The Complex Pathway towards Farm-Level Sustainable Intensiﬁcation: An Exploratory Network Analysis of Stakeholders’ Knowledge and Perception

: Farm-level sustainable intensiﬁcation of agriculture (SIA) has become an important concept to ensuring food security while minimising negative externalities. However, progress towards its achievement is often constrained by the di ﬀ erent perceptions and goals of various stakeholders that a ﬀ ect farm management decisions. This study examines farm-level SIA as a dynamic system with interactive components that are determined by the interests of the stakeholders involved. A systems thinking approach was used to identify and describe the pathways towards farm-level SIA across the three main pillars of sustainability. An explanatory network analysis of fuzzy cognitive maps (FCMs) that were collectively created by representative groups of farmers, farm advisors and policy makers was performed. The study shows that SIA is a complex dynamic system, a ﬀ ected by cognitive beliefs and particular knowledge within stakeholder groups. The study concludes that, although farm-level SIA is a complex process, common goals can be identiﬁed in collective decision making.


Introduction
The predicted increase in world population and shifts in human dietary trends are likely to cause a greater demand for food [1]. This places increased pressure on agriculture to intensify food production against a backdrop of increasing scarcity of additional land for agriculture [2] and major threats to the global environment from commercial farming [3][4][5]. In the face of these global challenges, the concept of sustainable intensification of agriculture (SIA) has come to the fore in recent years [6]. SIA represents an increase in agricultural production through sustainable development, which is widely accepted by international policy and research as a concept consisting of three main pillars: economic, social an environmental [7,8].
The European Union (EU) is the largest agricultural importer in the world [9]. As such, it is associated with environmental damage in exporting countries [10] and is food-dependent on regions where food security issues may arise in the future [11]. This makes SIA in Europe a necessity. However, global versus European perspectives differ in terms of SIA, e.g., European agriculture is already very intensive and problems such as rural-urban migration and widespread land abandonment are much greater than land scarcity and food security [12]. Therefore, for SIA in Europe, the critical issues are stakeholders' views. The potential outcome of this study is the creation of a tool that could identify blockages in the communication of stakeholders and assist in the identification of common goals.
The paper is outlined as follows: initially, the methodology is outlined in detail, including the data collection, materials, and the visualisation and analysis techniques. Then the results are presented in the form of tables and maps, followed by a discussion of the main findings. Finally, some policy implications are raised, before presentation of some concluding remarks.

FCM Participatory Process
To understand the structural and functional aspects of how different stakeholders conceptualise the implementation of SIA on European farms, FCMs were constructed from groups of stakeholders (farmers, advisors and policy implementers) that influence the farm management decision-making process. The FCMs produced for each group were compared using semi-quantitative analysis (outlined below) and aggregated to produce a final SIA map. Combining the FCMs produced a collective FCM that mapped system components (henceforth termed nodes), which linked to a number of selected sustainability indicators.
The main elements of an FCM are: nodes, which represent concepts (or components); edges, which represent the links between nodes (indicated by arrows); and edge weights, which indicate the influence (positive or negative) and strength of the relationship between nodes ( Figure 1). FCMs can then be analysed and explained using exploratory network analysis methods, which allow for the quantification of the map links and the in-depth explanation of their structure.
stakeholders' views. The potential outcome of this study is the creation of a tool that could identify blockages in the communication of stakeholders and assist in the identification of common goals.
The paper is outlined as follows: initially, the methodology is outlined in detail, including the data collection, materials, and the visualisation and analysis techniques. Then the results are presented in the form of tables and maps, followed by a discussion of the main findings. Finally, some policy implications are raised, before presentation of some concluding remarks.

