Multi-layered Scots pine forests in boreal Sweden result from mass regeneration and size stratification

Abstract Understanding historic development of multi-layered Scots pine ( Pinus sylvestris L.) stands and how they became multi-layered is essential for assessing the feasibility of using the selection system in these stands. To address this we measured trees (dbh ≥ 4 cm) and saplings (height > 0.5 m dbh  2  ha −1 the ingrowth of saplings past 1.3 m height essentially stopped but the size stratification among the small trees continued, further enhancing the multi-layered structure. The results indicate that to receive regeneration pulses and sustain a multi-layered structure in Scots pine forests, the basal area needs to be significantly reduced. The growth consequences of this need to be studied.