The area consists of the forest complex of the northeastern side of Mount Ossa. It begins at sea-level and reaches the highest peak of Profitis Ilias (1980 m). At lower altitudes, the main form of vegetation is evergreen broadleaf trees. Here we can find most of the relevant species which grow in Greece, such as Acer sp., Quercus sp., Corylus sp., Arbutus sp., Erica sp., Fraxinus sp., Phillyrea sp., Ulmus sp., Cornus sp. etc. At higher altitudes, human influence is evident as the control and pruning of the Castanea sativa (sweet chestnut) have led to the creation of pure groups of the species (kastanoperivola), particularly in parts of the forest which belong to the local communities.
The trees are exploited mainly for the collection of chestnuts and not so much for their wood. Where human influence is less marked, the Castanea grows along with Tilia, thus, yielding the typical Tilio-Castaneum at an altitude of 300-500 m. The next vegetation level goes up to 650 m. and corresponds to Quercetum-montanum with species of Quercus mainly Q. frainetto, Q. dalechampii and Q. pubescens. At higher altitudes (650-1,600 m) one can find psychrophylic and hydrophilic vegetation. The predominant forest species is beech and in particular the species Fagus moesiaca along with F. Sylvatica and F. orientalis at higher and lower altitudes respectively.
At Ossa, as well as in the rest of Eastern Thessalia, the timberline of Fagion moesiacae is not the formation line of the summer clouds (as is the case in Albania), while limited formations of the species Fagus can be found in wet areas even at an altitude of 280 m. The homogenous beech forest becomes heterogeneous at the level of 1,000-1,450 m where beech trees can be found along with fir trees (Abies borisii-regis). There is also a fir tree forest Abies borisii-regis which covers 13% of the area. The fir tree forest has receded in the last years due to its over-exploitation; however, its restoration has recently begun. Above the level of forest vegetation lies the subalpine zone sustaining a great variety of species.
The peak is a bare rock and its vegetation belongs to the Astragalo-Daphnion sub-zone. On Mount Ossa one can also come across Carpinus orientalis, ravines timbered with Aesculus hippocastanum, as well as formations of Pteridium aquilinum and Berberis cretica. At a low ratio, there are also broadleaf species such as Acer sp., Sorbus sp., Fraxinus sp. and riverside vegetation along the length of the stream currents.
The aesthetic forest of Ossa is a true botanical garden. The favorable environmental and climatic conditions of the area and especially the high level of rainfall, a result of easterly winds, are conducive to the creation of the wonderful forest complex of Ossa. Of equal interest are the landscape and local geomorphology since they give rise to a plethora of singular natural habitats which lead to a rich variety of kinds of vegetation, flora and fauna. The forest complex exhibits an exclusive variety of kinds of natural habitats and plant species. Observed is an alternating landscape with extensive closed forests of beech and fir on its eastern slopes and small mountain meadows, while its peak is a bare rock.
Several endemic plant species grow in the area such as Silene multicaulis genistifollia, Teucrium chamaedrys olympicum as well as species endemic to the Balkans such as Lamium garganticum striatum. The soil lends itself to forestry. Its productivity is considered low and unsuitable for farming or grazing purposes.
Area: 16900 hectares