Pedunculate Oak Seedlings Research Articles

Application of post-emergence herbicides in the regeneration of pedunculate oak (Quercus robur L.) forests

Weeds are an important limiting factor in the development of pedunculate oak seedlings. Weed control is very important on regeneration areas, particularly in the initial stages of young growth development, when the adverse effects of weeds on oak are greatest. Effective weed control should be based on the combination of several different measures. However, because of manpower shortage, high labour costs and large areas, forest managers frequently decide to use herbicides to control weeds. On oak regeneration areas, a major problem is often broadleaved weeds that grow vigorously. Post-emergence herbicides nicosulfuron, bentazon, imazamox and tribenuron-methyl were monitored in broadleaf weed suppression in pedunculate oak stands during the regeneration process. Field studies were performed at two sites during three growing seasons, i.e. herbicide selectivity was examined on 1-, 2- and 3-year-old seedlings. The study results show that the number and fresh and dry weights of weeds were significantly reduced by tested herbicides in treated sample plots when compared with controlplots.Theherbicidestribenuron-methylandbentazonhadphytotoxiceffectsonoakseedlings.Incontrast, nicosulfuron and imazamox did not show phytotoxic activity against the seedlings and can be applied in weed control in regenerated pedunculate oak forests.

Uticaj tipa kontejnera na rast i razvoj jednogodišnjih sadnica lužnjaka (Quercus robur L.) u rasadniku

In this paper are presented the research results of effect of the container type on growth and morphological parameters of Pedunculate oak seedlings. In the experiment were used three types of containers Bosnaplast 18, Bosnaplast 12 and HIKO V265. Seed collection was performed in the Pedunculate oak seed stand registration number RS-2-2-qro-12-197 which is managing by FE Kragujevac in autumn 2012 and seed sowing in containers was done in spring 2013 in the seedling nursery of Institute of Forestry in Belgrade. The analysis of one-year-old seedlings was performed in autumn 2013. The parameters that were measured are height and root collar diameter. Seedlings produced in containers Bosnaplast 18 with cell volume of 220 cm3 and HIKO V265 with cell volume of 265 cm3 have larger dimensions and they are more quality than seedlings produced in containers type Bosnaplast 12 that have cell volume of 120 cm3 . Researches have shown that container volume has positive effect on morphological characteristics of Pedunculate oak seedlings in conditions of seedling nursery.

Stress resistance levels at the time of lifting affect post-planting performance of Quercus robur seedlings

The objective of this study was to describe the physiological condition of bare-root pedunculate oak (Quercus robur L.) seedlings at the time of lifting for cold storage or planting in 1996/1997 and 1997/1998. Dormancy intensity and other physiological measurements and field performance were assessed. Heat treatments were used to assess the taproot resistance to stress using root electrolyte leakage, but the results indicated that the plants were least resistant when mostdormant. Root electrolyte leakage and root growth potential were lowest during the deep dormancy stage and increased again as shoot dormancy was released, coinciding with the period that the plants were most resistant to storage stresses. Dry weight fraction of the shoots was a good indicator of storability, but the other measures were less useful. Despite good survival rates, shoot quality was poor for seedlings lifted early (October) or late (April, May) in the lifting season.

Height growth characteristics of one-year-old pedun­culate oaks on regeneration areas with and without fungicide protection against oak powdery mildew (Microsphaera alphitoides Griff. et Maubl.)

Height growth characteristics of one-year-old pedunculate oaks were studied during three calendar years on comparative regeneration areas both with and without fungicide protection against oak powdery mildew (Microsphaera alphitoides Griff. et Maubl.). Three fungicides were used for the chemical protection of one-year-old pedunculate oaks: Microthiol special, Stroby DF and Anvil. The experiments were located in different site and stand conditions, and the growing seasons in which pedunculate oak seedlings were established were characterized by different precipitation sums and higher air temperatures when compared to multiannual average. The study sample included 1126 plants, and their shoot lengths were measured at the end of the growing season. In the analyzed sample, the second growth stage was recorded on 92.3%-100% of the treated plants and on 69.5%-100% of the untreated plants, the third growth stage was recorded on 52.6%-87% of the treated plants and on 42.1%-82% of the untreated plants, and the fourth growth stage was observed on 0%-37% of the treated plants and on 1.1-29% of the untreated plants. In the analyzed sample, the mean heights of one-year-old pedun-culate oaks were greater on the areas with fungicide protection, but the differences in the percentages of polycyclic growth and the differences in average lengths of individual flushes were not always statistically significant, when compared to the areas without protection, especially after the first stage. The study shows that the dominant effect on the percentage of the second, the third and the fourth stages and on their mean lengths was exerted by site and stand conditions, and that the effects of fungicide protection should be analyzed taking into account the polycyclism of pedunculate oak, i.e. the characteristics of polycyclic growth, which are the resultant of all the effects. In the studied conditions, the fifth stage of growth was recorded in five plants.

