by Audrey Verreault | 10 April 2020
Published in WIREs Energy Environment 7(5): e298. doi 10.1002/wene.298
Driven by the policy imperatives of mitigating greenhouse gas (GHG) emissions and improving energy security, an increasing proportion of global energy demand is being met by nonfossil energy sources. The socioeconomic and environmental benefits of replacing fossil fuels with bioenergy are complex; however, debate continues about issues such as best practices for biomass removal, stable supply chains, and GHG mitigation. With the greatest biomass per capita in the world, Canada could play an increasing role in the future of global bioenergy and the emerging bioeconomy. This paper reviews the utilization of feedstock salvaged after natural disturbances (fire and insect outbreaks) to supply wood-based bioenergy, by addressing the following multidisciplinary questions: (1) How much salvaged feedstock is available, and what are the uncertainties around these estimates? (2) How can sustainable practices to support increased removal of biomass be implemented? (3) What are the constraints on development of an integrated supply chain and cost-effective mobilization of the biomass? (4) Is the quality of biomass from salvaged trees suitable for conversion to bioenergy? (5) What is the potential for climate change mitigation? In average, salvaged feedstock from fire and insects could theoretically provide about 100 × 106 oven Dry ton (ODT) biomass per year, with high variability over time and space. Existing policies and guidelines for harvesting of woody biomass in Canadian jurisdictions could support sustainable biomass removal. However, uncertainties remain as to the development of competitive and profitable supply chains, because of the large distances between the locations of this feedstock and available processing sites. Another uncertainty lies in the time needed for a benefit in climate change mitigation to occur. A flexible supply chain, integrated with other sources of biomass residues, is needed to develop a cost-efficient bioenergy sector.
by Marie-Claude Boileau | 10 April 2020
Published in Heredity 121(2): 142-154. https://doi.org/10.1038/s41437-018-0061-6
Insect herbivory may drive evolution by selecting for trees with heritable resistance against defoliation. The spruce budworm (Choristoneura fumiferana, SBW) is a highly damaging forest insect pest that can affect population structure of white spruce (Picea glauca) in North America. Resistance against SBW was recently described in white spruce and was linked to three constitutive resistance biomarkers: the phenolic compounds piceol and pungenol, and expression of a beta-glucosidase encoding gene (Pgβglu-1). We investigated the phenotypic variability and heritability of these resistance biomarkers and of picein, the precursor of piceol, in the foliage of 874 trees belonging to 33 full-sib families and 71 clonal lines under evaluation in seven field locations in Eastern Canada. We aimed to (i) determine their genetic control, (ii) estimate the genetic and phenotypic correlations among defense biomarkers, and (iii) determine whether their constitutive levels are associated with detrimental trade-offs on growth. Quantitative genetics analyses indicated that all four traits are moderately to highly heritable. The full-sib and clonal analyses showed that additive and non-additive genetic effects play major and minor roles, respectively. Positive genetic and phenotypic correlations between resistance biomarkers and primary growth indicated that there is no trade-off between total height and height increment and resistance traits, contradicting the GDBH (Growth Differentiation Balance Hypothesis). Our findings about the predominant additive genetic basis of the resistance biomarkers show that adaptive evolution of white spruce natural populations to resist to SBW is possible and that potentially important gains could also be expected from artificial selection.
