by Claire Morin | 8 October 2020
Published in Frontiers in Plant Science 10: 1276. https://doi.org/10.3389/fpls.2019.01276
Climate change is steering tree breeding programs towards the development of families and genotypes that will be adapted and more resilient to changing environments. Making genotype–phenotype–environment connections is central to these predictions and it requires the evaluation of functional traits such as photosynthetic rates that can be linked to environmental variables. However, the ability to rapidly measure photosynthetic parameters has always been limiting. The estimation of Vc,max and Jmax using CO2 response curves has traditionally been time consuming, taking anywhere from 30 min to more than an hour, thereby drastically limiting the number of trees that can be assessed per day. Technological advancements have led to the development of a new generation of portable photosynthesis measurement systems offering greater chamber environmental control and automated sampling and, as a result, the proposal of a new, faster, method (RACiR) for measuring Vc,max and Jmax. This method was developed using poplar trees and involves measuring photosynthetic responses to CO2 over a range of CO2 concentrations changing at a constant rate. The goal of the present study was to adapt the RACiR method for use on conifers whose measurement usually requires much larger leaf chambers. We demonstrate that the RACiR method can be used to estimate Vc,max and Jmax in conifers and provide recommendations to enhance the method. The use our method in conifers will substantially reduce measurement time, thus greatly improving genotype evaluation and selection capabilities based on photosynthetic traits. This study led to the developpement of an R package (RapidACi, https://github.com/ManuelLamothe/RapidACi) that facilitates the correction of multiple RACiR files and the post-measurement correction of leaf areas.
by Marie-Claude Boileau | 7 October 2020
Natural Resources Canada, Canadian Forest Service. Information Report GLC-X-23. 156 p.
The Canadian National Vegetation Classification (CNVC) is an ecological classification of natural vegetation communities in Canada. Using eight hierarchical levels, it provides a nationally standardized framework for describing vegetation patterns within their ecological contexts at multiple conceptual and spatial scales. Natural Resources Canada, Canadian Forest Service (NRCan – CFS) has led the development of the CNVC since it began in 2000, working primarily on forest and woodland communities, and mainly at two levels of the hierarchy, the mid-level Macrogroup and the stand-level Association. CNVC development relies on partnerships with provincial and territorial government agencies for regional ecological expertise and data, and benefits from international collaborations for comparisons with other national classifications. This report introduces the CNVC, including its rationale, history and partnerships; presents the classification framework (hierarchy); documents methods employed to 2018 for the development of types, including information sources and the bioregional expert review process; and describes the products to date, available on the CNVC website and the Natural Resources Canada – Canadian Forest Service Publications website. Developing and maintaining a national classification framework requires considerable resources, and ongoing funding is needed to sustain the effort summarized here.
by Claire Morin | 7 October 2020
Published in Forest Ecology and Management 458: 117765. https://doi.org/10.1016/j.foreco.2019.117765
The impact of traditional even-aged forest management on landscape age structure, tree composition, and connectivity has been well documented. Very little, however, is known about the impact on stand structural diversity. This study aims to compare the structural and abiotic characteristics of forest stands disturbed by clearcut logging and by stand-replacing fire in Quebec’s boreal landscapes. We hypothesized that unlike fire, logging specifically targeted stands having a higher economic value, i.e., merchantable volume, leaving altered forest characteristics on post-harvested landscapes. We compared two aerial forest surveys of a 2200 km2 study area, one survey completed before any logging activity (preindustrial survey; 1980s), and the second survey collected >10 years after logging activity (modern survey; 2000s). Forest stands at the time of the preindustrial survey were primary forests. We identified stands as either burned, logged, or left aside after forest management of the area (remaining stands) between the two surveys and compared their structural and abiotic characteristics using logistic regression. The structural and abiotic characteristics of burned and logged stands differed significantly. Relative to the burned stands, logged stands were older, denser, and marked by poorer drainage and a higher proportion of black spruce; therefore post-harvest and post-burn landscapes differed in terms of their structural diversities. Traditional even-aged forest management has significantly altered the boreal forest landscape by targeting specific stands having higher economic value and leaving behind stands of lower economic value. Remaining high economic stands should be protected, and a more balanced approach to harvesting must be used in the context of ecosystem-based management.
by Claire Morin | 7 October 2020
Published in Tree Genetics & Genomes 16(1): 17. https://doi.org/10.1007/s11295-019-1409-7
Intensive plantation forestry is a potent strategy for forest managers to increase wood production on a smaller forest land acreage, especially with the use of genetically improved reforestation stock. The main drawback with conventional conifer improvement is the several decades it takes before stock deployment, which is particularly acute in the context of climate change and evolving wood markets. Use of genomic selection allows to drastically shorten breeding cycles, resulting in more flexibility and potentially increasing benefits. This study compares the financial performance of five white spruce (Picea glauca) breeding and deployment scenarios, from conventional breeding to genomic selection in conjunction with top-grafting or the use of somatic embryogenesis, in the context of plantations established by the Quebec government on public lands with banned herbicide use. We estimated the land expectation value (LEV) for the five scenarios applied to eight site productivity indices, and considered costs and revenues from breeding, plantation establishment, silviculture, and harvest. LEVs at 4% discount rate were positive for all scenarios on all site indices, and varied from $197 to $2015 ha−1 assuming mechanical brushing of the plantations. The scenarios integrating genomic selection resulted in the highest LEVs, which increased with site index. We also conducted sensitivity analyses with 3% and 5% discount rates, with a range of costs and benefits, and with herbicide control of competing vegetation. These results should help orientate public investment decisions regarding the integration of genomic selection at the operational level in tree breeding and reforestation programs on public lands.
by Claire Morin | 7 October 2020
Published in Forest Ecology and Management 458: 117765. https://doi.org/10.1016/j.foreco.2019.117765
The impact of traditional even-aged forest management on landscape age structure, tree composition, and connectivity has been well documented. Very little, however, is known about the impact on stand structural diversity. This study aims to compare the structural and abiotic characteristics of forest stands disturbed by clearcut logging and by stand-replacing fire in Quebec’s boreal landscapes. We hypothesized that unlike fire, logging specifically targeted stands having a higher economic value, i.e., merchantable volume, leaving altered forest characteristics on post-harvested landscapes. We compared two aerial forest surveys of a 2200 km2 study area, one survey completed before any logging activity (preindustrial survey; 1980s), and the second survey collected >10 years after logging activity (modern survey; 2000s). Forest stands at the time of the preindustrial survey were primary forests. We identified stands as either burned, logged, or left aside after forest management of the area (remaining stands) between the two surveys and compared their structural and abiotic characteristics using logistic regression. The structural and abiotic characteristics of burned and logged stands differed significantly. Relative to the burned stands, logged stands were older, denser, and marked by poorer drainage and a higher proportion of black spruce; therefore post-harvest and post-burn landscapes differed in terms of their structural diversities. Traditional even-aged forest management has significantly altered the boreal forest landscape by targeting specific stands having higher economic value and leaving behind stands of lower economic value. Remaining high economic stands should be protected, and a more balanced approach to harvesting must be used in the context of ecosystem-based management.
