Fungal Succession Research Articles

Occurrence and possible role of endophytic fungi associated with seed pods of Colophospermum mopane (Fabaceae) in Botswana

Endophytic fungi were isolated from different aged surface sterilised pods of Colophospermum mopane and succession patterns were investigated. Lignocellulolytic enzyme assays as well as histological and fine structural studies were used to investigate if succession was related to different lignocellulolytic abilities of the fungi. Representatives of the common genera ( Alternaria, Phoma and Phomopsis) were qualitatively tested for lignocellulolytic enzyme activity. Samples of endophyte infected and uninfected pod pericarps were fixed and sectioned for light microscopy and TEM. Samples were also viewed with SEM. A fungal succession was evident as pods aged, and detached from the tree. Strains of all three genera demonstrated lignocellulolytic abilities. Microscopy studies suggested that Phoma was only capable of utilising moderately lignified mesophyll cells whereas Phomopsis and Alternaria could degrade heavily lignified fibres. This could explain the pattern of succession observed: Phoma colonised younger pods where more unlignified resources were available, whereas Phomopsis and Alternaria colonised older pods, thus making use of the remaining lignified resources. Changes in endophyte abundance and diversity are related to the age and degree of decay of the pods, and determined by the lignocellulolytic abilities of the fungi. The potential role of these endophytes is discussed.

Succession of microfungal communities on decaying leaves ofCastanopsis fissa

A total of 38 fungal taxa were identified on senescent untreated and autoclaved Castanopsis fissa leaves during a 4-month study period. Seventy-six percent of the fungal genera found in this survey have not previously been recorded from Castanopsis. Frequency and time of occurrence of fungal taxa occurring on untreated senescent leaves were clustered into four groups when analyzed by cluster analysis, suggesting the replacement of microfungi in stages of succession on naturally senescent leaves. Autoclaved leaves revealed significantly different fungal communities, with only 26% of overlap with the natural ones and no clear patterns of replacement of fungal communities. Factors regulating the rates of decomposition are also discussed.

Lifestyles of Colletotrichum acutatum.

Lifestyles of Colletotrichum acutatum.

Fungal succession and decomposition ofCamellia japonicaleaf litter

AbstractDecomposition processes ofCamellia japonicaleaf litter were investigated over an 18‐month period with reference to the role of fungal succession in the decomposition of lignin and holocellulose. Decomposition and fungal succession were studied in bleached and nonbleached portions of litter, which were precolonized by ligninolytic and cellulolytic fungi, respectively.Coccomyces nipponicumandLophodermiumsp. (Rhytismataceae), which can attack lignin selectively, caused mass loss of lignin and were responsible for bleaching during the first 4 months (stage I), whereas cellulolytic fungi caused mass loss of holocellulose in adjacent nonbleached portions. Soluble carbohydrates and polyphenols also decreased rapidly during this stage.Pestalotiopsis guepini, coelomycete sp.1, and theNigrosporastate ofKhuskia oryzaecaused mass loss of holocellulose between 4 and 14 months (stage II) andXylariasp. caused mass loss of both lignin and holocellulose from 14–18 months (stage III). In stages II and III, decomposition was more rapid in bleached portions than in nonbleached portions probably due to the prior delignification of lignified holocellulose in bleached portions. Frequencies of these fungi showed different responses among species to the pattern of changes in lignin and holocellulose contents during decomposition. Total hyphal length increased in both portions over the study period, but mycelia of basidiomycetes accounted for about 2% of total hyphal length, suggesting that their role in fungal succession and decomposition was low. Lignin and nitrogen contents were consistently lower and holocellulose content was higher in bleached portions than in nonbleached portions during decomposition. The succession of ligninolytic and cellulolytic fungi was a major driving factor that promoted decomposition and precolonization by ligninolytic fungi enhanced decomposition.

