Vascular plant and bryophyte flora in midterm hybrid aspen plantations on abandoned agricultural land

Abstract

Short-rotation forest plantations with hybrid aspen on abandoned agricultural land are a novel use of land in eastern and northern Europe; however, to date, their impact on floristic diversity has not been thoroughly studied. Our aim is to determine the kind of vascular plant and bryophyte (including epiphytes) species that benefit from such plantations. Data on understorey and soil humus layer properties were collected as part of the repeated monitoring of 204 permanent vegetation plots in twenty-four 13- to 14-year old commercial hybrid aspen plantations in boreonemoral Estonia. Data analysis indicated that the understorey of midterm hybrid aspen plantations is formed of species with different ecological requirements, ranging from typical fallow species to shade-tolerant forest species. Midterm plantations were dominated by common grassland species; however, occasionally less frequent and protected grassland species were also found. No rare species of epigeic or epiphytic bryophytes were recorded. Overall, a slow succession towards a shade-tolerant understorey was observed when comparing midterm and young plantations, with the occurrence of forest species in negative correlation with the amount of canopy-transmitted total solar radiation. The number of species characteristic of forests growing on similar soil types was low. Further studies will clarify how close the habitat in such intensively managed plantations on abandoned agricultural lands can approach that of natural forests in hemiboreal conditions.