LONG-TERM SPECIES AND STRUCTURAL-CHANGES AFTER CLEANING YOUNG EVEN-AGED NORTHERN HARDWOODS IN NEW-HAMPSHIRE, USA

The effects of four cleaning practices (including a control) on specie s composition and structural characteristics were studied over a 31-ye ar period following treatment of an even-aged 25-year-old northern-har dwood stand that originated after complete clearcutting in 1933-1935. The treatments consisted of: a heavy and a light crop tree cleaning; a drastic species-cleaning treatment that removed nearly all pin cherry (Prunus pensylvanica L.f.), aspen (Populus tremuloides Michx. and gra ndidentata Michx.), striped maple (Acer pensylvanicum L.), and red map le (Acer rubrum L.) sprout clumps followed by a crop-tree cleaning; an d an uncut control. There were no significant differences among treatm ents in species and structural characteristics in the 56-year-old stan d at the end of the study period, except for the presence of a moderat e aspen component in the light cleaning and the control. Although prev ious research shows that cleaning treatments in young northern hardwoo ds may have silvicultural and economic benefits, the impact of such tr eatments on long-term stand development is relatively minor. (C) 1997 Elsevier Science B.V.