Arbuscular mycorrhizal fungi in non-grazed,restored and over-grazed grassland in the Inner Mongolia steppe

Arbuscular mycorrhizal (AM) fungal diversity was investigated in non-grazed, restored and over-grazed (fenced) plots of a grassland in the Inner Mongolia steppe. Plant cover and variety differ between the plots, being highest in the non-grazed to lowest in the over-grazed plots. A total of 19 AM fungal taxa belonging to six genera were found based on spores isolated from field samples and trap cultures. One belonged to Acaulospora, one to Archaeospora, one to Entrophospora, one to Gigaspora, 12 to Glomus and three to Scutellospora. Glomus was the dominant genus in all plots, and Glomus geosporum was the dominant species, whilst G. albidum and G. etunicatum were dominant in the restored plot. Scutellospora was the second dominant genus in the non-grazed plot with Scutellospora calospora being the dominant species. The mean spore density and mean species richness of AM fungi were significantly decreased by long-term over-grazing. The Sorenson’s similarity coefficients of AM fungal community composition ranged from 0.5 to 0.64 among the three types of plot management. The results suggest that the AM fungal diversity is greatly affected by long-term over-grazing and that fencing of degraded areas partly restores plant cover and AM fungal diversity in grassland ecosystems.     

Mechanical soil disturbance as a determinant of arbuscular mycorrhizal fungal communities in semi-natural grassland

While the effect of disturbance on overall abundance and community composition of arbuscular mycorrhizal (AM) fungi has been researched in agricultural fields, less is known about the impact in semi-natural grasslands. We sampled two AM plant species, Festuca brevipila and Plantago lanceolata, from an ongoing grassland restoration experiment that contained replicated plowed and control plots. The AM fungal community in roots was determined using nested PCR and LSU rDNA primers. We identified 38 phylotypes within the Glomeromycota, of which 29 belonged to Glomus A, six to Glomus B, and three to Diversisporaceae. Only three phylotypes were closely related to known morphospecies. Soil disturbance significantly reduced phylotype richness and changed the AM fungal community composition. Most phylotypes, even closely related ones, showed little or no overlap in their distribution and occurred in either the control or disturbed plots. We found no evidence of host preference in this system, except for one phylotype that preferentially seemed to colonize Festuca. Our results show that disturbance imposed a stronger structuring force for AM fungal communities than did host plants in this semi-natural grassland.     

Inner Mongolian steppe arbuscular mycorrhizal fungal communities respond more strongly to water availability than to nitrogen fertilization

Plant community productivity and species composition are primarily constrained by water followed by nitrogen (N) availability in the degraded semi‐arid grasslands of Inner Mongolia. However, there is a lack of knowledge on how long‐term N addition and water availability interact to influence the community structure of arbuscular mycorrhizal (AM) fungi, and whether AM fungi contribute to the recovery of degraded grasslands. Soils and roots of the dominant plant species Stipa grandis and Agropyron cristatum were sampled under two water levels and N) rates after 8 years. The abundance and diversity of AM fungi remained relatively resilient after the long‐term addition of water and N. Variation in the AM fungal communities in soils and roots were affected primarily by watering. AM fungal abundance and operational taxonomic unit (OTU) richness were significantly correlated with average aboveground net primary productivity and biomass of plant functional groups. Hyphal length density was significantly correlated with plant richness, the average biomass of S. grandis and perennial forbs. Both water and plant biomass had a considerable influence on the AM fungal assemblages. The tight linkages between AM fungi with aboveground plant productivity highlight the importance of plant–microbe interactions in the productivity and sustainability of these semi‐arid grassland ecosystems.     

