Beech Regeneration Research Articles

Fusarium species associated with naturally regenerated Fagus sylvatica seedlings affected by Phytophthora

AbstractFusarium diseases in forests, especially in naturally regenerated seedlings, are poorly recognized. Recently the rapid and severe decline of natural regeneration of European beech caused by Phytophthora spp. has been observed in Poland. The diseased beech seedlings were also co-infected by Fusarium species. The aim of this study was to isolate and identify the role of Fusarium species that may play a role in the decline of beech seedlings in Poland. A total of 487 Fusarium isolates were obtained from 450 symptomatic and asymptomatic beech seedlings: 466 from symptomatic plants and 21 from asymptomatic plants. Based on comparisons for two genes and phylogenetic analysis, all Fusarium strains were separated into 14 phylogenetically distinct species belonging to four Fusarium species complexes (SC), namely the F. incarnatum-equiseti species complex (FIESC), the F. nisikadoi species complex (FNSC), the F. sambucinum species complex (FSSC), and the F. tricinctum species complex (FTSC). Fusarium avenaceum and F. paeoniae were the most frequently isolated species from both above- and below-ground organs of seedlings affected by Phytophthora. In the pathogenicity trials, the most virulent species for beech seedlings were F. avenaceum and F. sporotrichioides. However, Fusarium isolates were significantly less aggressive compared to the P. × cambivora (positive control). Our results demonstrate that beech seedlings were frequently colonized by various Fusarium species. Fusarium species do not play an important role in the reduction of naturally regenerated European beech seedlings due to their low aggressiveness.

Changes in understory plant communities following soil scarification and amendments in a Northern Hardwood Forest

The regeneration dynamics of sugar maple-dominated stands in northeastern North America are intricately influenced by global changes such as soil acidification, invasive species, forest management, and climate shifts. A notable challenge is the expansion of American beech and its bark disease, threatening mature trees and ecosystem services. Although sylvicultural practices aim to control beech regeneration and enhance high-value species, their impact on understory plant communities remains poorly documented. In Valcartier, eastern Canada, we conducted a field experiment to assess the short-term effects of soil scarification and diverse soil amendments (nitrogen fertilization, liming, wood ash) on understory plant communities in a beech-invaded sugar maple stand. Over four years, we inventoried vegetation and measured various biotic and abiotic variables. Results showed that soil scarification significantly reduced diversity metrics like Simpson dominance, functional diversity, and redundancy (a metric correlated to community stability and resilience to disturbance). Negative effects of scarification were exacerbated by nitrogen, lime, or wood ash additions. Lime amendment without scarification enhanced diversity, suggesting its potential to support understory community stability. While scarification and amendments can promote sugar maple, yellow birch, and pin cherry seedling establishment, they have collateral effects on the understory, impacting productivity, diversity, and resilience in the short term. Land managers should exercise caution when combining these treatments, as they may transiently alter the stability and resilience of the understory and other forest functions. A more sustainable approach involves applying scarification and amendments on small, well-distributed patches within the targeted stands for treatment, avoiding extensive application over large areas.

Six year efficacy of silvicultural treatments to control American beech regeneration in stands affected by beech bark disease in Ontario, Canada

High beech regeneration density is a concern in northern shade tolerant hardwood forests. High densities of beech ( Fagus grandifolia Ehrh) regeneration can crowd out other desirable species, such as sugar maple ( Acer saccharum Marsh.), and jeopardize long-term sustainability since beech is under threat from beech bark disease ( Cryptococcus fagisuga/Neonectria spp. Complex). We examined the efficacy of three tending (no tending, brush saw, and basal bark herbicide) and two timing and harvesting (deferred 5 years post-single tree selection harvest, concurrent with uniform shelterwood harvest) treatments on reducing beech regeneration density and promoting sugar maple regeneration density over 6 years. Six years after tending, we found that large beech regeneration density was reduced, medium beech regeneration density had recovered to pre-tending levels in most treatments, and small beech regeneration density remained unaffected. Tending treatments had no effect on any size class of sugar maple regeneration density but the uniform shelterwood harvest promoted medium sugar maple density more than the single-tree selection harvest. Despite this increase, in all treatment combinations sugar maple regeneration densities remained below stocking targets. Our results suggest that while tending treatments can temporarily reduce beech regeneration densities, sugar maple is unable to take advantage of the increased growing space.

