Changes in diversity and storage function of ectomycorrhiza and soil organoprofile dynamics after introduction of beech into Scots pine forests

Diversity and storage function of mycorrhiza as well as soil organoprofile formation were investigated in a chronosequence of a pure Scots pine (Pinus sylvestris L.) stand, of Scots pine stands that were underplanted with beech (Fagus sylvatica L.) and in three pure beech stands of different age. Mycorrhiza diversity was higher in the pure beech stands compared to the pure pine stand. Beech and pine trees in the mixed stands had similar dominant mycorrhiza morphotypes. However, trees in two of the three pure beech stands were mycorrhized with other types. Mycorrhizal abundance and nutrient amounts of mycorrhizae associated with beech trees were higher in the mixed and in the pure beech stands compared to pine mycorrhizae indicating that nutrient uptake was higher in older beech than in older pine trees. Humus quality varied from pine to beech stands. Plant litter storage in the humus layer was highest in the youngest mixed stand and lowest in the oldest beech stand. Humus forms changed from moder grass-type in the pure Scots pine stand to mor-like moder and moder rich in fine humus with increasing age of beeches in the mixed stands. The older beech stands were characterised by oligomull and mull-like moder as the dominating humus forms. The ecologically favourable humus forms, i.e., nutrient rich humus forms in the older beech stands correlate well with the higher mycorrhizal diversity and abundance as well as the higher nutrient storage of their mycorrhizae in these stands. The results are also discussed with regard to the 'base-pump effect' of beech trees.     

Fungal communities in mycorrhizal roots of conifer seedlings in forest nurseries under different cultivation systems, assessed by morphotyping, direct sequencing and mycelial isolation

Fungi colonising root tips of Pinus sylvestris and Picea abies grown under four different seedling cultivation systems were assessed by morphotyping, direct sequencing and isolation methods. Roots were morphotyped using two approaches: (1) 10% of the whole root system from 30 seedlings of each species and (2) 20 randomly selected tips per plant from 300 seedlings of each species. The first approach yielded 15 morphotypes, the second yielded 27, including 18 new morphotypes. The overall community consisted of 33 morphotypes. The level of mycorrhizal colonisation of roots determined by each approach was about 50%. The cultivation system had a marked effect on the level of mycorrhizal colonisation. In pine, the highest level of colonisation (48%) was observed in bare-root systems, while in spruce, colonisation was highest in polyethylene rolls (71%). Direct internal transcribed spacer ribosomal DNA sequencing and isolation detected a total of 93 fungal taxa, including 27 mycorrhizal. A total of 71 (76.3%) fungi were identified at least to a genus level. The overlap between the two methods was low. Only 13 (13.9%) of taxa were both sequenced and isolated, 47 (50.5%) were detected exclusively by sequencing and 33 (35.5%) exclusively by isolation. All isolated mycorrhizal fungi were also detected by direct sequencing. Characteristic mycorrhizas were Phialophora finlandia, Amphinema byssoides, Rhizopogon rubescens, Suillus luteus and Thelephora terrestris. There was a moderate similarity in mycorrhizal communities between pine and spruce and among different cultivation systems.Electronic supplementary material Supplementary material is available for this article at and accessible for authorised users     

Growth and Mycorrhizal Community Structure of Pinus sylvestris Seedlings following the Addition of Forest Litter