青藏高原高寒草地AM真菌分布及其对近自然恢复的生态作用

超载过牧以及全球气候变化等导致大部分青藏高原高寒草地呈现持续退化态势。青藏高原高寒草地退化致使地上植物群落逐渐发生更替,地下土壤微生物群落多样性和丰富度发生改变。本文旨在探析青藏高原高寒草地丛枝菌根（arbuscular mycorrhizal,AM）真菌的分布特征、对近自然恢复的生理生态效应及其作用机制。青藏高原高寒草地中已报道4目14属61种AM真菌,约占已知AM真菌物种的20%。高寒草地禾本科植物根围AM真菌物种丰度最高,而莎草科植物根围AM真菌孢子密度最高。3种高寒草地植被类型中,高寒草原AM真菌丰度最高（33种）,山地灌丛草原次之（32种）,高寒草甸最低（22种）。高寒草原以光壁无梗囊霉Acaulospora laevis和闪亮和平囊霉Pacispora scintillans为优势种,山地灌丛草原以摩西斗管囊霉Funneliformis mosseae为优势种,高寒草甸以光壁无梗囊霉A. laevis、近明球囊霉Claroideoglomus claroideum和闪亮和平囊霉P. scintillans为优势种。高寒草地土著AM真菌与植物构建的菌根网络可以通过调节营养元素吸收、分配,促进植物建植和生长;但是毒杂草入侵可以改变土著AM真菌物种多样性和菌根网络,限制本地植被的实际生态位扩张。退化高寒草地中,AM真菌群落具有高的环境适应性和恢复力,其不仅调控地上植物群落建植和多样性,同时AM真菌建植也增加了代谢产物-球囊霉素相关土壤蛋白产生,进而协同改善地下土壤微生态系统,为退化高寒草地早期植被恢复塑造土壤生境。因此,AM真菌在退化高寒草地近自然恢复中具有较大的应用潜力。     

Occurrence and distribution of arbuscular mycorrhizal fungal species in three types of grassland community of the Tibetan Plateau

Arbuscular mycorrhizal (AM) fungal spore communities and distribution patterns were surveyed in montane scrub grassland, alpine steppe, and alpine meadow sites at altitudes ranging from 3,500 to 5,200 m a.s.l. on the Tibetan Plateau. Thirty-two representative soil samples were collected from the root zone of the dominant and common plant species in late May 2004. Twenty-three AM fungal species representing six genera (Acaulospora, Entrophospora, Glomus, Pacispora, Paraglomus, and Scutellospora) were detected and species richness varied from 5.3 ± 0.8 to 10.5 ± 2.5 per site. Some AM fungal species were restricted to one vegetation type and Glomus mosseae, Glomus intraradices, and Scutellospora calospora were detected in all three vegetation types. Glomus species were found to be the most frequent and abundant in all three vegetation types. Acaulospora occurred mostly in the alpine steppe and alpine meadow. Scutellospora occurred mostly in montane scrub grassland. At the species level, Glomus mosseae was dominant in the montane scrub, Acaulospora laevis and Pacispora scintillans were dominant in the alpine steppe, and Acaulospora laevis, Pacispora scintillans, and Glomus claroideum dominated the alpine meadow. It was evident from the distribution pattern of AM fungi in the different vegetation types that the abundance and diversity of AM fungal species were lowest in the montane scrub grassland than the other two plant communities. Climatic conditions, especially temperatures, and intensity of land use may be the most important factors influencing the AM fungal community.     

Defoliation effects on the community structure of arbuscular mycorrhizal fungi based on 18S rDNA sequences

The effects of defoliation on arbuscular mycorrhizal (AM) associations in the field were investigated in terms of the community structure of AM fungi colonizing roots of grassland plants; the carbohydrate balance of the host plants was also determined. We focused on two plant species dominating Japanese native grasslands: the grazing-intolerant species Miscanthus sinensis and the grazing-tolerant species Zoysia japonica. Community structures of AM fungi were determined from 18S rRNA gene sequences. The dominant fungal group in both plant species was the Glomus clade, which was classified into several phylogenetic groups based on genetic distances and topology. In Miscanthus roots, the Glomus-Ab, Glomus-Ac, and Glomus-Ad groups were detected almost equally. In Zoysia roots, the Glomus-Ab group was dominant. Defoliation effects on the community structure of AM fungi differed between the plant species. In Miscanthus roots, the percentage of root length colonized (%RLC) by the Glomus-Ac and Glomus-Ad groups was significantly reduced by defoliation treatment. On the other hand, AM fungal group composition in Zoysia roots was unaffected by defoliation except on the last sampling date. Decreased %RLC by Glomus-Ac and Glomus-Ad coincided with decreased non-structural carbohydrate (NSC) levels in host plants; also, significant positive correlations were found between the %RLC and some NSC levels. On the other hand, the %RLC by Glomus-Ab in both plant species was unaffected by the NSC level. These results suggest that AM fungal groups have different carbohydrate requirements from host plants.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00572-003-0286-x     

Plant functional diversity enhances associations of soil fungal diversity with vegetation and soil in the restoration of semiarid sandy grassland

