In February 1979 the "Wwf Forest of Vanzago" was officially designated as a "Local Reserve", while later, in March 1985, the area was classified as a "Partial forest and zoological Nature Reserve". The reserve, from a geological standpoint, is made of gravel deposits and quaternary sand aquifers. The moderate continental climate, typical of the Pianura Padana (Po Valley), is characterised by extreme temperature changes, with harsh winters and hot summers.
These geological and climatic conditions have led to the development of a lowland deciduous forest, characterised by the original plant association of the English oak, durmast oak and hornbeam. The oasis itself is structured on three concentric areas, the innermost (the true heart of the forest) is protected by a wall built to keep the plants and animals undisturbed. While the second area is fenced with wire mesh the outermost area is open to visitors without restrictions, for walking or cycling. All these three zones are characterised by alternating meadow areas, cultivated fields, areas with forests of tall trees, woods, fields and lakes, all natural environments that are characteristic of the Pianura Padana (Po Valley). The forest, which is the most precious ecosystem in the oasis, is inhabited by English and durmast oaks (including secular specimens), chestnut, birch, hornbeam, maple, locust trees and many others. The undergrowth includes the late blackthorn, hazel, elder, wild cherry, holly, hawthorn, different varieties of ferns, lilies of the valley, and hundreds of other herbaceous species.
All of these areas are home to numerous species: mammals such as the roe, the symbol of the nature reserve. Visitors may also stumble upon the hare, the wild rabbit, marten, badger, fox and hedgehog. The denser forest areas are also home to little rodents such as dormice, garden dormice and the hazel dormouse. Most noticeable, however, are the birds, nocturnal and diurnal raptors, ducks, herons and many passerines, which use the oasis to hibernate, rest, eat and nest. The reserve is also home to certain varieties of reptiles, amphibians (including the rare pond turtle), insects and fish. The visits are guided and are held on Saturday and Sunday, for groups and schools throughout the week by appointment.