Afforestation of Black Spruce Lichen Woodlands by Natural Seeding

Madec, Cécile; Walsh, Denis; Lord, Daniel; Tremblay, Pascal; Boucher, Jean‐François; Bouchard, Sylvie

doi:10.5849/njaf.11-042

Cited by 11 publications

(16 citation statements)

References 14 publications

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“…Perhaps their use as an indicator of water availability reflects the importance of lichen and graminoid ground cover [27] and whether the poor fen is more similar to a rich fen or a bog. Although graminoids can be an indicator of wet conditions (rich fen), they also can increase competition with that of seedlings, while lichen mats may produce poor seedbed conditions [28,29]. Many studies demonstrate the effectiveness of herbicides on seedling survival and growth post-MSP, as they eliminate the competing shrubs and graminoids [30,31].…”

Section: Seismic Line Regeneration Densitymentioning

confidence: 99%

Caribou Conservation: Restoring Trees on Seismic Lines in Alberta, Canada

Filicetti

Cody

Nielsen

2019

Forests

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Seismic lines are narrow linear (~3–8 m wide) forest clearings that are used for petroleum exploration in Alberta’s boreal forest. Many seismic lines have experienced poor tree regeneration since initial disturbance, with most failures occurring in treed peatlands that are used by the threatened woodland caribou (Rangifer tarandus caribou). Extensive networks of seismic lines, which often reach densities of 40 km/km2, are thought to have contributed to declines in caribou. The reforestation of seismic lines is therefore a focus of conservation. Methods to reforest seismic lines are expensive (averaging $12,500 per km) with uncertainty of which seismic lines need which treatments, if any, resulting in inefficiencies in restoration actions. Here, we monitored the effectiveness of treatments on seismic lines as compared to untreated seismic lines and adjacent undisturbed reference stands for treed peatlands in northeast Alberta, Canada. Mechanical site preparation (mounding and ripping) increased tree density when compared to untreated lines, despite averaging 3.8-years since treatment (vs. 22 years since disturbance for untreated). Specifically, treated lines had, on average, 12,290 regenerating tree stems/ha, which is 1.6-times more than untreated lines (7680 stems/ha) and 1.5-times more than the adjacent undisturbed forest (8240 stems/ha). Using only mechanical site preparation, treated seismic lines consistently have more regenerating trees across all four ecosites, although the higher amounts of stems that were observed on treated poor fens are not significant when compared to untreated or adjacent undisturbed reference stands.

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Section: Seismic Line Regeneration Densitymentioning

confidence: 99%

Caribou Conservation: Restoring Trees on Seismic Lines in Alberta, Canada

Filicetti

Cody

Nielsen

2019

Forests

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“…Soil scarification is a widely used soil preparation technique that creates furrows or patches of exposed mineral soil, which has been shown to be a suitable substrate for several conifer species, including black spruce (Viereck and Johnston, 1990;Prévost, 1992;Houle and Filion, 2003;Wang and Kemball, 2005;Kemball et al, 2006;Prévost and Dumais, 2018), by increasing mineralization rate, yielding favorable humidity and temperature conditions and reducing competing vegetation (Orlander, 1987;Prévost, 1992Prévost, , 1997Karlsson et al, 2002;Hébert et al, 2006;Prévost and Dumais, 2018;Sikström et al, 2020). Soil scarification not only improves planting success after cuttings (Sikström et al, 2020) but also promotes the germination and the establishment of seedlings derived from surrounding seed trees (Prévost, 1992;Karlsson et al, 2002;Madec et al, 2012;Hébert et al, 2013;Prévost and Dumais, 2018;Laine et al, 2020;Rosenvald et al, 2020;Kyrö et al, 2022). Therefore, planting operations, which are costly and time-consumingespecially in remote areas-may not be economically justified when scarification is followed by dense natural seeding and establishment (Cyr et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…However, natural regeneration is not always limited by seed production. In this case, natural regeneration may rather depend on seedbed quality and availability (Fleming and Mossa, 1994;Peters et al, 2005;Wang and Kemball, 2005;Kemball et al, 2006;Madec et al, 2012;Kokkonen et al, 2018), or seedlings' vigor, which is known to increase with seed size in black spruce (Skeates and Haavisto, 1995). For instance, Madec et al (2012) have shown that the density and the distribution of seed trees were not a limiting factor for seedling establishment in scarified LWs, which was rather mostly controlled by exposed mineral soil surface area (thereafter 'scarification intensity' in m 2 ha −1 or %).…”

