Arbuscular Mycorrhizal Infection Research Articles

The influence of spatial patterns of damping‐off disease and arbuscular mycorrhizal colonization on tree seedling establishment in Ghanaian tropical forest soil

Summary Milicia regia (Moraceae) is a dioecious light‐demanding (Pioneer) timber tree of West Africa. Experiments in shadehouses were used to examine the influence of light and soil source (beneath and away from conspecific adults) on mortality and growth of its seedlings in relation to fungal pathogens and arbuscular mycorrhizal (AM) colonization. The experiment in Ghana included treatments for light (2% and 20% of unshaded irradiance), three soil sources (under female, under male and 200 m distant from adults), and two different fungicide treatments. The results showed significant effects of irradiance, soil source and fungicide on both seedling mortality and accumulated biomass. Biomass was greater and mortality reduced at higher irradiance. Fungicide application reduced mortality in 2% irradiance, but had no significant effects at 20%, although AM infection of seedlings grown in soils from beneath adults was severely reduced. Mortality was greatest in soil from beneath female trees and least in soil distant from adult conspecifics. However, biomass in 20% irradiance was greater in soil from beneath females, possibly because of enhanced AM colonization: seedlings had a significantly higher percentage root length colonized by AM fungi beneath adult conspecifics, and biomass accumulation was significantly correlated with root length colonized by AM fungi. There were significant interactions amongst light, soil source and fungicide treatments that attest to the complexity of spatial effects on seedling establishment in tropical forest. Whilst there was clear evidence of pathogen‐mediated effects that provides support for Janzen‐Connell spacing mechanisms, and escape from the parent tree increases the chances of arriving in gaps, spatial differences in AM fungal communities may act in the opposite direction and enhance seedling growth close to adult conspecifics. The complexity of interactions between abiotic and biotic factors and the way in which these factors can vary spatially to affect seedling recruitment may be an important factor contributing to the maintenance of tree species diversity in tropical forests.

Influence of Arbuscular Mycorrhizal Fungus and Kinetin on the Response of Mungbean Plants to Irrigation by Seawater

An experiment was carried out to investigate the effects of pre-inoculation with the mycorrhizal fungus Glomus clarum and foliar application of kinetin on the growth of mungbean plant irrigated wht different dilutions of seawater. Arbuscular-mycorrhizal (AM) infection significantly increased dry weight, height, chlorophyll, sugar and protein content, nitrogen and phosphorus-use efficiencies, leaf conductivity, transpiration rate, nitrogenase, acid and alkaline phosphates activities of all salinized mungbean plants in comparison with control and non-mycorrhizal plants irrespective of the presence or absence of kinetin. Mycorrrhizal plants showed higher concentrations of N, P, K, Ca and Mg and lower Na/N, Na/P, Na/K, Na/Ca and Na/ Mg ratios than non-mycorrhizal plants when irrigated with certain dilutions of seawater Mungbean plants showed 597% and 770% dependency on AM fungus G. clarum in absence and presence of kinetin, respectively, for biomass production under a level of 30% of seawater. The average value of tolerance index for mycorrhizal plants accounted 267% and 364% in absence and presence kinetin respectively. This study provides evidence for the benefits of kinetin which are actually known for mycorrhizal than non-mycorrhzal plants. AM fungus and kinetin protected the host plants against the detrimental effects of salt. However, mycorrhizal infection was much more effective than kinetin applications. Thus management applications of this arbuscular mycorrhizal endophyte (G. clarum) with kinetin could be of importance in using seawater in certain dilutions for irrigation in agriculture.

Comparison of crop yield, soil microbial C, N and P, N-fixation, nodulation and mycorrhizal infection in inoculated and non-inoculated sorghum and chickpea crops

