Effect of Betula pendula clone and leaf age on Melampsoridium betulinum rust infection in a field trial

Ten 5‐year‐old Betula pendula clones were studied for their rust resistance in the field. The trees were treated by inoculating 10 leaves on a shoot with Melampsoridium betulinum urediniospore suspension or spraying the control leaves with water. The birch clones differed significantly in their resistance to M. betulinum leaf rust fungus and the clones also varied in their responses to the local rust strain and the inoculated rust strains. However, natural rust infections and inoculation treatment were positively correlated. The older leaves had fewer infections than the younger ones on the tip of the shoot in the control trees, but in the inoculation treatment no significant correlation was found between the leaf ages and rust infection. The factors behind the different leaf susceptibilities are discussed.     

Differences in the rust resistance of greenhouse and outdoor-grown white birch species,Betula spp.

The 2-year-old seedlings of five different white birch species (Betula platyphylla, Betula papyrifera, Betula pubescens, Betula pendula (two types) and Betula resinifera x Betula pendula) grown both in a greenhouse and outdoors, were inoculated in a leaf disc assay with two different birch rust (Mel-ampsoridium betulinum) isolates from B. pendula and B. pubescens. The resistance of these birch species varied significantly. Resistance to the B. pubescens rust isolate was not related to the resistance of the B. pendula rust isolate. The behaviour of a birch genotype grown in the greenhouse did not correspond to the behaviour of the same genotype grown outdoors. The outdoor growth environment greatly increased the contents of soluble proteins, rubisco, chloro-phyll and nitrogen in the leaves of diploid birch species (B. platyphylla, B. pendula and B. resinifera x B. pendula). For tetraploid and pentaploid species (B. pubescens and B. papyrifera, respectively) there was no such clear difference in the leaf physiological status between the seedlings grown outdoors and in the greenhouse. The C:N ratio was higher for the greenhouse-grown seedlings in all the birch species, but the difference was significant only with the diploid species. The incidence of rust in the birch species did not correlate with any of the leaf physiological parameters studied. The adaptability of birch genotypes to the environment in relation to their resistance to birch leaf rust is discussed.     

Variation in Melampsoridium resistance among European white-birch clones grown in different fertilization treatments

Resistance of 2-year-old plantlets of seven European white birch, Betula pendula, clones to birch rust, Melampsoridium betulinum, was studied in field experiments and in a leaf-disc bioassay. In addition, rust resistance of plantlets growing in a nursery under three fertilization treatments was tested. The birch clones clearly varied in their levels of resistance. One of the clones was consistently the most resistant, and two were very susceptible. Plantlets growing in the lowest fertility treatment were the most resistant. Clone × fertilization interaction was small. The plantlets grown in the lowest fertilization treatment, in particular, deviated from the other treatments. Generally good rust-resistance correlations were obtained between different experiments. The leaf-disc bioassay was an effective way of determining the field rust resistance of birch clones. The possibility of trade-offs between rust resistance and tree growth is discussed.     

Pre-penetration behaviour of the urediniospores of birch rust,Melampsoridium betulinum,on greenhouse-grown and microcultured leaves of Betula spp.

In two different experiments the urediniospores of Melampsoridium betulinum from Betula pendula and Betula pubescens germinated both on mature leaves of greenhouse-grown plants and on sterile in vitro leaves of micropropagated plantlets, which were cloned from the same B. pendula and B. pubescens genotypes. The urediniospores and germ tubes were more easily detached from the leaf surfaces of in vitro leaves. If germination took place on a leaf vein, the growth continued across the veinal ridges; otherwise, no determined growth towards the stomata could be observed with either of the leaf types studied. In both experiments on the in vitro leaves of B. pubescens clone V5944, the germ tubes of the rust isolate from B. pendula mislocated appressoria significantly more often than the germ tubes of the rust isolate from B. pubescens. On the mature leaves of B. pendula clone E4214 and B. pubescens clone V5940 there were also significant differences in appressorial locations between the two rust isolates but the clonal responses were inconsistent. The results of the inoculations suggest that the incompatibility of the rust isolates from B. pendula on the leaves of B. pubescens is not related to the significantly higher ratio of failures in locating appressoria in this host-rust combination.     