Colonization and succession of fungi during decomposition of Swida controversa leaf litter

Decomposition processes of Swida controversa leaves were investigated in initially sterilized (fungi-excluded) and nonsterilized freshly fallen leaves to examine the relationship between chemical changes and fungal succession during decomposition and the effect of exclusion of previously established phyllosphere fungi from leaves on subsequent decomposition and fungal succession. Fifteen species were isolated frequently from decomposing leaves with surface-disinfection and washing methods. These fungi were divided into early and late colonizers according to their occurrence during decomposition. The 1.5 y decomposition process was divided into three stages characterized by different dominant organic chemical constituents. A clear relationship was demonstrated between chemical changes and fungal succession. Total hyphal length and frequencies of some early colonizers were reduced in initially sterilized leaves at 3 wk, but this had no significant effect on loss of litter mass or chemical changes during the first 3 wk or on the subsequent decomposition and fungal succession.

Colonization and succession of fungi during decomposition of Swida controversa leaf litter

Decomposition processes of Swida controversa leaves were investigated in initially sterilized (fungi-excluded) and nonsterilized freshly fallen leaves to examine the relationship between chemical changes and fungal succession during decomposition and the effect of exclusion of previously established phyllosphere fungi from leaves on subsequent decomposition and fungal succession. Fifteen species were isolated frequently from decomposing leaves with surface-disinfection and washing methods. These fungi were divided into early and late colonizers according to their occurrence during decomposition. The 1.5 y decomposition process was divided into three stages characterized by different dominant organic chemical constituents. A clear relationship was demonstrated between chemical changes and fungal succession. Total hyphal length and frequencies of some early colonizers were reduced in initially sterilized leaves at 3 wk, but this had no significant effect on loss of litter mass or chemical changes during the first 3 wk or on the subsequent decomposition and fungal succession.

Analysis of fungal fruiting patterns at the Dawyck Botanic Garden

Since 1994 data on fungal fruiting have been gathered in the Dawyck Botanic Garden outside Edinburgh, including that for eight plots within a 7.5 ha wood, which has been left unmanaged in order to investigate relationships amongst fungal succession, habitat characteristics and local weather patterns. The climatic data are provided by a small meteorological station situated on site. To handle nearly 4000 entries of data so far collected a computer database was constructed. This assists querying of the information so that changes in fungal communities and patterns of succession can be observed, and the relevant data extracted for further analysis. To aid in this analysis, and to give the user full control over editing, updating and querying the database, a special computer program was compiled. Analysis of the database records revealed that the currently known Dawyck fungal community comprises over 620 different taxa, and the species list increases every year. Although some species of mycorrhizal fungi showed high specificity towards their preferred host either at species (e.g. Lactarius blennius with beech, Lactarius quietus with oak, Russula fellea and Russula mairei with beech), or at genus level (e.g. Suillus spp. with Pinaceae), some other common fungi (e.g. of the genus Amanita) were found to have very wide host ranges. In addition, unusual mycorrhizal associations have also been recorded. A lime tree ( Tilia), which is supposedly primarily endomycorrhizal, has been found regularly associated with Russula cyanoxantha, Russula parazurea, Russula pectinata and Inocybe fastigiata. Many common Scottish fungi were found to be associated with introduced exotic trees, which is illustrated on the example of Pseudotsuga menziesii (Douglas Fir). The software created utilises the Microsoft Office suite of programs. Microsoft Access was used to construct the database, and Microsoft Excel was used for statistical investigations. The software was programmed using Microsoft Visual Basic, and provided a means of extracting the necessary data stored in Access and controlling the formulae used in Excel for their analysis. The recorded seasonal patterns of fungal fruiting was successfully described by a simulation mathematical model comprising differential and algebraic equations. This model may now be used as a submodel within more complex models describing terrestrial ecosystem processes. Examples of model simulations and sensitivity analysis are given and implications for future research discussed.

