Landscape structure, resilience and ecogeographic relations between agro-forestry and forestry landscapes of Sicily: quantitative approaches

Abstract

Landscape ecology provides a wide spectrum of useful techniques for quantitative analysis of the land-mosaic patterns, on the basis of areal, linear and punctual parameters. According to the scale of analysis, data collection can be costly and time-consuming; this is especially true in areas with a very heterogeneous land-mosaic patterns and landscape-types for environmental variability and cultural reasons. Aims of this work are: 1) to assess the land-mosaic complexity of the traditional agricultural and agro-forestry landscapes (PAfT) of Sicily; 2) to highlight interfaces and structural gradients between main forest areas and closed PAfTs. These aims have the main purpose to pinpoint agricultural areas more closely linked to forest stands, both for spatial and for agro-ecological aspects, useful for the forest planning efforts to increase the regional forest resources and the ecological network. In this way, this work uses the database of the “AGRIT Agro-Ambiente” (AAA) Project (of the AGRIT 2010-11 program) realized, on the basis of robust survey methodologies, by the MIPAAF (Ministry of Agriculture, Food and Forestry Policies). This Project, in its first experimental phase, interested the entire island of Sicily by a wide data survey (a total of 7949 sample units – squares 250m wide) involving the entire land. This database carries information on land use (details according to the “Refresh” SIAN-AGEA legend), linear and punctual agro-ecological parameters, collected both by photo-interpretation and a wide field surveys. Moreover, information, such as the presence of soil erosion and landslides, useful to evaluate agro-ecological processes in action, were also collected. Landscape ecology indexes were derived to analyze the landscape configuration, composition and complexity. Results show as the solid AAA-database is useful to give a real representation of the Sicilian PAfTs and to supply a quantitative and stable characterization of the most important landscape parameters. For instance, PAfTs of the “coltura promiscua” and of the “semi-open fields”, spatially closed to the most important forest and semi-natural areas of Sicily, show the highest values regarding the land-mosaic configuration and complexity. Vice versa, the agricultural landscape of the “open-field” display strong ecological instability (widespread presence of soil erosion and landslides) and a low presence of linear and punctual elements (hedgerows and line breaks, dry-stone walls, isolated trees, centuries-old trees, etc…). With the aim to increase environmental complexity and resilience, forest planning and silviculture could have particular importance in these landscape contexts in next future. In this way, the AGRIT approach (in experimental phase in few Italian region at the moment) can represent a robust data source for powerful applicative tools for achronic and synchronic analysis, at a landscape/wide scale of survey where few data are currently available.