Beech Seedlings 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.

Indiferentní reakce sazenic borovice lesní a buku lesního ošetřených hydroabsorbenty

Super-absorbents are expected to amend soils as they are capable of retaining water, which turns dry loose powdery substances (also capsule) into hydrogel. These were applied to prevent an artificial regeneration failure due to drought events. Four commercially-available products were mixed with soil from planting holes (the capsule was put to the soil) in order to support bare-root Scots pine and European beech seedlings after a spring planting on eleven clear-cut sites in 2020–2021. The plantations were designed as rows with 4 × 150 plants treated with four hydrogels plus 150 plants without hydrogel as a control. The performance evaluation of new plantations was based on attributes such as mortality/survival and relative height and root-collar diameter increments. The plants, which lost their initial size, due to pine weevil damage, dry tops and damage by game, were excluded from the evaluation. Besides the plant response to the applied super-absorbents, the planting operations were evaluated from economic point of view. The 2020 plantations showed higher mortality than 2021 ones; both years showed an excessive loss. The hydrogels did not help the plants to survive better compared to control and growth data also showed ambiguous results. Therefore, from commercial perspective, the application of all tested super-absorbents just increased the renewal costs.

Silicon Modifies Photosynthesis Efficiency and hsp Gene Expression in European Beech (Fagus sylvatica) Seedlings Exposed to Drought Stress.

Background: Climate change is leading to severe and long-term droughts in European forest ecosystems. can have profound effects on various physiological processes, including photosynthesis, gene expression patterns, and nutrient uptake at the developmental stage of young trees. Objectives: Our study aimed to test the hypothesis that the application of silica (SiO2) influences photosynthetic efficiency and gene expression in 1- to 2-year-old Fagus sylvatica (L.) seedlings. Additionally, we aimed to assess whether silicon application positively influences the structural properties of leaves and roots. To determine whether the plant physiological responses are genotype-specific, seedlings of four geographically different provenances were subjected to a one-year evaluation under greenhouse conditions. Methods: We used the Kruskal-Wallis test followed by Wilcoxon's test to evaluate the differences in silicon content and ANOVA followed by Tukey's test to evaluate the physiological responses of seedlings depending on treatment and provenance. Results: Our results showed a significantly higher Si content in the roots compared with the leaves, regardless of provenance and treatment. The most significant differences in photosynthetic performance were found in trees exposed to Si treatment, but the physiological responses were generally nuanced and provenance-dependent. Expression of hsp70 and hsp90 was also increased in leaf tissues of all provenances. These results provide practical insights that Si can improve the overall health and resilience of beech seedlings in nursery and forest ecosystems, with possible differences in the beneficial role of silicon application arising from the large differences in wild populations of forest tree species.

Korištenje morfoloških značajki sadnica obične bukve (Fagus sylvatica L.) za selekciju reprodukcijskog materijala iz provenijencija vjerojatno zahvaćenih klimatskim promjenama

Global climate change causes the reduction of tree growth and spread of European beech (Fagus sylvatica L.) forests, thus indicating the need to preserve tree abundance due to the changes that have occurred. The comparison of beech seedlings from various provenances in southeast and central Europe was carried out based on the dimensions of root collar diameter and height to select the proper starting material that would reduce the negative consequences of the climate. There have been statistically significant differences in root collar diameter and height between various seedlings tested in European provenances. Clear differentiation was recorded between European countries in the growth performances of one-year-old and two-year-old seedlings of F. sylvatica based on the nursery test. The study's results indicate the potential for producing adaptable beech reproductive material from various European provenances. This finding lays the groundwork for future precise analyses that aim to select provenances tolerant to changing climate conditions.

Impact of various microplastics on the morphological characteristics and nutrition of the young generation of beech (Fagus sylvatica L.)