We report the effects of pine and oak litter on species composition and diversity of mycorrhizal fungi colonizing 2-year-old Pinus sylvestris L. seedlings grown in a bare-root nursery in Lithuania. A layer of pine or oak litter was placed on the surface of the nursery bed soil to mimic natural litter cover. Oak litter amendment appeared to be most favorable for seedling survival, with a 73% survival rate, in contrast to the untreated mineral bed soil (44%). The concentrations of total N, P, K, Ca, and Mg were higher in oak growth medium than in pine growth medium. Relative to the control (pH 6.1), the pH was lower in pine growth medium (5.8) and higher in oak growth medium (6.3). There were also twofold and threefold increases in the C content of growth medium with the addition of pine and oak litter, respectively. Among seven mycorrhizal morphotypes, eight different mycorrhizal taxa were identified: Suillus luteus, Suillus variegatus, Wilcoxina mikolae, a Tuber sp., a Tomentella sp., Cenococcum geophilum, Amphinema byssoides, and one unidentified ectomycorrhizal symbiont. Forest litter addition affected the relative abundance of mycorrhizal symbionts more than their overall representation. This was more pronounced for pine litter than for oak litter, with 40% and 25% increases in the abundance of suilloid mycorrhizae, respectively. Our findings provide preliminary evidence that changes in the supply of organic matter through litter manipulation may have far-reaching effects on the chemistry of soil, thus influencing the growth and survival of Scots pine seedlings and their mycorrhizal communities.     

Natural regeneration of Pinus resinosa on burned and unburned sites in Newfoundland

Abstract. Natural regeneration of Pinus resinosa (red pine) seedlings around mature trees was studied in burned and unburned stands. Growth inhibitory effects of the forest organic matter on red pine seedlings was tested by a stair-step experiment using leachate of forest soil monoliths and also by a seed germination bio-assay using forest floor substrates. To test if higher burning temperatures can remove the allelopathic effects of red pine-Kalmia organic matter, a laboratory bio-assay was conducted by germinating red pine seeds on the organic matter burned at 200, 400, 600 and 800°C. Deposition of dry needles and a thick duff layer under red pine stands affected seedling establishment. Red pine seedling establishment increased with the decreasing thickness of duff layer away from the stump of the seed-bearing trees. Wildfire helped in removing the duff layer and increased seedling establishment. A high fuel load within a 0 - 1 m radius around the tree stump caused a deep burn of the organic matter including part of the soil seed reserve. On a burned-over surface, more seedlings established in a band between 1 and 2 m around the stump than inside and outside the band. Primary root growth of red pine was severely inhibited when the seedlings were grown in unburned forest floor organic matter where Kalmia was the principal understory species. Water leachate of a Pinus resinosa-Kalmia soil monolith was inhibitory to red pine seedling growth. In greenhouse conditions, the seedlings grew well in burned-over soil from a Pinus resinosa stand. Burned organic matter from a red pine forest showed an increase in pH with a burning temperature of 600°C. Primary root growth of red pine seedlings was similarly increased with increasing temperature up to 600°C; at higher temperatures the root length of seedlings did not increase any further.     

Recent 14C-labelled assimilate allocation to Scots pine seedling root and mycorrhizosphere compartments developed on reconstructed podzol humus,E- and B- mineral horizons

In northern boreal forests, podzolic soils prevail that comprise of a distinct upper organic humus/mor (O) horizon that is supported by underlying eluvial (E) and illuvial (B) mineral horizons. The dominant tree species, Scots pine (Pinus sylvestris L.), is known to be highly dependent on root symbiosis with ectomycorrhizal fungi that develop in constituent podzol horizons for growth in these nutrient limited soils. The aim of this microcosm-based study was a quantification of photosynthetically fixed ¹⁴C allocation, following standard pulse-feeding of 7-month-old Scots pine seedling shoots, to respective root and mycorrhizosphere compartments that developed in the reconstructed podzol (O, E and B) profile. Biomass of roots and mycorrhizas decreased with increasing soil depth but no soil origin, control forest vs. clear-cut area, related differences were observed. Similarly, no major soil origin- or podzol horizon-related differences in categorised ectomycorrhizal morphotypes and number of mycorrhizas, in relation to pooled root and mycorrhiza biomass, were detected. However, the total recovery of ¹⁴C-label was significantly higher in clear-cut soil microcosms compared to control counterparts. A significant finding was equivalent ¹⁴C-carbon allocation to roots and ectomycorrhizas in all three major, organic and mineral, podzol profile horizons studied. These carbon allocation data provide additional support for direct (or indirect) roles of roots and symbiotic mycorrhizal fungi in mineral weathering and biodegradation of organic ligands that are central for plant acquisition of growth limiting nutrients and the podzolization process in boreal forest ecosystems.     

