Natural Regeneration Of Beech Research Articles

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.

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.

Structure and Abundance of Fusarium Communities Inhabiting the Litter of Beech Forests in Central Europe

Members of the genus Fusarium and related genera are important components of many ecosystems worldwide and are responsible for many plant diseases. However, the structure of beech litter-inhabiting Fusarium communities and their potential role in reducing the natural regeneration of European beech are not well understood. To address this issue, we examined Fusarium communities in the litter of uneven-aged, old-growth beech-dominated forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand (Poland). The fungi inhabiting beech litter were investigated using beechnuts and pine seedlings as bait. The pathogenicity of the most common species was investigated by inoculating beech germinants. Fusarium spp. were identified based on morphology and DNA sequence comparisons of RPB2 and TEF1-α genes, combined with phylogenetic analyses. Twelve fungal species were identified from 402 isolates, including nine known and three currently undescribed species. The isolates resided in three species complexes within the genus Fusarium. These were the F. oxysporum (one taxon), F. sambucinum (three taxa), and F. tricinctum (six taxa) species complexes. In addition, one isolate was assigned to the genus Neocosmospora, and one isolate could be placed within the genus Fusicolla. The most frequently isolated fungi from beechnuts and beech germinants were F. avenaceum (Fr.) Sacc., F. sporotrichioides Sherb. and Fusarium sp. B. The structure and abundance of species within Fusarium communities varied by beech forest type. The species richness of Fusarium spp. was greatest in old-growth beech-dominated stands, while abundances of Fusarium spp. were higher in managed beech-dominated stands. Pathogenicity tests showed that all four Fusarium species isolated from beechnuts and beech germinants could cause germinants to rot beech, suggesting that these fungi may play a negative role in the natural beech regeneration.

Modelling natural regeneration of European beech in Saxony, Germany: identifying factors influencing the occurrence and density of regeneration

The potential utilisation of natural regeneration of European beech (Fagus sylvatica L.) for forest conversion has received little attention to date. Ecological knowledge is necessary to understand and predict successful natural regeneration of beech. The objective of this study was to improve understanding of what drives the occurrence of beech regeneration and, once regeneration is present, what drives its density. In the study, we utilised a forest inventory dataset provided by Sachsenforst, the state forestry service of Saxony, Germany. The dataset was derived from 8725 permanent plots. Zero-altered negative binomial models (ZANB) with spatial random effects were used to analyse factors influencing occurrence and density simultaneously. The results provided by the spatial ZANB models revealed that the probability of the occurrence of beech regeneration is highly dependent on seed availability, i.e. dependent on source trees in close proximity to a plot. The probability of beech regeneration rises with the increasing diameter of a potential seed tree and decreases with increasing distance to the nearest potential seed source. The occurrence of regeneration is affected by overstorey composition and competition exerted by spruce regeneration. Where sites are affected by groundwater or temporary waterlogging, the impact on the occurrence of regeneration is negative. Although distance to the nearest potential seed source has an influence on occurrence, this variable exerts no influence on density. A high regeneration density arises in conjunction with a high beech basal area in the overstorey. Beech regeneration density, but not occurrence, is negatively affected by browsing intensity. These variables can be used to predict the occurrence and density of beech regeneration in space to a high level of precision. The established statistical tool can be used for decision-making when planning forest conversion using natural regeneration.

Root growth dynamics of three beech (Fagus sylvatica L.) provenances

European beech (Fagus sylvatica L.) is commercially and ecologically important tree species in Central European forests but its intra-specific variability in drought and temperature tolerance might endanger its future distribution in Europe. Beech phenological and growth traits have been studied in large-scale international beech provenance trials, yet the growth and turnover of its fine roots (FR) has not been included among the observations. FR growth dynamics and FR architectural traits of three beech provenances in the international beech provenance trial Straza/Kamenski hrib, established in Slovenia in 1998, and from a natural beech regeneration site growing at its border, were studied from 2007 to 2010. We studied FR biomass using soil cores (SC), root production using ingrowth soil cores (IC), and root longevity using minirhizotrons (MR). Significant differences in FR biomass (live and dead) between the provenance P37 and other provenances were discovered in SC, FR biomass of P37 being significantly higher than FR biomass of latter, which could be connected with overall excellent growth performance of P37 due to favourable environmental conditions at trial. Values of specific root length (SRL) in IC varied significantly among P37 and P54. The turnover rates in IC were at the end of the experiment close to MR results. Median MR-based longevities of FR varied between 625 and 934 days. Survival curve of the slowest growing provenance (considering its aboveground characteristics) was significantly different from the other two, median longevities of the latter being higher. Death of FR, older than two years, occurred most likely in the winter. Our results suggest that there are significant differences in FR longevity among provenances, which might contribute to their adaptation to future environmental conditions. Furthermore, the calculated annual C investment into FR growth per ha differs up to twofold between provenances, contributing to different C dynamics of their future stands.

