Based on recent studies that relate data on landscape ecology, social metabolism and observed biodiversity, ELIA indicator is a good predictor of species richness in the metropolitan area. This main energy-landscape integration indicator (B1) combines data from the energy balance (E, I) with landscape patterns and processes (Le, explained in section C). If information about certain bio-indicator species or taxa is available, it can also be used as biodiversity indicator (B2). As an indicator of the rural-urban interaction, biodiversity in urban public spaces, such as parks and beaches (Bu1) is considered.

Regarding landscape patterns and processes, we propose landscape complexity (Le; C1) as the main indicator that explains the interaction between the two secondary indicators that also aim to analyze: land use heterogeneity (H; C2), and the ecological connectivity index (ICE; C3). The latter, while evaluating how landscape patterns affect connectivity processes, requires a series of measures to affect anthropogenic barriers. Both indicators are determined from land cover maps. Regarding the interaction between urban and rural spaces the measure of connectivity of urban public spaces, can assess their ability to accommodate biodiversity (Cu1).

In terms of climate change, the calculation of greenhouse gas emissions (GHG, D1) is proposed as the main indicator. To get this indicator the metabolic balance is fundamental because it allows to define the emissions derived from the imports of external inputs and take into account not only the processes in agrarian spaces but their impacts on external territories as well. As secondary indicator, it is proposed the global ecological footprint (D2), in terms of land cost of agrarian sustainability. In interaction with urban metabolism, this indicator has the potential of identifying changes in global metabolism based on the global footprint of food imports to cities (Du1).

For this dimension we consider a greater number of sub-dimensions and indicators due the large amount and relevance of ecosystem services in the provision of goods and services that are useful for society and its regulation. We distinguish four main types of ecosystem services: support, regulation, provisioning and cultural.

In relation to supporting services, we propose an indicator that evaluates the recirculation of nutrients (E1A), which calculates the amount of nutrient flows that have internal origin in relation to total nutrient flows, which facilitates characterizing the integration among the different elements that take part of the agro-ecosystem. These ecosystem services can be complemented by water efficiency (E2A), given the relevance of water metabolism in Mediterranean environments. Regarding urban-rural relations we propose to calculate the urban water reuse for open spaces (Eu1A).

As regards regulatory ecosystem services, we introduce the carbon sink (E1B) as the main indicator that expresses the ability of the region for climate change mitigation. Based on the metabolic balances, and by means of information from both the IPCC and complementary local databases, we can calculate the carbon sink variation, in terms of the amount of CO2 emitted or captured per unit of surface, using a secondary indicator of carbon sequestration (E2B). In terms of relation with urban systems we propose to calculate the contribution of urban parks in air quality (Eu1B).

As provisioning ecosystem services, based on the metabolic balance, we propose an estimate of agricultural production (E1C), as well as total agriculture production (E2C), calculated in terms of dry matter per unit area. The existence of this secondary indicator allows to consider the contribution of non-food products that are also relevant in terms of provisioning. We propose a rural-urban indicator of proximity, as a measure of food sovereignty in the metropolis (Eu1C).

Finally, in relation to cultural ecosystem services, we use the main indicator of bio-cultural value of the landscape (E1D), and the secondary indicator of potential use of open spaces (E2D). As a rural-urban indicator we use the urban frequentation of open spaces (Eu1D).

 

The last dimension considered as a contribution of open spaces in the metropolitan system refers to social aspects. The aim is to incorporate the perspective of how these spaces contribute not only to the socioecological but also the socioeconomic performance. The main indicator we consider is the agricultural employment (F1). The calculation can be made based on the needs of workers for crop and livestock unit. On the other hand, beyond the generation of work, it is important that these open spaces improve welfare of agrarian population, so we propose as secondary indicator the income per unit of agricultural exploitation (F2). Finally, the indicator of social inequality along the food chain (Fu1) is considered.