Short-term effects of manipulated increase in acid deposition on soil, soil solution chemistry and fine roots in Scots pine (Pinus sylvestris) stand on a podzol

A manipulated increase in acid deposition (15 kg S ha⁻¹), carried out for three months in a mature Scots pine (Pinus sylvestris) stand on a podzol, acidified the soil and raised dissolved Al at concentrations above the critical level of 5 mg l⁻¹ previously determined in a controlled experiment with Scots pine seedlings. The induced soil acidification reduced tree fine root density and biomass significantly in the top 15 cm of soil in the field. The results suggested that the reduction in fine root growth was a response not simply to high Al in solution but to the depletion of exchangeable Ca and Mg in the organic layer, K deficiency, the increase in NH₄:NO₃ ratio in solution and the high proton input to the soil by the acid manipulation. The results from this study could not justify the hypothesis of Al-induced root damage under field conditions, at least not in the short term. However, the study suggests that a short exposure to soil acidity may affect the fine root growth of mature Scots pine.     

Growth and mycorrhizal community structure of Pinus sylvestris seedlings following the addition of forest litter

We report the effects of pine and oak litter on species composition and diversity of mycorrhizal fungi colonizing 2-year-old Pinus sylvestris L. seedlings grown in a bare-root nursery in Lithuania. A layer of pine or oak litter was placed on the surface of the nursery bed soil to mimic natural litter cover. Oak litter amendment appeared to be most favorable for seedling survival, with a 73% survival rate, in contrast to the untreated mineral bed soil (44%). The concentrations of total N, P, K, Ca, and Mg were higher in oak growth medium than in pine growth medium. Relative to the control (pH 6.1), the pH was lower in pine growth medium (5.8) and higher in oak growth medium (6.3). There were also twofold and threefold increases in the C content of growth medium with the addition of pine and oak litter, respectively. Among seven mycorrhizal morphotypes, eight different mycorrhizal taxa were identified: Suillus luteus, Suillus variegatus, Wilcoxina mikolae, a Tuber sp., a Tomentella sp., Cenococcum geophilum, Amphinema byssoides, and one unidentified ectomycorrhizal symbiont. Forest litter addition affected the relative abundance of mycorrhizal symbionts more than their overall representation. This was more pronounced for pine litter than for oak litter, with 40% and 25% increases in the abundance of suilloid mycorrhizae, respectively. Our findings provide preliminary evidence that changes in the supply of organic matter through litter manipulation may have far-reaching effects on the chemistry of soil, thus influencing the growth and survival of Scots pine seedlings and their mycorrhizal communities.     

An ericoid shrub plays a dual role in recruiting both pines and their fungal symbionts along primary succession gradients

Relative importance of positive and negative interactions between plant species may change along disturbance and resource gradients. Positive interactions are suggested to prevail in low resource, low productivity (high stress) conditions and negative interactions in high resource availability. A dwarf shrub, mountain crowberry Empetrum nigrum ssp. hermaphroditum, is known to have allelopathic impacts on both Scots pine Pinus sylvestris and its ectomycorrhizal symbionts. We aimed to study if the outcome of Empetrum impacts on Scots pine changes along primary succession gradients on the dune shores of Bothnian Bay, in Finland, where abiotic stress gradually changes to biotic stress along the succession. We found that Empetrum may act as a facilitator despite its allelopathic effects, since the proportion of Scots pine seedlings established in Empetrum patches was higher than in patches without the shrub in early and mid succession stages, whereas patches without Empetrum were preferred in late succession. The amount of mycelial fungal biomass (ergosterol) in the soil in the vicinity of the seedling roots was higher in Empetrum patches than in patches without Empetrum and it increased along the succession gradient. Proportion of pine root tips colonised by suilloid morphotypes with abundant external mycelia and the diversity of ectomycorrhizal morphotypes were higher in mid successional stage in Empetrum patches compared to patches without Empetrum. Our results suggest that in the harsh physical conditions of the dune shore Empetrum facilitates pine seedling establishment in the early and mid stages of succession by providing mechanical and physical shelter whereas in late succession negative interactions (competition and allelopathy) between the shrub and the pine are dominating. To our knowledge we present the first finding that an ericoid mycorrhizal shrub could enhance both the performance of the ectomycorrhizal host tree and the tree's fungal symbionts.     