Integrative analysis of ecological patterns in an untended temperate woodland utilising standard and customised software

The integration of a comprehensive monitoring programme conducted in a temperate woodland through statistical analysis and simulation modelling is presented here. The Heron Wood Reserve in Peebleshire, Scotland is a 7.5-ha wood, left untended to facilitate investigation into a natural Scottish Woodland Ecosystem. Data on fungal fruiting have been collected since 1994, and since November 2000 physico-chemical and biotic experiments on soil and woodland litter have also been conducted with the aim to construct and integrate a number of simulation submodels of the various ecological systems present in an untended Scottish woodland. Important systems for modelling include patterns of fungal succession, habitat characteristics and fungal biochemical patterns. A large volume of data has been collected so computer software is used for the storage and handling of data. Microsoft Access was the database used for storage; integration of functions available in Microsoft Excel with a customised software written in Microsoft Visual Basic and Microsoft VBA allowed various statistical modelling tests (e.g. Scheffé analysis of contrast) to be carried out, and the quick display of data in a suitable manner. Model Maker software is used to construct and test simulation models formulated from the data and ultimately to facilitate the running of various simulations. Integration of the separate lines of investigation is demonstrated on the example of a case study describing differences in the dynamics of decomposers in beech- and birch-dominated habitats. Integration of the information obtained allowed us to put forward the following hypothesis. The leaf litter produced by beech trees is of lower quality compared to birch, and decomposition in beech-dominated habitats is delayed (i.e. in comparison to birch-dominated) because of the differences in the extent to which these plants create and maintain a litter and humus layer ( sensu Wardle, Communities and Ecosystems. Linking the Aboveground and Belowground Components, Princeton University Press, Princeton, 2002). Hence, the decomposition in beech-dominated habitats mainly occurs somewhat deeper in the soil profile, and may be carried out with some considerable involvement of ectomycorrhizal fungi. The correct understanding of the site-specific peculiarities of the ecological patterns is important for the improvement of biodiversity of woodland and forest ecosystems both in Scotland and worldwide.

Ectomycorrhizal sporocarp succession and production during early primary succession on Mount Fuji

This article was printed in an uncorrected form in error and a corrected version is now available Summary • The species composition, succession and biomass production of ectomycorrhizal (ECM) sporocarps were studied during early primary succession on Mount Fuji, Japan, with special reference to developmental stages and the growth of associated hosts. • Weekly sporocarp surveys were conducted over 2 yr on a volcanic desert, where the total vegetation coverage was about 5%. We also quantified the growth of associated hosts in terms of size, photosynthesis, and leaf N and P concentration. • A total of 11 450 sporocarps of 23 species were recorded. They were associated almost exclusively with an alpine dwarf willow, Salix reinii. Two Laccaria and one Inocybe species were the first colonizers; subsequent fungal species were added as the host grew. There was no evidence of any fungus disappearing and being replaced in the sere of ECM fungal succession. • The biomass production of ECM sporocarps was exceptionally large, in general, and amounted to 19% of leaf biomass in the most productive associations. Annual ECM sporocarp production in individual ECM associations was strongly correlated with the growth of the associated host, especially with the photosynthetic rate, which appeared to be determined by leaf N and P concentration.

Effects of fenpropimorph on bacteria and fungi during decomposition of barley roots

The study examined the effects of the fungicide fenpropimorph (in the formulation Corbel) on primary decomposer organisms in soil. Bacterial and fungal succession was followed on dead young barley roots buried in fungicide-treated or untreated soil. Fenpropimorph was added to the soil in a concentration realistically achieved in field topsoil when using the recommended dose. Over a 56-day period we measured the length of active fungal hyphae, the abundance of total culturable bacteria, the abundance of two culturable subgroups relevant to the soil environment (hyphae-forming actinomycetes and Pseudomonas), and the diversity of bacterial DNA. The soil fenpropimorph content followed first order disappearance concomitant with the first order formation of fenpropimorphic acid. Fenpropimorph inhibited the growth of active fungi during the first 10 days, when fungal activity peaked in both the treated and non-treated root samples. The number of total culturable bacteria was significantly lowered by fenpropimorph at day 17 and stimulated at day 56, indicating a possible indirect effect of the fungicide on the culturable bacteria as a whole. Nevertheless, culturable Pseudomonas and actinomycetes were not affected. The succession of the two bacterial subgroups differed considerably, so, whereas Pseudomonas peaked in the early decomposition stages, actinomycetes were most abundant after 2 months, and on the very first sampling day. Thus, the present findings suggest a possible effect of fenpropimorph on soil fertility. The diversity of total bacterial DNA measured by denaturing gradient gel electrophoresis (DGGE) was unaffected by fenpropimorph treatment, there being a clear and highly reproducible succession in bacterial diversity during decomposition of the barley roots. The diversity in the hotspot on the last sampling occasion at two months was similar to the diversity of the bulk soil, thus indicating a return to the level prior to addition of the roots.