A conversion method of young hornbeam coppices and its possible impact on future stand structural attributes

The paper analyse the substitution of hornbeam coppice stands and conversion into high forest stands, formed by species that better valorise the site conditions. An improved alternative for the method of substitution in corridors is presented. The main goal of this new substitution-conversion alternative is to gradually conduct the actual structure of the coppice stands towards the target structure imposed by the forest management objectives, without a total elimination of the species that will be substituted. Two plot areas were selected in order to put into practice the proposed method. Bands were created for reducing the effective costs of the substitution process. 450 respectively 468, small seedlings (of beech, pedunculate oak and sessile oak) per hectare were planted in the created bands. The planting scheme took into account the shadow tolerance of the species from the target composition. Based on the field data and using the yield tables, the evolution of the stands in the two selected plots was simulated. In this respect, the forest treatments were parameterized according to the Romanian forest rules regarding the application of thinning and regeneration cuttings. The substitution-conver- sion process started from an almost pure hornbeam coppice and, simulating the application of the proposed method for 120 years, it was predicted that the method allows directing the actual stand structure to the target structure. The dynamics of species and structural diversity were assessed and the re- sults of 120 years simulation indicate an important increase of both the spe- cies (the Shannon species index increases from 0.203 to 1.073) and struc- tural diversity (the Gini structural index increases from 0.032 to 0.200). Keywords forest species substitution, forest conversion, forest management, hornbeam coppice, high forest, biodiversity.

High-light acclimation in Quercus robur L. seedlings upon over-topping a shaded environment

High developmental plasticity at the seedling-level during acclimation to the light environment may be an important determinant of seedling establishment and growth in temperate broadleaf forests, especially in dense understories where spatial light availability can vary greatly. Pedunculate oak (Quercus robur L.) seedlings were raised beneath a range of artificial light environments (high light, partial high light and low light) to examine morphological and photosynthetic acclimation to vertically stratified light availability. Acclimation observed at the seedling level included changes in proportional distribution of biomass and leaf area ratio to enhance either light gathering under low light availability or reduction of moisture stress under high light availability. Seedling-level acclimation was partially driven by plasticity at the flush level, but plasticity of traits determining flush morphology, such as leaf number, area, and mass, was largely controlled during bud formation rather than during shoot development. Therefore, flush-level acclimation was restricted when shoots elongated from a shaded environment into a high light environment. In contrast, traits influencing leaf-level acclimation, such as leaf thickness, specific leaf area, and pigment concentrations appeared to be driven primarily by the prevailing light environment during leaf development. The plastic response in leaf traits to light environments during shoot development enabled immediate acclimation of photosynthetic capacity to the prevailing light environment. In conclusion, oak seedlings displayed a large phenotypical plasticity on multiple levels that maximized whole seedling performance.

Consequences of cutting off distal ends of cotyledons of Quercus robur acorns before sowing

Production of seedlings, especially in containers, requires simultaneous germination and emergence. Mechanical scarification often speeds up the growth of embryo axes, increases the percentage of germinating seeds and seedling emergence. Cutting off the distal ends of cotyledons is a mechanical scarification technique sometimes used in the container production of oak seedlings. However the consequences of this procedure for seedling development are little known. We wanted to determine these effects on development and metabolic changes of pedunculate oak (Quercus robur L.) seedlings. The majority of seedlings from acorns with cut cotyledons emerged two weeks earlier, more simultaneously and their total emergence (due to rejecting spoiled acorns) was ca. 20% higher. The main result is that the strong damage to cotyledons (more than one fifth of acorn mass) caused a decrease of seedling height and mass even after the second growing season. Negative consequences on seedling root/shoot ratio or on their metabolism were not observed. We conclude that this method is useful for seedling production in containers when acorn mass is reduced by one fifth.