Ectomycorrhizal responses to organic and inorganic nitrogen sources when associating with two host species

While it is established that increasing atmospheric inorganic nitrogen (N) deposition reduces ectomycorrhizal fungal biomass and shifts the relative abundances of fungal species, little is known about effects of organic N deposition. The effects of organic and inorganic N deposition on ectomycorrhizal fungi may differ because responses to inorganic N deposition may reflect C-limitation. To compare the effects of organic and inorganic N additions on ectomycorrhizal fungi, and to assess whether host species may influence the response of ectomycorrhizal fungi to N additions, we conducted an N addition experiment at a field site in the New Jersey pine barrens. Seedlings of two host species, Quercus velutina (black oak) and Pinus rigida (pitch pine), were planted at the base of randomly-selected mature pitch pine trees. Nitrogen was added as glutamic acid, ammonium, or nitrate at a rate equivalent to 227.5 kg ha⁻¹ y⁻¹ for eight weeks, to achieve a total application of 35 kg ha⁻¹ during the 10-week study period. Organic and inorganic N additions differed in their effects on total ectomycorrhizal root tip abundance across hosts, and these effects differed for individual morphotypes between oak and pine seedlings. Mycorrhizal root tip abundance across hosts was 90 % higher on seedlings receiving organic N compared to seedlings in the control treatment, while abundances were similar among seedlings receiving the inorganic N treatments and seedlings in the control. On oak, 33–83 % of the most-common morphotypes exhibited increased root tip abundances in response to the three forms of N, relative to the control. On pine, 33–66 % of the most-common morphotypes exhibited decreased root tip abundance in response to inorganic N, while responses to organic N were mixed. Plant chemistry and regression analyses suggested that, on oak seedlings, mycorrhizal colonization increased in response to N limitation. In contrast, pine root and shoot N and C contents did not vary in response to any form of N added, and mycorrhizal root tip abundance was not associated with seedling N or C status, indicating that pine received sufficient N. These results suggest that in situ organic and inorganic N additions differentially affect ectomycorrhizal root tip abundance and that ectomycorrhizal fungal responses to N addition may be mediated by host tree species.     

Reaction of forest soil microflora to environmental stress along a moderate pollution gradient next to an oil refinery

Twenty-five study sites were established along a 57-km-long transect in order to estimate the impact of an oil refinery, mainly emitting sulphur dioxide (24000 t yr⁻¹), on forest soil (F/H-horizon) chemistry and microbiology. The study demonstrated the existence of a pollution gradient which was best represented by the logarithm of the concentration of vanadium in the analyzed F/H soil layer. Of the soil microbial characteristics measured, including length of fungal hyphae, soil respiration, microbial biomass C and N, and percentage mass loss of Scots pine (Pinus sylvestris) needle litter, only fungal hyphal length was suppressed by the pollution load. No reduction in basic cations (Ca, Mg, K, and Na) in the F/H-horizon, or enrichment of soluble aluminum in the F/H-horizon of the Scots pine forest could be detected to result from the deposition.     