The Dynamics of Stand Structure Development and Natural Regeneration of Common Beech (Fagus sylvatica L.) in Plitvice Lakes National Park

The authors investigate the structural characteristics, regeneration processes, growth, development, and survival of a young generation of common beech (Fagus sylvatica L.) based on three periodic measurements (1998, 2009, and 2018). The studied forest community (Lamio orvale-Fagetum sylvaticae (Ht. 1938) Bohridi 1963) is situated within a forest reserve in Plitvice Lakes National Park, Croatia. Monitoring was carried out according to UN/ECE (2000) for systematic and repeated research. The basic structural indicators, structural canopy elements, and appearance of the young generation were measured as the basic conditions of natural restoration in repeated phytocenological surveys (1980, 1988, 2004). The distribution of the number of trees of the first two measurements (1998–2009) indicates a distribution with pronounced right asymmetry. The structural dynamics observed during the surveys and alongside vegetation surveys indicate the dynamics of the growth and development of beech. The results show that the main drivers of development dynamics in protected forest ecosystems are structural breaks (gaps) that occur in stands due to the action of abiotic and biotic factors. The passive management model in effect in the national park should be replaced with a more active approach to facilitate natural processes with the aim of preserving and renewing the forest ecosystem.

Growth response and survival of American beech, yellow birch, and sugar maple regeneration to partial harvest

In northern hardwood stands, silvicultural treatments aimed at regenerating sugar maple and yellow birch, such as site preparation and mechanical control of American beech saplings, often results in the formation of dense thickets of beech regeneration. The objective of this study was to compare the growth and survival of beech regeneration originating from stump sprouts, root suckers and seedlings, with yellow birch and sugar maple regeneration in partially harvested stands under cervid browsing pressure. Over an eight-year period, 997 individuals of the three species were monitored in three northern hardwood stands dominated by sugar maple, yellow birch, and American beech in Quebec, Canada. Each stand included replicates of four partial harvesting treatments and a control, providing a gradient of light and competition conditions. Beech stump sprouts and root suckers had higher growth and survival probabilities than seedlings of all three species under all light and competition conditions. Results suggest that treatments triggering beech sprouts should be applied with caution and under conditions that ensure sufficient survival and development of desired species. This study also provides evidence that selective browsing by cervids could be an important overriding factor exacerbating the effect of beech competition on yellow birch regeneration.

Changes in seedlings’ composition and abundance following soil scarification and amendments in a northern hardwood forest

A combination of global changes (e.g., soil acidification, invasive species, forest management, climate) impacts the regeneration dynamics of sugar maple-dominated stands in northeastern North America. More specifically, there are concerns about the regeneration of sugar maple and other high-value species due to the expansion of American beech and its bark disease, killing mature trees, compromising fiber supply and other ecosystem services. Here, we set up a field trial to study the effect of soil scarification, amendments (nitrogen fertilization, liming, and wood ash), and their interactions, on tree species establishment following understory vegetation removal in a beech-invaded sugar maple stand to promote the establishment of high-value species (i.e. sugar maple and yellow birch), to control beech regeneration, and help reduce the impacts of beech bark disease on stand development. After four years of monitoring, we found that maple-beech stands with well-drained soils were promising sites for the success of sugar maple and yellow birch establishment. Soil scarification had a limited effect on sugar maple and beech establishment while it enhanced that of yellow birch, pin cherry and red maple. The combination of soil scarification and amendments was more effective in promoting the recovery of yellow birch and pin cherry and controlling the recovery of beech and red maple than their separated effects. Lime amendment promoted sugar maple establishment without favouring competitors such as yellow birch, pin cherry and red maple, and limited beech establishment. Overall, our results suggest that combining soil scarification and amendments on targeted site types could help fine-tune tree establishment conditions in northern hardwood forests.

