Effects of isolates of ectomycorrhizal fungi and endophytic Mycelium radicis atrovirens that were dominant in soil from disturbed sites on growth of Betula platyphylla var. japonica seedlings

Effects of ectomycorrhizal fungi and endophytic Mycelium radicis atrovirens Melin (MRA) on growth of Betula platyphylla var. japonica seedlings were investigated under aseptic culture conditions. Three isolates of ectomycorrhizal fungi and two isolates of MRA were used. One MRA isolate was Phialocephala fortinii. Previous field work revealed that these isolates were dominant on the roots of B. platyphylla var. japonica seedlings grown in a mineral subsoil that had been exposed by the removal of surface soil. After a 100-day incubation, the growth of the seedlings was significantly enhanced by the colonization of these ectomycorrhizal fungal isolates as compared with uninoculated seedlings. In contrast, the growth of seedlings was retarded by the colonization of the MRA isolates. The growth of seedlings that were co-inoculated with ectomycorrhizal fungi and MRA was similar to that of uninoculated seedlings in most cases. These results suggest that ectomycorrhizal fungi have a beneficial effect on the growth of B. platyphylla var. japonica seedlings and that they suppress the deleterious effect of MRA. Thus, these ectomycorrhizal fungi probably have an important role in establishing B. platyphylla var. japonica seedlings during the initial stage of re-vegetation following site disturbance by the removal of surface soil.     

Early colonization of red alder and Douglas fir by ectomycorrhizal fungi and Frankia in soils from the Oregon coast range

The potential for mycorrhizal formation and Frankia nodulation were studied in soils from six sites in the Pacific Northwest. The sites included young and old alder stands, a 1-year-old conifer clear-cut, a young conifer plantation, and rotation-aged and old-growth conifer stands. A bioassay procedure was used with both red alder and Douglas fir seedlings as hosts. After 6 weeks growth, seedlings of both hosts were harvested every 3 weeks for 21 weeks and numbers of nodules and ectomycorrhizal types estimated. Nodules formed on red alder and ectomycorrhizae formed on both alder and Douglas fir in soil from all sites. Nodulation potential was highest in soil from the alder stands and the conifer plantation. Seven morphologically distinct ectomycorrhizal types were recovered on Douglas fir and five on alder. Only Thelephora terrestris, a broad-host-range mycobiont, formed mycorrhizae on both hosts. New ectomycorrhizal types formed on both hosts throughout the bioassay. Ectomycorrhizal colonization of alder was greatest in the alder and clear-cut soils. Low ectomycorrhizal colonization on alder was found in soils from sites where conifers were actively growing. Ectomycorrhizal colonization of Douglas fir was highest in the young alder and conifer plantation soils and was low in the rotation-aged conifer soil. The highest diversity of ectomycorrhizal types was found on alder in the conifer clear-cut soil and on Douglas fir in the rotation-aged conifer soil. Effects of host specificity, nodulation and mycorrhiza-forming potential and nodule-mycorrhiza interactions on seedling establishment are discussed in relation to seral stage dynamics and attributes of pioneer ectomycorrhizal fungal species.     

Ectomycorrhizal and arbuscular mycorrhizal colonization of two species of floodplain willows

To understand the relationships between the distribution of Chosenia arbutifolia and Salix sachalinensis and their mycorrhizal colonization, changes in the quality and types of ectomycorrhizas and arbuscular mycorrhizas of the seedlings of two species were studied at five different sites with different soil conditions in the floodplain of the Satsunai River, Hokkaido. High ectomycorrhizal and low arbuscular mycorrhizal colonization were found in roots of both plants. Ectomycorrhizal colonization of S. sachalinensis in wet sandy or muddy soil conditions was at the same level as that in dry gravelly sites. In contrast, ectomycorrhizal colonization of C. arbutifolia seedlings was lower from wet sandy sites than that from dry gravelly sites. In all study sites, the same three morphological types of ectomycorrhizas were dominant.     

