Soil indicators of sustainability are currently limited to soil disturbance surveys and reductions in net areas to be reforested (Montréal Process 1995, Curran et al. 2005). More biologically-based indicators of soil function, productivity, and biodiversity would provide more sensitive criteria of management practices. Such indices would be similar to the Index of Biological Integrity (IBI) that is widely used in the United States to monitor water quality, and which is now being adopted in northwest B.C. for fisheries habitat and water quality (Ministry of Environment 2005). Soil indices could include soil fauna, ectomycorrhizal fungi, or terrestrial nonvascular plants (lichens/bryophytes/liverworts ? ?cryptogams?) (e.g. Pandolfini et al. 1997, van Straalen 1998, Kremsater 2003), both as indicator species or indirectly through community parameters such as functional diversity (Bengtsson 1998). For example, ectomycorrhiza communities are strongly affected by stand disturbance, and 12 mushroom species have been identified as late-seral dependent in the interior cedar-hemlock zone of northwest British Columbia (Kranabetter et al. 2005). These species provide an excellent cost-effective monitoring tool that will clearly demonstrate the recovery of fungal biodiversity in managed stands. Further development of similar indicators is needed to examine issues such as soil disturbance (e.g. compaction and organic matter loss), soil biodiversity (e.g. green tree retention), and soil sustainability (e.g. nutrient cycling under alternative silviculture systems).
A logical step in the development of soil indicators is a better characterization of biotic communities across sites representing full gradients in ecosystem productivity. Species that are limited in distribution to poor ecosystems, for example, could serve as biological indicators of site-degrading forest practices. Better information on species distribution and community composition is also essential in providing unambiguous indicators across spatial scales. For example, the 12 mushroom species limited to late-seral stands in the ICH were only tested on submesic ecosystems, and might not be valid for richer ecosystems in that landscape. We also have very little information on the natural range in variability for community measures in soils, such as total species richness or relative evenness in species distribution between sites. Targets or criteria extrapolated from studies limited to mesic sites could lead to poor assessments of management impacts on soils across variable landscapes. Ultimately, the goal of a forest manager is to maintain the historic, natural range of species within ecosystems of all kinds, so characterizing these biotic communities across the landscape gradient is an essential first step.
In British Columbia, forested landscapes have a range of common but distinct ecosystems that reflect differences in soil nutrient and moisture availability (from nutrient poor/dry to rich/wet across the edatopic grid). A network of replicated sites encompassing a full gradient in forest ecosystems (the 02 Pl ? Cladonia; the 01 Sxw ? Huckleberry; the 06 Sxw ? Oak fern; and the 09 Sxw - Devil?s club) was established in the SBSmc2 in mature stands with a mix of lodgepole pine, hybrid white spruce and subalpine fir. Three large and important biotic communities will be assessed (repeatedly where necessary): ectomycorrhizal species (mushrooms and fine root ECM fungal colonization); soil macro- and mesofauna; and plant (especially the terrestrial bryophyte/liverwort/lichen) species. Taxonomic expertise will be utilized to allow for as complete a species inventory as possible. Species distribution will be compared across site series and tested against site potential (asymptotic stand height) and measured soil parameters such as N availability and moisture content.
Bengtsson, J. 1998. Applied Soil Ecology 10: 191-199.
Curran, M.P., Miller, R.E., Howes, S.W., May ...
Kranabetter, J. Marty. 2009. Developing indicators of soil productivity, function and biodiversity through soil biotic communities. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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