Microplastics have the capacity to accumulate in soil due to their high resistance to degradation, consequently altering soil properties and influencing plant growth. This study focused on assessing the impact of various types and doses of microplastics on beech seedling growth. In our experiment, we used polypropylene and styrene granules with diameter of 4.0 mm in quantities of 2.5% and 7%. The hypothesis was that microplastics significantly affect seedlings' nutritional status and growth characteristics. The research analysed seedlings' nutrition, root morphological features, above-ground growth, and enzymatic activity in the substrate. Results confirmed the importance of microplastics in shaping the nutritional status of young beech trees. Microplastic type significantly impacted N/P and Ca/Mg stoichiometry, while microplastic quantity influenced Ca/Al and Ca+K+Mg/Al stoichiometry. Notably, only in the case of root diameter were significantly thicker roots noted in the control variant, whereas microplastics played a role in shaping the leaves' characteristics of the species studied. The leaf area was significantly larger in the control variant compared to the variant with polypropylene in the amount of 2.5% and styrene in the amount of 7%. Additionally, the study indicates a significant impact of microplastics on enzyme activity. In the case of CB and SP, the activity was twice as high in the control variant compared to the variants with microplastics. In the case of BG, the activity in the control variant was higher in relation to the variants used in the experiment. Research on the impact of microplastics on the growth of beech seedlings is crucial for enhancing our understanding of the effects of environmental pollution on forest ecosystems. Such studies are integral in shaping forestry management practices and fostering a broader public understanding of the ecological implications of plastic pollution.

Addressing the altitudinal and geographical gradient in European beech via photosynthetic parameters: a case study on Calabrian beech transplanted to Denmark

European beech (Fagus sylvatica L.) is becoming one of the go-to species in reconstructing declining conifer stands in Europe under climate change. Assisted migration may be considered when looking for suitable beech seedlings. Knowledge about the photosynthetic performance of beech seedlings is fundamental to understanding an essential part of their growth and survival potential in different planting conditions. We investigated the within-provenance variation in photosynthetic performance driven by altitude in contrast to inter-provenance variation given by geographical distance. The experiment was conducted on seedlings replanted in a Danish common garden comprising a cluster of provenances with various altitudinal subgroups transplanted from the Calabria region (Italy) and two local Danish provenances. Provenance and within-provenance variation in chlorophyll fluorescence (ChlF) kinetics, gas exchange (GE), flushing, and senescence were assessed. ChlF measurements revealed within-provenance differences based on altitude of origin and could distinguish between the two Danish provenances. In contrast, GE parameters detected variation in the geographical distance among Italian provenances. High-elevation subgroups of Italian provenances showed the best leaf-level photosynthetic performance in Danish weather conditions with high precipitation levels. Altitude of origin can be a significant source of within-provenance variation. We demonstrated that assessing this variation in young trees may be instrumental in maximizing the potential of provenance variation across diverse planting sites.

Winter and spring frost events delay leaf-out, hamper growth and increase mortality in European beech seedlings, with weaker effects of subsequent frosts.

The persistence of plant populations depends crucially on successful regeneration. Yet, little is known about the effects of consecutive winter and spring frost events on the regeneration stage of trees from different seed sources, although this will partly determine the success of climate warming-driven poleward range shifts. In a common garden experiment with European beech (Fagus sylvatica) seedlings from winter 2015/2016 to autumn 2017, we studied how simulated successive spring and winter frost events affect leaf-out dates, growth performance, and survival rates of 1- to 2-year-old seedlings from provenances differing in climate at origin. We further investigated the combined effects of successive frost events. The first spring frost after germination led to a mortality rate up to 75%, resulting in reduced seedling numbers but better frost tolerance of the survivors, as reflected in a weaker impact of the following winter frost event in the survivors compared to the non-acclimated control. Final plant height was most strongly reduced by the spring frost in the second year. The winter frost event delayed leaf-out by up to 40 days, leading to severe growth impairment in 2017. Our results indicate partly successful frost acclimation and/or the selection of frost-hardier individuals, because the negative growth effects of consecutive frost events did not add up after exposure to more than one event. Both mechanisms may help to increase the frost tolerance of beech offspring. Nevertheless, mortality after the first spring frost was high, and frost exposure generally caused growth reductions. Thus, achieving higher frost tolerance may not be sufficient for beech seedlings to overcome frost-induced reductions in competitive strength caused by winter frost damage and delayed leaf enfolding.

Recognition of Davidsoniella virescens on Fagus sylvatica Wood in Poland and Assessment of Its Pathogenicity.