A field experiment was conducted on a clay loam soil to assess the response of crops to inoculation and inorganic and organic fertilizers. Microbial biomass C, N and P under sorghum ( Sorghum bicolor L.) and chickpea ( Cicer arietinum L.) were significantly higher ( r=0.641–0.735, P<0.01) when a combination of Azospirillum brasilense or Rhizobium, Bacillus megaterium and Glomus fasciculatum were used, and was maximum with 50% recommended fertilizers (40 kg N ha −1 and 8.73 kg P ha −1 for sorghum; 10 kg N ha −1 and 8.73 kg P ha −1 for chickpea) along with bioinoculants. Biomass C, N and P in the rhizosphere soil of sorghum–chickpea sequences were greater after 30 days and decreased subsequently (at 60 days or at harvest). A strong correlation ( P<0.01) of biomass C, N and P was observed with N and P uptake of sorghum and chickpea indicating the role of microorganisms in crop response. Azospirillum population in the rhizosphere improved significantly from 38.0 cfu g −1 under recommended fertilizer to 176.8 cfu g −1 under farm yard manure (FYM) and bioinoculants. Nodule dry weight and acetylene reduction activity (ARA) were significantly higher in the treatments receiving Rhizobium inoculation. Vesicular arbuscular mycorrhizal (VAM) infectivity was also improved significantly with combined inoculants and FYM compared to sole application of FYM or fertilizers (N and P). Application of fertilizer nutrients along with FYM, use of nitrogen fixers, phosphate solubilizers and VAM significantly increased grain ( r=0.618, P<0.05) and straw yields ( r=0.602, P<0.05) and, in general, decreased C:N and C:P ratio. The results suggested that for maximum crop yield only 50% of the required fertilizer might be supplied along with bioinoculants.

Presence of different arbuscular mycorrhizal infection patterns in roots of Lotus glaber plants growing in the Salado River basin.

Morphological types of arbuscular mycorrhizal (AM) fungi associated with Lotus glaber in sodic soils of the Salado River basin were studied. At least eight colonization patterns (IP) of AM fungi in roots of L. glaber were observed after 30 plants were analyzed. Arum- and Paris-type infection were found in the same plant species. This result supports the idea that AM morphology is not solely under plant control, but is also influenced by fungal identity. One infection pattern, presumably corresponding to Glomus intraradices, and a second, possibly assignable to Glomus tenue, were the most commonly found. Our results reinforce previous suggestions that G. intraradices is well adapted to sodic-saline conditions and may play a role in the resistance of L. glaber to these soils.

Role of bioinoculants in development of salt-resistant saplings of Morus alba (var. sujanpuri) in vivo

Pot experiments were conducted for the development of salt-resistant saplings of Morus alba (var. sujanpuri) involving bioinoculants, namely arbuscular mycorrhizal (AM) fungi, Azotobacter and indole butyric acid (IBA). The IBA and sodium chloride (NaCl) concentrations were optimized prior to the experiments. By using both low and high concentrations, 15 ppm IBA and 0.05% NaCl (w/v) were found to be optimum in acting synergistically with AM fungi and Azotobacter and also for increasing all the growth parameters and microbial count in the rhizosphere. For in vivo development of salt-resistant saplings, the optimal concentration of IBA, along with AM fungi and Azotobacter in different combinations, was applied. The saplings were irrigated regularly with 0.05% NaCl water. Although growth parameters such as AM infection percentage, AM spores per 100 g soil and Azotobacter cells/g soil were affected by NaCl watering, the inoculation of both bioinoculants significantly enhanced survival percentage of saplings from 25 to 50% under salt stress. Maximum survival (55%) of saplings was found with IBA (15 ppm)+ AM fungi +Azotobacter .

Relationship between Arbuscular Mycorrhizal Fungal Development and Eupalitin Content in Bahiagrass Roots Grown in a Satsuma Mandarin Orchard

An experiment was carried out in a satsuma mandarin orchard with a bahiagrass (Paspalum notatum Fliigge.) covercrop to evaluate if the concentration of eupalitin, a growth stimulatory compound for arbuscular mycorrhizal (AM) fungi, is correlated with AM fungal development in soils. Root and soil samples were obtained monthly from the satsuma mandarin and bahiagrass to evaluate the AM infection in the roots and the number of AM spores in the soil. The root samples were kept in a freezer until analysed for eupalitin. Eupalitin was isolated and purified from bahiagrass root extracts by flash chromatography, gel filtration, and high pressure liquid chromatography (HPLC) and its concentration in each sample was determined based on a standard solution. The percentage of AM infection in both bahiagrass and satsuma mandarin roots was around 80% during the summer but decreased from October. The number of spores started to increase in March, attaining a maximum of around 800 in 25 g soil in June; the count subsequently decreased. Eupalitin concentration in bahiagrass roots was high from May to November, peaking in May and July. The concentration of eupalitin was significantly correlated with the AM infection in bahiagrass and the number of spores in soil, but not for the AM infection in satsuma mandarin. It suggests that there might be an interaction between AM fungal development and growth stimulatory compounds in soil.

