Desertification and Climate Change

The UNCCD declares the desertification is a process of "degradation of arid, semiarid and dry sub-humid soil environments resulted from several factors, including climatic variations and human activities" (UNCCD 1994).

The IPCC defines desertification as "the reduction or disappearance of biological or economic productivity and complexity of non-irrigated and irrigated croplands, pastures, forests or woodlands, which result from land uses or other phenomena originated from human activities and modes of settlement, including soil erosion by wind and water, the deterioration of physical, chemical, biological or economic properties of soil, and long-term disappearance of natural vegetation" (IPCC 2007a).

Desertification is thus constantly presented as a phenomenon due to both natural (climate and water cycle) and anthropogenic factors, which have an impact on how soil interacts with water cycle. In the IPCC Third Assessment Report (TAR), the role of unsustainable agricultural practices such as uncontrolled grazing and

1800 1600 1400 1200

1567

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2010

Year

Fig. 2.3 Yearly investments (million euro) in Italy to remediate landslides risk and damage (ISPRA 2011c). The allocated resources allowed a total of 3,642 operations, though only 1,798 are completed and 698 are still ongoing (Fig. 2.4)

deforestation is particularly highlighted (IPCC 2001). TAR also indicates that climate change and human activities are strongly related to land use, involving synergistic impacts on ecosystems and species in desert areas. In fact, desertification is closely linked to characteristic climatic conditions such as drought, dryness, erosion, and rainfall, whose variation inevitably changes the intensity of desertification processes (Gambarelli et al. 2007).

The United Nations Convention to Combat Desertification (UNCCD) identifies physical, chemical, and biological processes of soil degradation. Physical processes lead to loss of resources in terms of reduction of soil volume and surface (erosion, compaction, and consequent limitation in porosity and water infiltration). Chemical processes cause the degradation of soil chemical quality (contamination, saliniza-tion, leaching, acidification). Biological processes determine the alteration of biological resources and their features (loss of organic matter, fertility, erosion resistance, buffering, and biodiversity).

According to the Italian National Atlas, risk of desertification in Italy pertains to more than 20% of total surface and rise to more than 40% in southern Italy (Costantini et al. 2007). The Atlas identifies various systems that contribute to desertification such as water erosion, urbanization, salinization, and drought. Sensitive areas would amount to a total of 9.1%, especially in Sardinia, Sicily, Puglia, and Calabria, though important areas with vulnerable soils are also present in Campania, Tuscany, and Lazio (Gambarelli et al. 2007). Desertification in southern Europe has an impact on:

State of implementation

Fig. 2.4 Number of operations for landslides remediation based on their implementation state

(ISPRA 2011c)

State of implementation

Fig. 2.4 Number of operations for landslides remediation based on their implementation state

(ISPRA 2011c)

- Reduction in primary production and growth cycles of plants (Ogaya and Penuelas 2003).

- Reduction in turnover and availability of nutrients in soil (Sardans and Penuelas 2005).

- Changes in phenology and interactions among species (Maestre and Cortina 2004).

- Risk of fire. A longer dry season increases frequency and severity of fires (Pereira et al. 2005) and a reduced capacity for vegetation recolonization after fires encourages the growth of shrubs over trees.

- Soil erosion due to increased intensity of rainfall events (Giorgi et al. 2004; De Luis et al. 2003).

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