Davidsoniella virescens is so far only known in North America. However, recently in southern Poland, blackish growth consisting of fungal mycelia and sporulation structures was found on the wood of Fagus sylvatica. As a result of isolation, 17 cultures of this fungus were obtained. All cultures produced an intense sweet odor. This fungus, both in situ and in vitro, abundantly produced perithecia with long necks and asexual stage. Particularly characteristic was the production of variable endoconidia in two types of phialophores differing mainly in the width of the collarette. The nucleotide sequences for five gene fragments of representative cultures were used in phylogenetic analyses: 18S; the internal transcribed spacer regions ITS1 and ITS2, including the 5.8S gene (ITS); 28S region of the ribosomal RNA (rRNA), β-tubulin 2 (TUB2) and translation elongation factor 1-α (TEF1). Based on morphological and phylogenetic analyses, the fungus on European beech in Poland was identified as Davidsoniella virescens. The optimal temperature for radial colony growth was 20 °C. However, the differences between colony diameter at 25 °C compared to that at the optimal temperature were not statistically significant. Six D. virescens isolates were used for pathogenicity assay. They were inoculated into wounds on stems of two-year-old seedlings of Fagus sylvatica and Acer saccharum (36 seedlings of each tree species). Final evaluation was performed 4 months after inoculation. No external symptoms were observed in any A. saccharum seedling, neither in the crown nor on the stem. However, 13.9% of F. sylvatica seedlings showed wilting symptoms throughout the entire crown within 3-6 weeks after inoculation. Moreover, after 4 months on the stems of 30.6% beech seedlings, necrotic lesions with a length of 1.3 to 7.2 cm were formed, without any symptoms of wilting. The most noticeable internal symptom was the discoloration of the wood, which was observed in all inoculated seedlings of both tree species. All D. virescens isolates caused greater wood discoloration in F. sylvatica than in A. saccharum. Most of the differences found in the extent of discoloration between host plants were statistically significant. The discoloration caused by all D. virescens isolates in F. sylvatica was significantly greater than in the control. However, none of the isolates tested on A. saccharum caused significantly greater wood discoloration compared to the control. Pathogenicity tests showed that the D. virescens isolates identified in southern Poland may pose a greater threat to native European beech than to foreign sugar maple.

Drought acclimation of beech seedlings depends largely on their rooting patterns and less on the fungal communities in soils

Drought acclimation of beech seedlings depends largely on their rooting patterns and less on the fungal communities in soils

Planting in Paradise

The One Billion Trees project is an initiative led by the Ministry of Primary Industries where they aim to plant 1 billion trees by the year 2030 to transform New Zealand forests in a way that improves the productivity of the land, as well as helping the natural environment. Notably, a large proportion of the trees that have already been planted and established are Pinus radiata (exotic pine trees) which have a detrimental effect on the natural environment due to outcompeting native flora and compromising soil stability due to their shallow root systems. P. radiata are a fast establishing and cost effective option for landowners and farmers that are participating in the One Billion Trees project. Our project's aim was to understand what is required to support the establishment of native beech trees, using both on-campus and field trials, with a primary focus on assessing methods of delivering mycorrhizal inoculation to native beech seedlings. This would allow us to educate the Ministry of Primary Industries and to provide these landowners and farmers with information on how to regenerate their land using native trees instead of exotic. The field trial, located within the Motutapu Covenant at Mahu Whenua, incorporated various treatment options, such as planting beech with or without bracken rhizomes, Manuka seeds, Manuka duffpods, and beech duffpods. The on-campus trial was established in a controlled environment where beech and Manuka seeds were planted with or without their respective duffpods. Currently the results of these experiments are inconclusive, requiring additional time to observe the effects of different treatments on the planted seedlings and seeds which will in future contribute to sustainable and effective reforestation practices using native trees. Project Funded by: The Ministry for Primary Industries and The University of Otago