The trait‐based approach shows that plant functional diversity strongly affects ecosystem properties. However, few empirical studies show the relationship between soil fungal diversity and plant functional diversity in natural ecosystems. We investigated soil fungal diversity along a restoration gradient of sandy grassland (mobile dune, semifixed dune, fixed dune, and grassland) in Horqin Sand Land, northern China, using the denaturing gradient gel electrophoresis of 18S rRNA and gene sequencing. We also examined associations of soil fungal diversity with plant functional diversity reflected by the dominant species' traits in community (community‐weighted mean, CWM) and the dispersion of functional trait values (FD_is). We further used the structure equation model (SEM) to evaluate how plant richness, biomass, functional diversity, and soil properties affect soil fungal diversity in sandy grassland restoration. Soil fungal richness in mobile dune and semifixed dune was markedly lower than those of fixed dune and grassland (P < 0.05). Soil fungal richness was positively associated with plant richness, biomass, CWM plant height, and soil gradient aggregated from the principal component analysis, but SEM results showed that plant richness and CWM plant height determined by soil properties were the main factors exerting direct effects. Soil gradient increased fungal richness through indirect effect on vegetation rather than direct effect. The negative indirect effect of FDis on soil fungal richness was through its effect on plant biomass. Our final SEM model based on plant functional diversity explained nearly 70% variances of soil fungal richness. Strong association of soil fungal richness with the dominant species in the community supported the mass ratio hypothesis. Our results clearly highlight the role of plant functional diversity in enhancing associations of soil fungal diversity with community structure and soil properties in sandy grassland ecosystems.     

长期围封对不同放牧强度下草地植物和AM真菌群落恢复的影响

为探明人为干扰对草地生态系统生态恢复的影响,以不同放牧强度试验草地为研究对象,调查了围封14a后草地植物群落的多样性,并应用第二代高通量测序技术454测序法分析了植物根际土壤中AM真菌的群落结构。研究结果显示,14a围封保育使得不同放牧强度小区与长期封育小区植被盖度及植物多样性指数基本恢复至同一水平。土壤速效磷含量在重度放牧小区最低(1.00 mg/kg),轻度放牧区最高(2.25 mg/kg),其它土壤理化性质指标在不同小区之间没有显著差异。通过分子鉴定发现所有土壤样品中AM真菌共有87个分类单元(VT),隶属于Diversispora、Otospora、Scutellospora、Glomeraceae Glomus、Rhizophagus、Paraglomus和Archaeospora等7个属。对不同放牧强度小区AM真菌进行多样性分析,结果表明长期封育小区AM真菌Shannon多样性指数和Pielou均匀度指数最低,且显著低于中度放牧区,而AM真菌多样性在各放牧小区之间差异不显著。本研究表明长期围封可以有效促进退化草地植物群落的恢复,而AM真菌表现出与植物群落恢复的不同步性。对于草地生态系统退化及恢复过程中植物和土壤功能微生物类群的协同关系还需要进一步系统深入的研究。     

Distribution of dominant arbuscular mycorrhizal fungi among five plant species in undisturbed vegetation of a coastal grassland

Most plant species in mixed grassland vegetation are colonized by arbuscular mycorrhizal (AM) fungi. Previous studies have reported differences in host preferences among AM fungi, although the fungi are known to lack host specificity. In the present study, the distribution of phylogenetic groups of AM fungi belonging to a clade of Glomus species was studied in five plant species from a coastal grassland in Denmark. The occurrence of the fungi was determined by PCR analyses of fungal large subunit ribosomal DNA sequences amplified from root fragments using a specific primer set. The results showed that the dominant Glomus species were able to colonize all the studied plant species, supporting the view that the AM fungi represent a large underground interconnecting mycelial network.     

Communities of arbuscular mycorrhizal fungi in grassland: Seasonal variability and effects of environment and host plants

The seasonal dynamics of a community of endomycorrhizal fungal morphotypes in the roots of three grassland species (Achillea millefolium, Poa angustifolia, Plantago lanceolata) was evaluated, together with the effects of experimental treatment (mowing and phosphorus application) and the host plant properties. Strong seasonal variability was found in the fungal community, where clear seasonal patterns can be distinguished for several fungal morphotypes. The sampling date explained 20 to 30% of the total compositional variability for all three host species. ThePlantago roots host the highest number of arbuscular mycorrhizal (AM) fungal populations. There are two co-dominant fungal morphotypes inAchillea roots (assigned to the generaScutellospora andGlomus) and only one strongly dominant morphotype (assigned toGlomus), in thePoa roots. All three host species have a comparable pattern of richness of AM morphotypes with a single peak in the summer, possibly aligned with the flowering time of the host.     