Sustainable development and management of beech forests

Beech is a very widespread species on the entire Eurasian continent. It grows and develops in different ecological and habitat conditions in a wide horizontal and vertical amplitude. It can be found at altitudes below 100 and above 2,000 m. Beech forests develop in different age stands from young to very old (old-growth forests). They can be pure or mixed with other species or they can be very different in origin (generative or vegetative). They develop as eaven-aged or uneaven-aged stands, and some of the beech forests have the characteristics of forests with high natural values and are very important for the conservation of biodiversity. Their natural regeneration process is of essential importance for the survival and sustainable development of beech forests. Restoration of beech forests can be achieved naturally or artificially. In modern forestry science and practice, natural forest regeneration is always preferred. The processes of natural regeneration have different development depending on whether they take place under the protection of the parent stand or take place in an open canopy in the forest or on uncultivated terrain. The density of the canopy has a great influence, so that with the increase of the canopy of the parent stand during the natural renewal, there is a decrease in the number of regeneration individuals(offsprings) in all developmental stages. During the natural regeneration in different conditions of the stand canopy and the size of the openings within the forest, the most abundant and best regeneration is observed in the openings up to 500 m², then for openings within 500 and 1,000 m², and least in openings between 1,000 and 1,500 m². This clearly indicates that large openings within the forest are not suitable for the natural regeneration of beech because the number of offsprings, which are very necessary in the younger developmental stages, is continuously decreasing. The natural renewal that develops in the conditions of circular openings within the size of up to 500 m² has the best quality structure of the offspring. In such openings, about 60% of the offspring is of good quality, about 25% is of medium quality and about 15% is of poor quality. In openings between 500 and 1,000 m2 , the number of good quality natural regeneration is reduced to 41%, the number of medium quality natural regeneration is increased to 38% and from poor quality to 21%. The quality structure of natural regeneration is further reduced in openings between 1,000 and 1,500 m² where only about 20% of the offsprings is of good quality, about 30% is of medium quality and about 50% is ofpoor quality. With openings larger than 500 m², weeds are very common. Beech stands in different habitats have large differences in their productivity, caused by the wide range of the beech forests in different habitat conditions and in different cultivation forms. Aboveground biomass in beech forests varies depending on the age of the forest, the way it is managed and used, as well as numerous environmental factors. High values of aboveground biomass in preserved oldgrowth beech forests above 750 t·ha-1 are known. Moderate values in commercial forests range between 200 and 400 t·ha-1 . In dominant trees, the largest biomass is found in tree crowns, while in subdominant and suppressed trees, the largest biomass is in the trunk, which is the result of a smaller crown due to the lack of solar radiation. Generally, 1/3 or slightly less of the aboveground biomass comes from the branches, the leaves cover about 1-2%, while the largest biomass (60- 70%) is concentrated in the tree. Dead biomass in beech forests consists of dead biomass accumulated in the forest floor, as well as in standing and lying dead biomass. Forest biomass varies in European beech forests: beech forests in the north show less biomass of 3-12 t·ha-1 , while high values (25-75 t·ha-1 ) are registered for the southeastern parts. Standing dead biomass in forests amounts to 1.2-6.0% of living aboveground biomass or 2-5 t·ha-1 . Lying dead biomass in European beech forests varies to a very large extent depending on the conservation of beech forests and their developmental stage. The European range is 32-310 m3 ∙ha-1 , and values above 130 m3 ∙ha-1 belong to the preserved beech forest reserves. When choosing methods of beech forest management, one should always take into account the biological characteristics of beech in relation to the ecological conditions in the area where beech develops. Today, various and professionally supported methods of forest management with the aim of their sustainable development demand great importance for beech forests.

Resource-based growth models reveal opportunities to mitigate climate change effects on beech regeneration by silvicultural measures