Characterization of Cylindrocarpon‐like species associated with litter in the old‐growth beech forests of Central Europe

SummaryCylindrocarpon‐like fungi are globally distributed plant pathogens and have a wide range of host species. However, very little is known about the species that live in the topsoil of forests and their potential role in reducing the natural regeneration of tree species, particularly of forest trees that produce abundant fruit only once every few years. To enhance our understanding of the species that inhabit the topsoil, we studied the diversity and pathogenicity of Cylindrocarpon‐like fungi inhabiting the litter in old‐growth mixed‐beech forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand in the Krakowsko‐Częstochowska Highland (Poland). The fungi inhabiting the beech litter were investigated using beechnuts and pine seedlings as bait. Isolates were identified based on morphology and DNA sequencing. The pathogenicity of the most common species was investigated by inoculating beech germinants. A wide range of Cylindrocarpon‐like fungi were associated with the beech litter: 718 cultures representing 12 species were isolated. Five taxa were identified down to species level: namely Ilyonectria crassa, I. pseudodestructans, I. rufa, Neonectria candida and N. obtusispora, and seven species were identified to genus level (Neonectria or Ilyonectria species). Ilyonectria destructans, which is considered to be the sexual morph of ‘Cylindrocarpon destructans’, was not found. There were qualitative and quantitative differences between the different forest sites in terms of Neonectria and Ilyonectria species composition in beech litter. The isolation frequency and species richness of Cylindrocarpon‐like fungi were greatest in beech litter taken from old‐growth mixed‐beech forests. Neonectria and Ilyonectria species were capable of killing beech germinants, suggesting that they may play a negative role in natural beech regeneration.

The synchronicity of masting and intermediate severity fire effects favors beech recruitment

The fire ecology of European beech (Fagus sylvatica L.) is poorly understood. We analyzed beech recruitment after a mast year in recently burnt and unburnt stands to answer to the questions: (i) Does post-fire mast seed production and recruitment in beech depend on fire severity, and (ii) which are the processes by which fire and the environment affect beech seed production, germination and seedling emergence and establishment in the first year after masting?We selected three beech stands in the Southwestern Alps, burnt in either the winter of 2012 or 2013 but before the 2013 beech mast year. In the summer of 2013, at each stand, we established 30 sampling plots stratified by fire severity based on the percent basal area loss of beech (low; intermediate; high). Another 10 plots per stand were assigned to a control (unburnt) group. In the spring of 2014, we counted cupules, seeds, germinated seeds, and emergent seedlings (i.e., rooted in mineral soil) in four squares (0.4×0.4m) at each plot. In the summer of 2014, at each plot, we measured stand characteristics (i.e., a circular area of 12-m in a planar radius) and counted established seedlings in 12 squares (1×1m).Control stands had 448±38cupulesm−2 and 489±44seedsm−2 with a germination rate of 11%. In comparison to the control, production of cupules and seeds was significantly lower only under high fire severity (−75% and −63%, respectively). At intermediate and low severity sites, cupule and seed production were similar to unburnt sites, while seed germination and seedling emergence were higher. At intermediate severity sites established seedlings (86,000±10,574seedlingsha−1) were significantly more frequent than the control. Generalized linear and additive models demonstrated that intermediate disturbance of litter and canopy cover favored beech regeneration.Mixed severity fires are an important ecological factor for the natural regeneration of beech. Such insights in beech disturbance ecology can help improve silviculture and post-fire restoration of Alpine forests. The synergy between fire and masting raises new questions concerning the role of fire in temperate beech forests.

