Decisions and norms at the various hierarchical levels are taken according to societal demands organized in a more or less explicit value system. According to Abreu and Camarinha-Matos (2006) a value system can be understood as “the ordering and prioritization of a set of values that an actor or society of actors holds.” The value system reflects that components of the agroecosystem have a certain value attached based on societal priorities and rules, which can be expressed in a cultural (or socio-ethical) value and an economic or financial value (Fig. 2).

Cultural values are shaped by social interactions, historical events, and shared heritage. Together with traditional knowledge on resource use generated during the coevolution of agrarian societies with nature, the cultural aspect includes historical and architectural aspects and therefore both living and manufactured infrastructures that form an essential part of rural landscapes. Marketable goods and services are denoted commodities that have an economic value, and transformations can add value, which can be reflected in monetary terms. The economic value depends on human demand and local availability of products and services.

When doing a sustainability assessment exercise, breaking the system and the problems of the system down in clearly distinctive dimensions (Fig. 2) will facilitate the identification of context specific problems. Subsequently these can then be translated into critical properties and relevant indicators in a rather straightforward fashion. In this manner, the evaluation process is more concrete from the start, thereby increasing the opportunities for contributions of and participation by nonscientific stakeholders in assessment projects. This step of distinguishing dimensions to decompose the problem is part of a simplification process as stated by Marten (1988). It is not a departure from the systems perspective, which is maintained by acknowledging importance of different views on the different dimensions and the attached temporal aspects (e.g., short- and long-term changes and the needs of future generations), spatial scales (e.g., biodiversity impact at different hierarchical levels), and societal drivers (cultural and economic).

Fig.2 Views on an agroecosystem (grey box): the value system view (blue) consists of two dimensions and the component view (green) comprises four dimensions. The value system reflects that components of the agroecosystem have a certain value attached based on societal priorities and rules, which can be expressed in an economic and a cultural value. Temporal aspects are included to take into consideration supposed preferences, short- and long-term changes, and the needs of future generations. Spatial scales are included to acknowledge importance to potentially heterogeneous impacts of management options at different hierarchical levels.

Within the environmental dimensions of the system, the physical and ecological dimensions are, although highly interactive, fundamentally different by nature (living vs. nonliving). These dimensions pose different problems and provide strongly contrasting environmental services. In the physical or pedoclimatic dimension, problems of nutrient and biocide pollution of water, soil degradation and erosion are relevant to agricultural systems. The ecological or biotic dimension entails all biological processes in the system, including the growth and production of agricultural crops and animals, until they are being harvested. Problems encountered in the ecological dimension include reduction of the biomass production capacity and gene, species, and ecosystems diversity, posing a threat to the corresponding services supplied, such as food and fiber production, supply of genetic resources for, for example, crop resistance to pathogens, maintenance of habitats, bioremediation capacity, soil retention and regeneration, pollination, and biological pest control.

The productive dimension includes not only products harvested from ecological systems, but also artifacts from industrial or human cultivation processes that use both ecological and physical resources. These products can be transformed into other products (milk into cheese; engines, dashboards, and other components into tractors). The social dimension is the fourth and last and it is based on the human presence and the interrelations between people (either informal or institutionalized) within or outside the system. The social aspect reflects the current state of affairs in terms of human capital and participation in activities in the form of labor and social structures, for example, local interest groups and institutional arrangements.

Although the dimensions are conceptually independent, a myriad of interactions exists among them. For example, a decrease in the total biomass productivity of a market crop in the ecological dimension (e.g., due to depletion of clean water resources in the physical dimension) has a direct impact on the productive dimension as well via a reduction of harvested products and financial revenues associated with specific farm activities. In the long run this can reduce the labor investment into the cropping system with cascading effects of unemployment and migration from rural areas, all in the social dimension (for the purpose of demonstrating the overall principle the feedback loops were omitted in this example). As another illustration, production of crops results in disturbances of the physical and ecological dimensions, which can be observed as lower species abundance and diversity, and decline of soil organic matter content rendering soils more prone to erosion. The resulting negative effects on the physical dimension include soil degradation and compromised water and nutrient retention along with a reduction in soil purification capacity. These examples stress that to assess the interactions between the dimensions and to estimate the impacts of adjustments in management practices for agroecosystems a multidisciplinary approach is indispensable.