FCM Participatory Process
To understand the structural and functional aspects of how different stakeholders conceptualise the implementation of SIA on European farms, FCMs were constructed from groups of stakeholders (farmers, advisors and policy implementers) that influence the farm management decision-making process. The FCMs produced for each group were compared using semi-quantitative analysis (outlined below) and aggregated to produce a final SIA map. Combining the FCMs produced a collective FCM that mapped system components (henceforth termed nodes), which linked to a number of selected sustainability indicators.
The main elements of an FCM are: nodes, which represent concepts (or components); edges, which represent the links between nodes (indicated by arrows); and edge weights, which indicate the influence (positive or negative) and strength of the relationship between nodes ( Figure 1). FCMs can then be analysed and explained using exploratory network analysis methods, which allow for the quantification of the map links and the in-depth explanation of their structure.

Group Mapping Exercise
The FCMs from these stakeholder groups, representing farmers, agricultural advisors and agricultural/environmental policy makers were constructed in a participatory exercise, hosted in Ireland during a workshop organized within the Marie Curie INSPIRATION Innovative Training Network (project 675120). The workshop invited stakeholders' representatives to participate for a fee. In total, 48 people participated in the workshop, including farmers, advisors, social and agrienvironmental scientists, and policy implementers from a number of European countries including Ireland, the UK, Belgium, Germany, Greece and France. Please note no personal and demographic

Group Mapping Exercise
The FCMs from these stakeholder groups, representing farmers, agricultural advisors and agricultural/environmental policy makers were constructed in a participatory exercise, hosted in Ireland during a workshop organized within the Marie Curie INSPIRATION Innovative Training Network (project 675120). The workshop invited stakeholders' representatives to participate for a fee. In total, 48 people participated in the workshop, including farmers, advisors, social and Sustainability 2020, 12, 2578 4 of 20 agri-environmental scientists, and policy implementers from a number of European countries including Ireland, the UK, Belgium, Germany, Greece and France. Please note no personal and demographic data were recorded during the workshop, partly due to confidentiality issues, but mainly to avoid potentially biased behaviour between individuals in each group. Three stakeholder groups were formed: a group including farmers, a group including agricultural advisors and applied researchers and a group including policy makers. Because of the participation of researchers in the workshop, all groups included a number of researchers: the farmers' group included two, the advisory group four and the policy making group three. These were equal participants in the groups, and the trained facilitators were entrusted with ensuring the avoidance of bias. Representatives from applied research and academic institutions, with knowledge of the SIA concept, facilitated each group discussion. The main roles of the facilitators were to guide the discussion, to provide for the participation of all members of the group, and to ensure the avoidance of bias between group participants. To make sure that facilitators were able to help the group engage in productive conversation in a neutral and accepted way, two preparatory meetings, including the creation of "mock" FCMs, were held, where potential issues of bias were raised and discussed. The exercise was based on the method suggested by Gray [37], whereby nine SIA indicators (Table 1) were presented to each group to guide construction of the FCMs. At the beginning of the exercise, each group was given a 150 cm 2 blank sheet of paper containing nine pre-defined farm-level SIA indicators (Table 1), in random order (on sticky notes). Based on personal perception and experience, the groups were asked to link them using directed arrows (Figure 1), indicating their perceived degree of influence: negative high (-), medium (-) and low (-), and positive low (+), medium (++) and high (+++). Then, workshop participants were asked to engage in a brainstorming discussion, assisted by the facilitators, to identify other components that they considered to influence the indicators and structurally connect them to each other and to the indicators, as they perceived it to be realistic.

Selection of Farm-Level SIA Indicators
The indicators which groups were asked to build their maps around were selected from papers in the literature analysing SIA assessment at farm level [47][48][49], based on the following criteria: a.
They were measurable at farm-/farm household-level; b.
They were relevant to European agricultural production; c.
They represent intensive and/or intensifying farms. The term intensifying refers to farms that may not be as intensive, but have a likelihood to intensify in order to contribute to food security, for example livestock or arable farms as opposed to wine-making or flower producing farms; d.
They are identified in the literature as consistent and measurable across time; e.
They equally represent the three main sustainability pillars (environmental, economic and social).
The farm-level indicators of the SIA selected are presented in Table 1.