Residual benefits of promiscuous soybean to maize ( Zea mays L.) grown on farmers’ fields around Minna in the southern Guinea savanna zone of Nigeria

Biological nitrogen fixation (BNF) by promiscuous cultivars of soybeans ( Glycine max (L.) Merr.) in cereal-based cropping systems of Nigeria’s moist savanna zone offers a potential for minimizing the investment made by resource-poor farmers on nitrogen fertilizers. A 3-year trial was conducted on five farmers’ fields in the southern Guinea savanna zone of Nigeria to assess the residual effects of two successive crops of promiscuous soybean cultivars on the yield of a following maize ( Zea mays L.) crop. The soybean cultivars, TGX1456-2E (medium maturity) and TGX1660-19F (late maturity), were grown in 1996 and 1997. Treatments, imposed only in the first year of the trial, were: (i) uninoculated, (ii) inoculated with a mixture of two Bradyrhizobium strains, and (iii) fertilized with 60 kg N ha −1. A fourth treatment was a plot left to fallow. In 1998, all the previous soybean and fallow plots were sown to maize without any fertilizer application. Results in 1996 and 1997 showed a soybean response to inoculation in the first year, but differences due to the residual effect of inoculation in the second year were not significant. Both cultivars showed a similar response to inoculation but responses at the five sites were varied. Soybean cultivar 1456-2E fixed 43–52% of its N amounting to 56–70 kg N ha −1 and cultivar 1660-19F derived 39–54% of its N from N 2-fixation which amounted to 51–78 kg N ha −1. Both cultivars had a high N harvest index resulting in a net removal of 52–95 kg N ha −1 when both grain and stover were exported. Even when the stover was returned, there was a depletion of 23–65 kg N ha −1, with 1456-2E removing more N than 1660-19F. Arbuscular-mycorrhizal infection on maize roots was 11–27% and dependent on previous soybean treatments and farmers’ fields. Plant height, shoot biomass, grain yield, and N uptake of maize were significantly greater in plots previously sown to soybean than in the fallow plots. In general, plots sown to the late maturing cultivar 1660-19F exhibited better residual effect, producing larger yield parameters than the plots planted with medium maturing 1456-2E.

Mycorrhizal dependency of Chihuahuan Desert plants is influenced by life history strategy and root morphology

Arbuscular mycorrhizal (AM) fungal infection was assessed for dominant Chihuahuan Desert annual and perennial plant species. Annuals were determined to have significantly less AM infection than their perennial counterparts. Additionally, annuals were shown to have significantly smaller fine root diameters than perennials. Within 15 of the 17 species examined, the presence of AM hyphae in a root segment was not a significant determinant of root diameter, indicating than in most plant species mycorrhizal infection is not directly promoting root diameter increases. The results of this survey show that the dominant plant species of the Chihuahuan Desert group into two categories: (i) short-lived annuals with thin roots and low AM dependency, (ii) longer-lived perennials with thick mycorrhizal roots.

Responses to rhizobial inoculation by two promiscuous soybean cultivars in soils of the Southern Guinea savanna zone of Nigeria

TGX soybean lines were bred at IITA Ibadan for promiscuity with indigenous rhizobia in Nigerian soils. Two cultivars, TGX1456-2E and TGX1660-19F, were tested in a 2-year trial for their response to rhizobial inoculation in five farmers' fields within a 60-km radius of Minna town, in the Southern Guinea savanna zone of Nigeria. Using the ELISA method, the competitiveness and persistence of the two elite strains of rhizobia contained in the inoculant mixture were also studied. There was a close relationship between nodulation and the size of resident rhizobial populations, with wide variation in nodulation across the various sites irrespective of the treatments. Cultivar effect on height and nodule number was significant only in the first cropping season of the trial. The inoculant strains appeared to be less competitive, but more effective, than the indigenous populations. The proportions of the nodules occupied by the inoculant strains were 17% in the first cropping season, and 24% in the second. Inoculation with rhizobia increased the percent arbuscular mycorrhizal infection by an average of 50%. Although grain yield varied between sites, no significant cultivar effect was observed. However, inoculation increased grain yield by 40% in the first cropping season, while no such yield differences occurred in the second season. The proportion of nitrogen derived from N2 fixation ranged from 27% to 50% in both cropping seasons, and this was dependent on crop management on farmers' fields, rather than any cultivar or inoculation effect.