Section: Introductionmentioning

confidence: 99%

“…The natural regeneration dynamics following wildfires (Filion and Morin, 1996;Wang and Kemball, 2005;Kemball et al, 2006;Johnstone et al, 2009;Brown and Johnstone, 2012) or logging (Béland et al, 2000;Downey et al, 2018;Kokkonen et al, 2018;Prévost and Dumais, 2018;Laine et al, 2020;Rosenvald et al, 2020;Sikström et al, 2020;Kyrö et al, 2022) have been well documented in boreal forests but available data are much scarcer for scarified LWs, characterized by low seed tree density, low fertility and the presence of a competing cryptogamic vegetation (lichens and bryophytes). A few studies have shown the benefits of soil scarification in LWs for both natural seeding (Madec et al, 2012) and the growth of planted seedlings (Hébert et al, 2006(Hébert et al, , 2013, but as afforestation experiments in LWs started only a few decades ago, our long-term knowledge of natural regeneration dynamics in this habitat is limited. In addition, the growth of black spruce seedlings has been shown to be slow during the first five years following soil scarification in boreal forests and more research is needed to determine long-term survival and growth rates of seeded black spruce (Fleming and Mossa, 1994;Prévost and Dumais, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…The main goal of this study was to assess the potential and the dynamics of natural regeneration in boreal LWs of Québec, Canada, following soil scarification as a unique intervention. We addressed the following specific research questions: (1) Does the high seedling establishment reported by Madec et al (2012) within five years after soil scarification persist in time? ; (2) To what extent does substrate and seed availability limit natural regeneration in this habitat?…”

Section: Introductionmentioning

confidence: 99%

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Natural regeneration potential and dynamics in boreal lichen woodlands of eastern Canada following soil scarification

Marty

Fradette

Duchesne

et al. 2023

Front. For. Glob. Change

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Boreal lichen woodlands (LWs) are stable low tree-density zones of the Canadian boreal forest whose afforestation has been proposed as a way to create new C sinks and thus mitigate climate change. Planting operations in these remote areas are however costly and time-consuming, and may not be necessary when soil scarification is followed by dense natural regeneration. In the present study, we assessed the natural regeneration potential and dynamics in six boreal LWs of Québec, Canada, 11 years after soil scarification. The number, size (height and stem diameter) and age of seedlings were measured in 2-4 sampling plots per site (18 plots in total). Our data show that scarification operations produced on average 1,400 m2 ha–1 of exposed mineral soil (scarification intensity of 14%) with, however, a large within-site variability. The natural regeneration was mainly composed of black spruce seedlings (> 95%), averaged ∼12,000 seedlings ha–1 across the six sites and significantly varied among sites, mostly due to the variation in scarification intensity. Seedling density averaged ∼9 seedlings m–2 of exposed mineral soil and increased with seed tree mean diameter at breast height (DBH) (R2 = 0.51; P < 0.05) but not with the density of seed trees, revealing the importance of old and large seed trees in natural regeneration success. Together, scarification intensity and the DBH of remaining seed trees explained ∼60% of the variation in natural regeneration density across the 18 sampled plots. The rate of establishment of seedlings was generally high – with on average 60% of the carrying capacity of the substrate being reached within three years following scarification – and increased with seed tree mean DBH (R2 = 0.77; P < 0.05). However, the growth rate of seedlings was very low. Eleven years after scarification, 60% of the seedlings were < 15 cm and the height of 10-yr-old seedlings averaged 27.5 cm. Thus, even though seedling establishment was successful, the biomass accumulated by the natural regeneration was negligible in the span of a decade. Therefore, the implementation of afforestation following scarification appears to be necessary to create significant C sinks in the midterm.

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