Mycorrhizal inoculant alleviates salt stress in<Emphasis Type="Italic"> Sesbania aegyptiaca</Emphasis> and<Emphasis Type="Italic"> Sesbania grandiflora</Emphasis> under field conditions: evidence for reduced sodium and improved magnesium uptake

A field experiment was conducted to examine the effect of the arbuscular mycorrhizal fungus Glomus macrocarpum and salinity on growth of Sesbania aegyptiaca and S. grandiflora. In the salt-stressed soil, mycorrhizal root colonisation and sporulation was significantly higher in AM-inoculated than in uninoculated plants. Mycorrhizal seedlings had significantly higher root and shoot dry biomass production than non-mycorrhizal seedlings grown in saline soil. The content of chlorophyll was greater in the leaves of mycorrhiza-inoculated as compared to uninoculated seedlings. The number of nodules was significantly higher in mycorrhizal than non-mycorrhizal plants. Mycorrhizal seedling tissue had significantly increased concentrations of P, N and Mg but lower Na concentration than non-mycorrhizal seedlings. Under salinity stress conditions both Sesbania sp. showed a high degree of dependence on mycorrhizae, increasing with the age of the plants. The reduction in Na uptake together with a concomitant increase in P, N and Mg absorption and high chlorophyll content in mycorrhizal plants may be important salt-alleviating mechanisms for plants growing in saline soil.     

Distribution of Cren- and Euryarchaeota in Scots Pine Mycorrhizospheres and Boreal Forest Humus

Archaeal 16S rRNA gene sequences have been found in a variety of moderate-temperature habitats including soil and rhizospheres. In this study, the differences of archaeal communities associated with Scots pine (Pinus sylvestris L.) short roots, different types of mycorrhizospheric compartments, and uncolonized boreal forest humus were tested by direct DNA extraction, polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE), and sequencing. The results indicated that mycorrhizal colonization of Scots pine roots substantially influence the archaeal community of pine rhizospheres. Colonization of short roots by most mycorrhizal fungi tested increased both archaeal frequency and diversity. Most of the archaeal sequences encountered in mycorrhizas belonged to the phylum Euryarchaeota, order of Halobacteriales. The difference in archaeal diversity between the mycorrhizospheric compartments and humus was profound. Most compartments with fungal components contained euryarchaeotal 16S rRNA gene sequences, whereas a high diversity of crenarchaeotal sequences and no euryarchaeotal sequences were found in forest humus outside mycorrhizospheres.     

Effect of Plant Growth Promoting Bacillus Strains on Pine and Spruce Seedling Growth and Mycorrhizal Infection

Rifamycin-resistant derivatives of plant growth promotingBacilluspolymyxa strains L6, Pw-2, and S20 were used to evaluate theinteraction of bacterial–mycorrhizal co-inoculation onpine and spruce seedling growth. We were particularly interestedin determining if the mechanism by which bacteria stimulatedseedling growth depended on the presence of ectomycorrhizae.Mycorrhizal inoculum was introduced by adding 2ml of one ofsix forest floor soil types originating from different spruceand pine stands to seedling containers. Mycorrhizal roots developedin 34% of pine and 27% of spruce seedlings treated with forestsoil, but no differences between forest soils were detected.Most mycorrhizae were formed byWilcoxinasp. (E-strain) (98%for spruce and 67% for pine); small numbers ofAmphinema-like,Myceliumradicis atrovirens, Suillus-like,Thelephora-like, andTuber-likemycorrhizae were also found on pine (27% in total).Thelephora-likefungi comprised 2% of spruce mycorrhize. In the absence of bacterialinoculum, spruce seedling biomass was positively correlatedwith the number of mycorrhizal root tips, but this trend wasnot detected in spruce inoculated with bacteria or in pine.Bacterial inoculation did not influence the mycorrhizal statusof seedlings, but all threeBacillusstrains stimulated growthof both conifer species. Root biomass, in particular, was significantlyenhanced by up to 18% compared with uninoculated controls. Mycorrhizalfungi improved the growth of spruce seedlings, but plant growthpromotion byBacilluswas similar for mycorrizal and non-mycorrhizalseedlings of both species. Our results suggest thatBacillusstrainsL6-16R, Pw-2R, and S20-R enhance conifer seedling growth througha mechanism unrelated to mycorrhizal fungi. Hybrid spruce; Picea glaucaxengelmannii ; lodgepole pine; Pinus contortavar.latifoliaEngelm.; inoculation; Bacillus polymyxa; seedling growth promotion; mycorrhizae     