Exploratory Network Analysis
Gephi © software was used for the visualization and analysis of the FCMs. The FCMs were analysed using the exploratory network analysis method based on graph theory, according to which cognitive maps are transformed into adjacency matrices where the nodes are listed on the vertical and the horizontal axes. When a connection exists between two nodes its weight is coded in the matrix as a number [50,51]. According to graph theory, the results of the FCM can be quantified based on a number of statistical outcomes from the adjacent matrix. The metrics used to compare components and for structural analysis of FCMs are presented in Tables 2 and 3 were used to explore the content of the FCMs and compare the nodes that appear in each map.
The degree of centrality of a node pondered by the total weight of all its edges Dominant Table 3. Metrics used for structural analysis and comparison of FCMs.

Metrics Numerical Expression Definition
Number of nodes N The number of components in the map Number of edges E The total number of linkages between components Density Dn = E/N (N − 1) Indicates how densely nodes are connected.
Here, a represents each edge, i is the transmitter node of edge a, j is the receiving node of edge a and W is the weight of edge a.
Central nodes (high D) are the largest circles on a map (Figures 2-6), representing the most important components to the particular group, which have the most edges entering and exiting. Dominant nodes (high WD) are also signified by the high weights ('+++' or '-') of the arrows entering or exiting. They may or may not be central, but they also highly influence the system. A node is a receiver, where many arrows enter it (high ID). A node is defined as affected (high WID) when the overall weight of the arrows entering it is high. A node is a driver (high OD) when a large number of arrows exit it. A node is influential (high WOD) where the weight of the arrows exiting it is high. From the individual stakeholder types, "unique nodes" were also identified, representing factors that were only identified and considered by that particular stakeholder group. The comparison of the FCMs involves calculating values for the components of each system and indicating the similarities and differences between them. Once the aggregated map was constructed, common components were identified which occurred across all maps. Finally, for the discussion and interpretation of the results, further face-toface interviews and consultations with the facilitators (two per group) and some of the participants enabled verification and explanation of the results. These interviews were performed for the clarification of the meanings of the nodes and edges, as they emerged in the discussion during the creation of the FCMs. The outcomes of the interviews were, therefore, used as guidelines for the discussion of the results of our FCM analysis, along with the relevant literature.
The methodological flow combines this process of building group-designed cognitive maps with the quantitative exploratory analysis, all of which is verified by in-depth interviews. This combination of methods allows for a deeper investigation of farm-level SIA from different perspectives, therefore providing more robust results. It also allows for a thorough understanding of the combined stakeholder knowledge on farm-level SIA, not only for the researchers but also for the stakeholders themselves, thereby facilitating loop learning. Table 4 shows the results of comparing the FCMs. Table 5 presents the results of the analysis for the comparison of nodes within and between maps, and is a summary of important nodes for each group FCM and the aggregate FCM.

Map Aggregation
After an initial comparison, individual FCMs were aggregated into a final FCM with a new adjacent matrix and a "reinforced" weight for the edges that appeared in more than one FCM. The aggregation was conducted qualitatively [52]. Here, the reinforced edge weights are the result of adding the edge weight of the individual FCMs (example shown in Figure 2).
Once the aggregated map was constructed, common components were identified which occurred across all maps. Finally, for the discussion and interpretation of the results, further face-to-face interviews and consultations with the facilitators (two per group) and some of the participants enabled verification and explanation of the results. These interviews were performed for the clarification of the meanings of the nodes and edges, as they emerged in the discussion during the creation of the FCMs. The outcomes of the interviews were, therefore, used as guidelines for the discussion of the results of our FCM analysis, along with the relevant literature.
The methodological flow combines this process of building group-designed cognitive maps with the quantitative exploratory analysis, all of which is verified by in-depth interviews. This combination of methods allows for a deeper investigation of farm-level SIA from different perspectives, therefore providing more robust results. It also allows for a thorough understanding of the combined stakeholder knowledge on farm-level SIA, not only for the researchers but also for the stakeholders themselves, thereby facilitating loop learning. Table 4 shows the results of comparing the FCMs. Table 5 presents the results of the analysis for the comparison of nodes within and between maps, and is a summary of important nodes for each group FCM and the aggregate FCM.  Table 5. Comparison between FCM components: in-degree, out-degree and degree of centrality.

