Living without herbicides in Québec (Canada): historical context, current strategy, research and challenges in forest vegetation management
TL;DR: This article reviewed the historical context and the research conducted over the past 15 years that has led to the province's current vegetation management strategy and identified the major challenges of vegetation management being faced in Quebec in the context of intensive silviculture and ecosystem-based management.
Abstract: Vegetation management is crucial to meeting the objectives of forest plantations. Following public hearing processes, chemical herbicides were banned on Crown forest lands in Quebec (Canada) in 2001. Release now mainly relies on mechanical treatments. Our objectives are to review the historical context and the research conducted over the past 15 years that has led to the province’s current vegetation management strategy and to identify the major challenges of vegetation management being faced in Quebec in the context of intensive silviculture and ecosystem-based management. Research has led to an integrated management model without herbicides, adapted to the ecological characteristics of reforestation sites. The Quebec experience illustrates how, on most sites, vegetation management that is based on early reforestation, the use of tall planting stock and intensive mechanical release brings crop trees to the free-to-grow stage without the use of herbicides and without resulting in major effects on vegetation diversity. This vegetation management strategy is an asset in the implementation of ecosystem-based management. However, research demonstrates that mechanical release alone does not promote optimal crop-tree growth, due to rapid resprouting or suckering of competitors and competition from herbaceous species. Therefore, the current strategy poses important challenges in the management of plantations where the objective is to maximise wood production.
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TL;DR: In this paper, the current state-of-the-art concerning mechanical site preparation for improved tree establishment when carried out in different forest restoration situations, point out critical research gaps and provide some recommendations for future directions.
Abstract: Forest restoration projects have become increasingly common around the world and planting trees is almost always a key component. Low seedling survival and growth may result in restoration failures and various mechanical site preparation techniques for treatment of soils and vegetation are important tools used to help counteract this. In this article, we synthesize the current state-of-knowledge concerning mechanical site preparation for improved tree establishment when carried out in different forest restoration situations, point out critical research gaps and provide some recommendations for future directions. Mechanical site preparation often results in improved seedling survival and growth. However, if not intensive methods with much soil disturbance are used, it is a rather ineffective tool for controlling competing vegetation. Methods such as scarification, mounding and subsoiling also lead to multiple interactions among soil physical and chemical properties that affect plant survival and growth, and it may be difficult to determine the actual cause–effect relationship of any positive seedling responses. Most research to date on mechanical site preparation and plantation performance has been conducted using a few conifer tree species. Seedling responses differ among tree species and alternative species are often used during restoration compared to production forestry indicating a need for additional research for improved understanding. Several management objectives such as soil protection and increased biodiversity are many times relevant during forest restoration, and mechanical site preparation methods should be implemented carefully because they can have large impacts on the environment.
212 citations
TL;DR: In this article, a review examines the published work on bareroot and container stocktypes in forest restoration programs and defines overall trends between these two stocktypes and describes what they mean in terms of available information on their nursery and field performance.
Abstract: This review examines the published work on bareroot and container stocktypes in forest restoration programs. The objective was to define overall trends between these two stocktypes and describe what they mean in terms of available information on their nursery and field performance. Stock quality assessments show bareroot seedlings have larger shoot systems because they are typically grown at lower densities, and in many instances longer timeframes, than container seedlings. Container systems typically produce seedlings having a lower shoot to root ratio and a greater root growth potential, conferring greater drought avoidance potential. However, assessments of stress resistance and nutrition found no conclusive evidence that either stocktype has a performance advantage, other than the container plug acting as a source of water and nutrient storage available for outplanting performance. Bareroot seedlings are more sensitive to handling practices of lifting, storage, transport and planting and these practices can negatively affect their performance. Container seedlings can have a higher level of field survival which is related, in part, to their greater drought avoidance potential, thereby overcoming planting stress. Bareroot and container seedlings have comparable survival rates on sites with minimal planting stress. Once seedlings are established, bareroot and container seedlings can have comparable field performance. In many instances where plant competition is the main limiting site variable, larger sized bareroot and container stocktypes have the best chance for successful stand establishment. The lack of a natural root form and root distribution for both stocktypes is a debated mechanical stability issue, though risks of windthrow have not been consistently demonstrated for either stocktype.