Photosynthetic efficiency of Pedunculate oak seedlings under simulated water stress

Photosynthetic performance of seedlings of Quercus robur exposed to short-term water stress in the laboratory conditions was assessed through the method of induced fluorometry. The substrate for seedlings was clayey loam, with the dominant texture fraction made of silt, followed by clay and fine sand, with total porosity 68.2%. Seedlings were separated in two groups: control (C) (soil water regime in pots was maintained at the level of field water capacity) and treated (water-stressed, WS) (soil water regime was maintained in the range of wilting point and lentocapillary capacity). The photosynthetic efficiency was 0.642?0.25 and 0.522?0.024 (WS and C, respectively), which was mostly due to transplantation disturbances and sporadic leaf chlorosis. During the experiment Fv/Fm decreased in both groups (0.551?0.0100 and 0.427?0.018 in C and WS, respectively). Our results showed significant differences between stressed and control group, in regard to both observed parameters (Fv/Fm and T?). Photosynthetic efficiency of pedunculate oak seedlings was significantly affected by short-term water stress, but to a lesser extent than by sufficient watering.

Influenza della luce e dell’umidità del suolo sulla crescita e fisiologia della rinnovazione di farnia nelle radure di querceti misti

In “S. Rossore, Migliarino, Massaciuccoli” Natural Park (Pisa, I) six-month-old pedunculate oak seedlings (Quercus robur L.) were transplanted within natural gaps of a mixed oak forest. Micro-environmental variability for radiation and water soil content were measured for 145 seedlings during the year. Irradiation relative to the open field (IR) ranged from 5% to 57%. Seven classes of IR each with 20 seedlings were selected. Leaf mass per area was strongly influenced by IR. In the first 3 years survival was high (95, 76 and 75%, respectively) and seedling reached 14±6 cm, 27±13 cm and 39±19 (sd) cm of height. Even if IR and soil water content (SWC) were negatively associated, indicating a lower SWC at the centre of the gaps, height and its relative growth rate increased with IR (explored range: 8-40%) with a significant interaction with SWC in the 1st year, indicating the positive effect of soil moisture. In the 3rd year dimensional traits were higher in L+W+ (high light and humidity) followed by L-W+ (low light and high humidity), L+W- and finally by L-W-. Summer drought typical of the Mediterranean climate was evaluated by chlorophyll fluorescence of PSII on apical leaves of seedlings and mature trees at the beginning (21 June) and in mid-summer (20 July). While in June physiological traits did not differ between low and high IR, in mid-summer (at the peak of water-stress) seedlings of the two highest light classes showed chronic photoinhibition (Fv/Fm<0.75) and an increase in thermal dissipation (D) by constitutive term (Dc=1-Fv/Fm) and by regulated mechanisms of dissipation through xanthophyll-cycle term (Dx). Moreover, in July seedling leaf physiology largely differed with IR: leaves acclimated to high IR have higher photosynthetic potentialities, as shown by electron transport rate (ETR) and quantum yield (P) at saturating light maintained by an increase of the fraction of open reaction centres (qP), counterbalancing the efficiency decrease of the single reaction centres (Fv’/Fm’) dynamically protected via xanthophyll-cycle (Dx). Tree apical leaf physiology behaved differently from seedling leaves both in June (except Fv/Fm) and in July (except Dx). In June photochemistry was higher in tree apical leaves with higher ETR, P, qP and Fv’/Fm’ with a lower fraction of energy dissipated and in particular through lower loss by photoprotection through Dx as expected for high light conditions without stress; in July no chronic photoinhibition was observed in tree light leaves, the efficiency of single reaction centres (Fv’/Fm’) remained high but a drop in the fraction of open centre (qP) decreased significantly P and thus ETR. Consequently the highest potentialities in photochemistry (P) were observed in large gaps (at 40% IR).

Groundwater and Light Conditions as Factors in the Survival of Pedunculate Oak (Quercus Robur L.) Seedlings

A noticeable decline and physiological weakening of pedunculate oak (Quercus robur L.) has been recorded in the past decade in lowland parts of Slovenia. The triggers were dry climate, unfavourable precipitation patterns and human influence that brought about changes in watercourses and water tables. Regeneration and future management of this tree species is therefore questionable. To define a critical groundwater table which would permit successful regeneration, planted and naturally grown seedlings were compared in two forests differing in the degree of decline and physiological weakness of adult pedunculate oak trees. Comparison of stomatal conductance and pre-dawn water potential (PWP) showed differences of seedlings between and within forest complexes. Stomatal conductance dropped below 100 mmol m−2 s−1 at PWP values below −1.0 MPa, while closure of stomata was caused by a PWP between −1.6 and −1.9 MPa. Increased water stress equalized photosynthetic yield in both natural and planted oaks below −1.4 MPa.