Post-fire restoration of beech stands in the Southern Alps by natural regeneration

In the Southwestern Alps, the summer heat wave in 2003 was associated with unusually large wildfires in European beech forests, a tree species lacking from fire-specific traits and commonly considered as fire sensitive. Although knowledge regarding post-fire dynamics is a prerequisite for restoration measures, there is a considerable lack of studies on post-fire beech regeneration. We assessed the combined effect of fire, masting and salvage logging on natural beech regeneration after a mixed-severity fire in the summer of 2003 in the Italian Alps. The survey took place in 2010 in unmanaged stands and sites logged at different times after the fire. In unmanaged sites with steep and south-exposed terrain fire was severe, tree mortality was prompt and beech failed to resprout or regenerate from seeds. In moderate severity patches, mortality was delayed, permitting abundant beech seedling emergence as the effect of a masting in 2006. The progressive canopy opening provided intermediate light conditions which favoured sapling establishment. In managed sites, the time-lag between salvage logging and the masting affected beech regeneration. Sites logged in winter 2007 soon after the masting displayed higher beech regeneration in comparison to delayed cut or unmanaged stands. Post-fire pioneer species appeared to facilitate beech regeneration. Beech fire traits are discussed and ecologically-based silvicultural guidelines are provided for post-fire management in European beech stands.

A twig blight of understorey European beech (Fagus sylvatica) caused by soilborne Phytophthora spp.

Summary During and after prolonged periods of rainfall in late spring, blighted young twigs of European beech (Fagus sylvatica) were frequently observed in several beech stands in south-western and southern Germany. Long and short shoots of young understorey trees or lower branches up to 1.5 m above the soil level were affected. Symptoms also occurred regularly on twigs in heights up to 2 m and more above the ground. Necroses usually expanded within the current year’s tissue and often also reached into the previous year’s wood. Ponding rain water in the stands or along forest roads or open soil seemed to promote the disease. Of a total of 54 symptomatic twigs collected in four stands, 37 revealed Phytophthora isolates, of which 33 were P. plurivora and four were P. cambivora. Both species caused extensive lesions on beech twigs in laboratory pathogenicity tests. Patterns of the disease indicated that these pathogens, generally considered soilborne species, in most cases are transmitted from the soil to above-ground parts of the trees via rain splash. In larger heights, however, other vectors such as snails might be responsible for transmission. Although Phytophthora spp. are well known as causal agents of seedling blight as well as root and cambium rot and aerial bleeding cankers of mature beech, to our knowledge this is the first report of a twig blight in beech associated with soilborne Phytophthora spp. In particular in periods of high precipitation, this disease might pose an additional threat to Central European beech forests, especially endangering the success of artificial and natural regeneration of beech in affected stands.

Dynamics of natural regeneration of even-aged beech (Fagus sylvatica L.) stands at different shelterwood densities

The article presents results of research focused on the development of natural regeneration of beech stands in the National Natural Reserve Voděradské bučiny, based on information acquired in regeneration plots established in 2004 and 2009. After five years of the study, 5 different generations of beech, representing 97.4% of the whole woody regeneration, were registered. In the second year of life, the two oldest generations of seedlings had the highest mortality registered so far. The last year survival of seedlings was not influenced by increased canopy openings as a result of harvest or mortality. The data from a new plot with higher stand density confirmed the negative effect of high parent stand density on the formation of new regeneration. An elevated proportion of litter in the ground cover was found to be negatively related to the establishment and survival of beech seedlings.

Natural regeneration of senescent even-aged beech (Fagus sylvatica L.) stands under the conditions of Central Bohemia

The natural regeneration of beech (<I>Fagus sylvatica</I> L.) was studied under various shelterwood densities and silvicultural treatments in senescent beech stands in Central Bohemia. Four permanent research plots differed in shelterwood density, crown cover and average relative light intensities. Between 2003 and 2007, seed production, seedling emergence and survival were followed. The mean density of beech seeds (full and empty) per 1 m<sup>2</sup> was estimated in another forest stand. In the autumn of 2003 the values were distinctly higher than those indicated for full mast years of beech. Despite high losses during the wintering of seeds, relatively low germination and high first-season mortality, the high density of 1-year-old beech seedlings indicates that these elements are not the factors which hinder natural regeneration. The thickness of the humus horizons influenced the density of young beech seedlings during all the three years. Ground vegetation was more frequent outside the crown projections of parent trees and increased with distance from the nearest tree. A reduction of crown cover to the level of 80% was an appropriate measure that assured the high survival of beech regeneration during the observed four-year period. Border cutting with the outer face oriented towards the east has to be considered as less suitable for beech regeneration than shelterwood systems and group selection harvesting.