Diversity and host specificity of ectomycorrhizal fungi retrieved from three adjacent forest sites by five host species

Seedlings of Abies grandis (Dougl.) Lindl. (grand fir), Lithocarpus densiflora (Hook. & Arn.) Rehd. (tanoak), Pinus ponderosa Dougl. ex Laws. (ponderosa pine), Pseudotsuga menziesii (Mirb.) Franco (Douglas-fir), and Arbutus menziesii Pursh (madrone) were planted in mixture and monoculture in soil collected from three adjacent forest sites in southwestern Oregon (a clearcut area, a 25-year-old Douglas-fir plantation, and a mature 90- to 160-year-old Douglas-fir - pine forest) to determine the effect of host tree diversity on retrieval of ectomycorrhizal morphotypes. In this greenhouse bioassay, 18 morphotypes of mycorrhizae were recognized overall from all soils with a total of 55 host-fungus combinations: 14 types with ponderosa pine, 14 with Douglas-fir, 10 with tanoak, 10 with grand fir, and 7 for madrone. Four genus-specific morphotypes were retrieved (three on ponderosa pine and one on Douglas-fir), even in mixture situations, demonstrating selectivity of some fungal propagules by their respective host. Five types were detected on all hosts, but not necessarily in soils from all sites. The remaining nine types were associated with two, three, or four hosts, which indicates a wide potential for interspecific hyphal linkages between trees. More morphotypes were retrieved from the monoculture treatments compared with the mixture treatments, although the differences were not significant. Several examples of acropetal replacement of one fungus by another (interpreted as succession) were recorded on all hosts during the course of the experiment. These results illustrate the importance of different host species in maintaining ectomycorrhizal fungus diversity, especially fungi with restricted host range, and the strong potential for fungal linkages between trees in forest ecosystems.Key words: fungal succession, fungal communities, compatibility, Arbutus menziesii, Pseudotsuga menziesii, Pinus ponderosa, Abies grandis, Lithocarpus densiflora.

Fungal succession on leaves of Alchornea triplinervia (Spreng.) Muell. Arg. submerged in a stream of an Atlantic Rainforest in the state of São Paulo, Brazil

Leaves of Alchornea triplinervia (Spreng.) Muell. Arg. were submerged in a stream in an Atlantic Rainforest in Sao Paulo state, Brazil, from July/1988 to June/1989 and from July/1989 to May/1990. Fungi were isolated by the leaf disks washing technique followed by plating on culture media and also by using baiting techniques (using substrates with chitin, keratin and cellulose), what resulted on 565 fungal registers corresponding to 81 taxa. The most common species found during this study of the fungal succession were Trichoderma viride Pers. ex S.F. Gray and Fusarium oxysporum Schlecht emend. Snyd. & Hans. (23 registers), Penicillium hirsutum Dierckx (21 registers), Fusarium solani (Mart.) Appel & Wollenw. emend. Snyd. & Hans. (17), followed by 14 registers of: Cylindrocladium scoparium Morgan, Triscelophorus monosporus Ingold and Polychytrium aggregatum Ajello. Although the monthly obtained mycota had been composed by species of different taxonomic groups, the fungal succession was defined by the initial presence of typical terrestrial leaf inhabiting fungi (mostly Deuteromycotina), followed by species of Mastigomycotina and Zygomycotina. Combining culture methods and baiting techniques, it was possible to verify the presence of terrestrial fungi on the decomposition of submerged leaves and the importance of zoosporic fungi in the fungal succession. This is the first paper about the fungal succession on the decomposition of leaves submerged in a lotic ecosystem in Brazil.

