Mata do Bussaco extends over 105 hectares and is one of Europe’s most important dendrological masses.

The arboretum, or large forest planted by the monks, takes up 80% of the area. There is a mixture of indigenous species, such as oaks and bay trees, plus other species that were brought from overseas. The Bussaco cedar (Cupressus lusitanica) is particularly abundant and, even though it has a toponymic name, the species originated in Mexico and Guatemala and was brought to the area by Portuguese mariners. The oldest specimens date back to 1644 when planting began and some of them, such as the San José cedar situated next to the chapel of the same name, are still there today.

Many years after the monks were expelled in the mid-19th century, other very large species were planted. In particular, Californian redwoods, monkey puzzle trees, eucalyptus trees, camellias, Australian wattles and American ash trees.

One exception is an area in the far south-west part of the site called Floresta Relíquia. It is a primitive forest of Mediterranean species in an area of particular Atlantic influence. The green olive (Phillryea latifolia), a botanical rarity that continues to grow in the area next to oaks, bay trees and strawberry trees, is the main species of tree in that area.

Another unique feature stands out in the valley of ferns: a row of very large and ancient fern trees, which bring an exotic side to this mid-19th-century garden.

When it comes to fauna, hundreds of species inhabit the ecosystem, including pollocks, tits, nuthatches, chaffinches and kinglets. Booted eagles, falcons, goshawks and even  grey herons, as well as nocturnal species such as bats and owls, can frequently be spotted.

Over 150 vertebrates and over 600 invertebrates, some of which are endemic to the Iberian Peninsula, have been observed in the area, including species of cyprinid fish, golden-striped salamanders and the Iberian emerald lizard.