Assessment of seedling storability of Quercus robur and Pinus sylvestris

Pedunculate oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.) seedlings were lifted on several occasions during autumn 1997 to determine the relationships between storability and frost hardiness. On each lifting date their physiological status was determined by assessment of shoot and root electrolyte leakage and frost hardiness, assessed as freeze-induced electrolyte leakage. Additional seedlings were simultaneously cold-stored for field planting and assessment of preplanting root growth potential in April 1998. First year field performance was determined the following winter. Storability and cold acclimation patterns differed between the two species. Both were negatively affected by early lifting, but oak was less sensitive with respect to survival, and pine attained tolerance to cold storage more rapidly and earlier with respect to growth increment. The correlations between shoot frost hardiness and performance suggest that freeze-induced shoot electrolyte leakage (SELdiff−20) below a threshold of 5% is a good storability predictor for Scots pine in Denmark. A completely reliable criterion for pedunculate oak could not be established.

Effect of a strong cold storage induced desiccation on metabolic solutes, stock quality and regrowth, in seedlings of two oak species

Bare-root seedlings of pedunculate oak (Quercus robur L.) and northern red oak (Quercus rubra L.) were lifted in January and stored at 1.8°C, at 82% relative humidity, until their fresh weight declined by 33%. Root growth potential (RGP), fine root electrolyte leakage (REL), fine root water content (RWC), shoot tip water content (SWC), starch and metabolic solute contents in root and shoot, were measured just after lifting and after treatment. Survival of treated seedlings was also assessed in a field trial. RWC, SWC, REL, RGP were dramatically affected by desiccation during cold storage. In both species, root soluble carbohydrate level, inositol level and isocitrate level increased, whereas root starch level and shoot soluble carbohydrate level decreased. In northern red oak, treated seedlings had higher root contents of soluble carbohydrates, inositol and proline than in pedunculate oak. Moreover, treatment induced proline accumulation only in northern red oak roots. These differences could explain why field survival of treated seedlings was significantly better in northern red oak than in pedunculate oak.

Transport of organic sulfur and nitrogen in the roots of young mycorrhizal pedunculate oak trees (Quercus robur L.)

Uptake and xylem loading of organic sulfur and nitrogen were analyzed in detached mycorrhizal (Laccaria laccata L.) roots of pedunculate oak (Quercus robur L.) seedlings using radiolabeled reduced glutathione (GSH) and glutamine (Gln) for transport analyses. The experiments showed for the first time that GSH is taken up by plant roots from the nutrient solution and is partially allocated to the shoot. Apparently, GSH produced during mineralization processes in the soil can be used by plant roots as a sulfur source. GSH uptake into the roots showed biphasic kinetics within the concentration range studied (0–500 μM) with maximum transport velocities (vmax) and substrate affinities (Km) that were similar to the kinetics of Gln uptake. GSH uptake kinetics were also in the same range as previously reported for sulfate uptake by mycorrhizal roots of pedunculate oak. It may therefore be assumed that GSH and sulfate uptake can be of comparable significance for sulfur nutrition, provided both sulfur sources are available at similar concentrations at the sites of uptake. Xylem loading of GSH and Gln showed monophasic transport kinetics with vmax significantly lower than observed for the two respective uptake systems and, as indicated by the Km-values, a substrate affinity between the high and the low affinity uptake systems. The possible nature of the transport systems for GSH and Gln is discussed.

Interactive effects of elevated CO2 concentration and nitrogen supply on partitioning of newly fixed 13C and 15N between shoot and roots of pedunculate oak seedlings (Quercus robur).

Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second- and third-flush stages) in greenhouses at two atmospheric CO2 concentrations ([CO2]) (350 or 700 micromol mol(-1)) and two nitrogen fertilization regimes (6.1 or 0.61 mmol N l(-1) nutrient solution). Combined effects of [CO2] and nitrogen fertilization on partitioning of newly acquired carbon (C) and nitrogen (N) were assessed by dual 13C and 15N short-term labeling of seedlings at the second- or third-flush stage of development. In the low-N treatment, root growth, but not shoot growth, was stimulated by elevated [CO2], with the result that shoot/root biomass ratio declined. At the second-flush stage, overall seedling biomass growth was increased (13%) by elevated [CO2] regardless of N fertilization. At the third-flush stage, elevated [CO2] increased growth sharply (139%) in the high-N but not the low-N treatment. Root/shoot biomass ratios were threefold higher in the low-N treatment relative to the high-N treatment. At the second-flush stage, leaf area was 45-51% greater in the high-N treatment than in the low-N treatment. At the-third flush stage, there was a positive interaction between the effects of N fertilization and [CO2] on leaf area, which was 93% greater in the high-N/elevated [CO2] treatment than in the low-N/ambient [CO2] treatment. Specific leaf area was reduced (17-25%) by elevated [CO2], whereas C and N concentrations of seedlings increased significantly in response to either elevated [CO2] or high-N fertilization. At the third-flush stage, acquisition of C and N per unit dry mass of leaf and fine root was 51 and 77% greater, respectively, in the elevated [CO2]/high-N fertilization treatment than in the ambient [CO2]/low-N fertilization treatment. However, there was dilution of leaf N in response to elevated [CO2]. Partitioning of newly acquired C and N between shoot and roots was altered by N fertilization but not [CO2]. More newly acquired C and N were partitioned to roots in the low-N treatment than in the high-N treatment.

Comparison of the Susceptibility of Quercus petraea, Q. robur and Q. rubra to Collybia fusipes

Collybia fusipes is the cause of a root rot of Quercus petraea (sessile oak), Q. robur (pedunculate oak) and Q. rubra (red oak). This parasite is often reported to cause problems in stands of red oaks and field evidence suggests that this North American oak species is more susceptible than the two European oak species. Young saplings of the three oak species and of chestnut, Castanea sativa, in the glasshouse, and also mature sessile and red oaks growing in the same stand were inoculated with C. fusipes to compare their susceptibility. Red oak, both as young seedlings and mature trees, was more susceptible to C. fusipes than sessile oak. Chestnut seedlings were as susceptible as sessile oak. Susceptibility of pedunculate oak seedlings was intermediate between red oak and sessile oak. In one experiment this species was significantly less susceptible than red oak, and in the other it was as susceptible.

Somatic embryogenesis from stem and leaf explants of Quercus robur L.

Internodal and leaf segments from pedunculate oak (Quercus robur L.) seedlings were used as explant source to induce somatic embryogenesis. Auxin treatment influenced embryogenic response, which only occurred in explants initially cultured on media containing 4 mg/l naphthaleneacetic acid (NAA) and different benzyladenine (BA) concentrations. After 6 weeks of culture on induction medium, the explants were transferred to medium supplemented with 0.1 mg/l BA and 0.1 mg/l NAA, and 4 weeks later, they were subcultured in a growth-regulator-free medium, in which somatic embryos arose through indirect regeneration on the surface of a nodular callus. Somatic embryos were induced in explants of two out of four seedling provenances. The induction frequency ranged from 16% in leaf explants to 4% in internodal explants. Somatic embryos developed two cotyledons, which were translucent or opaque-white in appearance, but anomalous morphologies were also observed. Different embryogenic lines were established and maintained by repetitive embryogenesis in multiplication medium containing 0.1 mg/l BA plus 0.05 mg/l NAA. These results indicate that tissues from explants other than Q. robur zygotic embryos are able to produce embryogenic cultures.

Growth of pedunculate oak (Quercus robur L.) seedlings on blendsubstrates based on consolidated brackish sludge

Either in its pure form or as a base for a blend-substrate, brackish sludge can be used as a growth medium for trees. The objectives of the experiment were (1) to evaluate the quality of consolidated brackish sludge as a growth medium, (2) to assess the influence of substrate blending on tree growth (leaf area, tree height, biomass), and (3) to evaluate the need for substrate blending. Germinated acorns of the same mother tree were planted in containers and grown under controlled conditions. The substrate consisted of pure brackish sludge or of brackish sludge blended with peat, sand or wood chips, in stages of 25 volume percentage. Chemical analysis of the brackish sludge showed a neutral pH, a conductivity of 3.60 mS/cm and a sufficient amount of macro elements. The addition of sand contributed to an accelerated desalination of the substrate. The treatments with 100 % sludge and 25 % peat yielded a leaf area, a tree height and a biomass which were among the top three growing results. The growing results of the treatments with 25% sand and 50% peat were consistently among the top five. The blending of peat in brackish sludge had no influence on leaf area, tree height and biomass of seedlings. The use of wood chips or of more than 25 % sand resulted in a significant decrease of these three growth parameters. Foliage analyses of the trees grown on a substrate containing more than 50% sand or wood chips revealed deficits in available nutrients. These deficits manifested themselves in a loss of leaf area, tree height and biomass production. The nutritional status and the growth parameters of oak seedlings on brackish sludge were favourable. No influence of the salt and the heavy metal concentrations on growth was observed. Consolidated brackish sludge is a suitable growth medium for trees.