Fungal successions on pine needles fallen at different seasons: the succession of interior colonizers

Experimental studies were carried out to investigate seasonal effects on the fungal succession in the interior or decaying pine needles. At different seasons, the needles fallen for a short period were collected and marked, then placed on the surface of the O horizon in a pine forest. The needles were removed at intervals and their interior fungal communities were examined by using a surface sterilization technique. The successions of interior colonizers observed on the fallen needles at four different times are roughly divided into three groups based on the composition of species colonizing from litter. Seasonal shifts in the species combination were discussed with climatic and biotic factors. As a result, temperature at the surface of litter appeared to be a cardinal factor contributing to these seasonal changes in the succession of interior colonizers.

Fungal successions on pine needles fallen at different seasons: the succession of surface colonizers

Fungal successions on pine needles fallen at different seasons: the succession of surface colonizers

Endophytic fungi in leaves of ericaceous plants

Endophytic fungal assemblages were investigated in different leaf stages of eight species of Ericaceae (six species of Rhododendron, Enkianthus perulatus, and Pieris japonica). Guignardia sp. (anamorph: Phyllosticta sp.), Phomopsis sp., and Colletotrichum gloeosporioides were found in the leaves of all plants. The frequency of Guignardia sp. was highest in senescent leaves, while in young leaves it was lower than those of Phomopsis sp., and C. gloeosporioides. Discostroma tricellulare was isolated in high frequency from the leaves of Rhododendron obtusum. The colonization frequencies of these endophytic fungi on fallen leaves decreased as the leaves became old, while those of Pestalotiopsis, Alternaria, and others increased after the leaves fell. No significant differences were found among the compositions of endophytic fungal assemblages on ericaceous plants at the site investigated. It was considered that the endophytic fungi infect young leaves and remain latent in the leaves without producing symptoms while the hosts are physiologically active. Discostroma tricellulare was considered to be specific for R. obtusum. The colonization frequencies of the endophytic fungi were clearly lower on the leaves of P. japonica than on those of the other plants. It is considered that asebotoxin, which is known to be toxic to animals and insects, and other secondary metabolites retard fungal invasion in P. japonica.Key words: endophytic fungi, ericaceous plants, fungal succession.

Soil fungal communities in a young and an old Alnus viridis coenosis

Soil microfungal communities of two adjacent, but differently aged Alnus viridis coenoses were studied using the soil dilution plate method. A total of 84 taxa were isolated: 59 from the young community, 51 from the old and 26 taxa shared. Mortierella parvispora and Pythium sp. had the highest density values in the young and the old alder community, respectively. Species compositions were compared between plots of the two communities using a metric multidimensional scaling and a correspondence analysis. Both analyses grouped plots from the young and the old community separately, suggesting a correlation between the changes in the fungal species composition and the age of the alder communities. The correspondence analysis produced two species groups more related to one set of plots or the other, together with another group formed of Mortierella, Micromucor, Geomyces and Trichoderma species, whose distributions were more closely related to the general abiotic conditions than the age of the alder communities. It is proposed that the significant differences in the composition of the two fungal communities mirror the existence of a seral fungal succession paralleling the aging of the alder communities.

