Putting community data to work: some understory plants indicate red spruce regeneration habitat

When harvested, red spruce (Picea rubens) at low elevations is vulnerable to temporary displacement by balsam ®r (Abies balsamea) and hardwoods. If indicator plants can be found by which to assess spruce regeneration habitat, then biota dependent on red spruce dominance could bene®t. Associations between spruce seedlings (0.1±0.5 m tall) and understory plants, species life histories, and successional processes can be considered in managing for biodiversity; species richness alone is inadequate. Data from eight Maine sites in 50 permanent 0.0625 ha plots and 600 1 m subplots along a disturbance gradient included 30 understory species and nine environmental variables. In a canonical correspondence analysis (CCA), the ®rst two canonical axes accounted for 64.6% of the species±environment relationship; their eigenvalues accounted for 22% of the total variation. Spruce seedlings were sparse in clearcuts and most abundant in stands that were partially harvested at 20 year intervals and where Curtis' Relative density, softwood:hardwood ratio, and percent of understory plants visited by bees were all high. We propose a suite of common, widespread herbs and a liverwort as potential indicators, but recognize that parent trees probably in ̄uence red spruce seedling density more than does ground ̄ora composition. # Published by Elsevier Science 1999.