Effects of acid rain treatments on the birch rust,Melampsoridium betulinum and birch,Betula pendula

Effects of acidic rain on birch rust and on the growth of Betula pendula seedlings were studied by irrigating with acidic water at pH 3, 4 and 5.6. The seedlings were inoculated with uredospores of Melampsoridium betulinum and the development of rust and the severity of rust infection was examined. The increasing acidity of the irrigation water did not affect on the development of the rust, but the nitrogen in the acidified water resulted in an extension of seedling growth, and hence the leaves became senescent at a later date in autumn and the rust grew for a longer time.     

Early performance of native birch (<Emphasis Type="Italic">Betula</Emphasis> spp.) planted on cutaway peatlands: influence of species,stock types and seedlings size

The poor reputation of birch in Ireland is gradually changing, and the interest shown in it by foresters is growing, as is the recognition of the many advantages that this genus offers, especially from an afforestation and ecosystem development point of view. The potential of native birch species was investigated on industrial cutaway peatlands in the Irish midlands. Field experiments were established to evaluate differences (in terms of survival, growth attributes and form) between B. pendula and B. pubescens, between bare-root and container planting, and between small and medium size seedlings. After five growing seasons, B. pendula was found to be the superior species especially on well drained and shallow peat sites. Bare-root B. pendula will grow faster with reasonable form but containerised birch may be favoured on more difficult sites (with deeper and wetter peat). Larger seedlings performed better, regardless of species. This study demonstrated good growth potential for planted birch on cutaway peatlands and that this species should be integrated in further planting programmes.     

Endophytic foliar fungi in Betula spp. and their F1 hybrids

We examined foliar endophyte frequencies in two native (Betula pendula and Betula pubescens) and three exotic (Betula ermanii, Betula platyphylla and Betula resinifera) birch species and their hybrids in Punkaharju, Finland. The most frequently isolated endophytic fungi in the experimental trees were Fusicladium betulae and Gnomonia setacea making up 80–90% of all endophyte infections. Total endophyte infection levels varied from 0.5 colony forming units (CFU)/cm² in B. platyphylla to 8.6 CFU/cm² in B. pubescens that had highest total infection levels of both examined endophyte species. The resistance of hybrids was generally very close to the more resistant parent (the only exception being Fusicladium in B. platyphylla × B. pendula hybrid) supporting the hypothesis that the resistance of birch hybrids to these fungi is genetically based and caused by dominant inheritance of resistance traits.     

Early growth of planted yellow and paper birch and European birches in Vermont

Twelve native yellow birch (Betula alleghanensis Britt.) and paper birch (B. papyrifera Marsh.) sources and 9 European white birch (B. pendula Roth.) sources were planted on three sites in Vermont. Significant differences in growth were found among sources within two of the sites, and differences between sites were significant. Birch from Latvia appeard to be the best source on favorable sites attaining a total height of 5.18m, a total 6-year height increment of 4.29 m, and good stem form. Birches from Finland also showed good growth potential. Six yellow birch seed sources grew well on the best site and yellow birch ranks best there as a species group. European white birches do best as a group on the poor site. Silver birch (Betula pubescens Ehrh.) from Scotland grew poorest of the European birches.     

Experimental testing of rust fungus‐mediated herbivory resistance in Betula pendula

Correlative evidence suggests that pathogenic leaf rust fungus, Melampsoridium betulinum, in late summer may negatively affect folivorous insects in the following summer. Correlative association does not necessarily, however, reveal causality. Alternatively, other interconnected plant characters may determine rust densities and herbivore performance. In this study, we used birch clones and rust fungus inoculations to manipulatively test the effects of birch rust and birch genotypes on the growth performance of folivorous moth larvae of Epirrita autumnata (Lep. Geometridae) in the subsequent year. The inoculation treatment increased rust densities (three‐ to 60‐fold) compared with natural infection levels. E. autumnata performance varied among birch clones and showed 4% lower growth performance on rust‐inoculated trees. However, the larval performance did not differ between rust‐treated shoots and untreated control shoots and the use of tree‐specific rust densities as a covariant in statistical analyses failed to reveal any negative association between rust fungus and larval performance. As the slight difference in larval growth performance also levelled until pupation, we propose that rust infection has biologically insignificant importance to the performance of E. autumnata.     

