Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Forest die-back and impaired tree vitality have frequently been ascribed to Al-toxicity and Al-induced nutritional disorders due to increased acidification of forest soils. Therefore, in this experiment effects of Al were studied on growth and nutrient uptake with seedlings of five different forest tree species. During growth in culture solutions with and without Al all five species proved to be very Al-tolerant, despite high accumulation of Al in roots. In the coniferous evergreens Douglas-fir and Scots pine shoot as well as root Al concentrations were significantly higher than in the deciduous broad-leaved species oak and birch. Larch showed intermediate Al levels. In none of the five species did Al reduce nutrient concentrations or the Ca/Al ratio to values below the critical level. Besides differences in Al accumulation, coniferous and broad-leaved species also differed with respect to uptake and assimilation of nitrogen. Due to extra NH ₄ ⁺ uptake, oak and birch showed a much higher N uptake and higher NH ₄ ⁺ preference than the coniferous species. Especially with oak this high NH ₄ ⁺ preference in combination with a low specific root surface area resulted in a high root proton efflux density. In comparison to both broad-leaved trees and Scots pine the NO ₃ ⁻ reduction capacity of larch and Douglas-fir was extremely low. This may have important consequences for both species if grown in NO ₃ ⁻ -rich soils.     

Root-Associated Bacteria Contribute to Mineral Weathering and to Mineral Nutrition in Trees: a Budgeting Analysis

The principal nutrient source for forest trees derives from the weathering of soil minerals which results from water circulation and from plant and microbial activity. The main objectives of this work were to quantify the respective effects of plant- and root-associated bacteria on mineral weathering and their consequences on tree seedling growth and nutrition. That is why we carried out two column experiments with a quartz-biotite substrate. The columns were planted with or without pine seedlings and inoculated or not with three ectomycorrhizosphere bacterial strains to quantify biotite weathering and pine growth and to determine how bacteria improve pine growth. We showed that the pine roots significantly increased biotite weathering by a factor of 1.3 for magnesium and 1.7 for potassium. We also demonstrated that the inoculation of Burkholderia glathei PML1(12) significantly increased biotite weathering by a factor of 1.4 for magnesium and 1.5 for potassium in comparison with the pine alone. In addition, we observed a significant positive effect of B. glathei PMB1(7) and PML1(12) on pine growth and on root morphology (number of lateral roots and root hairs). We demonstrated that PML1(12) improved pine growth when the seedlings were supplied with a nutrient solution which did not contain the nutrients present in the biotite. No improvement of pine growth was observed when the seedlings were supplied with all the nutrients necessary for pine growth. We therefore propose that the growth-promoting effect of B. glathei PML1(12) mainly resulted from the improved plant nutrition via increased mineral weathering.     

Root-associated bacteria contribute to mineral weathering and to mineral nutrition in trees: a budgeting analysis

The principal nutrient source for forest trees derives from the weathering of soil minerals which results from water circulation and from plant and microbial activity. The main objectives of this work were to quantify the respective effects of plant- and root-associated bacteria on mineral weathering and their consequences on tree seedling growth and nutrition. That is why we carried out two column experiments with a quartz-biotite substrate. The columns were planted with or without pine seedlings and inoculated or not with three ectomycorrhizosphere bacterial strains to quantify biotite weathering and pine growth and to determine how bacteria improve pine growth. We showed that the pine roots significantly increased biotite weathering by a factor of 1.3 for magnesium and 1.7 for potassium. We also demonstrated that the inoculation of Burkholderia glathei PML1(12) significantly increased biotite weathering by a factor of 1.4 for magnesium and 1.5 for potassium in comparison with the pine alone. In addition, we observed a significant positive effect of B. glathei PMB1(7) and PML1(12) on pine growth and on root morphology (number of lateral roots and root hairs). We demonstrated that PML1(12) improved pine growth when the seedlings were supplied with a nutrient solution which did not contain the nutrients present in the biotite. No improvement of pine growth was observed when the seedlings were supplied with all the nutrients necessary for pine growth. We therefore propose that the growth-promoting effect of B. glathei PML1(12) mainly resulted from the improved plant nutrition via increased mineral weathering.     

