Retezat LTER site is located in the western part of the Southern Carpathians. Retezat massif was declared a biosphere reserve in 1979, due to its landscape diversity, geological complexity, composition of the flora and vegetation. Retezat National Park is famous for its floral diversity, hosting more than 1190 species of plants. Forests cover about 49 % of the area , the most widespread species are beech ( Fagus sylvatica ), spruce ( Picea abies ) , mountain pine (Pinus mugo ) , fir ( Abies alba), maple (Acer pseudoplatanus ) , birch ( Betula pendula) , alder ( Alnus viridis ) , elm ( Ulmus glabra) , Rowan ( Sorbus aucuparia ) . Pinus cembre opulation is probably the most representative of the Carpathian Mountains. The long term research network was placed in Retezat National Park in 2000, comprising 11 research plots (with a 0.25 ha surface) placed in representative forest or alpine ecosystems.