by Audrey Verreault | 24 September 2021
Published in Canadian Journal of Forest Research 52(1). https://doi.org/10.1139/cjfr-2021-0086
Fertilization of hybrid poplar (HP) plantations with papermill by-products is a promising solution to improve soil fertility and nutrient availability, increase plantation productivity, and provide added value to these materials that would otherwise be incinerated or sent to the landfill. We assessed the growth and foliar nutrition of a HP clone (Populus x. canadensis × P. maximowiczii) at six plantation sites aged three to five years in southern Quebec, Canada. Sites received a fertilization treatment consisting of a mixture of papermill biosolids (120 to 140 t ha-1, depending on site) and lime mud (10 to 15 t ha-1) before being planted, or no fertilization (control). Tree growth was significantly improved by fertilization, with fertilized trees showing a mean annual height increment of 1.3 m (all-site mean; SD = 0.2), compared with 0.5 m (SD = 0.4) for unfertilized trees. Foliar Ca and Mg increased following fertilization and levels met optimal thresholds at all sites, whereas N, P, and K concentrations also increased but nutritional deficiencies remained for these elements at several sites. Our results confirm the benefits of fertilizing hybrid poplars with papermill by-products, but indicate that adjustments in application rates or type of by-products could be made in order to fully satisfy nutritional requirements and thus optimize tree growth.
by equipewp | 5 August 2021
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The population of Québec has a strong sense of belonging to the wildlife sanctuaries, and considers them to be natural environments in which conservation of biodiversity, wildlife development and fair access to land and wildlife are of particular importance.
This Management Framework, through the orientations it sets out, will help the wildlife sanctuary network to become a showcase for sustainable development and integrated resource management.
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by equipewp | 15 July 2021
Published in For. Ecol. Manage. 495: 119375. https://doi.org/10.1016/j.foreco.2021.119375
Understory vegetation plays an important role in maintaining biodiversity, soil nutrient cycling and carbon stocks, yet the ability of understory functional traits to predict forest productivity after harvesting disturbance is unknown. Our objective was to investigate the utility of individual traits (the community-weighted trait mean) and combined information from multiple traits (functional diversity indices) of understory plants in predicting tree diameter growth of black spruce (Picea mariana (Mill.) B.S.P.) after two harvesting methods (clearcutting and careful logging). We used vegetation and tree growth data from a network of field plots (171 plots on 43 sites) established in black spruce dominated forests across Ontario and Quebec, in northeastern Canada. Functional traits (11 traits) of dominant understory species that reflect plant morphology, regeneration strategy, and resource utilization were collected. We then used generalized linear mixed models (GLMMs) to model the response of tree diameter increment to functional diversity indices, community-weighted trait means and their interactions with harvesting method. Our results showed that: 1) at the functional diversity level, functional richness had a positive relationship with tree growth in clear-cut forests, while functional evenness showed a negative and functional divergence a positive relationship with tree growth in careful logging forests; 2) at the individual trait level, understory species with relatively large morphological trait values often promoted tree growth in both forest types, with stronger relationships in careful logging than in clear-cut forests. For regeneration traits, heavier seed weight or permanent seed bank persistence of understory plants had negative relationships with tree growth, and those relationships were either only found in careful logging forests or did not depend on harvesting type. A positive relationship was found between vegetative propagation species and tree growth, which was stronger in careful logging than in clear-cut forests. Species preferring either humid or xeric habitat had positive relationships with tree growth; both shade-tolerant and shade-intolerant species also positively correlated to tree growth. In conclusion, our study shows the important roles of understory traits in predicting tree growth based on both niche complementarity and mass-ratio hypotheses. Moreover, disturbance severity influenced the balance or degree of the positive and negative interactions that occurred between understory plants and black spruce tree growth. We suggest that identifying the threshold of harvesting disturbance severity that can activate facilitation interactions between understory plants and crop trees would be an important topic for future study.
by equipewp | 15 July 2021
Published in For. Sci. https://doi.org/10.1093/forsci/fxab012
Acer saccharum and Acer rubrum, two main maple species in North America, will be affected by ongoing global warming. Several studies predict a southern limit contraction but limited northward expansion of maple distribution for the future. We aimed to understand the main drivers of current maple distribution to quantify potential changes to maple habitat in this context. We identified the local conditions of maple stands and assessed the potential changes under warming scenarios. We selected two regions in Quebec, Canada, at the northern distribution of the species and applied probability distribution function and principal component analysis to identify the factors explaining the occurrence of maple compared with other forest species, croplands, and grasslands. Maple habitat was estimated under warming scenarios up to 2°C. We observed a lower density of maple stands in the north (7.76 %), compared to the south (33.01 %). Warming increased maple stands by 3.54 and 1.45 % in the northernmost and southernmost regions, respectively, with the highest increases being estimated at the initial warming (+1.0°C). We conclude that maple of northern regions can benefit from local warming if precipitation does not become limiting. These changes could increase the potential for the regional maple industry and forest management.
Study Implications : Future warming may enhance the opportunities to exploit maple and its products at the northern boundary of this species, under a sufficient precipitation regime. Plantations could be considered in habitats favorable for maple, which would allow the value of the resource at the northern edge of the temperate mixedwood forest to be increased. Our spatially explicit outcomes will encourage forest managers and small landowners to plan new maple plantations. The local maple industry and forest management in northern regions could benefit from such an increase in maple habitat and enhanced production of hardwood species.