Ectomycorrhizal weathering of the soil minerals muscovite and hornblende

Ectomycorrhizal fungi are hypothesized to enhance mineral weathering in forest soils. Several studies have shown an increased uptake of mineral-derived nutrients by trees when in symbiosis with ectomycorrhizal fungi. However, it is difficult to determine from these studies if the improved nutrient uptake is the result of increased weathering or better exploitation of the substrate by the ectomycorrhizal fungi. In a pot experiment, Pinus sylvestris (Scots pine) seedlings were grown with or without ectomycorrhizal fungi, and with or without the mineral muscovite as the only potassium (K) source or the mineral hornblende as the only magnesium (Mg) source. After 27 wk, all pools of non-mineral-bound K or Mg were determined. The ectomycorrhizal fungus Paxillus involutus increased weathering of muscovite but not hornblende. The other ectomycorrhizal fungi tested, Piloderma croceum and Suillus bovinus, did not increase weathering of either muscovite or hornblende compared with the nonmycorrhizal trees. The P. involutus-mediated mobilization of K from muscovite resulted in increased K content of root plus adhering hyphae, but not of shoots. In conclusion, ectomycorrhizal fungi may increase weathering of minerals in response to nutrient deficiencies, but this response is species specific.     

Effects of water and nutrient applications in a Scots pine stand to tree growth and nutrient cycling

In a Scots pine forest stand, demineralized water and a complete set of nutrients with water were applied to the soil by means of frequent irrigation for four years in order to eliminate water and nutrient shortage of the trees. Apart from this optimization, dissolved (NH₄)₂SO₄ was irrigated at a rate of 120 kg N ha^-1 y^-1 to create a situation of N excess. Effect of treatments on tree growth and chemical composition of soil water and vegetation were monitored. From the first treatment year onwards basal area growth increased by ca. 35% as a result of the increased water supply. Nutrient applications increased K and P concentrations in pine needles immediately, but growth was enhanced only in the fourth treatment year and coincided with an improved K supply. Most of the applied P and K was retained in the soil, and only 6% was recovered in the vegetation. Tree nutrient status did not respond on Ca and Mg applications, whereas Ca and Mg seepage losses were increased with ca. 5 kg ha^-1 y^-1. The applied NH₄ was mostly retained in the 0–20 cm surface soil and caused a drastic increase of Al in soil solution. Tree growth was stimulated initially by extra NH₄, but was hampered after three years obviously because of a decreased P nutrition. The applied base cations were absorped to the soil and the accompanying anions were leached, thus temporarily increasing the acidification of the soil solution.     

Applications of mineral nutrients to heavily N-fertilized Scots pine trees: Effects on arginine and mineral nutrient concentrations

The aim of the investigation was to study if improved nutrient status in Scots pine (Pinus sylvestris L) trees would be reflected in decreased concentrations of arginine in the needles. The studies trees had imbalanced mineral nutrient composition and elevated needle arginine concentrations caused by long-term fertilization with N. Concentrations of arginine and mineral nutrients in needles were followed over three consecutive years of additional fertilization with N alone or with P, K, Mg and micronutrients in combination with and without N.Analysis of needle mineral concentrations suggested that there were deficiencies only in K and Mg. The N concentration increased both in trees fertilized with N alone and in trees fertilized with N in combination with mineral nutrients. In the control treatment and in trees fertilized with mineral nutrients other than N the N concentration remained fairly constant. The highest Ca/N, K/N and P/N ratios were found in trees fertilized with mineral nutrients other than N while the lowest ratios were found in trees fertilized with N alone. Arginine concentrations in needles from trees fertilized with N alone remained at a high level throughout the experiment while arginine concentrations in trees given the other treatments decreased.The results show that the mineral nutrient balance can be improved with appropriate fertilization and that this improvement is reflected in decreasing arginine levels. Furthermore the study demonstrates that when N supply is reduced the arginine concentration also decreases also as an effect of reduced N supply per se. The study also indicates that arginine may be a better measure of the N status in pine trees than total N.     

Aluminium causes nutrient imbalance and structural changes in the needles of Scots pine without inducing clear root injuries

The effects of aluminium chloride (AICI3) treatments (50 and 150 mg/l) on 3-year-old Scots pine (Pinus sylvestris L.) seedlings were studied in a sand culture during 2 growing periods in an open field experiment. Even by the end of the first growing period, a decline was observed in the concentrations of Ca, Mg and P within the needles, and of Ca and Mg in the roots. After the second growing period, increased N and K concentrations were observed in the needles of Al-treated seedlings. Both the needles and roots of Al-treated seedlings showed, after the second growing period, a decline in growth and increased concentrations of AI as the amount of AICI3 in the nutrient solution increased. Al-induced changes in needle structure were found to be symptomatic of a nutrient imbalance, particularly of Mg and P. Al-stress did not result in any observable changes in root anatomy or in the number of mycorrhizas. Scots pine proved to be rather resistant to Al-stress, indicating that direct Al-injuries are not likely in the field, though Al-stress may be a contributing factor in the formation of nutrient imbalances.     