High genetic variation in a small population of Cherry leaf roll virus in Betula sp. of montane origin in Corsica

Cherry leaf roll virus (CLRV) infection is common in Betula pendula and B. pubescens in Middle and North Europe, easily observable by chlorotic leaf vein banding, mottling and leaf roll, partially adherent with progressive loss of vitality or death of twigs and branches. In Fennoscandia, a severe viral epidemic in various birch species in forest stands, public greens and roadsides is associated with CLRV. In Corsica, CLRV‐typical symptoms were observed on birch trees (Betula sp.) in a montane stand (1470 m) at Col de Vergio. CLRV was detected by RT‐nested PCR in all leaf samples from 11 randomly selected birch trees exhibiting characteristic symptoms. Along with the fact that this is the first report of CLRV in Betula sp. of both montane and Mediterranean origins, remarkably high genetic variation and a new distinct phylogenetic cluster are comprised by a small randomly sampled CLRV population that has evolved in one of the few scattered birch stands in Corsica.     

Static bending properties of Finnish birch wood

The purpose of this study was to determine the modulus of elasticity (MOE) and the modulus of rupture (MOR) in the radial bending test for small, clear specimens of Finnish birch (Betula pendula Roth and B. pubescens Ehrh) wood originating from mature trees. The dependency of MOE and MOR on the specific gravity of birch wood was studied, and the relationship between MOE and MOR was modelled at the different heights and at the different distances from the pith of the tree. For B. pendula, the mean values for MOE and MOR were 14.5 GPa and 114 MPa, whereas B. pubescens had means of 13.2 GPa and 104 MPa, respectively. At the corresponding specific gravity, the bending stiffness and strength values did not differ between the two species. The results indicated a linear relationship between the MOE and MOR, irrespective of the birch species or the within-stem location. Both MOE and MOR increased clearly from the pith towards the surface of the tree and decreased slightly from the base to the top of the tree. It seems that if products with as high stiffness and bending strength as possible are wanted, sorting of raw materials into different grades according to their within-tree origin can be of value.     

Deciduous trees affect small-scale floristic diversity and tree regeneration in conifer forests

Abstract

There is a growing interest in the effects of deciduous trees on biodiversity, soil processes and long-term productivity in boreal, conifer-dominated forests. This study investigated whether individual birch trees allowed to grow to maturity in the coniferous forest can have a local effect on floristic richness and regeneration of tree saplings. The ground vegetation was compared in 2?m radius plots around the stem under the canopies of matched conifer–deciduous trees in a mature, conifer-dominated forest, and included in the analysis variables that could potentially mediate the tree effect (soil pH, cover of lichens, bryophytes, leaf and needle litter). The field layer vegetation was more species rich under birch (Betula pendula and B. pubescens) than under conifers (Picea abies and Pinus sylvestris), and several vascular plant species (including saplings of tree species) occurred more often under birch than under conifers. However, when the effect of the number of subordinate trees was taken into account the difference between birch and pine was not significant. The number of tree regenerations (saplings) was lowest under pines, but did not differ between spruce and birch. There were no effects of the canopy species on soil pH or on cover of lichens and bryophytes. The difference in diversity may be caused by the different effects of leaf and needle litter, and it is also likely that canopy structure has an influence via interception and throughfall and by affecting the light and microclimate.     

Structure of mixed Picea abies (L) Karst,and Betula pendula Roth and Betula pubescens Ehrh. stands in South and middle Sweden

Observed diameter distributions of forest stands are adapted to the Johnson S _b probability function. The stands investigated are untreated mixed stands of Norway spruce (Picea abies (L.) Karst.) and birch (Betula pendula Roth and Betula pubescens Ehrh.) aged between 20 and 32 years. The adaptation of the Johnson S_b probability function is made both on mixed spruce and birch, and on each species separately. Altogether 156 observations were tested with observed distributions against calculated distributions in the Kolmo‐gorov‐Smirnov test. The fractiles are predicted with multiple regression and two multivari‐ate techniques, simultaneous‐equation models (multivariate regression) and partial least squares with latent variables. The independent variables are characteristics of site and stand. Both multivariate methods predict diameter distribution well when tested.     

