Changes and drivers in Spanish landscapes at the Rural-Urban Interface between 1956 and 2018.

This paper presents unique comprehensive quantitative measures of the changes in Spanish rural landscapes, specifically in relation to the Rural-Urban Interface (RUI). Our objective was to investigate the urbanisation process in rural areas of Spain, thus the expansion of the RUI in an environmentally complex study area (it includes arid regions, continental areas or high mountains). The data were produced by the Spanish Rural Landscapes Monitoring System project (SISPARES), which has carried out five separate surveys for 1956, 1984, 1998, 2008 and 2018. SISPARES data provide RUI quantification by identifying urban patches, using aerial images, in a permanent network of 206 stratified random landscape sampling units (4 × 4 km each) deliberately located in rural areas. The cost-effective and spatio-temporal SISPARES approach enables the production of landscape geographical models at each survey date and the modelling of its evolution over each time period. We hypothesised that the RUI expansion did not follow a homogeneous spatio-temporal pattern, and therefore neither did the drivers responsible for it. Building on SISPARES data, we evaluated through CART analyses the relationship of RUI expansion with relevant environmental and anthropogenic driving factors, such as climate, bedrock, landscape composition and human population density. The historical narrative perspective was also used to aid discussion of the results. Historically, Spain contained few areas of RUI, but major changes were determined in the initial study period (1956-1984), which conformed a seminal geographic pattern for subsequent RUI increment. In contrast, the RUI expansion did not increase greatly during the following periods, between 1984 and 2018. The RUI expansion has been primarily driven by anthropogenic factors, constrained by the environmental characteristics of Spain. The expansion pattern is likely to has shifted from a national scale in the 1950s, to a continental scale at later dates as the result of the changes in socio-political scenarios.