by Claire Morin | 10 April 2020
Published in Environmental Reviews 26(2): 113-120. https://doi.org/10.1139/er-2017-0066
Exotic species invasions are among the most significant global-scale problems caused by human activities. They can seriously threaten the conservation of biological diversity and of natural resources. Exotic European earthworms have been colonizing forest ecosystems in northeastern United States and southern Canada since the European settlement. By comparison, Asian earthworms began colonizing forests in the northeastern United States more recently. Since Asian species have biological traits compatible with a greater potential for colonization and disturbance than some European species, apprehension is growing about their dispersal into new territories. Here we review the extent of the current northern range of Asian earthworms in northeastern North America, the factors facilitating or limiting their propagation and colonization, and the potential effects of their invasion on forest ecosystems. Data compilation shows that Asian earthworms are present in all northeastern American states. So far, only one mention has been reported in Canada. Data confirm that their distribution has now reached the Canadian border, particularly along the Michigan–Ontario, New York–Ontario, Maine–New Brunswick, and Vermont–Québec frontiers. Studies report that the presence of Asian earthworms is strongly associated with human activities such as horticulture, vermicomposting, and the use of worms as fish bait. Some climatic (temperature, soil moisture) and edaphic (soil pH) factors may also influence their distribution. Controlling their dispersal at the source is essential to limiting their spread, as there is currently no effective way to eradicate established earthworm populations without unacceptable nontarget effects. Proposed management options in the United States include the prohibition of fish bait disposal and better management of the international trade of horticultural goods, commercial nurseries, and vermicomposting industries. We conclude that although regulations and awareness may delay their expansion, Asian earthworms are likely to spread further north into Canada. They are expected to cause important changes to biodiversity and dynamics of the newly invaded forest ecosystems.
by Claire Morin | 10 April 2020
Published in Front. Biogeogr. 9(4): e33282. https://doi.org/10.21425/F59433282
Climate change already affects species in many ecosystems worldwide. Since climate is an important component of a species’ ecological niche, up-to-date information about climatic niches is needed to model future species distributions in a context of climate change. The eastern red-backed salamander (Plethodon cinereus) is a wide-ranging woodland species and one of the most abundant verte-brates in northeastern North America. Though salamanders contrib-ute to several forest ecosystem functions, little is known about their climatic niche and future distribution. Using a dataset of 400,090 observations from 8302 localities in 5 Canadian provinces and 22 American states, we determined the current climatic niche of P. cinereus and predicted how the species’ distribution could shift in a context of climate change, especially in the northern part of its range. We also aimed to document factors that could affect the species’ distribution. We show that P. cinereus can live in various geographic and climatic conditions and tolerate a wide range of seasonal temperatures. The species’ current potential and future (until 2061–2080) distributions show a gap of up to 400 km with the northern limit of its current observed distribution. Assuming a mean colonization rate of approximately 100 m per year, we calculated that P. cinereus would need about 4000 years to reach the northern limit of the future distribution range modeled for the 2061–2080 period. The climate-modeled future distribution suggests that the presence of P. cinereus could decrease in the south and increase in the north. This, combined with the potential presence of habitats that are unsuitable for the species’ colonization in the north and with interspecific inter-actions in the south, could induce a contraction of the species’ range. Regardless of climate warming, the physical environment and natural and anthropic disturbances could also limit the species’ northern post-glaciation migration.
by Marie-Claude Boileau | 10 April 2020
Published in Physiologia Plantarum 165(1): 29-38. https://doi.org/doi:10.1111/ppl.12735
Black spruce (Picea mariana [Mill.] BSP) is a boreal tree species characterized by the formation of an adventitious root system. Unlike initial roots from seed germination, adventitious roots gradually appear above the root collar, until they constitute most of mature black spruce root system. Little is known about the physiological role they play and their influence on tree growth relative to initial roots. We hypothesized that adventitious roots present an advantage over initial roots in acquiring water and nutrients. To test this hypothesis, the absorptive capacities of the two root systems were explored in a controlled environment during one growing season. Black spruce seedlings were placed in a double-pot system allowing irrigation (25 and 100% water container capacity) and fertilization (with or without fertilizer) inputs independent to initial and adventitious roots. After 14 weeks, growth parameters (height, diameter, biomass), physiology (net photosynthetic rate, stomatal conductance, shoot water potential) and nutrient content (N, P, K, Ca and Mg foliar content) were compared. Most measured parameters showed no difference for the same treatment on adventitious or initial roots, except for root biomass. Indeed, fertilized black spruce seedlings invested heavily in adventitious root production, twice as much as initial roots. This was also the case when adventitious roots alone were irrigated, while seedlings with adventitious roots subjected to low irrigation produced initial root biomass equivalent to that of adventitious roots. We conclude that black spruce seedlings perform equally well through adventitious and initial roots, but if resources are abundant, they strongly promote development of adventitious roots.