Growth,stem quality and nutritional status of Betula pendula and Betula pubescens in pure stands and mixtures

The growth, technical quality and nutritional status of pure and mixed silver birch (Betula pendula Roth) and downy birch (Betula pubescens Ehrh.) plantations were studied 21 and 22 years after planting on afforested organic soil arable land and on upland forest soil. In mixtures, 50% of both birch species was planted. Silver birch trees grew better, but had higher mortality than downy birch trees on both sites. Mortality of both species was highest, and the difference in their growth smallest, on organic soil. In pure stands on organic soil, downy birch dominant height, diameter and mean volume were 96%, 92% and 82% of those of silver birch and on mineral soil 87%, 84% and 60%, correspondingly. On mineral soil, silver birch had a higher mean annual increment (MAI) (5.8 m³ ha^?1a^?1) than downy birch (3.9 m³ ha^?1a^?1), but on organic soil the MAI of both species was similar (3.3–3.4 m³ ha^?1 a^?1). Planting birches in mixture did not affect the growth of the trees on organic soil. On mineral soil, the mean diameter and mean volume of silver birch trees were higher in mixed than in pure plantations. The technical stem quality of both tree species was low. On mineral soils, pure silver birch is more productive than mixture, but on peat soil the higher growth of silver birch could contribute to increased productivity and downy birch would ensure sufficient survival for future timber production.     

High‐resolution melting analysis allows rapid and accurate differentiation of the three Melampsoridium species occurring on Alnus

Alder (Alnus) leaves can be infected by three species of Melampsoridium rust: M. alni, M. betulinum and M. hiratsukanum. The latter is an invasive species in Europe that can be differentiated from the other two on the basis of morphological and molecular characters. This study presents a rapid, one‐step, closed‐tube and inexpensive method to differentiate species of Melampsoridium using two primer sets and high‐resolution melting (HRM) analysis of alder leaf material.     

Ecology of some fungi associated with an ageing stand of birches (Betula pendula and B. pubescens)

When stydying the growth of different provenances of Betula pendula and B. pubescens it was noted that fruitbody production by many sheathing (ecto-)mycorrhizal fungi followed distinctive patterns in time and place.When saplings of B. pendula and B. pubescens, from seed collected from ranges of locations in western Europe, were grown on a brown earth at latitude 55° 52′ N, autumnal yellowing and defoliation occurred sooner on saplings originating from northern locations (Scandinavia, 60°–66°N) than on those from the south (United Kingdom and Germany, 50°–55°N); the latter group of trees, particularly of B. pubescens, tended to be taller than the former.In the first 6 years after planting Betula spp., more than 90% of the fruitbodies (toadstools, earth-fans of Thelephora terrestris and elf-cups of Peziza badia), usually appearing in the autumn, were of fungi known, or suspected, to form sheathing mycorrhizas with Betula spp. Mean numbers of fruitbodies increased from 0.4 to 28 and 170 per tree in the 2nd, 4th and 6th years respectively after planting. Numbers of fungal species producing fruitbodies progressively increased from one, Hebeloma crustulvniforme, in the 2nd year to 14 (B. pubescens) and 18 (B. pendula) in the 6th year when Hebeloma spp. accounted for 79% of fruitbodies; Laccaria ‘laccata’, 15%; Inocybe lanuginella, 5% and Lactarius pubescens, 1%. Of the 6th year Hebeloma total, H. crustuliniforme, H. fragilipes, H. mesophaeum and H. sacchariolens accounted for 32, 33, 13 and 11% repectively.Mean distances between fruitbodies and the stems of trees widened at c. 0.16 m year^?1 for Hebeloma crustuliniforme; for Laccaria ‘laccata’ they increased by 0.27 to 0.87 m year^?1 between the 4th and 5th years after planting but remained virtually unchanged in the 6th year. Distributions differed within and between concentric 10 cm annuli. In the 6th year appreciably more Hebeloma fruitbodies, except those of H. sacchariolens, were found in intermediate annuli than in annuli nearest and furthest from trees. In contrast those of Laccaria ‘laccata’ and Inocybe lanuginella developed at densities of 1500 m^?2 and 500 m^?2 in most annuli.Fruitbodies of Laccaria ‘laccata’ were significantly clustered in sectors of the differing annuli possibly reflecting associations with radially growing secondarily thickened roots, whereas those of I. lanuginella occurred at random.From 2 to 6 years after planting the mean annual production of toadstools and elf-cups averaged 55 and 0.1 per tree originating from latitude 50° N and 66° N respectively. Earth fans of Thelephora terrestris were likewise less commonly associated with trees of northern origin.B. pubescens, unlike many provenances of B. pendula, seemed to resist invasion by the leaf rust Melampsoridium betulinum. The northern provenances of B. pendula were significantly more seriously infected than southern provenances.     