Effect of Salt Stress on Growth and on the Detoxifying Pathway of Pedunculate Oak Seedlings ( Quercus robur L.)

Summary The effect of NaCl salinity on young pedunculate oak trees was studied. Growth of the stem was affected after a 40 mM NaCl stress was applied. The leaf water potential was decreased from a 20 mM NaCl concentration in the nutrient solution. The Na + and Cl - contents were increased in plants submitted to salt stress, especially in the first flush leaves. Superoxide dismutase activity was increased under stress conditions whereas no change could be detected in the activities of ascorbate peroxidase and glutathione reductase. Moreover, the SOD isozyme pattern of oak leaves was modified. Taking these results into account, pedunculate oak could be classified as a highly salt sensitive species. However, modifications recorded in the SOD isozyme pattern suggested differences between organelles at the level of salt stress tolerance. In particular, mitochondria seemed to be less sensitive than chloroplasts, which were strongly affected.

Effects of substrate sterilization, fungicide treatment, and mycorrhization helper bacteria on ectomycorrhizal formation of pedunculate oak (Quercus robur) inoculated with Laccaria laccata in two peat bare-root nurseries

Pedunculate oak seedlings (Quercus robur) inoculated with the ectomycorrhizal fungus Laccaria lacata were grown for 1 year on fertilized sphagnum peat in two nurseries. Three factors affecting microbial populations in the substrate were studied, fungicide treatment of the seeds, peat disinfection before sowing (methyl bromide or steam pasteurization), and inoculation with mycorrhization helper bacteria. Treatment of acorns with Iprodione had no depressive effect on mycorrhiza formation. Both disinfection techniques were equivalent, stimulating or depressing mycorrhiza formation depending on the initial microflora in the peat. The introduction of two previously selected mycorrhization helper bacteria (one Pseudomonas fluorescens and one unidentified fluorescent pseudomonad), isolated from L. laccata sporocarps associated with Douglas fir—L. laccata ectomycorrhizas in other nurseries, significantly increased the mycorrhizal rate from 30 to 53% of the short roots. The implications of these results for the controlled mycorrhization of planting stocks and the specificity of mycorrhization helper bacteria are discussed.

Mineral nutrition and mycorrhizal infection of seedling oak and birch

summaryIn order to assess the importance of nutrient uptake and mycorrhizal infection for the establishment of seedlings of pedunculate oak (Quercus robur L.) and silver birch (Betula pendula Roth.), seedlings were grown on two nutrient‐poor soils and sequential harvests taken throughout the first growing season. Seedlings were artificially established in two woodland sites and in pots of soil collected from each field site.The pattern of nutrient depletion from oak cotyledons indicated that the initial N and P contents were completely utilized by the production of the first flush of leaves after 7 wk. Similarly, growth of birth in acid‐washed sand ceased after the production of the first pair of leaves. Growth rates of field‐grown seedlings were lower than those of pot‐grown seedlings in each case, such that pot‐grown plants were three times larger than field‐grown plants by the final harvest. Nutrient losses in abscised foliage constituted a significant proportion of the total nutrient uptake of both species: between 14 and 35 % of N, P and K was abscised in the case of birch. Taking losses of nutrients in abscised foliage into account, nutrient budgets of field‐grown seedlings were either slightly positive, or not significantly greater than zero.The onset of ectomycorrhizal infection of field‐grown plants was 2–4 wk more rapid than that of pot‐grown plants; initial infection of field‐grown seedlings was observed 3 wk after outplanting. Percentage infection of field‐grown seedlings tended to be higher than in pots throughout the growing season, by up to 40%. Different mycorrhizal types displayed contrasting patterns of development: for example, Paxillus involutus (Batsch) Fr. tended to increase rapidly, to maximum percentage infections of over 30 %; whereas Cenococcum geophilum Fr. was consistently recorded at 10% infection. The role of mycorrhizal infection during seedling establishment is discussed in the light of these results.