内蒙古地区白桦外生菌根形态类型及分子鉴定

以内蒙古不同地区白桦外生菌根为材料,采用形态解剖学方法和分子生物学手段对与白桦共生的外生菌根真菌多样性进行全面的调查,并经对所测序列与GenBank和Database比对。结果显示:在内蒙古地区与白桦共生的外生菌根真菌共13种,其中担子菌7种,子囊菌4种,分别来自于丝膜菌属、丝盖伞属、蜡壳耳属、毛革菌属、滑菇属和空团菌属、块菌属、地怀菌属。其中,菌根类型T₈和T₁₁未能提出其总DNA,根据其外生菌根形态类型并参照Agerer体视显微镜菌根图谱和Haug菌根图谱进行比较,分类鉴定为荷顿氏疣柄牛肝菌和白桦外生菌根真菌一种。结果表明,内蒙古地区白桦外生菌根真菌多样性相对较高,且与利用地上子实体鉴定的外生菌根真菌种类有一定的区别。     

Inoculation and field testing of Sitka spruce and Douglas fir with ectomycorrhizal fungi in the United Kingdom

Picea sitchensis and Pseudotsuga menziesii seedlings were grown in containers, inoculated with ectomycorrhizal fungi, and planted in British forestry sites. Root samples taken during the year after planting were assessed for mycorrhiza formation. Survival and shoot height were assessed at the end of each year. Observations were made each autumn on the occurrence of sporophores of ectomycorrhizal fungi. Pot experiments were used to assess the colonization potential of soils from the experimental locations. Assessment of mycorrhiza formation by the inoculant fungi both before planting and the following year showed much variation among the fungi used. Similar variation was found among field sites. Inoculation with Laccaria isolates was most successful. Height measurements are reported for the first 2 years after planting, at which time there were few significant effects on growth of Picea sitchensis or Pseudotsuga menziesii seedlings. Experimental assessment of colonization potential was of little value in this work for predicting events in the forest.     

Influence of aluminum on in vitro formation of Pinus caribaea mycorrhizae

The ability of Pinus caribaea var. hondurensis to form mycorrhizae was determined in vitro with seven species of ectomycorrhizal fungi in the presence of six levels of Al (added as AlCl₃) in a nutrient solution. The time required for mycorrhizal formation, the number of mycorrhizal root tips and the percent mycorrhizae were measured after 15, 30, 60, 90 and 120 days. Cenococcum graniforme was susceptible to Al toxicity at all Al concentrations. Pisolithus tinctorius and Suillus sp. were depressed at lower but stimulated at higher Al concentrations. The inverse was shown for Rhizopogon reaii and Hebeloma cylindrosporum. Tolerance to Al was verified for R. nigrescens and H. crustuliniforme. Pisolithus tinctorius had the largest mycorrhizal capacity, defined as the sum of the values for time, percent and number of mycorrhizae. Ectomycorrhizal fungi appeared to ameliorate Al damage to plant roots even in treatments where no mycorrhizae formed. Inoculation of pine seedlings with Al-tolerant mycorrhizal fungi is likely to improve reforestation efforts in highly-weathered tropical soils.     

Tree regeneration patterns on Mount Usu, northern Japan, since the 1977–78 eruptions

Although the summit of Mount Usu was deforested by the 1977–78 eruptions, vegetative regeneration on the caldera rim was rapid due to the erosion of thick volcanic deposits by snow and rain. To obtain the mechanisms underlying regeneration patterns after the eruptions, we monitored the growth of permanently-marked stems from 1983 to 1990. Regeneration was from resprouting-branches buried in the volcanic deposits on the caldera rim, while on the crater basin, where thick volcanic deposits accumulated, regeneration was from seedlings. The seedling regeneration lagged approximately 3 years behind vegetative regeneration. Stem densities averaged 14,000 ha^-1 in the vegetatively-regenerated community on the caldera rim, and 28,000 ha^-1 in the seedling regeneration on the crater basin. Populus maximowiczii accounted for ca. 75% of total stems on the caldera rim, while P. maximowiczii accounted for ca. 30% on the crater basin where Salix integra and Betula platyphylla var. japonica were also common. In both stands, immigration and mortality rates were very low. The growth of vegetatively regenerated stems expressed as stem height and diameter was significantly faster than that of stems grown from seedlings. Herbivory damage on the terminal shoots of tall stems was restricted on the caldera rim and was restricted for B. platyphylla var. japonica on the crater basin, perhaps due to fast growth supporting herbivore avoidance or low palatability. Height growth was restricted when neighbors established in close proximity, especially in the seedling-regenerated forest. The results suggest that vegetative regeneration is rapid due to three mechanisms: 1) faster plant growth; 2) herbivore avoidance; and 3) decreased interference by neighboring.     