AM Fungal Diversity in Selected Medicinal Plants of Kanyakumari District,Tamil Nadu,India

The association of Arbuscular Mycorrhizal Fungi (AMF) with three medicinally important plants viz., Eclipta prostrata, Indigofera aspalathoides, I. tinctoria collected from three different localities of Kanyakumari District, South India was examined. The study reports the colonization percentage, diversity and species richness of different AM fungi in the rhizosphere of the three medicinal plants and discusses the impact of soil physicochemical characteristics such as soil texture, pH and available macro- and micro nutrient content on AM fungal communities. A total 21 AM fungal species were identified in field conditions of the three plants from three sites. AM fungal species richness, colorization percentage and Shannon index were found to be high in the two Indigofera sp. growing in the hilly areas of Kanyakumari District and were low in E. prostrata collected from the damp regions in the foothills of the three study sites. Five species registered 100% frequency in all the study sites of the three medicinally important plants with Glomus as the dominant genera. The study states that the mean colonization and diversity patterns were dependant on edaphic factors and type of vegetation.     

Arbuscular mycorrhizal fungi associated with sedges on the Tibetan plateau

The arbuscular mycorrhizal (AM) status of nine dominant sedge species and the diversity of AM fungi in Tibetan grassland were surveyed in the autumn of 2003 and 2004. Most of the sedge species and ecotypes examined were mycorrhizal, but Carex moorcroftii and Kobresia pusilla were of doubtful AM status, and Kobresia humilis was facultatively mycorrhizal. This is the first report of the mycorrhizal status of eight of the nine sedge species examined. Intraradical vesicles and aseptate hyphae were the structures most frequently observed. Appressoria, coils, and arbuscules were found in the roots of a few sedge species. A strong negative correlation was found between soil organic matter content and the extent of mycorrhizal colonization. Using trap cultures, 26 species of AM fungi belonging to six genera, Glomus, Acaulospora, Paraglomus, Archaeospora, Pacispora, and Scutellospora, were isolated from the soil samples collected. The frequency of occurrence of different taxa of AM fungi varied greatly. Glomus and Acaulospora were the dominant genera, and Acaulospora scrobiculata was the most frequent and abundant species. The species richness of AM fungi was 2.73 in the study area. Species richness and diversity index differed among the sedge species but were not correlated with soil factors such as pH, available P, or organic matter content.     

Low congruence between the diversity of Waxcap (Hygrocybe spp.) fungi and vascular plants in semi-natural grasslands

The diversity of fungi in semi-natural grasslands is poorly known, partly due to difficulties in species identification in the field but also because there are few specialists available. Diversity assessments of grassland fungi would be facilitated if a potential surrogate group for fungal diversity could be identified. The aim of this study was to assess whether plant diversity patterns in semi-natural grasslands are congruent with diversity patterns of Waxcap (Hygrocybe spp.) fungi. Waxcaps, together with several other groups of fungi (e.g. the genera Entoloma, Dermoloma, Camarophyllopsis, and the families Clavariaceae and Geoglossaceae) have habitat requirements similar to many plants typical for semi-natural grasslands and they are all threatened by ceased management and nutrient enrichment. Diversity data from 31 semi-natural grasslands in southern Sweden were used to examine if there is congruence in species richness, nestedness, β-diversity and species composition between plants and Hygrocybe fungi. Species richness of Hygrocybe was significantly positively correlated with plant richness, although the relationship was not strong (r²=0.14). Both plant and Hygrocybe species composition was significantly nested, i.e. species-poor sites contain a subset of species from species-rich sites, which suggests that rare species mostly occur in the species-rich sites. A species similarity analysis between the grassland sites showed that there is low overlap between species composition of plants and Hygrocybe, indicating that conservation decisions based solely on plants may not fulfil the requirements of the Hygrocybe species. The conclusion is that there is low congruence between plant and Hygrocybe species diversity, making plants a poor surrogate group for Hygrocybe fungi, and probably also for other grassland fungi.     