Differential response of δ13C and water use efficiency to arbuscular mycorrhizal infection in two aridland woody plant species

During a revegetation field experiment in Southeast Spain, we measured foliar carbon isotope ratios (delta13C) and gas exchange parameters in order to evaluate the influence of arbuscular mycorrhizal (AM) infection on the water use efficiency (WUE) of two semiarid woodland species. WUE during drought was significantly enhanced by inoculation with Glomus intraradices in Olea europaea ssp sylvestris, but not in Rhamnus lycioides. While Olea is a long-lived, slow-growing evergreen tree with a conservative water use strategy, Rhamnus is a drought-deciduous shrub with a shorter lifespan; these differences may explain their dissimilar patterns of physiological response to inoculation with the same AM fungus. Differences in delta13C and WUE between Olea and Rhamnus were larger when comparing AM inoculated than non-inoculated seedlings. This result suggests that some of the interspecific variability in delta13C observed for aridland plant communities may be due to different physiological responses to mycorrhization.

Arbuscular mycorrhizal symbiosis changes the colonization pattern of Acacia tortilis spp. Raddiana rhizosphere by two strains of rhizobia.

The aim of the study was to assess the effect of the mycorrhizosphere of A. tortillis spp. raddiana mycorrhized with Glomus intraradices on the root nodulation by Sinorhizobium terangae (ORS 1009) and/or Mesorhizobium plurifarium (ORS 1096) in two different culture substrates (sandy soil and sand). The endomycorrhizal fungus only stimulated plant growth in the sandy soil. Moreover, arbuscular mycorrhizal infection enhanced the nodulation process in both culture substrates. Beside the stimulatory effects of the mycorrhizosphere on both rhizobia development, fungal symbiosis induces two different dynamics of each bacterial strains in the sand-grown plants. These results suggest specific relationships could occur during the development of the tripartite symbiosis, at physiological and molecular level. From a practical point of view, the role of arbuscular mycorrhizas in improving nodulation and N2 fixation is universally recognized. The fungal symbiosis could modify the development of bacterial inoculants along the root systems. This effect is of particular interest in the controlled inoculation of selected rhizobia.

Effects of fertilizers and vesicular–arbuscular mycorrhizas on the growth and photosynthesis of Azadirachta excelsa (Jack) Jacobs seedlings

Azadirachta excelsa (Jack) Jacobs is a fast growing indigenous species being promoted as a plantation species in Malaysia. However, the low fertility of most native soils is a primary constraint for good establishment of this species. The effects of fertilizer and vesicular–arbuscular mycorrhizal infection on growth and rate of photosynthesis in A. excelsa seedlings were assessed in a pot experiment. The mycorrhizal inoculated plants (without fertilizer) grew more slowly than control (uninoculated without fertilizer) seedlings, despite the higher percentage of infection. These results suggest that introduced mycorrhizal inoculum was not effective enough to improve seedling growth. Mycorrhizal development was depressed under high levels of fertilizer application. Fertilizer had the strongest effect on growth, biomass and photosynthetic rate, and leaf nutrient concentrations of A. excelsa seedlings. Plants supplied with slow release fertilizer (20N–10P 2O 5–5K 2O) alone gave the most vigorous growth and higher rates of photosynthesis among the fertilizer treatments. These results demonstrate the potential of using slow release fertilizer in promoting seedling growth.

Effect of root-zone flooding on mycorrhizal and non-mycorrhizal peach ( Prunus persica Batsch) seedlings

The effect of root-zone flooding on mycorrhizal and non-mycorrhizal peach seedlings growing in a low P medium was examined. Mycorrhizal seedlings showed relatively faster development prior to flooding and recorded significantly higher concentrations of shoot P, K and Zn and biomass yield. Ethanol accumulation was significantly higher in the taproots of non-mycorrhizal as compared to mycorrhizal plants after 3 days of flooding. A more rapid decline in plant health was also observed in non-mycorrhizal as compared to mycorrhizal seedlings. The presence or absence of the fungal partner led to significant difference in the ratio of roots that remained viable after extended flooding. Therefore, it is clear that arbuscular mycorrhizal (AM) infection confers limited tolerance to flooding on peach seedlings. This could be due to improved plant nutrition, the suppression of ethanol accumulation in roots and the extension of the duration of root activity in a flooded environment.

The Relationship Between Cultural Practices and Arbuscular Mycorrhizal(AM) Activity in Orchards Under Different Management Systems.

