by Audrey Verreault | 14 June 2022
Published in GCB Bioenergy. https://doi.org/10.1111/gcbb.12951
In the context of global change, a better understanding of the dynamics of wood degradation, and how they relate to tree attributes and climatic conditions, is necessary to improve broad-scale assessments of the contributions of deadwood to various ecological processes, and ultimately, for the development of adaptive post-disturbance management strategies. The objective of this meta-analysis was to review the effects of tree attributes and local climatic conditions on the time since death of coarse woody debris ranging in decomposition states. Results from our meta-analysis showed that projected warming will likely accelerate wood decomposition and significantly decrease the residence time in decay stages. By promoting such a decrease in residence time, further climate warming is very likely to alter the dynamics of deadwood, which in turn may affect saproxylic biodiversity by decreasing the temporal availability of specific habitats. Moreover, while coarse woody debris has been recognized as a key resource for bioenergy at the global scale, the acceleration of decay-stages transition dynamics indicates that the temporal window during which dead trees are available as feedstock for value-added products will shrink. Consequently, future planning and implementation of salvage harvesting will need to occur within a short period following disturbance, especially in warmer regions dominated by hardwood species. Another important contribution of this work was the development of a harmonized classification system that relies on the correspondence between the visual criteria used to characterize deadwood decomposition stages in locally developed systems the literature. This system could be used in future investigations to facilitate direct comparisons between studies. Our literature survey also highlights that most of the information on wood decay dynamics comes from temperate and boreal forests, whereas data from subtropical, equatorial and subarctic forests are scarce. Such data are urgently needed to allow broader-scale conclusions on global wood degradation dynamics.
by Audrey Verreault | 14 June 2022
Published in Evolutionary Applications 15(3): 383-402. https://doi.org/10.1111/eva.13348
With climate change, increasingly intense and frequent drought episodes will be affecting water availability for boreal tree species, prompting tree breeders and forest managers to consider adaptation to drought stress as a priority in their reforestation efforts. We used a 19-year- old polycross progeny test of the model conifer white spruce (Picea glauca) replicated on two sites affected by distinct drought episodes at different ages to estimate the genetic control and the potential for improvement of drought response in addition to conventional cumulative growth and wood quality traits. Drought response components were measured from dendrochronological signatures matching drought episodes in wood ring increment cores. We found that trees with more vigorous growth during their lifespan resisted better during the current year of a drought episode when the drought had more severe effects. Phenotypic data were also analyzed using genomic prediction (GBLUP) relying on the genomic relationship matrix of multi-locus gene SNP marker information, and conventional analysis (ABLUP) based on validated pedigree information. The accuracy of predicted breeding values for drought response components was marginally lower than that for conventional traits and comparable between GBLUP and ABLUP. Genetic correlations were generally low and nonsignificant between drought response components and conventional traits, except for resistance which was positively correlated to tree height. Heritability estimates for the components of drought response were slightly lower than for conventional traits, but similar single-trait genetic gains could be obtained. Multi-trait genomic selection simulations indicated that it was possible to improve simultaneously for all traits on both sites while sacrificing little on gain in tree height. In a context of rapid climate change, our results suggest that with careful phenotypic assessment, drought response may be considered in multi-trait improvement of white spruce, with accelerated screening of large numbers of candidates and selection at young age with genomic selection.
