Given the complexity of the area, there are numerous heterogeneous habitats. The limestone cliffs and screes of Val Rosandra, particularly rich in endemisms, should be mentioned as they are the only example of high cliffs on the northern Adriatic coasts, an ideal habitat for the Centaurea kartschiana stenoendemic, the Trieste coastal holm oak forest, the aquatic and riparian vegetation (Timavo river and karst lakes) and the halophilous grasslands with annual glasswort (Lisert), reaching here the northernmost limit of their distribution area in the Mediterranean basin. Among the most significant and valuable species there are: the Genista januensis, the Daphne alpina, the Genista holopetala, the Moehringia tommasinii, the Drypis spinosa (jacquiniana species), the Melampyrum fimbriatum, the Digitalis laevigata (also on M. Hermada) and the Lactuca quercina (chaixii species) (also on M. Lanaro) in the area of Val Rosandra. In the area of Mount Lanaro there are: the Satureja subspicata (liburnica species), the Carex fritschii, the Orchis pallens and Paeonia mascula. In the area of Mount Hermada, the Sesleria juncifolia, the Euphorbia fragifera and the Onosma dalmatica (= O. javorkae) and the Vicia loiseleurii could be found. On the Duino cliffs there is a high concentration of stenomediterranean and endemic species as well as the last north-Adriatic points of Urospermum picroides and Reichardia picroides. In the area of the Doberdò and Pietrarossa lakes there are rare thermophilic and hygrophilous species such as Lens ervoides, Asterolinon linum-stellatum (the only regional point), Crepis vesicaria, Rhagadiolus edulis, Roman Bellevalia, Thelypteris palustris, Alisma lanceolatum, Leersia oryzoides , Scilla autumnalis, Viola elatior, Ranunculus velutinus, Ranunculus illyricus, Ranunculus lingua, Veronica catenata, Ophioglossum vulgatum, Linum strictum ssp. corymbulosum, Zannichellia palustris and Utricularia australis. Five species of Potamogeton (P. cripsus, P. lucens, P. nodosus, P. pectinatus and P. pusillus) are concentrated in the waters of the lakes. This site brings together an extraordinary mosaic of wetlands and xerothermic areas of the Gorizia and Trieste Karst, and must be considered as one of the most important in Italy, also from a wildlife point of view.
In these areas there are numerous Balkan, Illyrian-Mediterranean (Carso triestino) and Italic (Carso goriziano) species, in an absolutely unique faunal community within Europe (Hyla arborea, Rana ridibunda, Algyroides nigropunctatus, Podarcis melisellensis, Telescopus fallax, Elaphe quatuorlineata, etc.). Among the most important species it is worth mentioning Proteus anguinus, Austropotamobius pallipes, Triturus carnifex, Rana latastei, Emys orbicularis, Ursus arctos, Canis aureus and a very remarkable number of birds (Accipiter gentilis, Bubo bubo, Strix uralensis, Otus scops, Picus canus, Dryocopus martius, Monticola solitarius, etc.). Zamenis longissimus, Podarcis sicula, Podarcis muralis, Felis s. silvestris, Muscardinus avellanarius, Erinaceus roumanicus and Chionomys nivalis are also frequent in the area. Among the insects it is worth mentioning the presence of Leptodirus hochenwarti, now limited to a single cavity of this area (Grotta Noè) within the whole Italian territory, as well as of Eriogaster catax, Euphydryas aurinia and Coenonympha oedippus. In the area there are also Lucanus cervus, Morimus funereus, Osmoderma hermit, Vertigo angustior, and Helix pomatia. The rocky coastline of Trieste is the elective habitat of Lithophaga lithophaga. Among the Zeuneriana marmorata insects, a north-Adriatic endemite considered extinct in the past has recently been reported for the Lisert area, while the presence of Caretta caretta has been repeatedly verified. Several species of cetaceans (Tursiops truncatus, Stenella coeruleoalba) regularly pass through the waters off the Sistiana bay and Duino Castle, but Delphinus delphis, Megaptera novaeangliae and Physeter catodon have also been reported.