Farmers' Group FCM
A visual representation of the farmers' group FCM is presented in Figure 3. The farmers' FCM ( Figure 3) has 30 nodes (including the 9 pre-defined indicators) connected with 84 edges, and a map density of 0.097 (Table 4). As seen in Table 5, the most central nodes are income, yield, succession, P balance and biodiversity. Yield and technology/infrastructure are the most dominant nodes, followed by knowledge transfer, income, social capital succession, farm innovation, agri-environmental schemes, biodiversity and weather extremes. The highest receivers are income and yield. Yield, income and market orientation were strongly positively affected, and P balance is the most negatively affected node (P balance appears as the most negative node because, although it is not the one where the highest number of edges come in, their cumulative weight is the highest in the map. This is based on farmers' understanding of the strong relations between P balance at farm level and the factors that affect it) No highly important drivers were identified. Knowledge transfer was highly positively influential (Table 2), together with technology/infrastructure, farm innovation and agri-environmental schemes. Weather extremes negatively influence the system. Six nodes are unique to the group: farmers' attitude, urban migration, labour market, farm fragmentation, land prices and agri-environmental schemes.

Farmers' Group FCM
A visual representation of the farmers' group FCM is presented in Figure 3.  (Table 4). As seen in Table 5, the most central nodes are income, yield, succession, P balance and biodiversity. Yield and technology/infrastructure are the most dominant nodes, followed by knowledge transfer, income, social capital succession, farm innovation, agrienvironmental schemes, biodiversity and weather extremes. The highest receivers are income and yield. Yield, income and market orientation were strongly positively affected, and P balance is the most negatively affected node (P balance appears as the most negative node because, although it is not the one where the highest number of edges come in, their cumulative weight is the highest in the map. This is based on farmers' understanding of the strong relations between P balance at farm level and

Advisors' Group FCM
A visual representation of the advisors' group FCM is presented in Figure 4. The advisors' FCM ( Figure 4) has 35 nodes (including the indicators), 96 edges, and a density of 0.077 (Table 4). According to Table 5, yield and less favoured area are the most central nodes, followed by succession, subsidies and water quality. The most dominant nodes are water quality, income, succession, yield and subsidies. The highest receivers are biodiversity and yield. Yield and income are positively influenced, whereas water quality is negatively influenced. There are no big influencers, but many nodes have equal smaller WIDs (except water quality with WD = −19). Eight nodes are unique to this group: farmers' identity, age, education, income support, water quality, labour units, and farm size.   (Table 4). According to Table 5, yield and less favoured area are the most central nodes, followed by succession, subsidies and water quality. The most dominant nodes are water quality, income, succession, yield and subsidies. The highest receivers are biodiversity and yield. Yield and income are positively influenced, whereas water quality is negatively influenced. There are no big influencers, but many nodes have equal smaller WIDs (except water quality with WD = −19). Eight nodes are unique to this group: farmers' identity, age, education, income support, water quality, labour units, and farm size.

Policy Makers' Group FCM
The policy group map has 39 nodes (including the indicators) and 85 edges. The density of the system is 0.056 (Table 4). Yield, income and resilience are the most central components of the map (Table 5, Figure 4).

Policy Makers' Group FCM
The policy group map has 39 nodes (including the indicators) and 85 edges. The density of the system is 0.056 (Table 4). Yield, income and resilience are the most central components of the map (Table 5, Figure 4).
Yield and resilience are also among the most dominant components, followed by future planning, slurry, research and nitrogen balance. Both yield and resilience are the highest receivers of the map and the most positively affected nodes, while N and P balances are the most negatively affected nodes. No node was identified as a major driver, whereas research is a positive influencer (WOD = 10, Table 5). No strong negative influencers were identified. Seven nodes were unique to the group: energy, non-farm activities on farm, policy design, future planning, research, insecticides and soil fertility. Yield and resilience are also among the most dominant components, followed by future planning, slurry, research and nitrogen balance. Both yield and resilience are the highest receivers of the map and the most positively affected nodes, while N and P balances are the most negatively affected nodes. No node was identified as a major driver, whereas research is a positive influencer (WOD = 10, Table 5). No strong negative influencers were identified. Seven nodes were unique to the group: energy, nonfarm activities on farm, policy design, future planning, research, insecticides and soil fertility.