Successful European beech (Fagus sylvatica L.) regeneration is both of great ecological and economical importance in European forest ecosystems and severely threatened by climate change impacts. To increase our knowledge of beech regeneration dynamics under climate change and the potential for controlling it through forest management, we studied interactive effects of solar radiation (PHAR), water and nutrient availability on the height growth of artificially (AR) and naturally regenerated (NR) beech seedlings. The study was conducted in the framework of experimental canopy gaps, under the influence of the 2018/19 drought and heatwaves. We measured PHAR by means of hemispherical photography, approximated water availability based on the inverse of modeled fine root density distributions of overstorey beech (BGRB) and oak (BGRO) and approximated nutrient availability based on soil fertility (SF), derived from forest site mapping. Results indicate that seedling resource availability and resulting growth responses increase with canopy gap size and vary among locations within the gap. Multiplicative non-linear mixed models suggest that AR and NR relative height growth (RI) was best explained by interactive effects of PHAR, BGRB, BGRO and SF, which reflect complementary resource use patterns of beech seedlings. At optimal resource availability, AR reached a potential RI of 174%, which is about 20% higher compared to NR. While the low light growth responses of AR and NR both reflect saturation at 5 to 15% PHAR, depending on individual size and the availability of the remaining resources, NR showed a higher RI than AR at intermediate and high PHAR levels in cases of limited BGR and SF. In contrast to AR, NR growth was affected to a lesser extent by SF and BGRB and not significantly affected by BGRO. These results suggest that overstorey oaks have a lower effect on water availability of beech seedlings than overstorey beeches. Additionally, NR showed higher tolerance to water and nutrient limitation than AR, probably due to better root system development. In conclusion, site-specific potential for mitigating the effects of climate change on beech regeneration through forest management lies in the adaptation of silvicultural systems, i.e., the creation of canopy gaps larger than 200 m2, thus significantly exceeding the average gap size of the natural disturbance regime, and the choice of the regeneration method.

Phytophthora species cause sudden and severe decline of naturally regenerated European beech (Fagus sylvatica) seedlings

AbstractNatural tree regeneration is a fundamental process in forest ecosystems ensuring the persistence and resilience of forest stands. Research on natural regeneration of European beech (Fagus sylvatica) in Central European forests has mainly focused on the impacts of abiotic processes, while little is known about the impact of pathogens. The aim of this study was to isolate Phytophthora species and identify the role that they may play in the decline of beech seedlings in Poland. A total of 1192 Phytophthora isolates were obtained from 300 symptomatic beech seedlings (60 seedlings from each of five stands): 638 isolates from seedlings exhibiting above‐ground symptoms and 554 isolates from seedlings that had roots with damping‐off symptoms. Based on morphological and molecular identification, the isolated species were Phytophthora cactorum, P. × cambivora, P. europaea, P. gonapodyides, P. plurivora and P. pseudosyringae. P. cactorum, P. × cambivora, P. europaea and P. plurivora were the most frequently isolated species from both above‐ and below‐ground organs. P. cactorum, P. × cambivora and P. plurivora were the most pathogenic species in the pathogenicity trials and caused 100% seedling mortality within 14 days of inoculation of the above‐ground organs. One single isolate of P. europaea was similarly pathogenic. P. gonapodyides, and P. pseudosyringae induced seedling mortality after inoculation of the cotyledons but not the roots. Our results demonstrate that Phytophthora may play an important role in reduction of naturally regenerated European beech seedlings.

Toward a Beech-Dominated Alternative Stable State in Dinaric Mixed Montane Forests: A Long-Term Study of the Pecka Old-Growth Forest

In the last century, a synchronous beech expansion has been observed for many mixed mountain forests in southeastern Europe. This change is associated with the interaction of various disturbances. We analyzed structural changes in the Pecka old-growth forest in Slovenia during the last century, using several inventories of the tree layer, regeneration, and site factors. Throughout the observation period, the density of silver fir in the regeneration layer and in the overstory steadily decreased. In 1893, silver fir accounted for about 60% of the growing stock, whereas in 2013 it accounted for less than 13%. This is likely because of silver fir’s decline in the canopy layer due to air pollution, successive windthrows, and overbrowsing. However, climate change may also have played an important role, as silver fir also declined in southeastern European old-growth forests where air pollution was less pronounced and ungulate densities were low. A gradual decline of silver fir in the overstory resulted in a decrease of overall tree density to 231 trees ha–1, while growing stock remained relatively high at 712 m3 ha–1. Median diffuse light at 1.3 m was 3.7% and regeneration density was 19,954 ha–1. Beech was dominant (94%), followed by silver fir (4%), and sycamore maple (2%). No silver fir seedlings larger than 0.2 m were recorded. Silver fir, sycamore maple, and beech regeneration showed 87, 76, and 45% browsing damage, respectively. Regression models indicated some evidence of niche partitioning between silver fir and beech. However, many processes may be masked by the silver fir’s avoidance strategy. Given current red deer densities, climate change, and existing forest structure, the Pecka old-growth forest will likely reach an alternative stable state dominated by beech in a few decades. This calls for immediate reduction of ungulate populations. Despite the interaction of multiple disturbances, the Pecka old-growth forest has maintained a relatively high overall growing stock, a favorable microclimate, and succession pathway with shade-tolerant beech. This indicates the intrinsic resilience of natural forests. The mechanisms discussed here can be applied to the future governance of old-growth and managed montane mixed forests.