The impact of roe deer ( Capreolus capreolus), seedbed, light and seed fall on natural beech ( Fagus sylvatica) regeneration

The aim of the present study was to quantify the effects of roe deer browsing relative to the effects of soil preparation, shelterwood density (light) and seed fall. Ultimately, the goal was better silvicultural guidelines to support the use of natural beech regeneration in the close-to-nature forestry context. In spring 1995, an experiment on natural regeneration with three experimental stands (0.28–0.6 ha) was installed in a beech ( Fagus sylvatica) dominated broadleaved forest inhabited by a dense roe deer ( Capreolus capreolus) population (24 deer km −2). The autumn of 1995 offered a large beech mast (stand average 307–1168 beechnuts m −2). Treatments installed included fencing to exclude deer, soil preparation, shelterwood thinning, and the relevant control treatments. Roe deer and soil preparation had dramatic effects on regeneration from the moment the seedlings sprouted in the spring 1996. The regeneration sprouted only sparsely in the unprepared seedbed producing only 5 seedlings m −2 (average across fence treatments) after 2 months, which was reduced to 1 sapling m −2 8 years later. Deer had no significant effect on the regeneration density of the unprepared seedbed. In contrast, the cultivated seedbeds produced initially (after 2 months) up to 191 seedlings m −2 protected by fence, whereas the densities in the unfenced treatments peaked by 22 seedlings m −2. By the end of the study, these densities were reduced to 22 saplings m −2 in the permanently fenced mineral soil seedbed and to 2 saplings m −2 in the unfenced mineral soil seedbed. Regeneration height outside the permanent fence was generally only half the height of the regeneration inside. Additionally, we found significantly positive effects of increasing light and seed fall on regeneration density and of light on regeneration growth. We conclude that the roe deer only reduced the regeneration density of the dense regenerations established in the cultivated seedbeds. However, the regeneration density of the unprepared seedbed was not sufficient to support a future high quality stand. We found no treatment that within the timeframe of this study could support successful regeneration establishment outside the permanent fences. Whether this will change in the future with more time given for the regeneration to establish is yet to be revealed.

Natural regeneration of beech in mixed stands of beech and fir with spruce (Piceo-Abieti-Fagetum) in the virgin forest "Perucica"

Natural regeneration of beech in mixed stands of beech and fir was researched in the virgin forest Perucica, e.g. the basic elements of stand structure with special reference to beech regeneration characteristics, and the regeneration process in the conditions of broken stand canopy. The analysis included the stand development stages in he virgin forest based on the elements of structure, as well as the silvigenetic phases on a transect 10?100 m. The characteristics of beech regeneration (abundance, height, crown size, length of apical and lateral shoots) were measured on the selected regeneration areas (initial regeneration gaps). The silvigenetic phases on the transect and the interdependence of beech regeneration characteristics were assessed based on regeneration characteristics, ways of occurrence and spatial distribution of the young growth.

Effects of vegetation control on nutrient removal and Fagus orientalis, Lipsky regeneration in the western Black Sea Region of Turkey

Dense Rhododendron ponticum (L.) understories of eastern beech ( Fagus orientalis Lipsky) stands in the Black Sea Region (BSR) of Turkey create challenging forest vegetation management problems relative to beech regeneration. Rhododendron traditionally is controlled in Turkish forests with grubbing and bulldozing. The effects of these practices on nutrient removal and natural beech regeneration have not been quantitatively studied. Two woody vegetation control treatments (bulldozing and hand-grubbing) were installed during late summer, 2002 in three mature beech stands with dense rhododendron understories in the Düzce Forest Management Directorate, in the Turkish western BSR. Aboveground biomass of each vegetation component, total aboveground vegetation biomass, nutrient concentrations, organic matter (OM) removal, and total amount of OM nutrients were determined for each woody vegetation control treatment. Soil bulk density and nutrient content, and beech seedling biomass, nutrient content, and natural regeneration also were studied. One year after treatment, the machine site preparation by bulldozing (MSP) that removed understory vegetation and attached roots, reduced mean forest floor OM content by about 84%, when compared to hand-grubbing. Mean soil C, N, K and Mg concentrations on the bulldozed sites were 36, 27, 50 and 55% less, respectively, than those on the grubbed sites. Total C and Mg amounts at the 5–10 cm soil depth were 24 and 47% lower, respectively, for mechanical site preparation (MSP) sites, when compared to grubbed sites. Overall, soil bulk density did not differ significantly between the grubbing and MSP treatments. Frequent passes on designated transects on MSP sites resulted in a significant ( P < 0.01) one-third increase in bulk density of the first 20 cm soil depth, when compared to grubbed sites. No natural beech regeneration occurred on untreated control sites. Mineral soil exposure on the MSP sites increased beech seedling germination substantially. One year after treatment, the mean number of naturally regenerated seedlings for MSP sites was 2.5 times greater than for grubbed sites. Woody control treatments had significant effects upon beech seedling chemistry, with N, P, K, Ca and Mg concentrations averaging 35, 47, 12, 33 and 25% lower, respectively, for MSP sites, when compared to grubbed sites. However, mean seedling biomass and nutrient content were significantly greater ( P < 0.05) on MSP sites. Long-term effects from windrowing on MSP site residues, associated topsoil and nutrients need to be evaluated.