Anaerobic induced ethanol synthesis in the stems of greenhouse-grown conifer seedlings

Ethanol synthesis was induced in stem segments from greenhouse-grown conifer seedlings by placing them in a N₂ atmosphere at 30 °C for 24 h. Stems from ponderosa pine,Pinus ponderosa Dougl. ex Laws., sugar pine,Pinus lambertiana Dougl., Pacific silver fir,Abies amabalis Dougl. ex Forbes, and lodgepole pine,Pinus contorta Dougl. ex Loud, produced the highest quantities of ethanol. This group also had the smallest and slowest growing stems. Within each of these species the amount of ethanol produced was inversely related to the stem volume. Stems from western hemlock,Tsuga heterophylla (Raf.) Sarg., grand fir, Abies grandis Dougl. ex Forbes, Douglas-fir,Pseudotsuga menziesii (Mirb.) Franco, and western redcedar,Thuja plicata Donn ex D. Don, all produced equivalent but low ethanol concentrations. These species had the largest and fastest growing stems. In this group only grand fir exhibited an inverse relationship between ethanol concentrations and stem volume. The relative amounts of ethanol synthesized by stems from Douglas-fir, western hemlock and western redcedar seedlings were not the same as subsequently observed in logs from mature trees of the same species under field conditions. Differences in the anaerobic environments for the two stem types could have affected the quantities of ethanol produced. The observed high amounts of ethanol produced by the stems from pine species were discussed in terms of their ability to handle periods of anaerobic stress or hypoxia.     

Laccaria bicolor S238N improves Scots pine mineral nutrition by increasing root nutrient uptake from soil minerals but does not increase mineral weathering

The role of ectomycorrhizal fungi on mineral nutrient mobilization and uptake is crucial for tree nutrition and growth in temperate forest ecosystems. By using a “mineral weathering budget” approach, this study aims to quantify the effect of the symbiosis with the ectomycorrhizal model strain Laccaria bicolor S238N on mineral weathering and tree nutrition, carrying out a column experiment with a quartz/biotite substrate. Each column was planted with one Scots pine (Pinus sylvestris L.) non-mycorrhizal or mycorrhizal with L. bicolor, with exception of the abiotic control treatment. The columns were continuously supplied with a nutrient-poor solution. A mineral weathering budget was calculated for K and Mg. The pine shoot growth was significantly increased (73%) when plants were mycorrhizal with L. bicolor. Whatever their mycorrhizal status, pines increased mineral weathering by factors 1.5 to 2.1. No difference between non-mycorrhizal and mycorrhizal pine treatments was revealed, however, mycorrhizal pines assimilated significantly more K and Mg. This suggests that in our experimental conditions, L. bicolor S238N improved shoot growth and K and Mg assimilation in Scots pine mainly by increasing the uptake of dissolved nutrients, linked to a better exploration and exploitation of the soil by the mycorrhizal roots.     

Response of understorey vegetation and Scots pine root systems to fertilization at multiple deficiency stress

The stump and root systems of Scots pine (Pinus sylvestris L.) and field-layer vegetation were sampled before and three growing seasons after drainage and fertilization of a low-shrub pine bog in SE Norway. Although the understorey vegetation roots responded significantly to nutrient application with higher concentrations of Ca and P, root biomass weights did not change. The fine and small pine roots responded with higher N, Ca, P and S concentrations, while those of Mn and Zn were significantly reduced. The NPK-application resulted in significantly higher pine root biomass. Relative to the total stores in the root zone the amounts of most elements in roots shifted to higher ratios at NPK-application. High figures for K, B and Mn indicate tight biochemical cycles of these elements. Compared to totals in above and below ground biomass, major parts of Fe and Pb were held by the roots. In contrast the field layer roots kept a very small per cent of total K, while the pine roots were low in Mn. The understorey vegetation was primarily restricted by P-deficiency, while the pine trees were also restricted by low supply of N. The field and the tree layer species seem to differ with respect to required nutrient concentrations in the root zone. These characteristics are important for direction and extent of successional changes after fertilization in low-shrub pine bog ecosystems.     