90 citations
Cites background from "Living without herbicides in Québec..."
...Response of large container seedlings Very large container conifer (e.g., Québec Canada—Jobidon et al. 2003; Thiffault et al. 2003; Thiffault 2004; Thiffault and Roy 2011) and hardwood (e.g., eastern United States— Dey et al. 2008) seedlings are now being produced to address sites with very…...
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TL;DR: The European Network for Forest Vegetation Management-Towards Environmental Sustainability was formed in 2005 and gathered scientists and practitioners from eighteen European countries with the objective of sharing current scientific advances and best practice in the field of forest vegetation management to identify common knowledge gaps and European research potentials as mentioned in this paper.
Abstract: COST (COST is an intergovernmental framework for European cooperation in science and technology. COST funds network activities, workshops and conferences with the aim to reducing the fragmentation in European research) Action E47, European Network for Forest Vegetation Management—Towards Environmental Sustainability was formed in 2005 and gathered scientists and practitioners from eighteen European countries with the objective of sharing current scientific advances and best practice in the field of forest vegetation management to identify common knowledge gaps and European research potentials. This paper summarizes the work of the COST action and concludes that although diverse countries have by necessity adopted different means of addressing the challenges of forest vegetation management in Europe in the 21st century, some common themes are still evident. In all countries, there is a consensus that vegetation management is a critical silvicultural operation to achieve forest establishment, regeneration, growth and production. It appears that herbicides are still in use to some degree in all the countries reviewed, although at a lower intensity in many of the northern countries compared to other regions. The most common alternatives to herbicides adopted are the use of mechanical methods to cut vegetation and achieve soil cultivation; overstorey canopy manipulation to control vegetation by light availability; and in some instances the use of mulches or biological control. Any reductions in herbicide use achieved do not seem to have been driven solely by participation in forest certification schemes. Other factors, such as national initiatives or the availability of additional resources to implement more expensive non-chemical approaches, may be equally important. The development of more cost-effective and practical guidance for managers across Europe on non-chemical control methods can best be brought about by future collaborative research into more sustainable and holistic methods of managing forest vegetation, through the identification of silvicultural approaches to reduce or eliminate pesticide use and through gaining a better understanding of the fundamental mechanisms and impacts of competition.
51 citations
Cites background from "Living without herbicides in Québec..."
...However, mechanical treatments alone do not always succeed in controlling competing vegetation (Thiffault and Roy 2010)....
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TL;DR: The length of the leading shoot was not affected by scarification after 14–18 years, indicating that scarification did not affect growth beyond the establishment phase, and the number of naturally regenerated trees increased with more than 100% to reach a mean value of 2300 stems per hectare.
Abstract: Scarification is the most common measure to improve the planting environment in Sweden. However, different scarification methods give varying results. During the early 1990s, a nation-wide experiment with 10 field installations was established in order to test the effect of several scarification methods, including two intensities of soil inversion and mounding, on growth of planted Norway spruce seedlings and in comparison with no scarification (i.e. control). Eighteen growing seasons after planting, a higher seedling survival was found following soil inversion (77 per cent for normal and 76 per cent for intensive) compared with mounding (67 per cent) and control (57 per cent). The mean height of the planted trees across all sites 18 years after planting was 413 and 430 cm following normal and intensive soil inversion, respectively, 424 cm after mounding and 346 cm in the control. The difference in height between the scarification treatments and the control corresponded to a time gain of approximate to 4 years of growth after 18 years. However, the length of the leading shoot was not affected by scarification after 1418 years, indicating that scarification did not affect growth beyond the establishment phase. Scarification reduced variation in height of the planted trees. On scarified plots, the number of naturally regenerated trees increased with more than 100 per cent to reach a mean value of 2300 stems per hectare.