Soil Fungal Communities in a Young and an Old Alnus viridis Coenosis

Soil microfungal communities of two adjacent, but differently aged Alnus viridis coenoses were studied using the soil dilution plate method. A total of 84 taxa were isolated: 59 from the young community, 51 from the old and 26 taxa shared. Mortierella parvispora and Pythium sp. had the highest density values in the young and the old alder community, respectively. Species compositions were compared between plots of the two communities using a metric multidimensional scaling and a correspondence analysis. Both analyses grouped plots from the young and the old community separately, suggesting a correlation between the changes in the fungal species composition and the age of the alder communities. The correspondence analysis produced two species groups more related to one set of plots or the other, together with another group formed of Mortierella, Micromucor, Geomyces and Trichoderma species, whose distributions were more closely related to the general abiotic conditions than the age of the alder communities. It is proposed that the significant differences in the composition of the two fungal communities mirror the existence of a seral fungal succession paralleling the aging of the alder communities.

Lanceispora amphibia gen. et sp. nov., a new amphisphaeriaceous ascomycete inhabiting senescent and fallen leaves of mangrove

Lanceispora amphibia gen. et sp. nov. in the Amphisphaeriaceae is described from senescent and fallen leaves ofBruguiera gymnorrhiza in mangrove forests in the Southwest Islands, Japan. The fungus produces immersed ascomata in leaf tissue, cylindrical asci with an apical ring staining blue with iodine, and oblanceolate ascospores with a septum above the middle. Studies on the fungal succession on the mangrove leaves revealed thatL. amphibia infects senescent leaves on the tree and inhabits intertidal fallen leaves, showing the highest frequency of occurrence at the late stage of decomposition. In culture the optimal conditions for hyphal growth were 20 ppt salinity and 30°C, and those for sexual reproduction were 10 ppt salinity and 25°C. Growth at 0 ppt (fresh water) was depressed. The fungus has amphibious habits, growing on the tree and in intertidal water; and it is adapted to the high osmotic conditions in leaf tissues of the mangrove tree and to the subtropical, brackish water environment of mangrove forests.

Host and geographical distribution of Verticicladium trifidum, Thysanophora penicillioides, and similar fungi on decaying coniferous needles

Dematious hyphomycetes such as Verticicladium trifidum and Thysanophora penicillioides are examples of equivalent species occupying the same ecological niche in different fungal successions. These two species fructify through the stomata of coniferous needles a few months after litter fall. Litter samples of 23 coniferous species from different European sites were examined to explain the fungal distribution. Thysanophora penicillioides colonized Abies, Picea, Pseudotsuga, and Tsuga needles, whereas V. trifidum was restricted to Pinus and Cedrus. Sometimes other fungal species occupied the stomata: on Pinus pinea needles, the niche was occupied by Cladosporium spp. and Alternaria alternata; Chaetopsina fulva have been found only on Pseudotsuga needles and Thysanophora canadensis on Picea. Verticicladium trifidum was apparently absent on Pinus litters from cold climates (high altitude or latitude) and probably from warm mediterranean regions, suggesting a climatic determinism. However, coexistence of Verticicladium and Thysanophora in some samples or colonization of some Pinus litter by Thysanophora suggests that these distributions result from competition rather than strict host specificity. Key words: ecological niche, equivalent species, conifers, needles, Verticicladium trifidum, Thysanophora penicillioides.

Competitive Hierarchies of Wood Decomposing Basidiomycetes in Artificial Systems Based on Variable Inoculum Sizes

In the laboratory, 12 species of wood decay basidiomycetes from various stages of fungal succession in logs of Norway spruce were investigated for their relative competitive ability. Pie slices of different sizes were cut from wood discs made from Norway spruce. After inoculation, the pieces were confronted in most species combinations on water agar in Petri dishes, and were left for six months. With this method the inoculum sizes could be varied, while the contact area remained the same. Photos of the discs were taken regularly during this time. At the end of the experiment, samples of the wood were taken from all discs and the remaining fungi were isolated. Combative success was measured as the ability to take over substrate from competing species by the end of the experiment. Both within and among successional stages, mycelial replacement occurred in a non-random fashion. Species usually producing fruit bodies in the later stages of succession in the field were strong competitors in the laboratory tests, while the species which often fruit during the earlier stages of field succession were weaker competitors.