Resprouting in European beech confers resilience to high-frequency fire

AbstractEuropean beech (Fagus sylvatica L.) can regenerate successfully from seeds after mixed-severity fires with mid-to-long fire return intervals (>60 years). However, if fire return interval is lower than the age of sexual maturity, post-fire seeding will be limited, leaving vegetative resprouting as the only viable option for recovery. This means that the forecasted increase in fire frequency driven by climate change may erode beech forest resilience to fire. Here, we surveyed tree regeneration in a European beech forest affected by two consecutive fires, in 2003 and 2017, and applied experimental clipping of tree saplings to address the following questions: (1) What is the fire resistance and post-fire recovery via resprouting of tree saplings? (2) Which factors drive post-fire resprouting of beech saplings? (3) Does post-fire clipping of tree saplings increase the probability of survival and resprouting vigor? We monitored 2195 beech saplings and 953 saplings of other tree species during three consecutive years, from 2018 to 2020. Almost all beech saplings were top-killed by fire, and two-thirds of them died completely. However, 3 years after the second fire, 30 per cent of beech saplings survived by resprouting from the base. Post-fire resprouting was less likely in small-diameter saplings and in those more injured by fire. Overall, the second fire did not cause a major decline of beech regeneration and consequently did not alter the dominant species composition of post-fire recovery. Given the low specific resistance to fire, post-fire resprouting of saplings is therefore a key component of beech resilience to short-interval fires. The effects of clipping on post-fire survival and resprouting vigor were very limited, suggesting the unsuitability of actively clearing burned beech regeneration as a post-fire management prescription. In conclusion, basal resprouting from beech saplings after fire-induced top-kill led to a higher-than-expected resilience of beech to short-interval fires (i.e. circa 15 years).

Evaluation of a Restoration Approach After One Century – Effects of Admixed European Beech on the Natural Regeneration Potential and Humus Condition in Spruce Stands

About 100 years ago, groups of European beech were reintroduced into Norway spruce stands in some parts of Germany as a restoration approach. The aim of this approach was to maintain or rehabilitate the ecological function of soil fertility and the regeneration option of beech for the next generation. The effect of beech groups on surrounding spruce stands was studied in the Ore Mountains by recording natural regeneration of beech and humus layer thickness and form. Point pattern statistics were used to analyse the spread of beech regeneration and to determine factors influencing its establishment. It was found that the density of regeneration decreases with increasing distance from the beech group. However, beech regeneration was found up to distances of 69 m. Furthermore, it becomes evident that PAR radiation (maximum regeneration densities at PAR values of 35 W/m2) and fencing (3.41 times higher regeneration density compared to unfenced areas) against deer have a positive influence on beech regeneration density. Ordered categorical models were used to model humus form and non-linear models were used to model humus layer thickness. It could be proven that the most bioactive humus forms and lowest humus layer thicknesses were found within the beech group. With increasing distance to the beech group, the total humus layer thickness and the proportion of mormoder in the spruce stand increased. The positive influence of the beech group on the humus composition extends to about 40 m from the centre of the beech group. Due to the former arrangement of the beech groups in the terrain, the effects can also extend to the spruce stands in between. The hypotheses on the restoration approach of reintroducing groups of beech into spruce stands formulated by foresters 100 years ago can thus be confirmed. For future restoration approaches of spruce stands, groupwise mixtures of beech should be established with a distance of 40–50 m.