Aggregate FCM
This FCM represents the complete farm SIA system ( Figure 6) as viewed by all stakeholders involved in this study.

Aggregate FCM
This FCM represents the complete farm SIA system ( Figure 6) as viewed by all stakeholders involved in this study.
It allows the boundaries of the realisation of SIA at farm-level to be defined, and depicts the path towards SIA in a holistic manner. The aggregate FCM has 53 nodes, 233 edges and a density of 0.08 ( Table 2, Table 4 and Figure 5). The most central nodes are yield, income, social capital, biodiversity and resilience. Due to the high number of nodes, degree values above 20 are considered high unless the absolute value of the highest degree is less than 20. This decision was made as part of the analysis. In the design of the workshop, it was possible to predict neither the number of nodes, nor their centrality, and therefore such a decision is not possible to make until the results are visible. Yield is the most dominant component, followed by succession, income, technology/infrastructure, knowledge transfer, resilience, social capital and weather extremes, with a negative WD ( Table 5). The highest receivers on the map are yield, income, and biodiversity. From the positively affected nodes, yield stands out with an ID of 56 (Table 5), and income and succession follow. The most negatively affected nodes are water quality and P balance. The aggregated system does not appear to have any high drivers (the highest OD is 13 for knowledge transfer, Table 5). Technology/infrastructure and knowledge transfer are positively influential and weather extremes is a major negative influencer. It allows the boundaries of the realisation of SIA at farm-level to be defined, and depicts the path towards SIA in a holistic manner. The aggregate FCM has 53 nodes, 233 edges and a density of 0.08 ( Table 2, Table 4 and Figure 5). The most central nodes are yield, income, social capital, biodiversity and resilience. Due to the high number of nodes, degree values above 20 are considered high unless the absolute value of the highest degree is less than 20. This decision was made as part of the analysis. In the design of the workshop, it was possible to predict neither the number of nodes, nor their centrality, and therefore such a decision is not possible to make until the results are visible. Yield is the most dominant component, followed by succession, income, technology/infrastructure, knowledge transfer, resilience, social capital and weather extremes, with a negative WD ( Table 5). The highest receivers on the map are yield, income, and biodiversity. From the positively affected nodes, yield stands out with an ID of 56 (Table 5), and income and succession follow. The most negatively affected nodes are water quality and P balance. The aggregated system does not appear to have any high drivers (the highest OD is 13 for knowledge transfer, Table 5). Technology/infrastructure and knowledge transfer are positively influential and weather extremes is a major negative influencer.

Nodes of Group and Aggregate FCMs.
Herein some of the most important nodes of the aggregate map are discussed. The discussion focuses on central and influential components identified by the stakeholders' groups that were not among the predefined indicators. The only exception is yield, because of its great centrality in the aggregate map.