The effects of shelterwood density and site preparation on natural regeneration of Fagus sylvatica in southern Sweden

The natural regeneration of beech ( Fagus sylvatica) was studied under various shelterwood densities and soil preparations in a 130-year-old beech stand in southern Sweden. Between 1990 and 1996, seedling emergence, survival, growth and damage were followed in a clear-cut and in two shelterwoods with different densities, in plots with undisturbed ground, bare mineral soil or ridges with mineral soil on top of humus. Irradiation, soil and air temperatures, soil moisture and precipitation were continuously recorded during the first three growing seasons. The seedling emergence was higher in the shelterwoods than in the clear-cut. The mortality was the highest during the first year. The seedling number was the highest on bare mineral soil and the lowest on undisturbed ground, for all cutting regimes. The increase in seedling height and dry mass was greater in the clear-cut and in the sparse shelterwood than in the dense shelterwood. Damage due to frost was more frequent in the clear-cut than in the shelterwoods. Effects of most kind of damage had only minor influence on the seedling height, whereas in seedlings experiencing frequent damage height was reduced.

Natural regeneration of beech ( Fagus sylvatica L.) with respect to canopy density, soil moisture and soil carbon content

The purpose of the present study is to model the regeneration success using quantifiable growth factors. The hypothesis is that the regeneration success can be predicted from a model that incorporates canopy and ground flora leaf area indexes (LAI), soil water content and soil carbon content. In April 1992, 10 plots (1 m 2) were established in each of 22 Danish beech stands with natural regeneration originating from the 1989 seed fall. The regeneration success was investigated until autumn 1994. In each of the 220 plots the light conditions, soil water supply and soil carbon content were quantified. The survival was high during the study period. From spring 1992 to autumn 1993 the mean number of saplings decreased from 58 m −2 to 54 m −2. The sapling number was reduced by increased canopy density but it was neither influenced by water supply nor by soil carbon content. The height growth variation was evident. After the fifth growing season (autumn 1994) the height of the tallest sam3pling per plot ranged from 7 to 120 cm. Generally, an increased canopy opening increased the potential for and variance of height growth. Increased soil water content caused a significant increase in the growth of the saplings; whereas, a significant reduction in growth occurred with increased soil carbon content. The shading from the competing ground flora had no significant effect. However, the contribution to the total sum of squares from the quantitative variables of the relevant statistical models was only 3%–13%. Therefore, the models were unable to predict regeneration success satisfactorily and it was not possible to establish the causal effects underlying silvicultural treatments and site. It is concluded that the beech saplings probably were so well established at the beginning of the study that they had become tolerant to poor growing conditions, such as the drought in 1992. This indicates that the growing conditions during the early phases of seedling establishment may be crucial for the regeneration success. For silviculturists, these conclusions stress the importance of creating favourable growth conditions prior to the first growing season. Future research should examine the early phases of seedling establishment by quantifying growth factors in more detail than was done in the present study.

Ecophysiological responses of Fagus sylvatica seedlings to changing light conditions. II. The interaction of light environment and soil fertility on seedling physiology