Home-Field Advantage of Litter Decomposition Faded 8 Years after Spruce Forest Clearcutting in Western Germany

Home-field advantage (HFA) encompasses all the processes leading to faster litter decomposition in the ‘home’ environment compared to that of ‘away’ environments. To determine the occurrence of HFA in a forest and adjacent clear-cut, we set up a reciprocal litter decomposition experiment within the forest and clear-cut for two soil types (Cambisols and Gleysols) in temperate Germany. The forest was dominated by Norway spruce (Picea abies), whereas forest regeneration of European Beech (Fagus sylvatica) after clearcutting was encouraged. Our observation that Norway spruce decomposed faster than European beech in 70-yr-old spruce forest was most likely related to specialized litter-soil interaction under existing spruce, leading to an HFA. Elevated soil moisture and temperature, and promoted litter N release, indicated the rapid change of soil-litter affinity of the original spruce forest even after a short-term regeneration following clearcutting, resulting in faster beech decomposition, particularly in moisture- and nutrient-deficient Cambisols. The divergence between forest and clear-cut in the Cambisol of their litter δ15N values beyond nine months implied litter N decomposition was only initially independent of soil and residual C status. We conclude that clearcutting modifies the litter-field affinity and helps promote the establishment or regeneration of European beech in this and similar forest mountain upland areas.

Northern hardwood regeneration dynamics 10 years after irregular shelterwood and mechanical control of understory American beech

In northern hardwood stands of the northeastern USA and southeastern Canada, the abundance and occurrence of American beech (Fagus grandifolia Ehrh) regeneration have increased substantially over the past decades, to the detriment of other deciduous species such as sugar maple (Acer saccharum Marshall) and yellow birch (Betula alleghaniensis Britton). To promote the regeneration of these declining species, we established an experimental study near Québec City (Quebec, Canada) to compare the effects of various partial cutting treatments and mechanical control of understory American beech. The design comprises 4 randomized complete blocks, each containing an uncut control, a hybrid single-tree and group selection cutting (SC), two intensities of continuous cover irregular shelterwood (CCIS) and an extended irregular shelterwood (EIS). American beech regeneration, which dominated the sapling layer before cutting, was removed with brush saws in gaps created in the SC and CCIS treatments as well as in the entire understory of the EIS treatment. In addition, gaps and the EIS understory were scarified to favor yellow birch regeneration, and 12 exclosures were built to prevent cervid browsing in CCIS gaps and in entire understory of the EIS treatment. Ten years after cutting, yellow birch regeneration was more abundant in gaps and in the EIS treatment than in the uncut control. These results confirm that increasing the understory light level, eliminating American beech saplings and scarifying the soil can successfully favor yellow birch establishment. However, preferential browsing of yellow birch outside exclosures maintained the overall dominance of American beech in the long term. Thus, under these conditions, damage from repetitive browsing outweighed the positive effects of actions aimed at promoting the regeneration of yellow birch. In the end, despite abundant seed availability, sugar maple remained only a minor component of the regeneration.

Dynamics of southern beech (Nothofagaceae) stands in the lowland North Island of New Zealand

ABSTRACT In south-central Chile, the dynamics of southern beech (Nothofagaceae) stands vary predictably along climatic gradients. Beeches form persistent stands at high elevations, but their establishment on lowland sites depends mainly on catastrophic disturbances. In New Zealand, nearly all studies of beech forest dynamics to date have reported all-sized, persistent populations. However, previous work has focused largely on the South Island or on North Island mountains, where beeches are widespread and often dominant. Little is known about beech dynamics in the warm North Island lowlands, where beeches are less common. We aimed to clarify the circumstances that enable beeches to establish on lowland sites in the North Island. We measured population structures of beeches and associated species on 11 plots distributed across a range of climate, lithology and topography. On sites where the most shade-tolerant broadleaved trees were absent or uncommon, all-sized populations showed that beech regeneration did not depend on major disturbances. These stands were located mostly on steep faces or ridges with soil carbon:nitrogen ratios > 18, usually with ericaceous understoreys. On sites with higher N availability, where shade-tolerant broadleaved trees were abundant, beech populations were generally sparser, with restricted age ranges. One of these ± even-aged beech stands appeared to have established after windthrow, the other four after fires. Recent dieback of Weinmannia racemosa associated with insect attack had resulted in another wave of beech regeneration in one of the post-fire stands. Establishment on landslides appears to only rarely enable beeches to capture new sites in the lowland North Island. We conclude that beeches form stable self-replacing stands on lowland North Island sites with low nitrogen availability, but that exogenous disturbances occasionally enable beeches to establish as pioneers on sites with higher nitrogen availability. The early successionalrole commonly seen in lowland south-central Chile thus appears less widespread in New Zealand.

