Canadian Forest Service Publications

Managing understory vegetation for maintaining productivity in black spruce forests: A synthesis within a multi-scale research model. 2013. Thiffault, N.; Fenton, N.J.; Munson, A.D.; Hébert, F.; Fournier, R.A.; Valeria, O.; Bradley, R.L.; Bergeron, Y.; Grondin, P.; Paré, D.; Joanisse, G. Forests 4:613-631.

Year: 2013

Issued by: Laurentian Forestry Centre

Catalog ID: 35068

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.3390/f4030613

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Sustainable management of boreal ecosystems involves the establishment of vigorous tree regeneration after harvest. However, two groups of understory plants influence regeneration success in eastern boreal Canada. Ericaceous shrubs are recognized to rapidly dominate susceptible boreal sites after harvest. Such dominance reduces recruitment and causes stagnant conifer growth, lasting decades on some sites. Additionally, peat accumulation due to Sphagnum growth after harvest forces the roots of regenerating conifers out of the relatively nutrient rich and warm mineral soil into the relatively nutrient poor and cool organic layer, with drastic effects on growth. Shifts from once productive black spruce forests to ericaceous heaths or paludified forests affect forest productivity and biodiversity. Under natural disturbance dynamics, fires severe enough to substantially reduce the organic layer thickness and affect ground cover species are required to establish a productive regeneration layer on such sites. We succinctly review how understory vegetation influences black spruce ecosystem dynamics in eastern boreal Canada, and present a multi-scale research model to understand, limit the loss and restore productive and diverse ecosystems in this region. Our model integrates knowledge of plant-level mechanisms in the development of silvicultural tools to sustain productivity. Fundamental knowledge is integrated at stand, landscape, regional and provincial levels to understand the distribution and dynamics of ericaceous shrubs and paludification processes and to support tactical and strategic forest management. The model can be adapted and applied to other natural resource management problems, in other biomes.

Plain Language Summary

This study is a synthesis of various research projects on the effects of understory vegetation on the productivity of black spruce stands, focusing primarily on heath (shrub species) and moss (sphagnum moss in particular).

After thinning operations in these stands, heath and moss can invade harvested sites and compromise regeneration, and cause growth stagnation in black spruce on certain sites. In the case of moss, the phenomenon whereby sphagnum peat moss gradually accumulates is called paludification.

Thanks to this study, forest managers will be able to take the effects of their treatments on this understory vegetation into account in order to maintain productivity in black spruce stands. They will also be able to consider the impact of this phenomenon at various levels (tree, stand, landscape, region and biome).