Hunting of sika deer over six decades does not restore forest regeneration

Abstract High densities of native and introduced deer hamper the regeneration of temperate forests worldwide. Sport hunting is often the sole means of deer control, but whether it can restore forest regeneration remains uncertain. We assessed the potential to restore forest regeneration using unrestricted sport hunting alongside commercial harvesting and government‐funded culling of introduced sika deer (Cervus nippon) across a 594 km2 landscape in North Island, New Zealand. We used six decades of repeated measurements of forest regeneration and deer presence, alongside monitoring of tagged stems in a 20‐year paired exclosure experiment, to determine whether deer control restored regeneration. In our exclosure experiment, mountain beech (Fuscospora cliffortioides) seedling and sapling density, growth and survival were variable but consistently higher when deer were excluded by fencing. Sapling counts in unfenced plots were ≈3–10 times lower after 60 years of deer control compared with unfenced plots, before sika colonisation and other mountain beech forests without sika deer. This result suggests canopy replacement remains at risk despite government‐funded culling and encouragement of sport hunting. Individual‐based demographic models show that mountain beech is unlikely to regenerate following canopy gap formation in our study landscape unless deer impacts are reduced from current levels. These demographic models predicted present‐day forest regeneration far better than two widely used proxies of deer impact: plot‐based counts of saplings and estimates of deer densities from faecal pellet counts. Synthesis and applications. Here, we show that intensive culling beyond that achievable by sport hunting is needed to reduce deer densities enough to assure canopy regeneration. These interventions will be necessary in the many places worldwide where sport hunting is being relied upon to protect forests but appears to be failing. Given the controversy associated with deer culling, and the need for clear evidence to justify its implementation, we suggest managers could strengthen the evidence base for their interventions by collecting data to build demographic models.

Естественное возобновление на валежной древесине в реликтовом лесу Янь Республики Сербской

The paper investigates the natural regeneration of downed deadwood in the Janj primeval forest. The old-growth forest is located in the southwestern part of the Republic of Srpska, which is dominated by dolomite geological base on which cambial soils were formed. The climate is perhumid and mountainous and the plantation belongs to the Piceo-Abieti-Fagetum community. The hectare contains 517 live trees with a total basal area of 53.0 m2/ha and a volume of 876 m3/ha. Twenty six downed deadwoods classified into three different degrees of decay were included in the study, where fir and spruce seedlings were found to be predominant and beech seedlings were rarely represented. The first degree of decay includes 7 (26.9 %), the second 8 (30.7 %), and the third 11 (42.3 %). The total volume of deadwood is 110.82 m3/ha with an average volume per tree of 4.2 m3/ha. The total number of seedlings on fallen dead trees is 836 seedlings (Abies alba – 89.59 %, Picea abies – 10.17 %, Fagus silvatica – 0.24 %). Fir seedlings are found on 25 fallen trees, spruce on 18 fallen trees, and beech on 2 fallen trees. Regarding quality, on average fir seedlings are better than spruce seedlings, but both species show a lot of senescence and very small size of current height increment. Most seedlings belong to the third quality class (fir – 46.2 %, spruce – 61.1 %), followed by second class (fir – 34.6 %, spruce – 22.2 %) and third class (fir – 19.2 %, spruce – 16.7 %). The total number of seedlings was found to have a statistically significant difference in the amount of downed deadwood depending on the degree of decay, and the number of seedlings depended on the degree of tree decay. The number of seedlings increased with increasing volume and length of rotten trees. For citation: Govedar Z., Prokhorova N., Babić V., Dukić V., Kanjevac B., Bilić S. Natural Regeneration on Deadwood in the Primeval Forest Janj. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 90–102. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-90-102

Induced Drought Stress Response of European Beech Seedlings Treated with Hydrogel and Ectomycorrhizal Inoculum

Bareroot European beech (Fagus sylvatica L.) seedlings are frequently used in reforestation programs in Central Europe. However, beech outplanting is often unsuccessful due to drought stress. In this study, the effects of a simulated water deficit and of a hydrogel and ectomycorrhizal fungi (EMF) application were estimated on the development of 1 + 1 beech seedlings. The roots of 1-year-old bareroot seedlings were treated with the additives at the time of transplanting to pots in spring and then exposed to the whole growing season under different watering regimes: (i) full watering (FW; volumetric water content 70%), (ii) reduced watering (RW; 40%), (iii) periodic watering (PW; substrate rewetted to 70% after drying), and (iv) no watering (NW). Almost all FW seedlings survived the whole growing season, whereas all NW seedlings died after 17 weeks of desiccation. The survival and growth of FW and NW seedlings were significantly higher and lower, respectively, than those under both PW and RW treatments. The additives significantly increased survival in RW seedlings only but had no effect on growth. A promoting effect of FW on the chlorophyll a fluorescence parameters was found. The number and EMF colonization of the short roots were significantly lower in FW seedlings compared to the other watering treatments. The additives did not affect these parameters. The occurrence of neither treatment-specific EMF root morphotype nor fungi applied in the inoculum and traced by molecular analysis indicated the formation of ectomycorrhizas with native EMF in all treatments. The seedlings in the water-deficient treatments exhibited higher foliar nutrient concentrations than FW seedlings. The additives increased the concentration of nutrients in PW and phosphorus in NW seedlings. The results suggest the significant effect of the water supply, but a weaker effect of the additives tested on beech seedling development under experimental conditions.

