by Audrey Verreault | 30 January 2019
Published in Hydrological Processes 23: 764-776
Summer stream water quality was monitored before and following the logging of 50% of the boreal forest within three small watersheds (<50 ha) nested in the ‘Ruisseau des Eaux-Volées’ Experimental Watershed, Montmorency Forest (Québec, Canada). Logging was conducted in winter, on snow cover according to recommended best management practices (BMPs) to minimize soil disturbance and protect advance growth. A 20-m forest buffer was maintained along perennial streams. In watershed 7.2, cut-blocks were located near the stream network and logging was partially allowed within the riparian buffer zone. In watersheds 7.5 and 7.7, logging occurred farther away from the stream network. Observations were also made for watershed 7.3 that collected the runoff from watersheds 7.2 and 7.5, and watershed 7.6, the uproad portion of watershed 7.7. The control watershed 0.2 was contiguous to the impacted watersheds and remained undisturbed. Following clearcutting, changes in summer daily maximum and minimum stream temperatures remained within ±1 °C while changes in diurnal variation did not decrease by more than 0.5 °C. Concentrations of NO3– greatly increased by up to 6000% and concentrations of K+ increased by up to 300% during the second summer after logging. Smaller increases were observed for Fetotal (up to 71%), specific conductance (up to 26%), and Mg2+ (up to 19%). Post-logging pH decreased slightly by no more than 7% while PO43- concentration remained relatively constant. Suspended sediment concentrations appeared to increase during post-logging, but there was not enough pre-logging data to statistically confirm this result. Logging of moderate intensity and respecting established BMPs may account for the limited changes of water quality parameters and the low exceedances of the criteria for the protection of aquatic life. The proximity of the cutover to the stream network and logging within the riparian zone did not appear to affect water quality.
by Audrey Verreault | 30 January 2019
published in Tree Seed Working Group – News Bulletin 40(December) p.3-4. https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/forestry/tree-seed/tree-seed-centre/tswgnewsbulletin40.pdf
The Ministère des Ressources naturelles, de la Faune et des Parcs from Québec provides all the tree seeds used for seedling production. Québec’s objective for 2005 is to produce 80% of all the seedlings from improved sources. About 135 million seedlings are planted each year.
by Marie-Claude Boileau | 30 January 2019
Published in Annals of Forest Science 66(2)
Although comparisons between methods of selecting trees for site index estimates are well documented in the literature, little is known on mortality rates of different canopy tree cohorts used for that purpose.
This study was initiated to test the hypothesis that the mortality rates of top height trees are lower than those of codominants only or a combination of codominant and dominant trees. To test this hypothesis, we used records from a network of permanent sample plots in Québec and studied the fate of different cohorts of site trees for five different species.
Our results did not show clear evidence of lower mortality rates for top height trees. Instead we found that depending on the species, top height trees have lower (Populus tremuloides, Pinus banksiana), higher (Picea mariana, Abies balsamea) or equal mortality rates (Betula papyrifera) than codominant trees or codominant and dominant trees combined.
These results suggest a tendency for shade intolerant species to maintain lower top height tree mortality rates over time when compared to shade tolerant species. In the latter case, it is also shown that spruce budworm epidemics (Choristoneura fumiferana) did not change the pattern of mortality rates of site trees of A. balsamea.
by Audrey Verreault | 30 January 2019
Published in Tree Seed Working Group – News Bulletin. Canadian forest genetics association. 50(December): 7-9.
In Quebec, the ministère des Ressources naturelles et de la Faune (MRNF, Québec Ministry of Natural Resources and Wildlife) manages the reforestation program from seed collection to planting. All the seeds required for seedling production are stored and tested at the tree seed centre in Berthier (Centre de semences forestières de Berthier, CSFB). About 4 billion seeds are stored at the CSFB. Every year, about 2500 hl of cones and hardwood fruit are harvested and treated at CSFB. In spring, seeds are sent to the 6 public and 15 private nurseries that produce the seedlings (between 150 to 180 million each year) for the MRNF.
by Svetlana Savin | 30 January 2019
Published in Molecular Ecology 19: 132-145
As the evolutionary significance of hybridization is largely dictated by its extent beyond the first generation, we broadly surveyed patterns of introgression across a sympatric zone of two native poplars (Populus balsamifera, Populus deltoides) in Québec, Canada within which European exotic Populus nigra and its hybrids have been extensively planted since the 1800s. Single nucleotide polymorphisms (SNPs) that appeared fixed within each species were characterized by DNA-sequencing pools of pure individuals. Thirty-five of these diagnostic SNPs were employed in a high-throughput assay that genotyped 635 trees of different age classes, sampled from 15 sites with various degrees of anthropogenic disturbance. The degree of admixture within sampled trees was then assessed through Bayesian clustering of genotypes. Hybrids were present in seven of the populations, with 2.4% of all sampled trees showing spontaneous admixture. Sites with hybrids were significantly more disturbed than pure stands, while hybrids comprised both immature juveniles and trees of reproductive age. All three possible F1s were detected. Advanced-generation hybrids were consistently biased towards P. balsamifera regardless of whether hybridization had occurred with P. deltoides or P. nigra. Gene exchange between P. deltoides and P. nigra was not detected beyond the F1 generation; however, detection of a trihybrid demonstrates that even this apparent reproductive isolation does not necessarily result in an evolutionary dead end. Collectively, results demonstrate the natural fertility of hybrid poplars and suggest that introduced genes could potentially affect the genetic integrity of native trees, similar to that arising from introgression between natives.
