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

When harvested, red spruce (Picea rubens) at low elevations is vulnerable t o temporary displacement by balsam fir (Abies balsamea) and hardwoods. If i ndicator plants can be found by which to assess spruce regeneration habitat , then biota dependent on red spruce dominance could benefit. Associations between spruce seedlings (0.1-0.5 m tall) and understory plants, species li fe histories, and successional processes can be considered in managing for biodiversity; species richness alone is inadequate. Data from eight Maine s ites in 50 permanent 0.0625 ha plots and 600 1 m(2) subplots along a distur bance gradient included 30 understory species and nine environmental variab les. In a canonical correspondence analysis (CCA), the first two canonical axes accounted for 64.6% of the species-environment relationship; their eig envalues accounted for 22% of the total variation. Spruce seedlings were sp arse in clearcuts and most abundant in stands that were partially harvested at greater than or equal to 20 year intervals and where Curtis' Relative d ensity, softwood:hardwood ratio, and percent of understory plants visited b y bees were all high. We propose a suite of common, widespread herbs and a liverwort as potential indicators, but recognize that parent trees probably influence red spruce seedling density more than does ground flora composit ion. (C) Published by Elsevier Science 1999.