In the north-east of the Community of Madrid we find the Cuenca Alta del Río Manzanares Regional Park (Upper Manzanares river basin), which was declared a Biosphere Reserve by UNESCO in 1993. Heights range between 600 and 2,300 metres, forming a landscape of peaks, lower mountain, and plains that are the habitat of numerous Mediterranean species. The corridor that links the urban centre of Madrid with Sierra de Guadarrama is an area of incalculable natural value, thanks to the river that crosses it.
The Upper Manzanares river basin has granitic peaks like La Pedriza, a place where griffon vultures and peregrine falcons dwell. This rugged landscape becomes smoother around Sierra del Hoyo del Manzanares, giving rise to holm oak, oak and ash forests. These woods alternate with pasturelands used for grazing, creating meadows that are good for raising bucks and red deer. In the lower parts, like around the Santillana reservoir and the Soto de Viñuelas, we find water-related crops and numerous colonies of water birds.
This way, the so-called "agro-sylvo-pastoral" systems (pasturelands, meadows and grazings) are formed, which are very important for the conservation of the natural environment. In the area nearest to the Manzanares River there are wooded patches formed by willows, black poplars, ash trees and birch. Among the shrubs found here, notice the blackberries, the wild rose bushes and the honeysuckle. Keeping company the red deer and the bucks company in the Upper Manzanares river basin are badgers, wild cats, otters and wild boars.