Spatial pattern of seedlings 1 year after fire in a Mediterranean pine forest

Summary The spatial distribution of seedlings of the dominant perennial plant species (Pinus halepensis, Cistus salviifolius, Rhus coriaria) and may annual species was studied after a wild fire in an eastern Mediterranean pine forest. The spatial distribution of all seedlings is affected by the location of the old burned pine trees. Seedling density of Pinus and Cistus is higher at a distance from the burned pine canopy and lower near the burned pine trunk. It is also higher beneath small burned pine trees than under big ones. Rhus seedling density is higher under big burned pine trees and also near the burned trunks. Seedlings of Pinus, Cistus and Rhus growing under the burned canopy of big pine trees tend to be taller than seedlings under small ones or outside the burned canopy. Most annual species germinate and establish themselves outside the burned canopies, and only a few annual species are found beneath them. It is suggested that variation in the heat of the fire, in the amount of ash between burned pine trees of different sizes, and in the distance from the burned canopy are responsible for the observed pattern of seedling distribution. The possible ecological significance of the spatial pattern of seedlings distribution and their differential growth rate are discussed.     

Nitrogen metabolism of Douglas fir and Scots pine as affected by optimal nutrition and water supply under conditions of relatively high atmospheric nitrogen deposition

Nitrogen metabolism of the needles of 40-year-old Douglas fir and Scots pine trees, growing in two forest stands on cation-poor and acidic sandy soil with a relatively high atmospheric nitrogen deposition was studied. The composition of the free amino acid (FAA) pool, the concentrations of total nitrogen and soluble protein and the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were determined in the needles. An excessive nitrogen supply by a high atmospheric nitrogen deposition in both forest stands was indicated by the high concentrations of total nitrogen and the amino acids arginine, glutamic acid, glutamine and aspartic acid in control trees. In addition the effect of optimal nutrition and water supply (fertigation) on the needle nitrogen metabolism was evaluated. The total concentration of the FAA pool in needles of both tree species was lower in the fertigated than in the non-fertigated (control) trees, except for 1-year-old needles of Scots pine, in which the concentration after fertigation did not differ from the control. The lower total FAA concentration in the fertigated trees could be attributed to arginine, the concentration of which was on average 60% lower than in the control. Neither the concentration of soluble protein nor the activity of GS were influenced by fertigation. The activity of GDH in fertigated trees only differed significantly from the control in October. Scots pine needles had higher concentrations of protein (50%) and higher activities of GS (44%) and GDH (25%) than Douglas fir needles. Possible explanations for the lower vitality of Douglas fir compared to Scots pine are given.     

Nutritional disturbances of young Scots pines caused by pine bark bugs in a dry heath forest

This study deals with the effect of pine bark bugs (Aradus cinnamomeus Panzer) on the nutrition of young Scots pines (Pinus sylvestris L.). Soil and needle samples for analytical purposes were collected from a young pine stand growing on a dry barren mineral soil afflicted by pine bark bugs.The damage to vascular tissues caused by pine bark bugs disturbed the nutrition of the trees, especially in the top part of the crown. The foliar calcium, magnesium, manganese and sulphur concentrations were highly reduced. Scots pines suffered from a lack of calcium, magnesium, nitrogen and phosphorus. These deficiencies were secondary by nature, because no differences were observed between the nutrient concentrations of the underlying soil of the healthy and affected trees. The symptoms of trees damaged by pine bark bugs resembled most of all calcium deficiency symptoms.     

Relationship of aluminium and calcium to net CO2 exchange among diverse Scots pine provenances under pollution stress in Poland