不同生境下川麦冬根围土壤丛枝菌根真菌多样性北大核心CSCD

采用高通量(Illumina Miseq)测序技术对栽培和野生2种生境下川麦冬根围的丛枝菌根(AM)真菌多样性和群落结构进行测定,并结合土壤理化因子进行相关性分析,以明确两种生境下川麦冬根围土壤AM真菌多样性和优势群落的分布特点,探讨AM真菌群落分布差异的驱动因子,为AM真菌应用于麦冬生产提供理论依据和技术支持。结果表明:(1)不同生境下川麦冬根围土壤中共鉴定出AM真菌3属10种,其中野生川麦冬根围土壤鉴定出的AM真菌3属7种,分别隶属于无梗囊霉属(Acaulospora)、多孢囊霉属(Diversispora)和球囊霉属(Glomus),而栽培环境下鉴定出AM真菌1属6种,隶属于球囊霉属。2个生境优势属均为球囊霉属。(2)不同生境下川麦冬根围AM真菌之间存在显著差异,野生生境下川麦冬根围土壤AM真菌多样性指数ACE和Shannon均显著高于人工栽培生境,而Simpson指数则相反。(3)相关性分析表明,AM真菌多样性指数及群落组成结构均与土壤理化因子存在相关性,其中全钾(TK)、全磷(TP)、全氮(TN)对AM真菌多样性指数和群落结构组成均存在显著影响。研究认为,不同生境下川麦冬根围AM真菌群落存在显著差异,球囊霉属为川麦冬互利共生的关键属,TK、TP、TN是不同生境川麦冬根围AM真菌群落差异的主要驱动因子。     

Arbuscular mycorrhizal fungi associated with common pteridophytes in Dujiangyan,southwest China

The colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with common pteridophytes were investigated in Dujiangyan, southwest China. Of the 34 species of ferns from 16 families collected, 31 were colonized by AM fungi. The mean percentage root length colonized was 15%, ranging from 0 to 47%. Nineteen species formed Paris-type and 10 intermediate-type AM. In two ferns, only rare intercellular non-septate hyphae or vesicles were observed in the roots and AM type could not be determined. Of the 40 AM fungal taxa belonging to five genera isolated from rooting-zone soils, 32 belonged to Glomus, five to Acaulospora, one to Archaeospora, one to Entrophospora, and one to Gigaspora. Acaulospora and Glomus were the dominant genera and Glomus versiforme was the most common species. The average AM spore density was 213 per 100 g air-dried soil and the average species richness was 3.7 AM species per soil sample. There was no correlation between spore density and percentage root length colonized by AM fungi.     

Arbuscular mycorrhizal and dark septate endophyte fungal associations in South Indian grasses

We examined arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal association in 50 south Indian grasses from four different sites. AM fungal diversity was also compared among the different sites. Forty-four of the 50 grasses examined had AM association and dual association with DSE fungi occurred in 25 grasses. We report for the first time AM and DSE fungal status in 23 and 27 grasses respectively. Arum-type AM morphology was the dominant occurring in 21 grasses with typical Paris-type colonization occurring in 6 grasses. AM morphology is reported for the first time in 35 grasses. Over the different sites, spore density in the soil ranged from 5–22 per 100 g air-dried soil. Spores of 11 AM fungal taxa were isolated from the soil samples of grasses of which nine belonged to Glomus, one to Acaulospora and one to Scutellospora. No significant relationship existed between AM fungal colonization and spore numbers. Species richness was high in site II and Glomus aggregatum, Glomus viscosum and Glomus mosseae were most frequent species at different sites. Overall species diversity indices (Simpson index, Shannon-Weaver index, species equitability index) differed significantly between sites.     

Arbuscular mycorrhizal fungi associated with the Meliaceae on Hainan island, China

Species richness, spore density, frequency of occurrence, and relative abundance of AM fungi were determined in rhizosphere soil samples from nine tropical rainforest sites on Hainan island, south China, and the arbuscular mycorrhizal (AM) status of members of the Meliaceae was examined. All 28 plant taxa investigated (25 species including two varieties of 1 species and three varieties of another) were colonized by AM fungi. The mean proportion of root length colonized was 56% (range 10–95%). Vesicles were observed in 27 and hyphal coils in 26 of the 28 plant taxa. Mycorrhizas were of the Paris-type or intermediate-type, with no Arum-type mycorrhizas observed. Species richness of AM fungi varied from 3 to 15 and spore density from 46 to 1,499 per 100 g rhizosphere soil. Of 33 AM fungal taxa in five genera isolated and identified, 18 belonged to Glomus, 9 to Acaulospora, 1 to Entrophospora, 2 to Gigaspora, and 3 to Scutellospora. Acaulospora and Glomus were the dominant genera identified. Glomus claroideum was the taxon most commonly isolated, with a frequency of occurrence of 56.5% and relative abundance of 10.4%. A positive correlation was found between percentage of root length colonization and species richness. However, there was no correlation between spore density and percentage of root length colonized by AM fungi.     