48 citations
TL;DR: The broad array of treatments that could be used to control competitive vegetation in conifer plantations in the boreal forests of Canada are discussed and the need to further assess the effectiveness of forest vegetation management strategies in the context of multi-purpose plantations that consider ecological, social and silvicultural objectives is concluded.
Abstract: In this paper, we discuss the broad array of treatments that could be used to control competitive vegetation in conifer plantations in the boreal forests of Canada. We present vegetation management alternatives screened based on their treatment efficacy, which we defined as their ability to (a) control competitive vegetation and (b) not cause undue damage to conifer seedlings. The treatments reviewed range from pre-harvest (preventative) to post-plant release (reactive) treatments, and are organized into five categories: (i) silvicultural and harvest systems, (ii) physical treatments such as mechanical site preparation, cutting, girdling and mulching; (iii) thermal treatments such as prescribed fire and steaming; (iv) cultural treatments such as seedling culture, cover cropping, and grazing; and (v) chemical and biological spray treatments. We based our assessment of treatment efficacy on previous reviews, expert opinion, and published literature. We conclude on the need to further assess the effectiveness of forest vegetation management strategies in the context of multi-purpose plantations that consider ecological, social and silvicultural objectives.
47 citations
Cites background from "Living without herbicides in Québec..."
...Planting as soon as possible after site preparation is another strategy that will help reduce the impact of competing vegetation on crop tree establishment and growth (Ball and Kolabinski 1986, Thiffault and Roy 2011)....
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...For example, larger seedlings have been shown to outperform smaller seedlings on competitive sites (Iverson 1984, Jobidon et al. 1998, Lamhamedi et al. 1998, Kiiskila 1999, Pacific Regeneration Technologies Inc. 2000, Jobidon et al. 2003, Boateng et al. 2006, Thiffault and Roy 2011)....
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References
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01 Jan 1972
1,353 citations
"Living without herbicides in Québec..." refers background in this paper
...In Canada, New Zealand and the Netherlands, this fungal pathogen has been studied to obtain a better understanding of its ecology and pathology (de Jong 2000; Gosselin et al. 1999; Ramsfield 2006)....
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...Following public hearing processes, chemical herbicides were banned on Crown forest lands in Québec (Canada) in 2001....
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...Lawrence forest regions of Canada (Rowe 1972), which roughly correspond to the boreal and the northern temperate vegetation zones (biomes) of the Québec ecological classification system (Fig....
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...In Québec (Canada), chemical herbicides were banned for use on Crown forest lands (*90% of the provincial forest land base) in 2001, a unique situation in Canada (Thompson and Pitt 2003)....
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...Lawrence forest regions of Canada (Rowe 1972), which roughly correspond to the boreal and the northern temperate vegetation zones (biomes) of the Québec ecological classification system (Fig....
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TL;DR: In this paper, the authors highlight the ecological importance of understory vegetation, both in the short term by influencing tree seedling regeneration, and in the longer term by affecting belowground processes such as decomposition, nutrient flow, and buildup of soil nutrients.
Abstract: Vegetation research in boreal forests has tended to focus on the tree component, while little attention has been paid to understory components such as dwarf shrubs, mosses, and reindeer lichens. However, the productivity of understory vegetation is probably comparable to that of the trees. We review recent research in the boreal forest of northern Sweden to highlight the ecological importance of understory vegetation, both in the short term by influencing tree seedling regeneration, and in the longer term by affecting belowground processes such as decomposition, nutrient flow, and buildup of soil nutrients. Wildfire resulting from lightning strike is a primary determinant of understory vegetation, and as such is a major driver of forest community and ecosystem properties. Forest management practices that alter the fire regime and the composition of understory vegetation may have long-term consequences for both conservation goals and commercial forest productivity.
712 citations
"Living without herbicides in Québec..." refers background in this paper
...Similarly, vegetation management through mechanical site preparation in the boreal forest can be used to alter the secondary succession where ecosystem retrogression is observed following ericaceous shrub invasion (sensu Nilsson and Wardle 2005)....