Nodes of Group and Aggregate FCMs
Herein some of the most important nodes of the aggregate map are discussed. The discussion focuses on central and influential components identified by the stakeholders' groups that were not among the predefined indicators. The only exception is yield, because of its great centrality in the aggregate map.
• "Yield" is the only predefined indicator that solely represents agricultural intensification. Increased yield generally results from intensification, with its primary purpose to increase farm output and farm income. Therefore, yield is considered more an outcome affected by management decisions rather than a contributor to the sustainable development of a farm system [53]. The FCMs produced during this study support this theory; in all FCMs, yield was a significant receiver and by far the most influenced component, but itself was a weak driver, affecting only the other two economic indicators (Figures 3-6). This suggests that yield "stands above" the whole farm system, and can be considered a goal in its own right [54]. At the same time the high centrality of yield across all stakeholder groups indicates how important they all consider it for the farm (and SIA therein) and how it is interrelated to all components and elements in the SIA system. • "Knowledge transfer" (KT) is a component common to all three stakeholder groups and one of the strongest influencers in the aggregate map. In the farmers' map, KT directly affects all social indicators, two economic indicators and one environmental indicator (resilience, succession, social capital, yield, market orientation, biodiversity), while it indirectly links to income through yield (Figure 3). This link between KT and all three sustainability pillars (Table 1) is an acknowledgement of the perceived benefits of KT services by farmers. [55]. In the advisors' map, KT is directly linked to the economic indicators and to subsidies. According to the advisors, this outcome reflects the view that advisors mainly act as administrators who deal with farm grant and subsidy applications and ensure the financial stability of farms [56]. However, with most farm subsidies promoting best-practice methods of production [57], it is not surprising that there is a strong indirect effect of KT on environmental indicators. For policy makers, KT did not feature as strongly in their FCM. The over-riding concern of policy makers is the development of policies and achieving stated objectives, thus they are not so concerned with the details of KT services and how those may influence farm management. As expected, in the aggregate map, knowledge transfer is a highly dominant component with a strong positive influence. This highlights the overall importance of KT for SIA at the farm level, which is confirmed in previous studies [33,56,58]. • "Water quality" is an ecosystem service that can be monitored and regulated at the farm level, primarily through the control of nutrient inputs [59]. Intensive agriculture is often thought to impose greater pressure on water quality [60]. However, less intensive production systems can pose a significant threat too, under certain biophysical and climate conditions [61]. Water quality is a dominant component of the advisors' FCM, and although unique to this group, the weighted degree value of water quality is high enough to make it a dominant component in the aggregate map. Agricultural advisors play a key role in the dissemination and enforcement of regulations set out by the EU Water Framework Directive and thus recognise the importance of water quality in the SI of agricultural systems. Conversely, farmers do not consider water quality such an important aspect of SI, due possibly to the lack of a direct link between water quality and farm productivity [62]. • "Weather extremes" refer to uncontrollable weather events such as storms, flooding and drought, and are a common component of all the FCMs. Weather extremes are the main negative influencer in the aggregate map. According to the FCMs, weather extremes play an important role in the farm system, by influencing the decision-making process while being outside human control. An example of this is the requirement to import feed for livestock during periods of fodder shortage caused by storms or drought, which adds significantly to the annual feed bill. All stakeholder groups identified a negative influence of weather extremes on farm resilience (Figures 3-6). The references to extreme weather in this study are likely to reflect the negative impact extreme weather events have on agricultural production [63,64]. Such extreme weather events are increasing in frequency due to climate change effects [65]. As weather extremes become more frequent [66], policies for SIA will need to include measures that increase resilience of farm systems to severe weather events, a fact that, as this study confirms, is recognized by all stakeholders. • Improved "technology/infrastructure" has a positive influence on farm SIA according to the aggregate map and is strongly linked to all economic and social indicators. The link between technological and infrastructure development in rural areas, and the economic and social sustainability of farming enterprises is depicted in research [23,67,68]. Despite this, only the farmer group considered technology and infrastructure to be a dominant component that influences the farm system (Table 5). According to farmers, technology and infrastructure refers to various services in their locality, ranging from broadband access to health and financial services to rural life quality. The importance of technology and infrastructure perceived by farmers for farm SIA is supported by Buysse, Verspecht [69]. However, the influence of technology and infrastructure on SI appears to be underestimated by the other stakeholder groups. This contradiction was explained in further discussions with the facilitators: infrastructure is important to the farmers as individuals, but it is not always essential for a farm to survive. Therefore, although advisors and policy makers may recognize its importance to the farmers' quality of life, they do not fully appreciate its importance for farm-level SIA.