It has been demonstrated that soil disturbance, excessive fertilization and the use of some agrochemicals affect the survival and function of arbuscular mycorrhizal (AM) fungi. To clarify the effect of different cultural practices on mycorrhizal activity in orchards, spore population dynamics, soil and plant mineral content and mycorrhizal infection were surveyed monthly from May to October, 2000 in kiwifruit, Japanese chestnut, Iyo tangor, satsuma mandarin, Japanese persimmon, apple, peach, Japanese plum and grape plantings, subjected to different management regimes. In intensively managed orchards, levels of major elements in the soil were generally high, owing to periodic fertilization ; consequently, the content of these elements in the leaves was within the recommended range for normal growth and function. High levels of AM infection were maintained throughout the season in the apple orchard that received no fertilizer or fungicide. The infection levels on roots of kiwifruit vines decreased in July and August after three fungicide sprays in June ; it also decreased in Iyo tangor in July following four fungicide applications in May and June. These orchards had no under-story cover plants. However, the infection level of peach trees under sod culture remained relatively high even after five fungicide sprays from May through August. Thus, population density of AM spores in the soils seems to be low in the clean cultivated orchards, subjected to frequent fungicide sprays, whereas it was high under sod culture. We conclude that excessive fertilization, frequent fungicide sprays and clean culture have an adverse effect on AM spore populations and tree infection in orchards.

Arbuscular mycorrhizal infection changes the bacterial 16 S rDNA community composition in the rhizosphere of maize

Mycorrhizal and non-mycorrhizal (NM) maize plants were grown for 4 or 7weeks in an autoclaved quartz sand-soil mix. Half of the NM plants were supplied with soluble P (NM-HP) while the other half (NM-LP), like the mycorrhizal plants, received poorly soluble Fe and Al phosphate. The mycorrhizal plants were inoculated with Glomus mosseae or G. intraradices. Soil bacteria and those associated with the mycorrhizal inoculum were reintroduced by adding a filtrate of a low P soil and of the inocula. At 4 and 7weeks, plants were harvested and root samples were taken from the root tip (0-1cm), the subapical zone (1-2cm) and the mature root zone at the site of lateral root emergence. DNA was extracted from the roots with adhering soil. At both harvests, the NM-HP plants had higher shoot dry weight than the plants grown on poorly soluble P. Mycorrhizal infection of both fungi ranged between 78% and 93% and had no effect on shoot growth or shoot P content. Eubacterial community compositions were examined by polymerase chain reaction-denaturing gradient gel electrophoresis of 16S rDNA, digitisation of the band patterns and multivariate analysis. The community composition changed with time and was root zone specific. The differences in bacterial community composition in the rhizosphere between the NM plants and the mycorrhizal plants were greater at 7 than at 4weeks. The two fungi had similar bacterial communities after 4weeks, but these differed after 7weeks. The observed differences are probably due to changes in substrate composition and amount in the rhizosphere.

The impact of alien plant invasion on mycorrhizas in mountain fynbos vegetation

We examined the effect of dense alien plant invasion on vegetation development following clearing, from a nutrient-acquisition perspective. The majority of fynbos plants form arbuscular mycorrhizas but Hakea and Pinus , two of the most invasive alien plant genera in mountain fynbos, do not. We hypothesised that these aliens would negatively impact on arbuscular mycorrhizal infectivity and thereby influence post-clearing vegetation development. The mycorrhizal status of vegetation at two mountain fynbos sites was compared between invaded and uninvaded sites before clearing and after alien clearing and fire. On cleared sites, non-mycorrhizal guilds were under-represented and arbuscular mycorrhizal guilds were over-represented. Soil arbuscular mycorrhizal infectivity and spore numbers were not affected by alien plants, possibly because an understorey of arbuscular mycorrhizal species had persisted in the alien stands. We conclude that following a single cycle of dense alien vegetation, arbuscular mycorrhizal plant species are not negatively affected and that other effects of alien vegetation on the environment are responsible for changes in plant guilds. Soil under alien plants was enriched and this may have contributed to the success of the arbuscular mycorrhizal guild after clearing.