Arbuscular mycorrhizal fungal community structure and diversity in response to long-term fertilization: a field case from China

The influences of different fertilizer treatments on spore community structure and diversity of arbuscular mycorrhizal (AM) fungi (AMF) were investigated in a long-term fertilization experiment with seven treatments: organic manure (OM), half organic manure N plus half fertilizer N (1/2 OMN), fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). Fertilization generally increased the nutrient contained in the fertilizer and treatments with NPK and 1/2 OMN produced the highest crop yields. Thirty-five species of AMF within 6 genera, including 8 previously undescribed species, were recovered. Similarly in all seven treatments, the most abundant genus was Glomus, and followed by Acaulospora. All the fertilization treatments changed AM species composition, and NK treatment had the slightest influence. Fertilization with fertilizers NP, PK and NPK markedly increased AM fungal spore density, while 1/2 OMN, OM and NK treatments showed no significant influences. All the fertilizer treatments, especially OM, significantly decreased species richness and species diversity (Shannon-Weiner index). There were no significant correlations between AM fungal parameters (spore density, species richness and species diversity) and soil properties. The findings indicate that long-term fertilization all can change AM fungal community structure and decrease species diversity, while balanced fertilization with NPK or 1/2 OMN is the most suitable fertilization regime if taking both crop yields and AM species diversity into account.     

Host plant species effects on arbuscular mycorrhizal fungal communities in tallgrass prairie

Symbiotic associations between plants and arbuscular mycorrhizal (AM) fungi are ubiquitous in many herbaceous plant communities and can have large effects on these communities and ecosystem processes. The extent of species-specificity between these plant and fungal symbionts in nature is poorly known, yet reciprocal effects of the composition of plant and soil microbe communities is an important assumption of recent theoretical models of plant community structure. In grassland ecosystems, host plant species may have an important role in determining development and sporulation of AM fungi and patterns of fungal species composition and diversity. In this study, the effects of five different host plant species [Poa pratensis L., Sporobolus heterolepis (A. Gray) A. Gray, Panicum virgatum L., Baptisia bracteata Muhl. ex Ell., Solidago missouriensis Nutt.] on spore communities of AM fungi in tallgrass prairie were examined. Spore abundances and species composition of fungal communities of soil samples collected from patches within tallgrass prairie were significantly influenced by the host plant species that dominated the patch. The AM fungal spore community associated with B. bracteata showed the highest species diversity and the fungi associated with Pa. virgatum showed the lowest diversity. Results from sorghum trap cultures using soil collected from under different host plant species showed differential sporulations of AM fungal species. In addition, a greenhouse study was conducted in which different host plant species were grown in similar tallgrass prairie soil. After 4 months of growth, AM fungal species composition was significantly different beneath each host species. These results strongly suggest that AM fungi show some degree of host-specificity and are not randomly distributed in tallgrass prairie. The demonstration that host plant species composition influences AM fungal species composition provides support for current feedback models predicting strong regulatory effects of soil communities on plant community structure. Differential responses of AM fungi to host plant species may also play an important role in the regulation of species composition and diversity in AM fungal communities. Received: 29 January 1999 / Accepted: 20 October 1999     

Arbuscular mycorrhizal status of spring ephemerals in the desert ecosystem of Junggar Basin, China

A survey was made of the arbuscular mycorrhizal (AM) status of 73 spring ephemeral plant species that grow in the desert ecosystem of Junggar Basin, northwest China. The proportion of AM colonization ranged from 7 to 73% with a mean value of 30%. A total of 65 plant species studied were AM with coils/arbuscules or vesicles and the remaining eight species were possibly AM with no coils/arbuscules or vesicles but with fungal mycelia in the root cortex. AM fungal spores were isolated from rhizosphere samples of all 73 plant species and identified. The mean spore density was 22 per 20 ml of air-dried soil, ranging from 0 to 120. Colonization and spore density of perennials were slightly higher than of annuals and varied among different plant families. A total of 603 AM fungal spore (or sporocarp) specimens were isolated belonging to six genera, Acaulospora, Archaeopora, Entrophospora, Glomus, Paraglomus, and Scutellospora; Glomus was the dominant genus. We conclude that spring ephemerals may be highly dependent on AM associations for survival in the very infertile and arid soils of this desert ecosystem.Electronic supplementary material Supplementary material is available for this article at