Group Comparison
The farmers' map shows a relatively closed system (density of 0.1). The high density of the farmers' map indicates that farmers recognize that all farm management elements are interrelated and they understand the dynamic nature of the farm management process. It also expresses the belief that farm-level SIA can be achieved by balancing the existing components, without greatly increasing the complexity of the system. Based on this system description, farm-level SIA appears as a more feasible goal (compared with the other two groups) that can be achieved through strategic changes to the most dominant nodes (e.g., yield, income, water quality, weather extremes, knowledge transfer etc.). However, the higher density of the farmers' map also indicates that the farmers' goals are specific to their farm businesses and have little focus on their role in achieving SIA beyond the boundaries of their farms [62]. In addition, the components identified as important show that farmers evaluate farm efficiency based on practical conditions on their farms, and their perception of sustainable management is only relevant to reaching specific goals [70].
The advisory group map depicts a moderately closed system with no highly central or dominant nodes (except water quality). This means that many nodes have small but equal interactions with the system. This indicates that advisors' knowledge of farm-level SIA does not focus on specific areas within the SIA system and, like farmers, this group sees potential in balancing the existing components for achieving SIA. Conversely, the policy map showed an open system, with many components that loosely interact with each other. In addition, most nodes in the policy FCM are identified only as receivers (OD = 0) or drivers (ID-0) ( Table 5) and have very low WIDs and WODs. This indicates a direct causal relationship between a few components, but a low overall interaction of components within the system. A possible explanation for this is that policy involves several elements from design to monitoring and regulation, and can include various actors (e.g., experts, consumers, etc.) who often represent conflicting interests while generally grouped under the policy design umbrella. In turn, this could explain the fact that policy design can often send multiple signals and uphold conflicting interests, which may lead to conflicting policy messages [71]. Indeed, for policy makers, farm SIA can be viewed from different perspectives depending on context, and its goals remain subjective. On the other hand, if SIA is viewed as an overall purpose, then as an open system it provides an opportunity to re-consider practices and develop new approaches [72].
The aggregate map appears to be a highly complicated system ( Figure 6). The complexity of the map depicts the "real life" complexity of achieving farm-level SIA when all stakeholder opinions converge. This confirms that, presently, SIA is not a defined aim but an abstract goal, and achieving it is not a linear process but a dynamic complex approach. The complexity of the map indicates, in principle, that collective decision-making would take longer to resolve [32]. However, this map can provide invaluable knowledge on what needs to be prioritized to achieve SIA, when a farm is "co-managed" by many stakeholders. It allows for the identification of the most important parts of a co-managed system, and enables stakeholders to identify its most important elements.
By examining the unique nodes in each map, the aspects of farm-level SIA that are important to each group but neglected by the others become apparent. For farmers, these include farmers' attitude, and a number of nodes that show the relationship of farm sustainability to socio-economic structures that are beyond a farmer's control. Farm and farmer characteristics are mentioned by the advisors as factors influencing sustainable farm management, a view confirmed widely in the literature [33,73,74]. Finally, policy makers did not include nodes that directly relate to decision-making processes but included concepts that enhance sustainable intensification at wider levels, such as policy design, non-farm activities, farm innovation, research, soil fertility, and future planning, which, as concepts, are all within policy agendas [75]. Particularly for the latter, group participants explained that for them, farm-level sustainable intensification is a common goal and its achievement depends on strategic planning, rather than on the farm and farmer's characteristics. This point seems to have been neglected by the other two groups; however, it indicates that policy makers fail to recognise the individualistic nature of farm-level decision making.

Method Evaluation
The exploratory analysis of FCMs provided an efficient means to investigate stakeholders' views on the pathways towards SIA. For this study, it presented an opportunity to describe elements and factors that they consider important, but also to identify and define how these are interlinked. The method gives stakeholder groups an opportunity to engage. Feedback from face-to-face interviews after the workshop indicated that most participants found the mapping task easy to follow and insightful. Participants reported that the exercise gave them an opportunity to receive an understanding of how their peers viewed SIA and the exercise opened them to conflicting opinions and broadened their own perspective.
The map aggregation process proved valuable for understanding the complexity of the "real life" situation and provided a robust impression of the opportunities and caveats in achieving farm-level SIA, when stakeholders with conflicting opinions have to co-operate for a common goal. The identification and confirmation of this complexity would be difficult without such an approach.
An area for caution with respect to the method is the limited qualitative description of the specific meaning of the components and links, particularly where similar concepts appear in different maps. Furthermore, it is important to know the discussions that led to group choices to avoid data misinterpretation, and when using FCMs for exploratory analysis the lack of qualitative information can be problematic [76]. To overcome this, and to ensure an accurate representation of the thoughts and logic of each group, the role of the facilitators was extended: in addition to co-ordinating the group exercises, facilitators held interviews with group participants after the workshop to ensure the information was captured in an accurate manner and to remove potential bias.

