Abstract
Ecoregionalization is the process by which a territory is classified in similar areas according to specific environmental and climatic factors. The climate and the environment strongly influence the presence and distribution of vectors responsible for significant human and animal diseases worldwide. In this paper, we developed a map of the eco-climatic regions of Italy adopting a data-driven spatial clustering approach using recent and detailed spatial data on climatic and environmental factors. We selected seven variables, relevant for a broad set of human and animal vector-borne diseases (VBDs): standard deviation of altitude, mean daytime land surface temperature, mean amplitude and peak timing of the annual cycle of land surface temperature, mean and amplitude of the annual cycle of greenness value, and daily mean amount of rainfall. Principal Component Analysis followed by multivariate geographic clustering using the k-medoids technique were used to group the pixels with similar characteristics into different ecoregions, and at different spatial resolutions (250 m, 1 km and 2 km). We showed that the spatial structure of ecoregions is generally maintained at different spatial resolutions and we compared the resulting ecoregion maps with two datasets related to Bluetongue vectors and West Nile Disease (WND) outbreaks in Italy. The known characteristics of Culicoides imicola habitat were well captured by 2/22 specific ecoregions (at 250 m resolution). Culicoides obsoletus/scoticus occupy all sampled ecoregions, according to its known widespread distribution across the peninsula. WND outbreak locations strongly cluster in 4/22 ecoregions, dominated by human influenced landscape, with intense cultivations and complex irrigation network. This approach could be a supportive tool in case of VBDs, defining pixel-based areas that are conducive environment for VBD spread, indicating where surveillance and prevention measures could be prioritized in Italy. Also, ecoregions suitable to specific VBDs vectors could inform entomological surveillance strategies.
Highlights
Ecoregions have been defined as areas “within which there are associations of interacting biotic and abiotic features” [1]
We showed that the spatial structure of ecoregions is generally maintained at different spatial resolutions and we compared the resulting ecoregion maps with two datasets related to Bluetongue vectors and West Nile Disease (WND) outbreaks in Italy
The varimax rotation matrix highlights the relations between the input variables and the factors derived from Principal Component Analysis (PCA) (Table 1 for 250 m resolution, S3 and S4 Tables for 1 km and 2 km respectively)
Summary
Ecoregions have been defined as areas “within which there are associations of interacting biotic and abiotic features” [1]. Orography, geological factors (abiotic) and vegetation (biotic), are the characteristics commonly used to define homogeneous land units, within which natural communities and species interact with the physical elements of the environment [2]. For Italy, the most recent classification available derives from a hierarchical, deductive and divisive expert-based method, vegetation-oriented, that, at its finer scale, divides the Italian land in 33 areas, homogeneous by climate, physiography, biogeography and vegetation [2]. This classification has been further evolved into an ecosystem mapping of Italy, where it was integrated with the CLC and the potential natural vegetation through an expert-based overlay [8]
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