The Potential for Future Shifts in Tree Species Distribution Provided by Dispersal and Ecological Niches: A Comparison between Beech and Oak in Europe

(1) Due to global warming, distribution ranges of temperate tree species are shifting northwards and upslope to cooler areas. Shifts in distribution first become visible through changes in regeneration dynamics. However, the future distribution of tree species in the face of rapid climate change depends not only on the climatic suitability of the tree species, but also on its ability to disperse into new habitats. The aim of the study was therefore to examine how the distribution of European beech and European oak shifts and how species can spread from fragmented seed trees. (2) In order to investigate the shift in distribution of beech and oak, the bioclimatic envelopes of the old trees and different size classes of the natural regeneration were compared. Subsequently, a simulation of the potential distribution for the present climate, as well as for the climate for the reference period 2091–2100, for three different representative concentration pathways (RCP) scenarios was determined. In order to determine which of these areas can actually be colonised, a dispersal potential for the species was determined using a quantile regression, taking habitat fragmentation into account. (3) The results of the present study demonstrate range shifts of the tree species regeneration distribution (B0, B1 and B2) compared to the overstorey distribution (OST). While oak regeneration shows an expansion of its distribution in the cold-wet range, beech regeneration shows a reduction of its distribution in the dry-warm range. As the dispersal potential of oak exceeds that of beech, it is expected that oak will be better able to spread from fragmented seed trees. However, the results also indicate that many areas, despite climatic suitability, cannot be colonised due to too large dispersal distances. (4) For the forest management, this results in an important planning tool for future tree species composition, as climatic suitability, habitat connectivity and dispersal ability are taken into account.

Forest floor alteration by canopy trees and soil wetness drive regeneration of a spruce-beech forest

Natural regeneration of European beech (Fagus sylvatica) and Norway spruce (Picea abies) plays a crucial role in the future of many European mountain forests. It is affected by various soil and stand-related factors whose relative importance, especially in mixed stands, is still not known. In this study, we assessed the importance of stand composition, soil wetness, disturbances and different microsites and seedbeds for regeneration of beech and spruce in a mixed old-growth mountain forest. We also focused on how the effects of these factors change as regeneration gets older.We sampled all regeneration in 563 plots from different microsite types (deadwood, intact soil, treethrow pits and mounds), distinguishing three seedbeds (mosses, beech litter, bare substrate) for seedlings. We used soil survey and tree census data with generalized linear mixed models and variance partitioning to identify the main factors driving tree regeneration and their relative importance.Although beech was slightly less abundant in the canopy than spruce, it strongly outnumbered spruce in regeneration. Beech regeneration showed an affinity for beech litter-rich microsites and drier soils, while spruce was more common on deadwood and moister soils and its response to the seedbed was microsite-specific. The regeneration of both species was positively related to the proportion of their own species in the canopy, but more so in seedlings than in older regeneration cohorts, where soil wetness was more important.The overall pattern of tree regeneration thus resulted from a complex interplay between site conditions and their alterations by current and former generations of canopy trees through the creation of new microsites (deadwood, uprooting mounds) or litter production.Where beech regeneration is not suppressed by excess soil wetness, it is much more successful than spruce due to its shade tolerance and ability to be established in the beech litter that dominates the forest floor. On the other hand, spruce regeneration is mostly restricted to elevated microsites with lower litter accumulation, such as deadwood and treethrow mounds. Our results indicate that both species exhibit an ability to modify their environment in favor of their own regeneration, but under current conditions, beech is more successful than spruce and can be expected to increase its dominance in the future.