Conclusions
In this study, a group-discussion approach was used to investigate how various stakeholder groups perceive the path towards farm-level SIA and to examine the complexities of achieving a common goal when all opinions are considered. The study showed that sustainable intensification is not a simple target, but a complex dynamic system that includes institutional structures, personal goals, stakeholder interests and socio-economic factors, and is affected by cognitive beliefs and particular knowledge within a stakeholder group. The results showed how experience, knowledge and beliefs affect the perception of farm-level SIA by various stakeholder groups, and how this knowledge is often fragmented and miscommunicated. Farmers consider farm-level SIA to be a closed system, with nodes that interact highly with each other and are related to farm management and resource availability. Policy makers consider it to be an open system with more direct links between nodes, and identify policy design and research-related elements as important for its balance. Advisors see farmers' attitudes and characteristics as dominant nodes for the achievement of SIA, enabling the advisors to be the communicators between policy and the farmers.
The fuzzy cognitive technique proved useful in obtaining key concepts for farm-level SIA. The exercise confirmed the hypothesis that farm-level SIA cannot be simply measured through established indicators, but has to be seen as a dynamic process in which farm performance is affected by various factors, with the complexity of the process increasing when different stakeholder interests and beliefs combine for farm management.
Some main research and policy recommendations for future approaches arise from this study: (a) Stakeholders look at SIA only from their own perspective if there is no satisfactory interaction, resulting in a confusing system when their knowledge is combined. This calls for essential and meaningful knowledge exchange. The FCMs provide insight on which concepts and relationships are neglected in discussions, and identify what the sustainability debate should focus on to advance a common, broader and sustainable intensification goal. (b) Stakeholders' knowledge and contributions to achieving SIA are fragmented. This creates the requirement for more integrated systems thinking approaches. Collective systems thinking would enable stakeholders to adjust their thinking to include nodes that, in principle, are not important to their group. The aggregation process allows perspective barriers to be overcome and creates common reference points. The central and important drivers and receivers are potential "starting points" for working towards bridging the gap between stakeholders' views and guiding actions towards sustainable intensification. (c) The results of this study show the importance of involving the different stakeholders, bringing them together and creating the opportunity for open discussion and collective understanding. More importantly, the results indicate the need for in-depth incorporation of farmers' understanding of farm-level SIA in discussions. This could help in bridging the gaps between policy design and implementation, and assist in achieving consensus between groups with conflicting interests on future approaches.
From a practical perspective, the application of such a participatory tool, which is able to aggregate and quantify stakeholders' knowledge, could assist in effective decision making for the management of farm systems. The use of this tool could be very informative, but it always has to be borne in mind that it is context specific, and therefore encoding stakeholders' knowledge should be applied at the local level and include a learning process.
The fundamental practical requirement is the support and engagement of the decision makers themselves throughout the whole process. This could be challenging at times, as conflicting interests, time limitations and different understandings of the procedure can impede such a process. In addition, the success of this tool is based on the participating stakeholders' mutual understanding and willingness to compromise, which are mainly built through the creation of trust between them.
In conclusion, treating SIA as a system created an opportunity to identify key concepts that are factored into the decision-making process to achieve farm-level sustainable intensification. When stakeholders with conflicting interests come together to identify the path towards farm-level SI, a complicated process is revealed. The results of this study can provide valuable insights on what the strengths and weaknesses of co-management are, and what future debates on farm-level SIA should focus on, for agriculture to take steps forward towards more sustainable intensification.