The two “P.N.A.L.I” (protected natural areas of local interest) in Monte Castellare and the Delle Fonti Valley protect some parts of the southern slope of Monte Pisano. The Monte Castellare area, near San Giuliano Terme, is characterised by the garrigue plants that grow in the chalky soil, a product of fires and grazing (there are traces of human settlements dating back to prehistory). The vegetation you see today consists of shrubs that have adapted to the dry climate of the area and which often have very fragrant leaves, for example: myrtle, cistus, thyme, felty germander, savoury and rue are common. The rare terebinths that grow next to the more common mastic trees and mahaleb cherry trees are particularly interesting.
The Delle Fonti Valley, near Asciano, meets with the Zambra river valley and joins the ridge that leads to Monte Faeta (830m above sea level), whose name calls to mind the beech trees of ancient times. The valley owes its name to its abundance of springs of clear, chalk-less water that fed the Medici Aqueducts around Pisa. Dense forests with rows of deciduous trees and shrubs, products of the damp soil, characterise the area: alders, willows, elders, dogwoods and even hazels make up these plant communities in which you can find rare evergreens like holly and bay trees.
Common wild clematis and the rare silk vine grow in the trees, while numerous ferns grow in the undergrowth: of these, the royal fern is particularly important owing to its rarity. Other weeds in the undergrowth stand out for their flowers. Interestingly, the bryophyte flora with its numerous species of liverworts, mosses and especially sphagnums, is in some cases also very rare.