Soil biotic and abiotic thresholds in sugar maple and American beech seedling establishment in forests of the northeastern United States

Soil biotic and abiotic thresholds in sugar maple and American beech seedling establishment in forests of the northeastern United States

First report of the beech leaf disease nematode Litylenchus crenatae mccannii (Nematoda: Anguinidae) in Michigan.

The North American beech leaf disease (BLD) nematode, Litylenchus crenatae mccannii Handoo, Li, Kantor, Bauchan, McCann, Gabriel, Yu, Reed, Koch, Martin and Burke, 2020, is recognized as a newly emergent nematode species that causes BLD in beech trees (Fagus spp.) in North America (Carta et al. 2020; Kantor et al. 2022a). Since the first report of BLD on American beech (Fagus grandifolia Ehrh) within the Lake County, located at the north-eastern corner of the state of Ohio in 2012 (Carta et al. 2020), the disease has rapidly spread to other US states and a province in Canada (Erwing et al. 2018; Carta et al 2020; Marra and LaMondia 2020; Reed et al 2020; Kantor et al. 2022b). Currently, besides Ohio, this nematode has been reported in Pennsylvania, New York, Connecticut, Massachusetts, Maine, Rhode Island, New Jersey, West Virginia, and Virginia, as well as Ontario, Canada. Different life stages of L. crenatae mccannii were isolated from symptomatic American beech leaves from an isolated natural maple-beech stand in rural Saint Clair Cty., Michigan, US; presenting typical symptoms of beech leaf disease, i.e., swelling and darkening of interveinal leaf tissues. Samples were taken to the Forest Pathology Laboratory at Michigan State University where L. crenatae mccannii presence was confirmed in the leaves after which samples were sent to the Mycology and Nematology Genetic Diversity and Biology Laboratory (USDA-ARS) in Beltsville, Maryland for official confirmation. Nematodes were identified based on morphology and sequence analysis of the internal transcribed spacer (ITS), and the D2D3 region of the 28S large subunit ribosomal DNA. To validate the morphological identification two different ribosomal DNA loci were amplified, sequenced and the phylogenetic relationships were generated. The amplification yielded fragments of 784 and 741 bp flanked by the ITS (GenBank accession no. OP689654) and D2D3 (GenBank accession no. OP689710) primers, respectively. The sequences obtained for the specimens collected in Michigan revealed 100% similarity to L. crenatae mccannii sequences obtained from specimens collected from other geographical areas in the US, and therefore validating the morphological analyses as well. The ITS sequence shared a 99.75% similarity with the subspecies L. crenatae (GenBank accession no. LC383724.1), and 90.53% similarity to L. coprosma Zhao, Davies, Alexander and Riley, 2011 (GU727548.1). While the D2D3 sequences of both L. crenatae subspecies revealed a 100% similarity (versus LC383725.1), they revealed 95.35% similarity to L. coprosma (KY679564.1). Since the first confirmed detection of BLD in June 2022 in St. Clair Cty, BLD has been reported in Oakland and Wayne Ctys (7 reports total across the three counties), suggesting BLD spread in the SE of Michigan. BLD confirmation was based on either physical symptoms (leaf banding), and/or the presence of the beech leaf nematode by morphological or molecular confirmation. The presence of the beech leaf nematode in symptomatic leaves follow the results obtained by Carta et al. (2020) after inoculation of beech seedlings with L. crenatae mccannii. Based on both morphological and molecular analyses the specimens collected in the state of Michigan were identified as L. crenatae mccannii. To our knowledge, this is the first report of this species in conjunction with symptomatic F. grandifolia leaves in this state.

A multifaceted approach to reveal the very-fine root's response of Fagus sylvatica seedlings to different drought intensities.

