The natural vegetation of the Liaodong Peninsula is not well preserved, because of the extent of cultivation and settlement. The forests that remain, mostly on the eastern sides of the hills, contain birches, limes, elms, and pines, together with typical Manchurian trees—oaks, apples, and ashes. On the western sides, trees are scarce. Wild animal life is now meagre, almost limited to rodents.
However, a nature reserve centred on Mount Laotie, at the southern tip of the peninsula, is a major stopover for southbound migratory birds from northeastern Asia in autumn. Thousands of birds from more than 200 species, including red-crowned cranes (Grus japonensis) and mandarin ducks (Aix galericulata), rest there before flying farther south. In addition, nearby Snake Island (Shedao), just off the tip of the peninsula, is a breeding ground for thousands of Halys pit vipers (Gloydius halys).
Vegetation is highly mixed in western Liaoning and includes oaks, birches, pines, limes, and spruces. In former times, especially between 1911 and 1948, there was much indiscriminate cutting and thinning of the forests there, so that many areas now have scattered woodland where formerly thick forests stood. The animal life of the western highlands is impoverished by the extent of both forest clearance and human settlement, but it includes wolves, foxes, marmots, and some kinds of deer.