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High abundance of large herbivore has major impacts on the composition, structure, and functioning of forest ecosystems, which can result in regeneration failures. Reduction of large herbivore density, however, does not warrant the successful establishment of tree species sensitive to browsing. In such contexts, planting in combination with silvicultural treatments can be used to restore forest cover over large areas. Using an experimental plantation on Anticosti Island (Quebec, Canada), we investigated how white-tailed deer ( Odocoileus virginianus ) browsing affects the performance of planted balsam fir ( Abies balsamea L. Mill.) seedlings following site preparation and mechanical release. After seven growing seasons, seedling height, leader length and ground-level diameter were 30% bigger in fenced plots compared to unfenced ones as a result of cumulative browsing. Seedling survival was low (62%) and unaffected by either silvicultural treatments or deer after the onset of the mechanical release treatment. Site preparation and mechanical release did not improve morphological parameters and did not increase browsing occurrence on fir, likely because they had little influence on surrounding plants that compete for resources and may hide seedlings from deer 7 years after planting. Selective browsing on neighbouring plants also acted as a release treatment for balsam fir seedlings, allowing them to reach full sunlight at a lower height (125–146 cm), compared to fir seedlings in deer exclosures (161–184 cm). We propose that managers aim at target deer densities that promote browsing positive effects. In such context, prescription for site preparation and mechanical release should be based on other considerations than promoting seedling growth, such as facilitating practical reforestation work. [ABSTRACT FROM AUTHOR]

• Historical deer abundance limits cedar sapling recruitment at the landscape scale. • Proximity to deer overwintering areas limits sapling recruitment. • Accurate browsing and regeneration data are needed in national forest surveys. • This would help forest managers to limit browsing-induced regeneration failures. By selectively feeding on the new vegetation from forest regeneration, cervids influence the abundance of understory species. This can lead to recruitment failure for the consumed species. The impact of cervids on regeneration is generally studied at fine scales, making it difficult to generalize about the species distribution scale for co-occurring cervid and tree species. This is especially problematic for species such as northern white cedar (Thuja occidentalis L.), which is susceptible to browsing and has been declining throughout much of its range. In our study, we aimed to determine the effect of the spatio-temporal variations in white-tailed deer (Odocoileus virginianus Zimmerman) abundance on northern white cedar recruitment over a broad spatial scale. We combined distinct forest and wildlife monitoring databases for two Canadian provinces, Québec and New Brunswick. We also surveyed cedar regeneration and deer browsing pressure in a subset of plots located in Québec. In both provinces, we detected a negative effect of deer abundance and deeryard proximity on the recruitment of cedar saplings. In Québec, local deer browsing pressure also had a negative effect on cedar seedling abundance. As deer browsing pressure can vary considerably over a short distance, we recommend the inclusion of browsing indicators in national forest surveys to precisely assess the impact of browsing on regeneration and recruitment. This would allow managers to identify areas that are highly vulnerable to browsing and adapt forest management accordingly to reduce browsing-induced regeneration failures. [ABSTRACT FROM AUTHOR]

Increasing abundance of large herbivores combined with changes in forestry practices has led to increased forest damage in many temperate and boreal forest areas. The role of alternative forage as a driver for browsing pressure on tree species important for forestry has received increased attention. However, actions to reduce damage through altering forage abundance must be carried out at spatial scales that correspond to the behavioural processes that generate the browsing pattern. We used a multi-scaled dataset on browse abundance and utilisation in Southern Norway to assess how pine browsing damage was related to abundance and quality of browse measured at different spatial scales. Pine trees had a lower probability to be browsed at high pine abundance at all spatial scales. However, the abundance and quality of alternative browse was negatively related to pine browsing (i.e. associational resistance) at several spatial scales, with the highest explanatory power at the largest spatial scale. Management actions to reduce pine browsing by moose should focus on facilitating high abundance of both pine and alternative high-quality browse, and should be carried out at sufficiently large spatial scales (moose home range scale or larger). [ABSTRACT FROM AUTHOR]

Highlights: [•] We assess the top-down and bottom-up effects of deer and competition in plantation. [•] We evaluate the early growth of 3 seedling stock sizes in fenced and unfenced plots. [•] Despite smaller biomass at t 0, medium seedlings caught up with larger ones after 3years. [•] Taller seedlings had higher risk of being browsed while medium ones had lower mortality. [•] Size-adapted seedling stock can optimize the effectiveness of restoration scheme. [ABSTRACT FROM AUTHOR]