Empirical survival model for European beech (Fagus sylvatica L.) seedlings in response to interactive resource gradients and (a-) biotic conditions within an experimental canopy gap study

The success of beech regeneration depends on resource availabilities, which are both heterogeneously distributed in forests and influenced by climate change impacts such as drought and heat waves. To ensure beech regeneration success in the future, it is therefore of great interest to understand the influences of different resource availabilities and their potentially interactive effects on beech seedling survival. In an experimental canopy gap study, we investigated the effects of direct (DIRSF) and diffuse (DIFFSF) solar radiation, soil fertility, groundwater influence, micro-site elevation, vegetation and root competition of overstorey trees on the survival of beech seedlings two years after planting in 2017. The inverse of fine root densities found for overstorey beech (BGRB) and oak (BGRO) was interpreted here as an approximation of the availability of below ground resources, mainly soil water. A logistic model demonstrated positive and interactive effects of DIFFSF, BGRB and soil fertility, emphasizing the complementary resource use pattern of beech seedlings. DIRSF showed a negative effect on survival that was enhanced on groundwater-dominated and higher elevated micro-sites and linked to intensified water limitation. The initial stature of seedlings, the presence and biomass of vegetation and BGRO had no significant effects on beech seedling survival. The unexpected extend to which DIFFSF affected beech seedling survival, the given significance of complementary effects of DIFFSF, BGRB and soil fertility, as well as found interactive effects of DIRSF are discussed in the context of the 2018/19 drought event. Our results suggest that silvicultural measures, such as the creation of larger gaps, can significantly improve resource availabilities, providing an opportunity to increase survival of beech seedlings in the face of climate change impacts.

Increased levels of harvest may favour sugar maple regeneration over American beech in northern hardwoods

The increasing dominance of American beech regeneration (Fagus grandifolia Ehrh.) to the expense of sugar maple (Acer saccharum Marsh.) challenges the long-term economic viability of forest management in northern hardwoods. Based on earlier studies showing that more light in the understory favours sugar maple over beech, the irregular shelterwood system has shifted from experimental to operational over the last decade. In this paper, we evaluate the success of this shift toward irregular shelterwood for promoting sugar maple over beech by measuring the frequency, abundance of sugar maple and beech seedlings and saplings, and growth of seedlings three to six years after logging in northern hardwood forests of western Quebec, Canada. Results showed a dominance of beech regeneration regardless of the harvest intensity, particularly among tall seedlings and saplings. However, we found that the transition probability indices (projected relative combined abundance and growth) of sugar maple could be favoured, albeit to a limited extent, by an increased basal area removal, particularly where the initial occurrence of sugar maple in the advance seedling regeneration is lower than 60% and the initial beech basal area is low in the overstory (i.e. < 6 m2 ha−1). Our results highlight the importance of refining our operational management strategy to effectively limit the increasing abundance of regeneration of American beech over sugar maple in northern hardwood forests.

Effect of game browsing on natural regeneration of European beech (Fagus sylvatica L.) forests in the Krušné hory Mts. (Czech Republic and Germany)

Abstract Tree damage by game browsing is one of the biggest threats to forest ecosystems at the time of climate change and large-scale forest disturbances. The aim of the paper was to determine the effect of browsing by ungulates on the diversity, abundance and species composition of natural regeneration in forest stands dominated by European beech (Fagus sylvatica L.). The research was conducted on 10 permanent research plots in the Krušné hory Mts. in the Czech Republic and Germany. The density of natural regeneration was in the range of 23,300–114,100 recruits ha−1. A higher proportion of silver birch (Betula pendula Roth.) and rowan (Sorbus aucuparia L.) was found in the regeneration compared to the mature stands. A total of 78% of recruits was damaged by browsing. The most frequently damaged tree species were sycamore (Acer pseudoplatanus L.; 98%) and black alder (Alnus glutinosa [L.] Gaertn.; 97%), while Norway spruce (Picea abies [L.] Karst; 31%) and sessile oak (Quercus petraea [Matt.] Liebl.; 50%) were the least affected. Seventy-nine percent of European beech recruits were damaged. The game significantly reduced the height of regeneration by up to 40%, especially by terminal browsing. Browsing also negatively affected the quality and abundance of regeneration. For successful dynamics of species-rich natural forest ecosystems, it is necessary to minimize tree damage by game browsing. These main measures include the reduction of ungulate population levels and the optimization of their age structure and sex ratio, an increase in the number of overwintering enclosures and food fields for game and a change in the political approach to game management with sufficient consideration of forestry interests.