Betula pendula Ssp. distribution and growth in the sub-Carpathian curvature

Birch ssp. in the sub-Carpathians curvature can be found in composition with beech and other resinous species, unevenly distributed from the mountain peaks at around 1200 m down to 500-600, mainly from high hills to depressions at 600m, rarely seen on plain sites, crossing different geomorphological structures and overall accounting for 3857.1 ha. The main objective of the paper was to analyze the site and stand characteristics of Betula pendula ssp. Roth. in the subCarpathians curvature as followed: stand structure, stand types and stand site types, soils and different metrics, from growth to yields and its connectivity.The ecological adaptability to climate and soil and early fast growth, makes silver birch fulfill the overall requirements as a pioneer species, mostly naturally regenerated. Birch distribution is highly influenced by stand structure having low proportion in compositions, mean height of 15 m at age 50, and a diameter of 20m. Regarding the site, characteristics are more commonly found on fertile soils, corrugated or fragmented site type with a slope of 20-50° and it is distributed as secondary species in stands, averaging 750m in attitude, ranging from 500 to 1200m, 90% being in mixtures with other species with a mean annual increment of approximately 7 m³/year/ha regardless of stand site type. As an early successional species, it serves as a first colonizer but secondary species and quite often as an ecological instrument to improve the soil characteristics, biodiversity and prevent landslides in certain sites, lacking economic value other than fuel wood or other non-wood products.