Current issue: 54(2)

Under compilation: 54(3)

Impact factor 1.683
5-year impact factor 1.950
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles by Nelson Thiffault

Category: Research article

article id 10230, category Research article
Mohammed Henneb, Osvaldo Valeria, Nelson Thiffault, Nicole Fenton. (2019). Black spruce seedling growth response in controlled organic and organic-mineral substrates. Silva Fennica vol. 53 no. 4 article id 10230. https://doi.org/10.14214/sf.10230
Highlights: Seedling height and diameter were highest on clay and mesic substrates respectively; Foliar nutrients were relatively high in seedlings that were established on mesic substrates; We recommend the application of mechanical soil preparation techniques that promote the creation of organic-mesic substrates to support regeneration establishment.

In the boreal forest of eastern Canada, a large proportion of black spruce (Picea mariana [Mill.] Britton, Sterns & Poggenb.) stands are affected by paludification. Edaphic conditions that are created by paludification processes, including an abundance of microsites with high moisture and low nutrient contents, hinder forest regeneration. Disturbance of paludified sites by mechanical soil preparation (MSP) reduces organic layer thickness, while generating a range of substrates for regeneration establishment. Yet, little information is available regarding the effects of these substrates on tree growth. Our objective was to determine the effect of organic, mineral and organo-mineral substrates that are created following MSP of a paludified site on the growth and root development of black spruce seedlings in a semi-controlled environment. We demonstrated that substrate exerted a significant effect on seedling growth and foliar concentrations of N, P and K. Increase in height and diameter were respectively greatest on clay (mineral) and mesic substrates. Substrate effects did not affect total biomass increases or final root biomass. Foliar nutrients (N, P, K) were relatively high in seedlings that were established on mesic substrates and relatively low for those established on clay substrates. To ensure successful seedling establishment, we recommend the application of MSP techniques that expose organic-mesic substrates on sites that are susceptible to paludification.

  • Henneb, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada ORCID ID: http://orcid.org/0000-0003-4507-1219 E-mail: mohammed.henneb@uqat.ca (email)
  • Valeria, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada ORCID ID: http://orcid.org/0000-0002-9921-7474 E-mail: osvaldo.valeria@uqat.ca
  • Thiffault, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Natural Resources Canada, Canadian Wood Fibre Centre, 1055 rue du PEPS, P.O. Box 10380, Stn Sainte Foy, Quebec, QC G1V 4C7, Canada ORCID ID: http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
  • Fenton, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada ORCID ID: http://orcid.org/0000-0002-3782-2361 E-mail: nicole.fenton@uqat.ca
article id 10209, category Research article
Claudie-Maude Canuel, Nelson Thiffault, Michael K. Hoepting, James C.G. Farrell. (2019). Legacy effects of precommercial thinning on the natural regeneration of next rotation balsam fir stands in eastern Canada. Silva Fennica vol. 53 no. 4 article id 10209. https://doi.org/10.14214/sf.10209
Highlights: We investigated the potential legacy effects of precommercial thinning in next rotation, dense natural balsam fir stands; Precommercial thinning had few legacy effects on next rotation stands and should not impair their regeneration; Balsam fir dominated the regeneration layer. Other tree species were almost absent.

The Green River precommercial thinning (PCT) trial was established between 1959–1961 in New Brunswick (Canada) within natural balsam fir (Abies balsamea (L.) Mill.)-dominated stands. Three silviculture scenarios differing only by the increasing nominal spacings of PCT treatments (1.2 m, 1.8 m, 2.4 m) were compared to an unthinned control within randomized replicates that were clearcut harvested in 2008 and treated with herbicide in 2011. During the fourth post-harvest growing season, we assessed regeneration, competing vegetation and coarse woody debris (CWD; differentiated between large woody debris and slash) to assess the legacy effects of PCT on regeneration of next rotation stands. Our results confirmed that silviculture scenarios including PCT significantly increased conifer stocking in treated plots compared to control conditions, but only in the 1.8 m nominal spacing. Considering that treated and untreated stands were fully stocked, we conclude that PCT using the spacing gradient tested has no legacy effect on the regeneration of next rotation natural balsam fir stands. Given the known sensitivity of balsam fir to future climate conditions in this region, we suggest that future treatments should promote tree species diversity to support ecosystem resilience to climate change by favouring more warm-adapted species, such as some hardwoods.

