ABSTRACT
Potential indicator species for forest management were explored in a series of
studies of old-growth boreal stands encompassing a range of inherent site productivity.
The biota surveyed included terrestrial cryptogams, ectomycorrhizal fungi on roots of A.
lasiocarpa, epigeous ectomycorrhizal mushrooms, mesofauna of the forest floor (mites
and springtails) and macrofauna (beetles, ants, and spiders). Manuscripts on the
cryptogams and ectomycorrhizal fungi are completed, and final resolution of a few
remaining faunal taxa is almost complete. Some interim conclusions on the overall
patterns of biodiversity are presented here. The number of species per plot (0.15 ha)
ranged from 145 to 205 (vascular plants, cryptogams, ectomycorrhizal fungi, springtails,
spiders and ants), which represents about 1/3 rd the total diversity of this landscape (607
species; not including beetles, mites). Total species richness by plot increased by approx.
33% and then plateaued with site productivity, suggesting that greater amounts of soil
moisture, nutrients and organic matter allowed for the development of a richer
community of soil organisms. Beta diversity, which is the turnover of species across a
landscape, averaged 31% by plot, meaning any one individual plot had approx. 30% of
the total species found over the 19 plots. The uniqueness of species assemblages by site
series was moderate, and so, for example, preserving mesic sites alone would provide
habitat for about 50% of the total landscape organisms. Capturing a range of dry to moist
upland sites as oldgrowth management areas or wildlife reserves would therefore
potentially double the total number of species within the conservation areas. Our results
might also be considered in monitoring programs for late-seral species, which generally
use space for time substitution as an experimental design. Such an approach would be
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less dependent on site for soil fauna, as the majority of these species were ubiquitous,
whereas cryptogams and ectomycorrhizal fungi could be confounded by edaphic effects
on species assemblages. The benefit of this finer site association, however, is that these
species could provide more sensitive indicators for ongoing changes in soil fertility under
forest management. Overall we found a large source of biodiversity associated with
forest soils and substrates (6 x the diversity of the vascular plants), and a large pool of
potential species for environmental monitoring. Indicators could include those species
representing oligotrophic, mesotrophic or eutrophic soil conditions, and functional
organization such as the balance of rare versus common species on the landscape.