How temperate trees respond to drier summers strongly depends on the drought susceptibility and the starch reserve of the very-fine roots (<0.5 mm in diameter). We performed morphological, physiological, chemical, and proteomic analyses on very-fine roots of Fagus sylvatica seedlings grown under moderate- and severe drought conditions. Moreover, to reveal the role of the starch reserves, a girdling approach was adopted to interrupt the flux of photosynthates toward the downstream sinks. Results show a seasonal sigmoidal growth pattern without evident mortality under moderate drought. After the severe-drought period, intact plants showed lower starch concentration and higher growth than those subjected to moderate drought, highlighting that very-fine roots rely on their starch reserves to resume growth. This behavior caused them to die with the onset of autumn, which was not observed under moderate drought. These findings indicated that extreme dry soil conditions are needed for significant root death in beech seedlings and that mortality mechanisms are defined within individual compartments. The girdling treatment showed that the physiological responses of very-fine roots to severe drought stress are critically related to the altered load or the reduced transport velocity of the phloem and that the changes in starch allocation critically alter the distribution of biomass. Proteomic evidence revealed that the phloem flux-dependent response was characterized by the decrease of carbon enzymes and the establishment of mechanisms to avoid the reduction of the osmotic potential. The response independent from the aboveground mainly involved the alteration of primary metabolic processes and cell wall-related enzymes.

Restoring mixed forests through conversion of Norway spruce stands: effects of fencing and mechanical site preparation on performance of planted beech and natural tree regeneration

Conversion of Norway spruce (Picea abies) plantations to more diverse and resilient forest types is an important task for European forest managers in the face of climate change and increased focus on ecosystem services beyond timber production. However, there is a lack of knowledge on how to cost-effectively restore such forests. This study reports the influence of vicinity (distance) of forest type (mixed or spruce), fencing and mechanical site preparation (MSP) on the early performance of planted beech (Fagus sylvatica) seedlings and natural regeneration of other tree species following clear-cuts of Norway spruce in southern Sweden. After 6 years, we found clear effects of fencing and MSP, but not of vicinity of forest type. Fencing had a positive effect on height growth of Scots pine (Pinus sylvestris) but not on height of planted beech and naturally regenerated birch (Betula pendula, B. pubescens). There was a positive effect of MSP on survival and height growth of planted beech, and on the amount of natural regeneration of Scots pine. We conclude that establishment of beech forest is greatly accelerated by active regeneration approaches such as planting. In addition, the combination of planting beech, natural regeneration of other species, fencing and MSP is effective to promote the transition to mixed and diverse stands with both broadleaves and conifers. Fencing represented the highest cost among the treatments, and its cost-effectiveness depends on the local ungulate browsing pressure. In our study, fencing was critical to protect natural regeneration of Scots pine from browsing. Finally, natural regeneration of birch was abundant in our study and relatively unaffected by fencing and MSP treatments. With time, pre-commercial thinning of the naturally regenerated birch will be needed to maintain a diverse mixture of tree species.

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.

Interaction between growth environment and host progeny shape fungal endophytic assemblages in transplanted Fagus sylvatica

Fungal endophytes are an integral part of the leaf microbiome of forest trees. Most of these endophytes are horizontally transmitted, however little is known about their assembly drivers. Endophytic assemblages differ in composition according to geography and host individuals. In addition, climate and genetic diversity are also reported to lead to host plant adaptation. To determine the impact of the host progeny and respective adaptation to environmental conditions on endophytic assemblages, we designed a transplantation experiment in beech trees ( Fagus sylvatica ). Beech nuts were collected from distant geographical regions and germinated in a common greenhouse. One-year-old beech seedlings were transplanted to the different locations and the leaf-endophytic assemblages were characterized in the second growth season after planting by cultivation-independent metabarcoding. The chlorophyll and flavonoid content of the respective leaves were also measured. The results revealed host progeny effects in shaping leaf-endophytic fungal assemblages, that might be concealed by major geographical effects. We hypothesise and discuss possible interactions of different assembly drivers. • Most leaf endophytic fungi are acquired from the surrounding environment. • Endophytic assemblages are mainly shaped by climate, followed by the host. • Interactions are often concealed by dominant geographical effects. • The host adaptation to the local climate is reflected by the phytochemistry. • Phytochemistry has a weak influence on the associated endophytic assemblages.