The threatened plant intermediate wintergreen (<Emphasis Type="Italic">Pyrola media</Emphasis>) associates with a wide range of biotrophic fungi in native Scottish pine woods

The plant intermediate wintergreen (Pyrola media, Ericaceae) is in need of conservation action in Scotland. Although widespread, it is locally distributed in dwarf shrub heath and more commonly in Scots pine (Pinus sylvestris) woodlands. A recent study on the mycorrhizal status of Pyrola suggested that they associate with a restricted range of ectomycorrhizal (ECM) fungi. Here, we examined the hypothesis that specialisation by P. media for fungi usually associated with Scots pine is a factor in promoting its occurrence in this habitat. The fungal community associated with the roots of P. media growing in a Scots pine forest was determined by morphotyping, polymerase chain reaction, cloning and sequencing. Molecular identification found 49 taxa representing ecto- and ericoid mycorrhizal fungi, dark septate endophytes, saprotrophs, and fungi of unknown trophic status. The majority of the taxa (67.4%) were Basidiomycota, with 24.4% known to be ECM fungi specific to Pinus sp. or conifers. However, a wide range of other mycorrhizal fungi with varying degrees of host specificity were also found, including taxa usually associated with deciduous hosts. In conclusion, the broad range of mycorrhizal fungi recovered from the roots of P. media suggests that specialization is not a major factor in determining its distribution.     

Changes in dissolved lignin-derived phenols, neutral sugars, uronic acids, and amino sugars with depth in forested Haplic Arenosols and Rendzic Leptosols

A major part of the dissolved organic matter produced in the organic layers of forest ecosystems and leached into the mineral soil is retained by the upper subsoil horizons. The retention is selective and thus dissolved organic matter in the subsoils has different composition than dissolved organic matter leached from the forest floor. Here we report on changes in the composition of dissolved organic matter with soil depth based on C-to-N ratios, XAD-8 fractionation, wet-chemical analyses (lignin-derived CuO oxidation products, hydrolysable sugars and amino sugars) and liquid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Dissolved organic matter was sampled directly beneath the forest floor using tension-free lysimeters and at 90cm depth by suction cups in Haplic Arenosols under Scots pine (Pinus sylvestris L.) and Rendzic Leptosols under European beech (Fagus sylvatica L.) forest. At both sites, the concentrations of dissolved organic carbon (DOC) decreased but not as strongly as reported for deeply weathered soils. The decrease in DOC was accompanied by strong changes in the composition of dissolved organic matter. The proportion of the XAD-8-adsorbable (hydrophobic) fraction, carboxyl and aromatic C, and the concentrations of lignin-derived phenols decreased whereas the concentrations of sugars, amino sugars, and nitrogen remained either constant or increased. A general feature of the compositional changes within the tested compound classes was that the ratios of neutral to acidic compounds increased with depth. These results indicate that during the transport of dissolved organic matter through the soils, oxidatively degraded lignin-derived compounds were preferentially retained while potentially labile material high in nitrogen and carbohydrates tended to remain dissolved. Despite the studied soils' small capacity to sorb organic matter, the preferential retention of potentially refractory and acidic compounds suggests sorption by the mineral soil matrix rather than biodegradation to govern the retention of dissolved organic matter even in soils with a low sorption capacity.     

TRAP: a modelling approach to below-ground carbon allocation in temperate forests

