Canadian Forest Service Publications

Effects of post-windthrow salvage logging on microsites, plant composition and regeneration. 2014. Waldron, K.; Ruel, J.-C.; Gauthier, S.; De Grandpré, L.; Peterson, C.J. Appl. Veg. Sci. 17:323-337.

Year: 2014

Issued by: Laurentian Forestry Centre

Catalog ID: 35392

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1111/avsc.12061

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Question: How does windthrow influence plant diversity and composition as well as regeneration and microsite characteristics? What are the consequences of post-windthrow salvage logging on these key attributes?

Location: Eastern black spruce–moss forest, Quebec, Canada.

Methods: A total of 92 plots were sampled, each with a radius of 11.28 m; 49 of these plots were salvaged while 43 were unsalvaged. Regeneration density, plant diversity and seedbeds were characterized. We tested the effect ofmicrotopography and windthrow severity on species richness and Shannon diversity index for salvaged and unsalvaged windthrows using a mixed model. Partial redundancy analysis (RDA) determinedwhich environmental and stand characteristics weremost important in explaining differences in plant species and forest floor types among the treatments. The effects of treatments (salvaged and unsalvaged windthrows), microtopography attributes, windthrow severity and regeneration species on seedling and sapling abundance were tested using a linear mixedmodel.

Results: Salvagedwindthrow,with a large proportion of skid trails, deadmosses and Sphagnum, had a lower degree of seedbed heterogeneity. Also, some understorey species present in the unsalvaged ecosystem were absent from the salvaged windthrow. Sphagnum and other moss species were clearly associated with the unsalvaged treatment. White birches were positively associated with moundmicrotopography in the unsalvaged windthrow.

Conclusion: From an ecosystem-based forest management perspective, natural post-windthrow understorey conditions and microsite heterogeneity can be in part maintained in salvaged cut blocks by incorporating retention patches that include downed and standing dead wood and living trees of diverse sizes. These steps should favour plant regeneration and augment diversity for salvage logging after wind disturbance.

Plain Language Summary

Windthrows are natural disturbances caused by wind. Windfallen trees can be harvested in certain situations. The researchers evaluated the impact of this operation in black spruce-moss stands in eastern Quebec. More specifically, they studied its effect on plant diversity, regeneration density and the quality of seedbeds for germination.

Since the harvested timber must be removed, harvesting fallen trees creates multiple skid trails. The creation of these trails destroys mosses and sphagnum and reduces the heterogeneity of seedbeds. In addition, the researchers found that the act of working in the forest decreases the diversity of understory vegetation.

To ensure that forest operations mimic natural processes as much as possible (ecosystem-based forest management), the researchers recommend that the planning of post-windthrow operations should include leaving portions of land intact. These patches would contain areas with favourable conditions for regeneration and would contribute to maintaining plant diversity.