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TL;DR: In this article, the authors provide a broad array of management recommendations, most of which apply to most regions, and many patterns are evident, such as: during establishment, managers should consider innovations in snag and reserve tree management (e.g. leave strips), where mature native trees and/or understory vegetation are left unharvested or allowed to regenerate.
658 citations
"Living without herbicides in Québec..." refers background in this paper
...1) identified many issues related to ecosystem composition (Thiffault et al. 2007) for which the chemical-free forest vegetation management strategy is well adapted (Hartley 2002)....
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...2007) for which the chemical-free forest vegetation management strategy is well adapted (Hartley 2002)....
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TL;DR: The development of strategic-level forest management planning approaches and silvicultural techniques designed to maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain natural variability in the boreal forest.
Abstract: The combination of certain features of fi re disturbance, notably fi re frequency, size and severity, may be used to characterize the disturbance regime in any region of the boreal forest. As some consequences of fi re resemble the effects of industrial forest harvesting, conventional forest management is often considered as a disturbance that has effects similar to those of natural disturbances. Although the analogy between forest management and fi re disturbance in boreal ecosystems has some merit, it is important to recognise that it also has its limitations. Short fi re cycles generally described for boreal ecosystems do not appear to be universal; rather, important spatial and temporal variations have been observed in Canada. These variations in the fi re cycle have an important infl uence on forest composition and structure at the landscape and regional levels. Size and severity of fi res also show a large range of variability. In regions where the natural matrix of the boreal forest remains relatively intact, maintenance of this natural variability should be targeted by forest managers concerned with biodiversity conservation. Current forest management tends to reduce this variability: for example, fully regulated, even-aged management will tend to truncate the natural forest age distribution and eliminate over-mature and old-growth forests from the landscape. We suggest that the development of strategic-level forest management planning approaches and silvicultural techniques designed to maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Although we use the boreal forest of Quebec for our examples, it is possible to apply the approach to those portions of the boreal forest where the fi re regime favours the development of even-aged stands in burns.
476 citations
"Living without herbicides in Québec..." refers background in this paper
...…et al. (1999) Comparative assessment of effects of mechanical and chemical release treatments on conifer growth on sites with moderate competition Bergeron et al. (1999, 2001, 2002) Fenton et al. (2009) Development of natural disturbance-based management guidelines, which promoted the use of…...
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TL;DR: The public view of tree plantations is somewhat ambiguous as mentioned in this paper, and while planting a single tree is generally considered good for the environment, planting a million trees raises concerns in some circles. Although plantations are often used to compensate for bad forestry practices, to simplify otherwise complex forest ecosystems, or as a strategy for allowing the current petroleum-based economy to continue on its course, they have a legitimate place in the sustainable management of forests.
Abstract: The public view of tree plantations is somewhat ambiguous. While planting a single tree is generally considered good for the environment, planting a million trees raises concerns in some circles. Although plantations are often used to compensate for bad forestry practices, to willingly simplify otherwise complex forest ecosystems, or as a strategy for allowing the current petroleum-based economy to continue on its course, we believe plantations have a legitimate place in the sustainable management of forests. Multi-purpose plantations, designed to meet a wide variety of social, economic, and environmental objectives, can provide key ecosystem services, help preserve the world's remaining primary forests, and sequester an important proportion of the atmospheric carbon released by humans over the past 300 years.
445 citations
"Living without herbicides in Québec..." refers background in this paper
...The establishment of well-planned and well-managed plantations can be used to meet a large variety of objectives within the context of sustainable forest management (Paquette and Messier 2009)....
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...…of natural forests through enhanced productivity of intensively managed plantations (Messier et al. 2003; Wagner et al. 2004), carbon sequestration (Ouimet et al. 2007) and forest ecosystem restoration (Paquette and Messier 2009) are examples of the benefits that can be derived from plantations....
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...…is a need to develop forest vegetation management strategies compatible with the management of multi-purposed plantations, which produce an array of outputs such as key ecological services while simultaneously delivering many other important social and economic benefits (Paquette and Messier 2009)....
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