ECOSYSTEM SERVICES DEMAND, SUPPLY AND BUDGET ALONG THE URBAN-RURAL-NATURAL GRADIENT

Landscapes can be viewed as a continuum and studied using spatial gradients, along which environmental modifications are ordered in space and determine the structural and functional components of ecosystems. The anthropogenic land uses generate specific gradients that can be recognised along the succession of urban–suburban–cultivated–managed-natural landscapes. From this point of view, the traditional urban-rural dichotomy can also be considered as a gradient, produced by a sliding level of human influence on ecosystems. Since the Millennium Ecosystem Assessment (2005), many scientists are directing their effort to studying and quantifying the benefits people obtain from ecosystems, synthesised by the concept of Ecosystem Services (ES). One of the major approaches for ES assessment is based on the analysis of stock and the condition of the biodiversity of the usual components of habitat, ecotopes or biomes. Despite this increasing interest, spatially explicit methods to analyse ES are still lacking. The research aimed to develop an innovative methodology supporting landscape analysis and planning processes by means of (a) the identification and characterisation of the types of landscape along the urban-rural-natural gradient and (b) the analysis of potential ES demand and supply within said types of landscape. The Kernel Density Estimation technique was applied to calculate continuous intensity indicators associated with urbanisation, agriculture, and natural elements, considered as key components of the formation of the landscape gradient. A multivariate, spatial analysis enabled the identification of different landscape structures constituting the gradient of the study area. The classification highlighted not only specific “pillar” landscapes, dominated by one of the three components (urban, agricultural, and natural), but also transitional landscapes, where the most relevant relationships between land uses were identified. The potential ES demand, supply, and budget within each landscape area were assessed using specific indices, based on an expertknowledge approach, retrieved from the bibliography and combined with the intensity indicators calculated for the landscape components under investigation. This method enabled a large group of ES to be quantified simultaneously by means of comparable demand, supply and budget indicators. Results showed a complex organisation of pillar and transitional landscapes along the identified urban-rural-natural gradient, which match different bundles of ES demand and supply. The research findings contribute to a new interpretation of ES demand and supply on the landscape scale and can support a better spatial contextualisation of the ecological and socio-economic issues characterising landscape gradients.