The survival and growth of natural beech regeneration after canopy removal is variable and little is known about ecophysiological mechanisms of these responses. Biomass, nonstructural carbohydrate levels and nitrogen concentrations were measured in an Italian population of European beech seedlings. Seedlings were container‐grown in two types of soil, organic and mineral, collected at the study site. The seedlings were grown under three light treatments: under full beech canopy (understory), exposed to full sun only during midday (gap) and under full sun (clearing). Leaf gas exchange and chlorophyll a fluorescence parameters were measured and then foliar analyses were conducted for chlorophyll, phenolic and tannin levels. Biomass and allocation were significantly affected by light and soil treatments. The clearing seedlings and those in organic soil were larger than seedlings in the other light treatments or soil type. Total nonstructural carbohydrate concentrations were lower in the understory seedlings and significant differences between soil types were present in the gap and clearing seedlings. Nitrogen concentrations were higher in the understory seedlings and those growing in the organic soil compared to the other treatments. Gas exchange rates were highest in clearing and the organic soil seedlings. Gap seedlings exhibited photosynthetic acclimation that allowed them to utilize high light of midday and any sunflecks during the morning and afternoon. Relative fluorescence was significantly influenced by both light treatment and soil type, with the highest values observed in the gap seedlings. Light response curves showed decreasing apparent maximum quantum efficiency from the understory to clearing, while maximum photosynthetic rate was highest in the gap seedlings. Chlorophyll concentration was highest in understory seedlings and those growing in organic soil and higher in seedlings growing in organic than in mineral soil. Both foliar tannin and phenolic levels were highest in clearing seedlings, and only tannin concentrations were affected by soil type. Understory seedlings had the highest mortality and insect herbivory; the latter was found to be inversely related to tannin concentration. Overall, growth and photosynthesis in beech seedlings responded positively to high light associated with small canopy gaps. Organic soil increased seedling size, particularly in the gap and clearing environments. We conclude that forest gaps are favorable for photosynthesis and growth of European beech seedlings.

Effects of seedbed type on wintering of beech nuts ( Fagus sylvatica) and deer impact on sprouting seedlings in natural regeneration

Natural regeneration of beech ( Fagus sylvatica) is often initiated by soil preparation before seed fall in the mast years. The wintering of beech nuts and the sprouting of beech seedlings in mixed and mineral soil seedbeds were investigated in six Danish beech stands after the 1989 seed fall. Previously, the mineral soil seedbed was considered to give the best wintering conditions for beech nuts owing to a relative low level of fungal attack. In the present investigation average number of undamaged nuts and sprouting seedlings were up to ten times larger in the mineral soil seedbed compared with the mixed soil seedbed within the same stand. However, the fungal attack was not significantly affected by the seedbed type. It is suggested that rodents collect undamaged nuts, leaving empty and damaged nuts behind, and that they prefer to seek for nuts in the mixed soil seedbed. Thereby, the method used for the collection of samples in previous investigations may have yielded misleading results concerning the effects of seedbed type on fungal attack.

Effects of soil water content, fertilization, light, weed competition and seedbed type on natural regeneration of beech ( Fagus sylvatica)

Natural regeneration of beech ( Fagus sylvatica) is regarded as an inexpensive and generally satisfactory, though unreliable, method fo forest regeneration. In order to improve the understanding of the ecological conditions behind the growth and survival of beech seedlings, factorial experiments were carried out in each of two beech stands with different canopy openings. The effects of soil water content and nutrient supply in relation to light intensity, weed competition and seedbed type were studied. Under the open canopy (13% light) the seedling growth was increased three to four times when both fertilized and irrigated in a mineral soil seedbed compared with seedlings that were neither fertilized nor irrigated. The seedling response to treatments was small in the mixed soil seedbed under the open canopy and in both seedbed types under the closed canopy (5% light). Seedling growth was increased only with increased soil water content under the open canopy in fertilized plots. Weed competition did not reduce seedling growth significantly. Fertilization reduced soil water content up to about 20%. It was concluded that primary growth factors like light intensity, soil water content and nutrient supply should all be quantified or manipulated when the growth of beech seedlings is investigated. Otherwise, the correct interpretation of complex effects such as silvicultural treatments, soil types and weed competition must be regarded as very difficult or impossible to make.

Mortality of Holly (Ilex Aquifolium) Seedlings in Relation to Natural Regeneration in the New Forest

Natural regeneration of the unenclosed woods of the New Forest has not proceeded evenly over the last 300 years, but has been more or less confined to two 110-year periods, 1650-1760 and 1850-the present day (Peterken & Tubbs 1965). Correspondence between the fluctuating success of regeneration and changes in the populations of deer, ponies and cattle is particularly good for the nineteenth and twentieth centuries, for which the information is relatively abundant, so Peterken & Tubbs concluded that the browsing pressure exerted by these large herbivores has regulated the success of regeneration, implying that the present-day lack of regeneration is the result of the browsing pressure, which is at its highest level since 1850. This is confirmed by two inclosures set up in Mark Ash beechwood. Within these small (< 0.25 ac, 0-1 ha) and therefore psychologically deerproof areas, natural regeneration of beech and other trees is profuse, in striking contrast to the surrounding woodland in which it is almost entirely absent. In the present paper the relationship between seedling mortality, the factors causing their death, and regeneration is examined in greater detail with reference to holly (Ilex aquifolium).