Effect of Temperature on the Induction of Bud Dormancy in Ecotypes of Betula pubescens and Betula pendula

The purpose of this study was to determine the influence of temperature applied during short day-induced budset on induction of dormancy in six ecotypes of Betula pubescens Ehrh. and two ecotypes of Betula pendula Roth. Seedlings were grown in a phytotron at constant temperatures of 9–21°C under a 12 h photoperiod (SD) during dormancy induction. Induction of dormancy was monitored by following bud flushing and shoot growth after transfer to long photoperiod conditions (24 h) at 18°C. Chilling requirement was studied in seedlings exposed to 10 weeks of SD. In both species induction of bud dormancy developed most rapidly at 15–18°C, and both 9–12°C and 21°C delayed the induction of dormancy. Raising the temperature (from 9 to 21°C) applied during induction of dormancy significantly increased the chilling requirement. These responses were noted for all ecotypes tested, but in general the northern ecotypes entered dormancy more quickly than the southern ones. No such trend was recorded for chilling requirement, although a B. pubescens ecotype from Iceland and another from the coast of northern Norway appeared to require a longer chilling treatment than the other ecotypes. In conclusion, induction and depth of bud dormancy in birch are significantly affected by temperature conditions and these effects may explain some of the annual variation in dormancy and chilling requirement observed in nature.     

Models for Assessing Timber Grade Distribution and Economic Value of Standing Birch Trees

In order to obtain a more precise prediction of the distribution of each timber grade or log grade with regard to the volume of birch (Betula pendula Roth., B. pubescens Ehrh.) in models for long-term planning, ordered probit models were developed. These models were developed by using data from three mixed birch and Norway spruce stands in Norway. The data consisted of 168 stems. In Norway, three ordinary birch saw log grades are commonly used, with pulpwood as a fourth grade. In this study, these four grades were applied in addition to waste timber, which was treated as a fifth grade. The developed models showed that the grade distribution of birch trees of mixed birch and spruce stands was highly correlated with tree height (p<0.01) and height to first visible dry branch (p=0.081). The statistical significance of both models was good (p<0.0001), as measured by log likelihood test statistics. Classifying the 168 stems by saw timber or pulpwood in butt log led to greatly improved estimates (p<0.01). The developed models would allow the incorporation of timber grade in stand simulators, enabling more precise predictions regarding the economic implications of alternative management strategies for birch trees.     

Alder rust,Melampsoridium hiratsukanum Ito,identified from Wales,UK and British Columbia,Canada

An epidemic rust, Melampsoridium hiratsukanum, originating from East Asia has spread to Europe over the last two decades. We report the first observation of this rust in the British Isles on leaves of Alnus incana and A. glutinosa. In addition to M. hiratsukanum, a native M. betulinum–like rust co‐occurred on the same leaves as a mixed infection. We also confirm that a rust on A. rubra in Western Canada is identical to M. hiratsukanum present in East Asia and Europe.     

Effects of coppicing on the root and stump carbohydrate dynamics in birches

Whole birch stems were cut off in order to determine how coppicing affects root and stump starch, glucose, fructose and sucrose concentrations and their correlation with shoot regeneration capacity. The Betula pubescens Ehrh. and B. pendula Roth studied included intact trees, trees that had been coppiced 8 years earlier, trees coppiced at the beginning of the experimental season, and birches that had been coppiced twice, 8 years earlier and at the beginning of the experimental season. Carbohydrate accumulation differed between 8 years earlier coppiced and intact trees. Recent coppicing clearly decreased the starch and sugar concentrations of the roots, which were often highest in the thin roots. The concentrations of these compounds in the stumps were always low, although the carbohydrate concentrations of stumps, in particular, correlated with shoot regeneration capacity. Starch was the most labile of the carbohydrates measured and most clearly reacted to coppicing. Differences in starch- and sugar-reserve dynamics indicate a difference between these birch species in the use and replenishing of root and stump reserves. This information may also be of help when the effects of other stresses, for example, severe animal damage or burning, on the regrowth of young birch stands are estimated.