend on political lobbying and on national and European Union subsidies; they also struggle with an unfair price policy set by mainstream retail chains. Even educational organizations seem to depend on funding driven by economic or political interests (N5, R14). Niche and regime resource subsystem interviewees (N4, N8, R14, R15) criticize mainstream retail chains and gastronomy for their lack of sustainability resulting from a low and aggressive price policy. Moreover, several niche actors stated (N5, N7, N10) that mainstream retail chains and the food industry would misuse powers (e.g., lobbying, manipulation, putting pressure on other actors).
Finally, public organizations (R19, R20) perceive a lack of financial resources for food purchasing. Hence, sustainability quotas of public food procurement programs set by municipal authorities are difficult to meet.
Collaboration towards food system sustainability
Food actors established different collaboration types towards food system sustainability within or across the niche and the regime level, to jointly produce results, which cannot be achieved individually. Social collaborations occur both at niche and regime level. Niche actors meet and exchange within local networks, within their niche (N1-N3) or across niches (N1, N2, N5, N6, N8) as well as trans-locally. As the number of niche innovations rises, interviewees (N1, N2, N6-N10, R28) highlight the need for increased trust-building collaborations among niche actors and their stakeholders to empower them and to create a clear joint vision. Networking towards food system sustainability happens within (R11, R18, R20) and across different subsystems at the regime level. Both regime and niche interviewees (N1, N7-N10, R11, R22, R32) mention an exchange towards food system sustainability with municipal authorities and political parties. Several niche and regime actors (N3-N5, R22, R28) aim to exchange with educational institutions to spread or source information about food system sustainability.
Furthermore, resource collaborations towards food system sustainability are frequent at the niche and the regime level. At the niche level, actors collaborate materially with each other but also with regime actors by being supplied with food products (N2, N7, N9), by exchanging food products (N1), and by sharing agricultural machines (N1, N5). Moreover, niche actors of the resource subsystem provide or share agricultural fields or stalls on farmer markets (N1, N3, N4). Furthermore, the latter (N1-N3, N7, N8) also mentioned the provision of space and infrastructure (e.g., agricultural fields, kitchen, storage space) by regime actors (e.g., mainstream farmers, retailers, and restaurateurs), enabling niche actors to offer their food products and to experiment. Yet, at the regime level, interviewees seem to build material or spatial resource collaborations rarely. At the regime level, interviewees from the governance subsystem (R18, R28, R32) mentioned resource collaborations with niche actors who support their innovations with financial subsidies. Vice versa, niche interviewees (N2, N5-N9) claimed to receive financial subsidies from the latter. If needed, food citizens (e.g., friends and family) also support them financially (N1, N6, N8). At the regime level, interest groups and research institutions (R11, R12, R24, R31, R34) receive subsidies for taking sustainable measures (e.g., increasing the organic food share, training activities, academic work).
Institutional collaborations (concerning rules, regulations, and laws towards food system sustainability) are frequent between niche (N2-N4, N7) and regime actors of the governance subsystem (e.g., R27, R29) (e.g., implementing laws in favor of innovations). Regime actors collaborate to push regulations and interests (e.g., organic food) (R12, R14) and to implement guidelines and labels imposing sustainability criteria (R11, R26).
Niche interviewees (N1-N3, N7) perceive the lack of temporal and financial resources as barriers to networking and establishing collaborations. While niche actors (N1, N7) perceive that high bureaucracy levels seem to impede the building of collaborations, several interviewees (N1, N2, N7, N10, R14) sense that niche actors are often too radical and their innovations too expensive, which seems to keep regime actors from collaborating with them. Also, niche actors' low capacities (and sometimes unwillingness) to upscale and to adapt to mainstream structures seem to make a collaboration challenging (N10, R17). Furthermore, niche interviewees perceive a lack of trust (N3) and skepticism (N2) by regime actors (e.g., potential investors). Vice versa, a retail chain (R17) perceives a lack of trust by niche interviewees (N1, N5, N7, N10) (e.g., presumed non-adherence to agreements).
(Co-)learning towards food and the food system
Within VUFS, actors, at the niche and the regime level, produce different knowledge types about food and the food system; and they share it in one-way or mutual interaction(s). All niche interviewees produce strategic knowledge on how their innovations could solve specific sustainability issues within the food system. Niche actors seem especially interested in potential leverage effects they could nudge with their innovations (N2, N3, N6-N8). They also seem to develop ideas on how to change the food system with their innovations by involving food citizens (N7, N10), suppliers (N2, N7), investors (N6), or municipal authorities (N2, N10). Furthermore, niche and regime interviewees (N1-N3, N6-N8, R11, R18, R25, R27) strategically learn about landscape settings in and beyond Vienna (e.g., spatial conditions, legal concerns, food trends, potential target groups, collaboration partners). At the regime level, actors form the resource and governance subsystems (R12, R14, R25, R32) co-produce strategic knowledge with municipal authorities (e.g., R31) and/or universities (e.g., on innovations and measures that address specific sustainability issues) (e.g., R34). Several niche actors are international first movers in their field on a local or trans-local scale. Therefore, they have to create their own experiences, as other learning sources are rare (N1-N3, N5, N7, N8). Experiential knowledge production through trial and error is common among niche actors (N1, N4-N7). Only interest groups and a wholesale market at the regime level mentioned exchanging experiential knowledge with niche actors (R11, R32) or other regime actors (R15, R20).
Several niche actors and some regime actors, such as interest groups (R25), local authorities (R30), and research institutions (R24, R34), support food citizens in the creation of experiential food knowledge by organizing tastings and cooking courses (N2, N3, N9, R24), by enabling farm and garden visits as well as guided farm tours (N1, N3, N5, R25, R34) or by creating spaces for discourse about food and the local food system (N8, N10, R30). Scientific knowledge on niche innovations is often produced in cooperation with universities (N1-N3, N5, N7) and expert panels (N2, N3). At the regime level, actors from all subsystems either conduct studies about food system sustainability themselves (R12, R16, R28, R32, R33) or in co-production with municipal authorities (R24 with R28), with universities, or with other research institutes (R14, R22, R32).
Interviewees identified a lack of knowledge about food and the food system, especially of food citizens. Several interviewees noticed a decrease in citizens' food literacy (e.g., cooking skills (N6, N8)) as well as in knowledge on seasonality (N8), origin (N1, N4, R21), and food quality (N4, N8). Niche interviewees sense barriers towards (co-)learning in scarce financial and time resources (N1, N2, N10) as well as in the inability to limit knowledge production to the most relevant topics (N1, N2, N4). Niche and regime actors from the resource and governance subsystems (N1-N4, N6-8, R14, R22, R28) perceive that especially educational institutions, politicians, media, and other powerful actors have the potential and the responsibility to raise more awareness towards food and the food system. However, interviewees (N1-N5, R14) even named the production of questionable knowledge by media as a significant barrier. Moreover, one interviewee (N5) stressed that lobbyists influence knowledge production (e.g., by granting financial support to educational organizations). Finally, several interviewees from the resource subsystem (N1-3, N7, N8, R14, R21) criticized regime actors, such as retailers, the food industry, and restaurateurs, for their "greenwashing" strategies (e.g., manipulative advertising, misinformation) and their unwillingness to provide knowledge about food quality, origin, and seasonality.