Comparative analysis of net land take in Portugal's Metropolitan Areas

Abstract

Urban development in Europe is being shaped by the "No Net Land Take by 2050" target, set by the 2011 Roadmap to a Resource Efficient Europe [1] and reinforced by the EU Soil Strategy for 2030 [2]. In pursuit of sustainable use of soil, this strategy recommends that Member States set, by 2023, their targets aimed at net land take reduction by 2030 and report on their progress by making measurable contributions towards the 2050 target.  

Land take means the “loss of undeveloped land to human-developed land” [3, p. 4] over a given period. Net land take accounts for the difference between land take and re-naturalization of developed land, which is the reverse process of land take. Reducing net land take can be achieved through the reuse of already developed land, or an increase in the re-naturalization of developed land, which is rarely practiced [4]. Soil sealing is considered the most intense form of land take, as it causes a total and irreversible loss of ecosystem services and functions provided by soil.

To limit land take and soil sealing, the soil strategy also proposes the adoption of a hierarchy in land use planning that prioritizes the reuse of developed land. Whenever land take cannot be avoided, measures should be implemented to compensate for the loss of ecosystem services (e.g. green buildings or green roofs).

The main objective of the research was to quantify and compare the land take, re-naturalisation, and reuse of developed land between 2007 and 2018 in Portuguese metropolitan regions: Lisbon Metropolitan Area (AML) and Porto Metropolitan Area (AMP). 

This study aims to contribute to (1) assess the situation of the above regions and their municipalities regarding the 2050 target; (2) deepen the knowledge about the drivers of net land take in both AML and AMP, to support the setting of regional and local targets, which have not been defined yet; (3) raise awareness among decision-makers and public authorities about the processes addressed.

The assessment was based on the Portuguese land cover/land use maps (known in Portugal as COS). It is worth noting that this study assumed that the COS classes relating to artificial surfaces represent developed or urban land and that the remaining COS classes represent undeveloped or non-urban land.

Between 2007 and 2018, the increase in artificial land surface area was 4.6% in AML and 4.9% in AMP, slightly lower than in mainland Portugal (5.7%). The rate of land take represented an average expenditure of undeveloped land of 0.85 ha/day in AML and 0.64 ha/day in AMP. Re-naturalisation and reuse of developed land rates were 0.14 and 0.03 ha/day, respectively, in AML, and 0.05 and 0.02 ha/day in AMP, showing the shortage of their practices. Thus, to meet the 2050 target, the net land take rate in both Metropolitan Areas (0.7 ha/day in the AML and 0.6 in the AMP) still needs to decrease.

The main drivers of land take in both AML and AMP were the new industrial and commercial sites, transport networks, construction sites, and dispersed residential areas, although their relative importance changes.