  • Canuel, Faculté de foresterie, géographie et géomatique, Université Laval, Québec, QC G1V 0A6, Canada;  Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S., P.O. Box 10380, Sainte-Foy Stn., Québec, QC G1V 4C7, Canada ORCID ID:E-mail: claudie-maude.canuel.1@ulaval.ca
  • Thiffault, Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S., P.O. Box 10380, Sainte-Foy Stn., Québec, QC G1V 4C7, Canada ORCID ID: http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca (email)
  • Hoepting, Canadian Wood Fibre Centre, Natural Resources Canada, 1219 Queen St. E., Sault Ste. Marie, ON P6A 2E5, Canada ORCID ID:E-mail: michael.hoepting@canada.ca
  • Farrell, Canadian Wood Fibre Centre, Natural Resources Canada, 1350 Regent Street, P.O. Box 4000, Fredericton, NB E3B 5P7, Canada ORCID ID:E-mail: jamescg.farrell@canada.ca
article id 918, category Research article
Nelson Thiffault, François Hébert, Robert Jobidon. (2012). Planted Picea mariana growth and nutrition as influenced by silviculture x nursery interactions on an ericaceous-dominated site. Silva Fennica vol. 46 no. 5 article id 918. https://doi.org/10.14214/sf.918
We aimed at evaluating the interacting effects of silvicultural and nursery practices on planted black spruce (Picea mariana (Mill.) BSP) dimensions, growth, survival and nutrition, 8 years following planting on a carefully logged boreal stand heavily invaded by Kalmia angustifolia L. and Rhododendron groenlandicum (Oeder) Kron & Judd. We also evaluated functional traits related to light and nutrient acquisition and key environmental resource availability to interpret treatment impacts on spruce seedling leaf traits and growth. An experimental black spruce plantation, consisting in a randomized block split-split-split plot design with 13 replicates was established in northeastern Quebec (Canada). Scarification (single-pass, double-pass), fertilization at the time of planting (control; macronutrients only; macro + micronutrients), stock type (container-grown; bare-root), and initial foliar N concentration (4 increasing levels) treatments were applied, and measurements were performed 5 and 8 years following planting. Double-pass scarification significantly increased soil temperature and reduced the competition cover, compared to the single-pass treatment. As a result, double-pass scarification promoted seedling growth over the single-pass treatment, and influenced the expression of other treatment effects. However, the relative gains associated with the second scarification pass have to be balanced against the supplemental investment involved by the treatment before being recommended. Our results point to variable effects of fertilization at planting to stimulate seedling initial growth. In this ecosystem, it appears that the silvicultural gains of this treatment depend on the variable of interest. Bare-root seedlings grew faster than containerized seedlings in the most intense site preparation treatment, but the differences have limited silvicultural impacts.
  • Thiffault, Ministère des Ressources naturelles du Québec, Direction de la recherche forestière, 2700 rue Einstein, Québec, QC, Canada G1P 3W8 ORCID ID:E-mail: nelson.thiffault@mrnf.gouv.qc.ca (email)
  • Hébert, Ministère des Ressources naturelles du Québec, Direction de la recherche forestière, 2700 rue Einstein, Québec, QC, Canada G1P 3W8 ORCID ID:E-mail: ffrancois.hebert@mrnf.gouv.qc.ca
  • Jobidon, Ministère des Ressources naturelles du Québec, Direction de la recherche forestière, 2700 rue Einstein, Québec, QC, Canada G1P 3W8 ORCID ID:E-mail: robert.jobidon@mrnf.gouv.qc.ca

Category: Research note

article id 1716, category Research note
Nelson Thiffault, Alain Paquette, Christian Messier. (2017). Early silvicultural guidelines for intensive management of hybrid larch plantations on fertile sub-boreal sites. Silva Fennica vol. 51 no. 2 article id 1716. https://doi.org/10.14214/sf.1716
Highlights: Satisfactory growth can be obtained using a wide range of site preparation intensities; There is a net advantage of performing two motor-manual release treatments over a single release; A second release treatment cannot be replaced by more intensive site preparation; Planting depth had no influence on planted seedling growth after 6 years.

Use of fast-growing tree plantations on dedicated areas is proposed as a means of reconciling fibre production with conservation objectives. Success of this approach however requires fine-tuning silvicultural scenarios so that survival and growth are optimized while management and environmental costs are minimized. This is particularly challenging for hybrid larch (Larix × marschlinsii Coaz), a shade-intolerant species planted on fertile sites in Quebec (Canada) where legislation prevents the use of chemical herbicides. In this context, multiple motor-manual release treatments are often required, with high impacts on costs and social issues related to the scarcity of a qualified workforce. We established a split-split-plot design on a recently harvested site to assess the main and interaction effects of mechanical site preparation (MSP) intensity (five modalities of trenching or mounding), motor-manual release scenario (one or two treatments) and planting depth (0–3 cm or 3–10 cm) on hybrid larch seedling growth and survival six years after planting. Mechanical site preparation intensity and planting depth did not influence seedling growth after 6 years. The lack of significant interaction between MSP and release scenarios indicates that these operations should be planned independently. A more intensive MSP treatment cannot replace a second motor-manual release on fertile sites, as proposed to reduce costs. Our results also show the significant advantage of performing two motor-manual release treatments two years apart (the first one early in the scenario), over performing a single treatment. Our study provides silvicultural guidelines for the establishment of high-yield exotic larch plantations.

  • Thiffault, Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec, 2700 rue Einstein, Québec, QC, Canada G1P 3W8; Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8 ORCID ID: http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@mffp.gouv.qc.ca (email)
  • Paquette, Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Université du Québec à Montréal, Département des sciences biologiques, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8 ORCID ID: http://orcid.org/0000-0003-1048-9674 E-mail: alain.paquette@gmail.com
  • Messier, Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Université du Québec à Montréal, Département des sciences biologiques, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Institut des Sciences de la Forêt tempérée (ISFORT), 58 rue Principale, Ripon, QC, Canada JOV 1V0 E-mail nelson.thiff ORCID ID:E-mail: christian.messier@uqo.ca

Register
Click this link to register for Silva Fennica submission and tracking system.
Log in
If you are a registered user, log in to save your selected articles for later access.
Contents alert
Sign up to receive alerts of new content
Your selected articles

Committee on Publication Ethics A Trusted Community-Governed Archive