Interactions between phosphorus supply and total nutrient availability on mycorrhizal colonization, growth and photosynthesis of cucumber

The effects of arbuscular mycorrhizal (AM) infection by Glomus mosseae (Nicolson & Gerdemann) Gerdemann & Trappe on growth, photosynthesis and nutrient concentration of cucumber ( Cucumis sativus L. var. Telegraph Improved) were studied in sand culture with three different nutrient solutions based on the Long Ashton formula. These were high P+high concentrations of the other essential nutrients (full-strength solution containing 1.3 mM P), low P (0.13 mM)+ high concentrations of the other nutrients and low P+low concentrations of the other nutrients (10% of the full-strength nutrient solution). AM infection was found to depend on both P supply and the availability of other nutrients. Plants grown at low P with high concentrations of other nutrients had the highest AM infection, and a higher biomass due to an enhanced maximum net photosynthetic rate ( P m). Although this was unrelated to the N concentration of leaves, there was evidence that the higher P m was associated with a low leaf P concentration and the significance of these results is discussed. With high P and high concentrations of the other nutrients, a growth depression was found with +AM plants, although this was not due to a reduction in photosynthesis or an increase in leaf dark respiration rate. It was, however, associated with a reduction in photosynthetic nitrogen use efficiency. Overall, the present study indicates that any advantages or disadvantages associated with AM infection in cucumber are a result of complex interactions between P supply and the availability of other essential nutrients.

Modeling arbuscular mycorrhizal infection: is % infection an appropriate variable?

Several available models of arbuscular mycorrhizal infection are based on fitting % infection to a logistic curve and then relating the various parameters to biological functions. I suggest here that this direction is misleading. Percent infection is a value derived from the growth of two interdependent but distinct organisms, each of which is seeking to maximize its own growth and survival. I suggest that two-organism models, such as those derived from Lotka-Volterra equations, are more useful for understanding the biology and functioning of mycorrhizae.

Chlorosis occurrence, natural arbuscular‐mycorrhizal infection and stilbene root concentration of ungrafted grapevine rootstocks growing on calcareous soil

Ungrafted rootstocks of fifteen grapevine genotypes with considerable resistance and susceptibility to lime‐tolerance [iron (Fe) deficiency chlorosis] were grown outdoors in pots with a fine, mixed (calcareous) mesic Typic Ustorthents soil, to determine the correlation between degree of lime‐tolerance, natural arbuscular mycorrhizal (AM) infection, and AM infection relationship with root levels of stilbenes (antifungal compounds). During the second year of growth, shoot length was measured and degree of chlorosis symptoms was evaluated four times as SPAD readings. At the end of the growing season, shoot and root dry weight, root length, AM infection, root concentration of stilbene compounds (trans‐ and cis‐resvaratrol, ϵ‐viniferin, pterostilbene) were determined. The most significant findings were: a) a negative correlation between degree of chlorosis and natural AM infection (expressed as total length of infected roots per plant); b) no significant correlation between AM infection and root stilbene concentration for the different rootstocks; c) positive relationship between chlorophyll leaf concentration and root dry weight, and d) a negative correlation between ϵ‐viniferin root level and shoot dry matter.

Vegetation dynamics and arbuscular mycorrhiza in old-field successions of the western Italian Alps

The relationships between vegetational and arbuscular mycorrhizal (AM) dynamics were investigated in an old-field succession in the western Italian Alps. Vegetation and AM colonization were determined in eight sites corresponding to different stages of successional dynamics: (a) a field under cultivation; (b) fields abandoned for 1, 2 and 3 years supporting ruderal vegetation; (c) grasslands; (d) shrublands; (e) early wood communities; (f) mature woods. AM colonization was evaluated on the roots of representative plants from each community. The data thus obtained, together with those from the literature, were then used to calculate the plant community mycorrhizal index. This index provides qualitative and quantitative information concerning the relative percentage of non-mycorrhizal, AM and ectomycorrhizal plant cover in an entire plant community. The AM inoculum potential of each site was also determined using a bait approach. Farming disturbance temporarily reduced soil infectivity. Non-mycorrhizal ruderal annuals dominated after 1 year abandonment and covered 90–100 % of the surface. After 2 or 3 years, a rapid change to AM-colonized competitive and competitive-ruderal perennials was observed. The increase in AM inoculum was associated with an increase in floristic richness and equitability in the community. AM were also dominant in the shrublands and early wood communities, but gave way to ectomycorrhizal species in the mature woods. The observed AM inoculum potentials are in accordance with these findings. The results of this study further emphasize the need to take into account AM infection in plans for the renaturalization of degraded areas.