by Audrey Verreault | 13 April 2020
Published in Journal of Vegetation Science 28: 57-68. doi: 10.1111/jvs.12466
Aims: Our study aimed to: (1) document the preindustrial (1925) forest composition prior to extensive logging; (2) document the magnitude of changes from 1925 to 2005; and (3) identify the relative influence of logging and natural disturbances as drivers of the present-day forest composition.
Location: Boreal forest in central Quebec, eastern Canada.
Methods: We used a dense network of georeferenced historical (~1925) forest plots (n = 30 033) to document preindustrial forest composition. We evaluated the magnitude of changes with the present-day using modern plots (1980s to 2000s). We reconstructed a long-term, spatially explicit history of logging, spruce budworm outbreaks (Choristoneura fumiferana [Clem.], SBO), and fire using historicalmaps and field surveys.
Results: In the preindustrial period, late successional coniferous taxa (Abies balsamea and Picea spp.) dominated the landscape, whereas early successional deciduous taxa (Betula spp. and Populus spp.) were confined to recently burned areas. In the present-day landscape, large areas dominated by late successional coniferous taxa have been replaced by early successional deciduous taxa. Forest communities dominated by early successional deciduous taxa increased sharply throughout the study area. Logging has been a minor driver of these changes compared to fire and SBOs.
Conclusions: This study demonstrates the importance of documenting the long-term history of both anthropogenic and natural disturbances in order to assess their relative contributions to the development of the present-day forest ecosystems. Natural disturbances have remained the main drivers of forest composition during the 20th century, whereas logging played a less important role. In the current context of global change, long-term experimental research is required to help forecast impacts of natural disturbances and forest management on boreal forest composition.
by Audrey Verreault | 13 April 2020
Published in Landscape Ecology 32: 361-375
Context: Although logging has affected circumboreal forest dynamics for nearly a century, very few studies have reconstructed its influence on landscape structure at the subcontinental scale.
Objectives: This study aims to document spatiotemporal patterns of logging and fire since the introduction of logging in the early twentieth-century, and to evaluate the effects of these disturbances on landscape structure.
Methods: We used historical (1940–2009) logging and fire maps to document disturbance patterns across a 195,000-km2 boreal forest landscape of eastern Canada. We produced multitemporal (1970s–2010s) mosaics providing land cover status using Landsat imagery.
Results: Logging significantly increased the rate of disturbance (+74 %) in the study area. The area affected by logging increased linearly with time resulting in a significant rejuvenation of the landscape along the harvesting pattern (south–north progression). From 1940 to 2009, fire was the dominant disturbance and showed a more random spatial distribution than logging. The recent increase of fire influence and the expansion of the proportion of area classified as unproductive terrestrial land suggest that regeneration failures occurred.
Conclusions: This study reveals how logging has modified the disturbances dynamics, following the progression of the logging frontier. Future management practices should aim for a dispersed spatial distribution of harvests to generate landscape structures that are closer to natural conditions, in line with ecosystem-based management. The challenges of defining sustainable practices will remain complex with the predicted increase in fire frequency, since this factor, in combination with logging, can alter both the structure and potentially the resilience of boreal forest.
