Condizioni di conservazione dei suoli su substrati carbonatici assoggettati ad intensa pressione antropica

In Sardinia carbonate environments are present on a surface of 7.2%. In these environments there are phenomena of regression of plant cover (typically Mediterranean) and soil (Alfisol-mollisol-inceptisol-entisol). The causes of the deterioration was due to over-grazing of goats (Capra hircus) of forest cutting and more generally to human activities. The aim of the thesis has been the search for a set of indices of soil degradation and vegetation present in a basin with an area of 3,377 located in Central East Sardinia, in the resort of Cala Gonone, City of Dorgali. The research was conducted at a basin scale and detail with a scale of 8 experimental sites dimensions of 5 x 5 m. The basin scale was investigated with the CORINE Soil Erosion Risk method. It was determined the degree of danger potential and current of erosion of the soil with a scale of values ranging from 1 to 3. The High Risk (Level 3) is present on the 0.13% of the basin and is located where the vegetation is sparse and not very structured, with the aggravating circumstance of high gradients. In basin formation most common vegetable, and ecologically more stable, are the woods of holm oak (Quercus ilex L.) investigated in 8 experimental areas, both in the vegetation (mean height,% cover of soil, density and biological diversity) with subdivision into 4 layers of vegetation (tree layer, shrub layer, herbaceous layer and layer of forest regeneration), and organic matter in soil (pH, conductivity, C, CO,% SOM and humic substances). The holm-oak woods are closed formations dominated the tree layer. The forest regeneration is poor because of grazing, however, shows cyclicality. Lacking all the intermediate stages of forest regeneration and mature forest. In the experimental areas there are reports (133 statistically significant correlations with p-level ≤ 0.05 and with R> of 0.7) between the SOM and plant parameters. At present (Poor bibliography) as a general hypothesis, these relationships are due to nutritional aspect. It was concluded that, in the catchment area of Cala Gonone, you must give more attention to the loads of goats, so the effect on soil and vegetation and in particular on forest regeneration. The lack of an adequate stage of regeneration of the forest trees, in the coming decades, with the death of the forest now present, will be a big problem of soil conservation. The major actions should be aimed at containing the grazing and conversion of different plant formations high trees.