Ectomycorrhizal synthesis on seedlings of Afzelia quanzensis Welw. using various types of inoculum

Ectomycorrhizal synthesis on seedlings of Afzelia quanzensis was initiated in the greenhouse and in the field using basidiospores or soil inoculum originating from fungi associated with adult trees of A. quanzensis, Brachystegia microphylla, B. spiciformis, and Julbernardia globiflora. Of the spore inocula used, only a Pisolithus sp. associated with adult A. quanzensis formed mycorrhizae. Seedlings raised in contact with all soil inocula formed mycorrhizae; however, the mycorrhizal types formed differed between soil inoculum used in the greenhouse and soil inoculum directly used in the field. A. quanzensis has a low specificity for mycorrhizal association. The concepts of ectomycorrhizal succession are also applicable to African savanna ecosystems.     

The effects of heat treatments on ectomycorrhizal resistant propagules and their ability to colonize bioassay seedlings

The effect of disturbance on the resistant propagule community (RPC) of ectomycorrhizal fungi has been given relatively little attention. In this study we investigate the effects of heat, one important factor of fire disturbances, on the ability of ectomycorrhizal RPC fungi to colonize Pinus jeffreyi seedlings in greenhouse bioassays. Prior to planting the seed, soils were collected from an old growth mixed-conifer forest in the southern Sierra Nevada, California, USA and then subjected to four heat treatments of none, 45 °C, 60 °C, and 75 °C. After eight months, seedlings were harvested and the ectomycorrhizal fungi colonizing the roots were characterized by molecular methods (PCR-RFLP and DNA sequencing). Rhizopogon species increased in dominance on seedlings grown in soils receiving the 75 °C heat treatment. One species significantly increased in frequency, Rhizopogon olivaceotinctus, and two species (Cenococcum geophilum and Wilcoxina sp.) significantly decreased in frequency in the 75 °C treatment. The increase of R. olivaceotinctus, coupled with other features of its behavior, suggests that substantial heat disturbances may benefit this species in competing for roots.     

Survival of inoculated Laccaria bicolor in competition with native ectomycorrhizal fungi and effects on the growth of outplanted Douglasfir seedlings

The survival, development and mycorrhizal efficiency of a selected strain of Laccaria bicolor along with naturally occurring ectomycorrhizal fungi in a young plantation of Douglas fir was examined. Symbionts were identified and their respective colonization abilities were determined. Eight species of symbiotic fungi, which may have originated in adjacent coniferous forests, were observed on the root systems. Mycorrhizal diversity differed between inoculated (5 taxa) and control (8 taxa) seedlings. Ectomycorrhizal fungi which occurred naturally in the nursery on control seedlings (Thelephora terrestris and Suillus sp.) did not survive after outplanting. Both inoculated and naturally occurring Laccaria species, as well as Cenococcum geophilum, survived on the old roots and colonized the newly formed roots, limiting the colonization by other naturally occurring fungi. Other fungi, such as Paxillus involutus, Scleroderma citrinum and Hebeloma sp. preferentially colonized the old roots near the seedling's collar. Russulaceae were found mainly in the middle section of the root system. Mycorrhizal colonization by Laccaria species on inoculated seedlings (54%) was significantly greater than on controls (13%) which were consequently dominated by the native fungi. Significant differences (up to 239%) were found in the growth of inoculated seedlings, especially in root and shoot weight, which developed mainly during the second year after outplanting. Seedling growth varied with the species of mycorrhizae and with the degree of root colonization. Competitiveness and effectiveness of the introduced strain on improving growth performances of seedlings are discussed.     

Hyphal mats formed by two ectomycorrhizal fungi and their association with Douglas-fir seedlings: A case study

The ectomycorrhizal fungi Gautieria monticola and Hysterangium setchellii both form dense hyphal mats in coniferous forest soils of the Pacific Northwest. We recently observed that all Douglas-fir seedlings found under the canopy of a maturing 60–75 year stand were associated with mats formed by ectomycorrhizal fungi. The significance of these mat communities in relation to seedling establishment and survival is discussed.     

