Descrizione 1
Angela Cimini, Luca Congedo, Paolo De Fioravante, Ines Marinosci, Stefano Pranzo
Territorial fragmentation is the process that leads to a progressive reduction in the area of natural and semi-natural environments and an increase in their isolation. This process, which transforms large land patches into smaller and more isolated parts, is primarily driven by urban expansion phenomena, which can take more or less sustainable forms, and the development of infrastructure networks aimed at improving connections between urbanized areas through linear works. In 2023, 42.34% of the national territory was classified as highly and very highly fragmented. The regions with the largest areas of very high fragmentation are Veneto (39.98%), Lombardia (33.57%), Emilia-Romagna (25.87%), and Campania (25.69%). This data confirms the strong correlation between fragmentation and urbanization density.
Territorial fragmentation is the process of reducing the continuity of ecosystems, habitats, and landscape units due to phenomena such as urban expansion and the development of infrastructure networks. These phenomena lead to the transformation of large land patches (areas free of significant artificial elements that fragment the area and interrupt its continuity) into smaller and more isolated land parts.
The degree of territorial fragmentation is assessed using the "effective mesh-density" index (Seff), which measures the obstacle to movement due to the presence of so-called "fragmenting elements" on the land. This index represents the density of territorial patches (number of meshes per 1,000 km²) calculated according to the effective mesh-size (meff) methodology (Jaeger, 2000), which is correlated to the probability that two randomly chosen points within a certain area will be located within the same patch. The methodology has been appropriately modified according to the "cross-boundary connections procedure (CBC)", which ensures the continuity of land beyond the boundaries of the reporting unit (1 km² cell).
To assess the degree of land fragmentation caused by the presence of artificial land cover, which leads to the reduction of ecosystem continuity, habitats, and landscape units.
Achieving the priority objectives of the 8th PAA requires fully leveraging ecosystem-based approaches and green infrastructure, ensuring the restoration of biodiversity and strengthening the integrity and connectivity of ecosystems.
The National Strategy for Sustainable Development emphasizes among its strategic goals the need to "ensure the restoration and de-fragmentation of ecosystems and promote ecological connections between urban and rural areas" (Planet Area, Objective III.4).
Descrizione 2
Jaeger J.A.G., (2000) Landscape division, splitting index, and effective mesh size: new measures of landscape fragmentation. Landscape Ecology 15: 115–130.
Moser B., Jaeger J.A.G., Tasser E., Eiselt B., Tappeiner U. (2007). Modification of the effective mesh size for measuring landscape fragmentation to solve the boundary problem. Landscape Ecology 22: 447–459.
Carta nazionale ISPRA-SNPA del consumo di suolo.
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In the future, the index could be implemented with respect to “reporting units” other than 1 km2 cells, referring for example to appropriately selected land cover classes (e.g. ecosystem units).
Qualificazione dati
National, Regional (20/20)
2006, 2012, 2023
Qualificazione indicatore
The effective mesh-density was calculated at the national level using a regular grid with 1 km² cells (reporting unit), considering artificial land cover as the fragmenting elements obtained from the ISPRA-SNPA national soil consumption map, which was processed to enhance the identification of linear infrastructures (roads and railways).
In line with the indicator implemented by the European Environment Agency (EEA), "Landscape fragmentation indicator effective mesh density (Seff)", five classes have been defined, representing increasing levels of fragmentation (as the mesh density increases, the territory becomes more fragmented):
- Very low fragmentation (0 – 1.5 meshes per 1,000 km²)
- Low fragmentation (1.5 – 10 meshes per 1,000 km²)
- Medium fragmentation (10 – 50 meshes per 1,000 km²)
- High fragmentation (50 – 250 meshes per 1,000 km²)
- Very high fragmentation (>250 meshes per 1,000 km²)
In 2023, 42.34% of the national territory presents a high or very high degree of fragmentation, and overall, 18.74% falls into the very high fragmentation category (Table 1). The regions with the largest areas of very high fragmentation are Veneto (39.98%), Lombardy (33.57%), Emilia-Romagna (25.87%), and Campania (25.69%) (Table 1).
The status, as represented by the provided data, cannot be evaluated in the absence of objective reference parameters. The degree of fragmentation is closely related to the level of soil consumption affecting the territory.
The temporal evolution of fragmentation levels is correlated with the trend of artificial cover and its density on the national territory. The continuous increase in artificial surfaces in the national territory leads to progressively higher levels of fragmentation in agricultural and natural lands.
Between 2012 and 2023, there was an increase of 2.23% in areas with very high fragmentation (Table 3), while compared to 2006, these areas increased by 6.28% (Table 2). Areas with high fragmentation, on the other hand, show a more limited increase of 0.29% compared to 2012 and 1.74% compared to 2006. The extension of areas with medium fragmentation did not undergo significant changes between 2012 and 2023, while compared to 2006, there was a reduction of 1%. The most significant changes occurred mainly in areas with low fragmentation between 2012 and 2023 (-2.68%) and very low fragmentation areas between 2006 and 2023 (-6.15%) (Tables 2 and 3).
The trend of fragmentation levels is updated annually, as the availability of new satellite data related to land consumption allows for the best estimates throughout the historical series.
Dati
Table 1: Land coverage by fragmentation classes (2023)
ISPRA elaborations on SNPA cartography
Table 2: Change in the extent of fragmentation classes, in percent from 2006 (2006-2023)
ISPRA elaborations on SNPA cartography
Table 3: Change in the extent of fragmentation classes, as a percentage from 2012 (2012-2023)
ISPRA elaborations on SNPA cartography
Figure 1: Land fragmentation index (2023)
ISPRA elaborations on SNPA cartography
Figure 2: Land coverage (%) by fragmentation classes (2023)
ISPRA elaborations on SNPA cartography
From the analysis of the 2023 data, almost a quarter (23.61%) of the territory is characterized by high fragmentation, while areas with medium fragmentation cover just over a quarter of the national territory (26.79%) (Table 1).
At the regional level (Figure 2), Valle d'Aosta and Trentino-Alto Adige are dominated by low fragmentation classes due to the large extent of mountainous areas, while in other regions of the North, the presence of both the Po Valley and Alpine areas leads to a prevalence of extreme classes (very high and very low fragmentation). In Lombardy and Veneto, high urbanization rates with low and medium density are accompanied by high percentages of the territory with very high fragmentation, while in Central-Southern Italy and the Islands, medium fragmentation areas prevail.
Regional changes from 2023 compared to 2006 (Table 2) and 2012 (Table 3) show a general increase in territorial fragmentation. Excluding Valle d'Aosta, Liguria, Marche, Lazio, and Abruzzo (where the variation is zero), in the period 2006-2023, areas with very low fragmentation have decreased in all regions. In the 2012-2023 period, low fragmentation shows a slight increase in Trentino-Alto Adige, where, however, the expansion of this class is related to an increase in fragmentation of areas previously categorized as very low fragmentation. In the Northern regions, there is a reduction in areas with "high" fragmentation, which is attributed to an increase in fragmentation in these territories and their shift to the "very high" fragmentation class; this last class shows an increase in all regions except Valle d'Aosta,areas with "high" fragmentation expand in the South and Islands.
The reduction in ecological connectivity resulting from increased fragmentation negatively impacts both the resilience and the ability of habitats to provide certain ecosystem services, as well as the access of wildlife species to resources due to their increasing isolation and, consequently, their vulnerability. The negative effects of fragmentation indirectly affect human activities and quality of life, due to the reduction in the quality and value of the landscape and its impact on agricultural activities, such as increased production costs and fuel consumption for agricultural work.