Abstract: Forests are often managed for the timber resources they contain, but they also provide habitat for large and commonly increasing populations of cervids. Interactions between forest management and cervid browsing are thus of importance, but are rarely investigated except within isolated exclosure studies. In this study we use a regional network of exclosures in the forests of mid and south Norway, where large and recently peaked populations of moose Alces alces are present, to assess the impact of moose browsing on forests regenerating after clear-cutting. We found marked influences of moose browsing on tree (individual and population) regeneration following clear-cutting. For the highly selected birch and rowan, which dominate in early successional stages from clear-cuts, height growth of 1m tall individuals was prevented when around 45% of shoots were browsed. By developing a regional-level relationship between moose density and browsing intensity, this was linked to a density of 3.0 moosekm−2. Pine growth was prevented when 30% of shoots were browsed whilst spruce maintained growth when over 60% of shoots were browsed. Although coniferous species were less likely to be browsed, moose browsing caused apparent slowing of succession from coniferous to deciduous trees in the regenerating forests. The increase in height growth and decrease in density of the deciduous species in the exclusion treatment suggests that intra- and inter-specific competition from unbrowsed stems may cause self-thinning and drive a reduction in the density of deciduous species, and hence a shift in community composition towards a more coniferous state in the absence of moose. By taking a regional approach, this study has been able to link the growth response of trees to moose density, and highlights the key role of cervids in influencing regeneration of managed forests. [Copyright &y& Elsevier]

Abstract: Tree species composition in forests can be strongly modulated by high densities of cervid herbivores ultimately leading to local extirpation of species. To establish which cervid densities are compatible with the recruitment of a browse sensitive tree species, seedlings and saplings should be surveyed under variable cervid densities rather than in their presence or absence alone. We studied the growth and survival of different demographic stages of balsam fir (Abies balsamea) on Anticosti island (Québec, Canada) under controlled densities of white-tailed deer (Odocoileus virginianus). In a seven-year experiment using deer enclosures, we followed the life stage and fate of individually tagged balsam fir seedlings/saplings under forest cover and forest logged at the start of the experiment. Almost no regeneration into the sapling stage (>30cm) was observed under ambient deer densities after 7years and decreased survival and growth were observed under an experimental deer density of 15km−2. However, mortality at ⩽15deerkm−2 decreased over time and with age and stem height, converging towards mortality observed at 0deerkm−2. Given the relatively high stem density of saplings at 15deerkm−2 7years after the start of the treatment, our data indicate that at this density considerable balsam fir regeneration may occur, although the ultimate contribution of balsam fir to the canopy remains uncertain. The notion that small seedlings are most vulnerable to deer browsing and that balsam fir recruitment rapidly decreases after logging suggests that maintaining low deer densities is most crucial immediately after a stand-initiating disturbance (e.g. logging). [Copyright &y& Elsevier]

Situations where a natural resource is both an asset, as well as a threat, to the integrity of ecosystem function and biodiversity are difficult to manage sustainably. One such situation happens when native deer populations, which are managed for sport are overexploiting forests to a point where they severely compromise natural forest regeneration. Managers facing those situations need support from the scientific community to analyse and synthesise information on deer–forest relationships and thus help to predict the potential outcomes of different management options for both the deer and the forests. Research scientists are increasingly expected to provide expertise and support into the decision-making process. One way to achieve this is to develop decision support tools (DSTs) based upon sound, scientific understanding of the deer–forest systems. Our objective is to explore a range of approaches that have been used for the development of DSTs for deer–forest management and to propose criteria for selecting a specific approach or combination of approaches for specific situations. DST and research-oriented models were catalogued according to two modelling paradigms: bottom-up models, which simulate systems through inductive inference, by scaling up from fundamental processes to the inherent behaviour of the system—the best known applications are forest gap and individual-based models; and top-down models which proceed by deductive, rule-based inference—they include expert systems, qualitative simulation models, frame-based models, Markovian process models and Bayesian networks. Uncertainty assessment in both modelling paradigms is discussed. The analysis is put in the context of two very different examples of deer–forest systems currently requiring DST development to guide their management: (1) the upland red/roe deer—fragmented temperate/boreal forest system of Scotland; and (2) the white-tailed deer—eastern boreal forest system of Anticosti Island, Que´bec, Canada. We conclude that a top-down approach with explicit uncertainty assessment should be aimed for, as a deliverable product to the end-users, keeping in mind that simulation models from the bottom-up family may be required to gain insights about the underlying mechanisms. [Copyright &y& Elsevier]