Light-saturated net photosynthesis (A_sat), dark respiration (RD), and foliar nutrient content of eight European Scots pine (Pinus sylvestris L.) provenances were measured at experimental sites in western Poland. Two-year-old seedlings were planted in 1984 at two sites with similar soils in areas of contrasting air pollution. One site was near a point source of SO₂ and other pollutants, and another 12 km to the southeast in an area free of acute air pollution was treated as a control. The eight provenances were from a large north-tosouth latitudinal range (60 to 43° N). At the heavily polluted site Scots pine trees exhibited lower growth rates and crown dieback and deformation. Soil pH, Ca and Mg were at least 10 times lower, and Al 10 times higher at the polluted than the control site. In 1991, concentrations of Al, P, Ca, S, Mn, Fe, and Zn in oneyear old Scots pine foliage were higher and Mg lower at the polluted than control site. At both sites foliar Mg levels were within the range considered deficient (0.6 mg g^-1), and at the polluted site, Al concentrations were very high (670 to 880 g g^-1). In all provenances, RD of one-year-old needles was higher (by 22% on average) and A_sat was lower (by 37% on average) at the polluted than the control site. The ratio of A_sat: RD was half as great in all provenances at the polluted (4 to 6) than control site (8 to 11). Provenances of southern origin had greater increases in RD and water-use efficiency at the polluted site than other provenances. Within the polluted site alone, or across both sites, A_sat in Scots pine was negatively correlated to the Al: Ca ratio (p<0.001, r=–0.93). Across sites RD increased with needle N and Al (multiple regression, p<0.001). The data suggest that at the polluted site there is excessive soil Al and deficient Mg availability, low needle Mg and high Al concentrations and high Al: Ca ratios, and that these have resulted in reduced photosynthetic capacity and increased respiration.     

Growth and nutrient characteristics in bog and fen populations of Scots pine (Pinus sylvestris)

Nutrient content in peat and growth rate, rate of nutrient accumulation and allocation patterns in Scots pine Pinus sylvestris L. from eleven natural Swedish peatlands were examined. The peatlands studied represented a wide range of climatic conditions and mire types. Whole and even-sized pines with intact root-systems were excavated to give the whole-pine budget for growth and nutrient accumulation. All samples originated from hummock communities.Pine growth and nutrient characteristics were much more variable in the minerogenous sites than in the ombrogenous sites, which indicates a larger environmental heterogeneity within the minerogenous sites. In the ombrogenous sites, rate of pine growth was constant, approximately 1 mg day^-1, and independent of latitudinal variation. There was either no relationship between latitudinal location and growth rate in the minerogenous sites, which suggests that pine growth is largely controlled by site-specific, very local conditions. The growth rate of pines was not correlated with any peat nutrient. The pines allocated a large proportion of their nutrient-pool to the metabolically active current year's growth. This is likely a trait that enables Scots pine to occupy a wide range of peatland types in which it experience a marked imbalance and shortage of nutrients.     

Molecular cloning and functional expression of a stress-induced multifunctional O-methyltransferase with pinosylvin methyltransferase activity from Scots pine (Pinus sylvestris L.)

Formation of pinosylvin (PS) and pinosylvin 3-O-monomethyl ether (PSM), as well as the activities of stilbene synthase (STS) and S-adenosyl-l-methionine (SAM):pinosylvin O-methyltransferase (PMT), were induced strongly in needles of Scots pine seedlings upon ozone treatment, as well as in cell suspension cultures of Scots pine upon fungal elicitation. A SAM-dependent PMT protein was purified and partially characterised. A cDNA encoding PMT was isolated from an ozone-induced Scots pine cDNA library. Southern blot analysis of the genomic DNA suggested the presence of a gene family. The deduced protein sequence showed the typical highly conserved regions of O-methyltransferases (OMTs), and average identities of 20–56% to known OMTs. PMT expressed in Escherichia coli corresponded to that of purified PMT (40 kDa) from pine cell cultures. The recombinant enzyme catalysed the methylation of PS, caffeic acid, caffeoyl-CoA and quercetin. Several other substances, such as astringenin, resveratrol, 5-OH-ferulic acid, catechol and luteolin, were also methylated. Recombinant PMT thus had a relatively broad substrate specificity. Treatment of 7-year old Scots pine trees with ozone markedly increased the PMT mRNA level. Our results show that PMT represents a new SAM-dependent OMT for the methylation of stress-induced pinosylvin in Scots pine needles.     