Response of ectomycorrhizalPinus banksiana andPicea glauca to heavy metals in soil

Pinus banksiana andPicea glauca inoculated or not with the ectomycorrhizal fungusSuillus luteus were grown in a sandy loam soil containing a range of Cd, Cu, Ni, Pb and Zn concentrations. Ectomycorrhizal colonization rates were significantly reduced on Pinus and Picea seedlings by the heavy metals, particularly Cd and Ni. Needle tissue metal concentrations were lower in ectomycorrhizal seedlings at low soil metal concentrations. However, at higher soil concentrations, heavy metal concentrations of needle tissue were similar in ectomycorrhizal and nonmycorrhizal plants. The growth of nonmycorrhizal seedlings exposed to heavy metals was reduced compared to those inoculated withSuillus luteus. Apparently ectomycorrhizal colonization can protect Pinus and Picea seedlings from heavy metal toxicity at low or intermediate soil concentrations of Cd, Cu, Ni, Pb and Zn.     

Species-specific measurements of ectomycorrhizal turnover under N-fertilization: combining isotopic and genetic approaches

Ectomycorrhizal fungi play a significant role in the transfer of nutrients between plant and soil pools. Here we combine natural abundance ¹⁴C measurements with restriction fragment length polymorphism (RFLP) to study the effects of nitrogen fertilization on the residence time of carbon within ectomycorrhizal species. We show that the carbon in ectomycorrhizal fungi turns over every 4–5 years, indicating that these fungi are relatively long-lived. Moreover, ectomycorrhizal fungi responded in a species-specific way to fertilization. Cenococcum geophilum contained younger carbon on average in nitrogen-fertilized plots than in control plots, even though turnover rates of the community as a whole did not shift significantly. Our results suggest that the response of ectomycorrhizal fungi to N availability is complex, and alterations in tissue turnover within this microbial pool may vary depending on community structure.     

Photosynthetic responses of birch and alder saplings grown in a free air CO2 enrichment system in northern Japan

Though birch and alder are the common pioneer tree species which dominate in northeast Asia, little is known about the effects of the predicted increase in atmospheric CO₂ concentrations ([CO₂]) upon their photosynthesis in field conditions. To investigate this, we grew 2-year-old saplings of three Betulaceae species (Betula platyphylla var. japonica Hara, Betula maximowicziana Regel, and Alnus hirsuta Turcz) for 2 years in a free air CO₂ enrichment system in northern Japan. Since the effect of high [CO₂] is known to depend on soil conditions, we evaluated the responses in two soils which are widely distributed in northern Japan: infertile and immature volcanic ash (VA) soil, and fertile brown forest (BF) soil. For B. platyphylla, photosynthetic down-regulation occurred in both soils, but for B. maximowicziana, down-regulation occurred only in VA soil. The explanation is reduced nitrogen and Rubisco content in the leaf. For A. hirsuta, down-regulation occurred only in BF soil because of the accumulation of starch in foliage, which restricts CO₂ diffusion inside the chloroplast. The higher photosynthetic rate of A. hirsuta in infertile VA soil could be due to the sink for photosynthates in the N₂-fixing symbiont. These three species are all able to down-regulate at high [CO₂]. However, it is possible that A. hirsuta would dominate in VA soil and B. maximowicziana in BF soil in the early stages of forest succession in a CO₂-enhanced world.     

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.     

The feeding preference of mycophagous Collembola varies with the ectomycorrhizal symbiont

The interactions of the collembolan insect Proisotoma minuta with ectomycorrhizal and/or pathogenic fungi was examined in three experiments: (1) in vitro analysis of feeding patterns, (2) in vitro food preference test, and (3) in situ analysis of ectomycorrhizal colonization in relation to population density. The ectomycorrhizal fungi Laccaria laccata, Pisolithus tinctorius, Suillus luteus, Thelephora terrestris and the pathogenic fungi Rhizoctonia solani were employed in all experiments. In vitro and in situ experiments revealed that Pr. minuta consumed all the ectomycorrhizal fungi tested but the feeding pattern and consumption varied with each isolate. In a comparative in vitro feeding preference test, where Pr. minuta was given a choice, R. solani was grazed more heavily than the ectomycorrhizal fungi. Among the ectomycorrhizal fungi examined, Pi. tinctorius was consumed significantly less than L. laccata, S. luteus or T. terrestris in the presence of R. solani. A 10-week in situ analysis of loblolly pine (Pinus taeda L.) seedling root systems inoculated with Pr. minuta revealed that ectomycorrhizal colonization was significantly less than that of control plants (without Pr. minuta). Collectively, these data suggest that mycophagous Collembola may play a major role in the distribution and biomass of ectomycorrhizal fungi in the rhizosphere of tree seedlings.     

Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern Japan

Aim Information has been compiled on disturbance regimes and the life‐history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species. Location The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan. Methods First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life‐history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed‐bank formation, size and age at reproduction, and the life span of canopy trees. Results Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old‐growth forests. As typical pioneers, the two species showed similar life‐history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age‐related characteristics such as minimum age of reproduction and life span. Main conclusions The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old‐growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank.     

三种松树内生真菌的分离鉴定及其对红脂大小蠹伴生真菌的拮抗作用

【背景】松树的内生真菌会影响红脂大小蠹及其伴生真菌的生长及扩散,从而影响红脂大小蠹的入侵。【目的】掌握赤峰地区红脂大小蠹寄主树种内生真菌的物种多样性,筛选对其伴生菌有拮抗作用的菌株,为红脂大小蠹的生物防治提供资源。【方法】采用组织分离法、形态学鉴定和internal transcribed spacer (ITS)序列分析相结合的方法对红脂大小蠹寄主树种油松、樟子松和潜在寄主落叶松进行内生真菌多样性研究,并用两点对峙法进行拮抗菌株筛选。【结果】松树内生真菌鉴定为2门6纲10目18科19属,其中落叶松韧皮部分离到的内生真菌数量最多,为39株,隶属于9属12种,真菌检出率为43.33%;油松次之,为30株,隶属于7属8种,真菌检出率为33.33%;樟子松最少,为29株,隶属于10属13种,真菌检出率为32.22%。3个树种的内生真菌相似性较低,无共有的菌种,青霉属(Penicillium)和篮状菌属(Talaromyces)是唯二的共有菌属,且青霉属在3个树种中均为优势菌属。平板对峙结果表明90%以上的树木内生真菌均能够与伴生真菌形成稳定的对峙,抑制率在50%-86%之间,且Phialocephala sp.和Pochonia bulbillosa对伴生菌的抑制率能高达93.7%。【结论】松树韧皮部的内生真菌具有较高的生防潜力,Phialocephala sp.和P. bulbillosa对红脂大小蠹伴生菌有较好的抑制效果,可作为红脂大小蠹的生防资源。     

Effects of P fertilisation and ectomycorrhizal fungal inoculation on early growth of eucalypt plantations in southern China

Eucalypt plantations in China have largely been established on soils that are low in phosphorus (P) and have few eucalypt-compatible ectomycorrhizal fungi. Effects of P application and ectomycorrhizal fungal inoculation on early tree growth in plantations of Eucalyptus urophylla Blake in Guangdong (Gaoyao) and E. globulus Labill. in Yunnan (Chuxiong) in southern China were investigated as part of a larger study. Application of superphosphate at establishment, in the presence of a basal fertiliser, increased early growth of E. urophylla and E. globulus. The optimum treatments for maximum stand volume at year 3 were 200 kg P ha^–1 which increased stand volume by 750% on the strongly acidic, P-deficient lateritic red oxisol at Gaoyao, and 40 kg P ha^–1 which increased stand volume by 55% on the mildly P-deficient red ultisol at Chuxiong, at 3 years. Superphosphate increased tree survival at Gaoyao as well as at Chuxiong. Nursery inoculation of eucalypt seedlings with ectomycorrhizal fungi significantly affected tree height and stand volume of the E. urophylla plantation, but the effect (positive or negative) was isolate-dependent and related to tree survival rate. A Laccaria isolate (CSIRO E4728) significantly increased stand volume by 27% at Gaoyao and a Scleroderma (MURU LH041) increased growth by 15% at Chuxiong at age 3 years. All isolates increased tree growth under P-limited soil conditions and only one isolate increased tree growth at marginal soil P. The results suggest that tree growth should be able to be optimised in plantations by the use of effective ectomycorrhizal fungi combined with a judicious fertilisation program at establishment.     

Vesicular endophytes in roots of the Pinaceae

Vesicles and hyphae typical of vesicular-arbuscular mycorrhizae (VAM) were common in seedlings of Pseudotsuga menziesii, Abies lasiocarpa and Tsuga mertensiana growing in openings where herbaceous hosts of these fungi were common. Seedlings of A. lasiocarpa, Tsuga heterophylla, and T. mertensiana growing under closed forest canopies also had vesicles but at a much lower incidence than seedlings in the openings. The Pinaceae are generally assumed to be ectomycorrhizal, but Glomus-type colonizations occurred on the same seedlings as the ectomycorrhizae. The ecological significance of abundant VAM-type endophytes in otherwise ectomycorrhizal hosts deserves comprehensive study.