Value of selectively cut deciduous forest for understory herb conservation: An experimental assessment

Abstract

Deciduous forest stands managed for timber production by selective cutting could also be valuable for conservation of herbaceous plants, if herbs are not negatively affected by partial canopy removal. The short-term effect of partial canopy removal on forest herbs was assessed by recording how many species either disappeared or occurred less frequently 2 years after selective tree cutting (33% or 66% removal of tree basal area) in experimental plots of three sizes (0.01, 0.05, 0.20 ha). A similar percentage of herbaceous species disappeared from permanent quadrats within cut plots (3–12% of herbs) as within adjacent uncut plots (9–13%). The percentage of herbaceous species that occurred less frequently 2 years after cutting was significantly smaller in cut plots (13–36%) than in uncut plots (34–37%). The short-term to longer effect of partial canopy removal on forest herbs was assessed by comparing their frequency in canopy openings and under adjacent intact canopy in stands selectively cut 2, 5 and 9 years earlier. The percentage of herbaceous species occurring less frequently in canopy openings than under intact canopy did not differ significantly among 2-, 5-, and 9-year-old stands (i.e. 29%, 17% and 25%, respectively). Nor did the percentage of herbaceous species absent from canopy openings differ significantly among 2-, 5- and 9-year-old stands (i.e. 14%, 28% and 19%, respectively). These results indicate that selectively cut forest may be valuable for species conservation as well as timber production.