Mycorrhizal networks and distance from mature trees alter patterns of competition and facilitation in dry Douglas-fir forests

The distribution of dry Douglas-fir forests in western North America is expected to shift northward with climate change and disappear from the grassland interface in the southern interior of British Columbia. This shift may be accentuated by clearcutting, a common harvesting practice that aims to reduce the competitive effects of residual mature trees on new regeneration, but in so doing, ignores their facilitative effects. In this study, we investigated the net effects of competition from and facilitation by mature trees retained on harvested sites on seedling establishment in the dry interface Douglas-fir forests. We demonstrate that access to a mycorrhizal network (MN) and proximity to trees have important influences on seedling performance. On six sites, we established trenched plots around 24 mature Pseudotsuga menziesii var. glauca (Douglas-fir) trees, then planted Douglas-fir seedlings into four mesh treatments that served to restrict MN access (i.e., planted into mesh bags with 0.5-, 35-, or 250-μm pores, or without mesh) or into impermeable bags (grown in isolation) at four distances (0.5, 1.0, 2.5, or 5.0 m). Seedling survival tended to be greater and water stress lower where seedlings had full access to the MN. Seedling height, shoot biomass, needle biomass, and nutrient uptake peaked at 2.5–5.0 m from mature trees. Seedlings 0.5 m from mature trees had lower CO₂ assimilation rates and wood δ¹³C compared to seedlings 5.0 m away. Competition for soil resources was highest near mature trees but facilitation was relatively greater at further distances, resulting in a zone of net benefit for seedlings. These results show that intraspecific tree-seedling interactions are both competitive and facilitative in dry Douglas-fir forests, and that they are spatially dependent. After disturbance, maintaining residual mature trees may be important for their beneficial regeneration zones. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A method for establishing ectomycorrhiza on conifer seedlings in steady-state conditions of nutrition

Scots pine ( Pinus sylvestris L.), and Norway spruce ( Picea abies (L.) Karst.) seedlings, inoculated with Suillus bovinits (L. ex Fr.) O. Kuntze and Paxillus involutus (Batsch) Fr., were grown on sloping plastic plates in growth units. A circulating nutrient solution flowed continuously over the plates. Nutrients in balanced proportions previously found to be appropriate for conifers, were added at a specified relative addition rate, in exponentially increasing amounts. The conductivity of the solution was kept low and stable (<50 μS cm⁻¹). No carbohydrates were added.
Seedling nitrogen concentration and relative growth rate attained steady states in both inoculated and uninoculated treatments. The fungi infected the short roots within a few days and formed typical mantles and Hartig nets. This occurred in all treatments, including conditions of free access to nutrients, in which the nutrient concentration of the seedlings was optimal. The growth rate of the extramatrical mycelium was very high.     

Influence of Norway spruce seedlings on the nutrient availability in mineral soil and forest floor material

A greenhouse experiment was performed to evaluate the effect of Norway spruce (Picea abies (L.) Karst.) seedlings on net nutrient availability in five different growing media containing F- or H-layer and mineral soil originating from a haplic podzol in northern Sweden. The initial total amounts of eight nutrient elements (N, K, P, Ca, Mg, Mn, Fe, Zn) and exchangeable amounts of the same elements were analyzed in pots with or without spruce seedlings. In the planted pots seedling nutrient uptake was also estimated. After 26 weeks, higher net nutrient availability with seedlings was found in 25 out of the 40 (62%) growing media and nutrient element combinations. A positive seedling effect on net nutrient availability might be explained by rhizodeposition stimulating the soil microorganism activity and accelerating the weathering of minerals or by seedling roots promoting the nutrient providing processes through changes in soil chemical and physical properties. Nitrogen availability was primarily affected by what part of the forest floor the growing medium contained although the positive response to seedling presence was apparent. The positive net availability response of P, Ca, Mg, Mn, Fe and Zn to seedling presence was on the other hand relatively strong. In the case of P, K, and Zn the growing medium composition (if the F- and H-layer was pure or mixed with mineral soil) was also an important factor for the estimated net availability. Pure F-and H-layer provided greater P- and K-availability while the availability of Zn increased when mineral soil was added. The influence of growing plants ought to be considered when soil samples are used for assessing the nutrient availability.     

The effects of toxic metals,content of nutrients and inoculation with mycorrhizal fungi on the level of phenolics in roots and growth of Scots pine seedlings

The effects of two substrates and several strains of mycorrhizal fungi on the content of soluble phenolics in roots and growth of Scots pine seedlings was investigated. The first substrate was fertile and contaminated with copper, zinc and lead, whereas the second one displayed nutrient deficiency. The dry weights of needles, trunks, roots and the total biomass were higher in groups of seedlings inoculated with mycorrhizal fungi on fertile and polluted substrate. Inoculation of pine seedlings on this substrate resulted in a decrease in concentration of phenolics in roots and except for seedlings inoculated with Laccaria laccata negatively influenced the above-ground part: root ratio.