by Claire Morin | 13 April 2020
Published in Journal of Environmental Quality 46: 950-960. https://doi.org/10.2134/jeq2017.03.0119
Large areas of mine tailings are reclaimed by applying organic amendments such as paper mill sludge (PMS). Although mining industries can use PMS freshly generated by paper mills, operational constraints on paper industries make temporary landfilling of this material an unavoidable alternative for the paper industries, creating the most prominent PMS source for mining industries. This study aimed to quantify soil greenhouse gas (GHG) emissions (N2O, CO2, and CH4) after application of landfilled PMS (LPMS; i.e., excavated from a landfill site at a paper mill) and LPMS combined with a seeding treatment of white clover (Trifolium repens L.) on nonacidic mine tailings site prior to reforestation. Soil N2O, CO2, and CH4 fluxes were measured after applications of 50 and 100 Mg dry LPMS ha−1 during two consecutive snowfree seasons on two adjacent sites; LPMS was applied once in the first season. The LPMS application increased N2O emissions (7.6 to 34.7 kg N2O-N ha−1, comprising 1.04 to 2.43% of applied N) compared with the unamended control during the first season; these emissions were negligible during the second season. The LPMS application increased CO2 emissions (~5800 to 11,400 kg CO2–C ha−1, comprising 7 to 27% of applied C) compared with the unamended control on both sites and in both seasons. Fluxes of CH4 were negligible. White clover combined with LPMS treatments did not affect soil GHG emissions. These new GHG emission factors should be integrated into life-cycle analyses to evaluate the C footprint of potential symbioses between the mining and paper industries. Future research should focus on the effect of PMS applications on soil GHG emissions from a variety of mine tailings under various management practices and climatic conditions to plan responsible and sustainable land reclamation.
by Marie-Claude Boileau | 13 April 2020
Published in Frontiers in Plant Science 8(1264): 13
Biological material is at the forefront of research programs, as well as application fields such as breeding, aquaculture, and reforestation. While sophisticated techniques are used to produce this material, all too often, there is no strict monitoring during the “production” process to ensure that the specific varieties are the expected ones. Confidence rather than evidence is often applied when the time comes to start a new experiment or to deploy selected varieties in the field. During the last decade, genomics research has led to the development of important resources, which have created opportunities for easily developing tools to assess the conformity of the material along the production chains. In this study, we present a simple methodology that enables the development of a traceability system which, is in fact a by-product of previous genomic projects. The plant production system in white spruce (Picea glauca) is used to illustrate our purpose. In Quebec, one of the favored strategies to produce elite varieties is to use somatic embryogenesis (SE). In order to detect human errors both upstream and downstream of the white spruce production process, this project had two main objectives: (i) to develop methods that make it possible to trace the origin of plants produced, and (ii) to generate a unique genetic fingerprint that could be used to differentiate each embryogenic cell line and ensure its genetic monitoring. Such a system had to rely on a minimum number of low-cost DNA markers and be easy to use by non-specialists. An efficient marker selection process was operationalized by testing different classification methods on simulated datasets. These datasets were generated using in-house bioinformatics tools that simulated crosses involved in the breeding program for which genotypes from hundreds of SNP markers were already available. The rate of misidentification was estimated and various sources of mishandling or contamination were identified. The method can easily be applied to other production systems for which genomic resources are already available.
by Marie-Claude Boileau | 13 April 2020
Published in Journal of Forestry 115(3): 190-201. doi: 10.5849/jof.2016-024
Despite growing interest in management strategies for climate change adaptation, there are few methods for assessing the ability of stands to endure or adapt to projected future climates. We developed a means for assigning climate “Compatibility” and “Adaptability” scores to stands for assessing the suitability of tree species for projected climate scenarios. We used these scores to determine whether mixed hardwood-softwood stands or “mixedwoods” were better suited to projected future climates than pure hardwood or pure softwood stands. We also examined the quantity of aboveground carbon (C) sequestered in the overstory of these mixtures. In the four different mixedwood types that we examined, we found that Pinus echinata–Quercus mixtures in the Ozark Highlands had greater Compatibility scores than hardwood stands and greater Adaptability scores than pure Pinus echinata stands; however, these mixtures did not store more aboveground overstory C than pure stands. For Pinus strobus–Quercus rubra, Picea-Abies-hardwood, and Tsuga canadensis-hardwood mixtures, scores indicated that there were no advantages or disadvantages related to climate compatibility. Those mixtures generally had greater Adaptability scores than their pure softwood analogs but stored less aboveground overstory C. Despite the many benefits of maintaining mixedwoods, regenerating and/or recruiting the softwood component of these mixtures remains a persistent silvicultural challenge.