Tree root systems, which play a major role in below-ground carbon (C) dynamics, are one of the key research areas for estimating long-term C cycling in forest ecosystems. In addition to regulating major C fluxes in the present conditions, tree root systems potentially hold numerous controls over forest responses to a changing environment. The predominant contribution of tree root systems to below-ground C dynamics has been given little emphasis in forest models. We developed the TRAP model, i.e. Tree Root Allocation of Photosynthates, to predict the partitioning of photosynthates between the fine and coarse root systems of trees among series of soil layers. TRAP simulates root system responses to soil stress factors affecting root growth. Validation data were obtained from two Belgian experimental forests, one mostly composed of beech (Fagus sylvatica L.) and the other of Scots pine (Pinus sylvestris L.). TRAP accurately predicted (R = 0.88) night-time CO₂ fluxes from the beech forest for a 3-year period. Total fine root biomass of beech was predicted within 6% of measured values, and simulation of fine root distribution among soil layers was accurate. Our simulations suggest that increased soil resistance to root penetration due to reduced soil water content during summer droughts is the major mechanism affecting the distribution of root growth among soil layers of temperate Belgian forests. The simulated annual rate of C input to soil litter due to the fine root turnover of the Scots pine was 207 g C m^–2 yr^–1. The TRAP model predicts that fine root turnover is the single most important source of C to the temperate forest soils of Belgium.     

Oviposition preference and larval survival of Diprion pini on Scots pine clones in relation to foliage characteristics

1 When laying eggs, adult female Diprion pini discriminated between clones of Scots pine, Pinus sylvestris. 2 Larval survival was affected by Scots pine clone but was not correlated with oviposition preference. 3 Diprion pini laid most eggs on tougher needles of Scots pine. 4 There was no evidence to suggest that D. pini is responding to the monoterpene composition of the foliage.     

Effect of nitrogen level on acid phosphatase activity of eight isolates of ectomycorrhizal fungus Paxillus involutus cultured in vitro

The higher levels of nitrogen in ammonium form stimulated the growth of mycelia and increased the accessible as well as the total acid phosphatase activity of Paxillus involutus (Batsch) Fr. isolates grown in pure culture. Rates of mycelia growth and acid phosphatase activities varied widely from one isolate to another. Scots pine (Pinus sylvestris L.) seedlings were inoculated with different P. involutus isolates in axenic conditions. Shoots of pine seedlings with mycorrhizae contained more phosphorus than shoots of non-mycorrhizal seedlings. The relations between growth and phosphatase activity of P. involutus isolates and their efficiency in supplying the host plant with phosphate are discussed.     

Seed screening of three pine species for glyphosate sensitivity for forest restoration

Austrian black pine (Pinus nigra J.F. Arnold), Scots pine (Pinus sylvestris L.), and maritime pine (Pinus pinaster Aiton) are commonly used in restoration practices in the Mediterranean base including Turkey. Direct seeding can secure desired level of tree establishment and survival on degraded sites wherever, favorable safe sites are scattered throughout the landscape. Glyphosate is a commonly used herbicide for weed control in forest, nursery and restoration sites worldwide, due to its broad-spectrum efficacy and considerably less toxicity on the environment compared to other chemicals. The present study screened the glyphosate phytotoxicity of three dominant pine species in Turkey during a seed germination trial, after seeds had been presoaked in 15 different dose-glyphosate solutions varying between 0 and 5%, v:v. Glyphosate applications damaged seed germination speed more than cumulative germination rate. As a systemic herbicide, glyphosate appeared highly phytotoxic to Austrian black pine. Scots pine showed an intermediate glyphosate phytotoxicity. Maritime pine was the least sensitive species, tolerating glyphosate at ≤1% doses. In conclusion, glyphosate may be used at low doses on restoration sites seeded with maritime pine while it is not recommended to be used on degraded sites seeded with Austrian black pine and Scots pine.     

Content of phenolics in mycorrhizal roots of Pinus sylvestris seedlings grown in vitro

The effect of Paxillus involutus, Laccaria laccata, Suillus luteus, S. bovinus, Hebeloma crustuliniforme and a strain of the ectendomycorrhizal fungus Mrg X (Ascomycotina) on the content of phenolic compounds: ortho-diphenols and total soluble phenols in roots of Pinus sylvestris seedlings grown in vitro was investigated. Mycorrhizal fungi varied significantly in the ability to influence the concentration of phenolics in Scots pine roots. Plants inoculated with S. luteus accumulated the lowest amount of the phenolics, whereas the amount of phenolics in pine roots inoculated with L. laccata was the highest.