• Assisted migration (AM) plantations could fail under high herbivory from mammals. • We analyzed the chemistry of eight tree species to predict their browsing susceptibility. • Predicted susceptibility corresponded to the degree of browsing reported in the literature. • Chemical analyses could be used as a preliminary tool for selecting species for AM plantations. • Intraspecific variations also suggest this approach could be used to select genotypes. To promote the sustainability of forest ecosystems and maintain ecosystem services to human populations in the context of climate change, forest managers are considering several adaptation tools. One of those, assisted migration, consists of displacing tree species and/or populations to locations with suitable future climate conditions. Assisted migration plantations, however, could fail to produce viable forests under high herbivory pressure from mammalian herbivores. Thus, selecting species and genotypes with low susceptibility to herbivores could be a key condition for the recruitment of translocated seedlings. We developed an approach to predict susceptibility to mammalian herbivores, based on the seedlings' chemical content (a proxy of phytochemical defence and susceptibility to herbivores). We used the approach on eight North American tree species of three climate analogues regions each (i.e. locations where the current climate is similar to the future climate at plantation site). We built chemical profiles and ranked species and climate analogue based on their potential susceptibility. To assess the reliability of our approach, we compared the chemical profiles to a systematic review of these species' chemistry and of mammalian browsing throughout their native geographic range. For most species, our chemical profiles and browse susceptibility rankings were congruent with information available in the literature, both for phytochemical defence and for browsing. Two of the eight species (Pinus strobus and Thuja occidentalis) were more susceptible than predicted based on their chemical profile. These discrepancies could be linked to specific mammalian herbivores, that were unaffected by the phytochemical defence of these species. We observed a generally higher susceptibility of broadleaf species, which could be taken into account when devising adaptive silvicultural strategies. Furthermore, we propose the chemical profiling approach as a preliminary screening tool to identify species more resistant to mammalian herbivores, but also potentially to other herbivores and pathogens. Our chemical profile approach, based on the objective assessment of multivariate analyses results, could be replicated to compare the potential susceptibility of other species. This approach could be especially useful when contending with novel plant-herbivore relationships, such as forestry and conservation assisted migration or species invasion. [ABSTRACT FROM AUTHOR]

• Balsam fir stands of northeastern North America are resilient to spruce plantation. • Naturally regenerating species recovered to the detriment of planted species. • Planting in a resilient forest could put silvicultural investments at risk. • Balsam fir stands are resilient because of their effective regeneration processes. • Maintaining functional regeneration processes is a way to maintain resilience. • We propose initiatives to mitigate potential threats to resilience. Globally, there is an increasing demand for wood products. Because of their productivity, forest plantations will increasingly serve to meet this demand. A cumulative anthropogenic disturbance, such as a plantation scenario, could alter resilience of natural forests, thereby triggering alternative successional pathways towards a state that is predominated by planted species. These alternative ecosystems could represent a threat to biodiversity and ecosystem services that are provided by natural forests. Our objective in this study was to evaluate whether a spruce plantation scenario alters the resilience of natural balsam fir stands in the balsam fir ecological region of Quebec (Canada). We studied successional pathways in 897 spruce plantations covering a 40-year period. The spruce plantation scenario does not seem to have altered resilience of natural balsam fir stands. The main tree species naturally regenerating on balsam fir ecological site types had indeed recovered from the plantation scenario to the detriment of planted spruce species. Balsam fir stands are resilient to the spruce plantation scenario, largely because of the effective regeneration processes of balsam fir and birch species, compared to spruce species. Maintaining functional regeneration processes is a way to maintain resilience and insure that biodiversity and ecosystem services will be gradually restored after anthropogenic disturbances. Regeneration processes should enable a resilient forest to follow natural successional pathways back to its pre-disturbance composition, structure and functions. Hence, planting a tree species in a resilient forest that is not in accordance with the successional pathway of the natural forest could put silvicultural investments at risk. With increasing use of plantations to meet wood demand, some sites inevitably will undergo consecutive cycles of the plantation scenario. Cumulative effects of consecutive plantation scenarios may then be detrimental to the resilience of balsam fir stands. We propose initiatives to mitigate these potential threats. [ABSTRACT FROM AUTHOR]