by Audrey Verreault | 14 June 2022
Published in Geoderma 29: e00523. https://doi.org/10.1016/j.geodrs.2022.e00523
The Quebec continental land represents 1,512,000 km2 of forests (59.9%), wetlands (12.5%), water bodies (11.7%), and agricultural land (4.2%) (Delisle, 2020). The rest of the territory (24.2%) is represented by tundra and bare surfaces, much of which within the permafrost zones. Soils are greatly influenced by geology and climate, and the whole province was affected by the last glaciation, so soils are young (<13,000 year-old). Five major soil regions have been mapped in Québec(nomenclature based on Soil Classification Working Group, 1998): 1) St. Lawrence Lowlands mainly with fine-textured Gleysol; 2) Appalachians with loamy Podzols or Brunisols; 3) Laurentians on the Canadian Shield with stony coarse-textured Podzols; 4) Abitibi and James Bay Lowlands with fine-textured soils (mainly Gleysols and Organic soils); and 5) Mistassini Highlands with stony coarse-textured Brunisols or Podzols. Although not mapped in detail, Organic soils and Cryosols are abundant in the Northern part of the province. Typical soil profiles from Québec are presented in Fig. 1. Québec soils are therefore quite variable and represent huge land surfaces. They also present different and significant challenges and priorities in terms of management and protection that are summarized below.
by Marie-Claude Boileau | 14 June 2022
Published in Oecologia 199: 27-38. https://doi.org/10.1007/s00442-022-05160-5
Nutritional ecologists aim to predict population or landscape-level effects of food availability, but the tools to extrapolate nutrition from small to large extents are often lacking. The appropriate nutritional ecology currencies should be able to represent consumer responses to food while simultaneously be simple enough to expand such responses to large spatial extents and link them to ecosystem functioning. Ecological stoichiometry (ES), a framework of nutritional ecology, can meet these demands, but it is typically associated with ecosystem ecology and nutrient cycling, and less often used to study wildlife nutrition. Despite the emerging zoogeochemical evidence that animals, and thus their diets, play critical roles in nutrient movement, wildlife nutritional ecology has not fully embraced ES, and ES has not incorporated nutrition in many wildlife studies. Here, we discuss how elemental currencies are “nutritionally, organismally, and ecologically explicit” in the context of terrestrial herbivore nutritional ecology. We add that ES and elemental currencies offer a means to measure resource quality across landscapes and compare nutrient availability among regions. Further, we discuss ES shortcomings and solutions, and list future directions to advance the field. As ecological studies increasingly grow in spatial extent, and attempt to link multiple levels of biological organization, integrating more simple and unifying currencies into nutritional studies, like elements, is necessary for nutritional ecology to predict herbivore occurrences and abundances across regions.
by Marie-Claude Boileau | 14 June 2022
Published in Forest Ecology and Management 517: 120278. https://doi.org/10.1016/j.foreco.2022.120278
Rising temperatures are likely to increase the risk of drought across the globe over the next century. Boreal forests are particularly vulnerable to drought because temperatures within these biomes are projected to warm the fastest. Warm and dry conditions can reduce tree growth, particularly in regions that are already moisturelimited, which may reduce forest productivity. Forest stand density management, such as pre-commercial thinning (PCT), can reduce moisture stress for residual trees by reducing canopy evaporation and increasing soil water availability. PCT is applied 15–20 years after clearcut and removes smaller stems to increase resource availability to residual trees, thereby increasing diameter growth and wood value. How PCT can mitigate climate change impact in boreal forests is still unclear, partly due to heterogeneity in moisture availability and growth response. This study tests the relative effect of PCT on radial growth of black spruce (Picea mariana (Mill.) B.S.P.) on sites with varying water availability to inform forest managers about PCT’s potential to mitigate anticipated effects of drought on tree growth. Tree discs from PCT and non-thinned plots were harvested from three contrasting site types in eastern Canada (warm-dry, warm-wet and cool wet). Using dendrochronology, the relationship between annual ring width index (RWI) and standardized-evapotranspiration index (SPEI) was explored in the time since PCT and during known climate anomalies. RWI showed a positive growth response to increasing SPEI on warm-dry sites, but a negative growth response on warm-wet and cool-wet sites. PCT provided a greater benefit to radial growth on warm-dry site types in the 15 years since treatment but provided no additional benefits during years of climate anomalies. Results suggest that PCT will remain an important forest management practice on moisture-limited sites in order to maintain black spruce productivity, whereas tree growth may benefit from future warming on relatively wet sites.
