Mükoriisse sümbioosi levik ja roll taimekooslustes

Väitekirja elektrooniline versioon ei sisalda publikatsiooneMükoriisne sümbioos soontaimede ja mullaseente vahel on maismaaökosüsteemides laialt levinud ja mängib olulist rolli nende toimimises. Antud doktoritöö avardab teadmisi mükoriissuse levikust taimkattes, seda mõjutavatest keskkonnateguritest ja sellest, kuidas mükoriissus mõjutab taimede kooseksisteerimist ja mitmekesisust. Eesti taimekoosluste analüüsimisel selgus, et parasvöötme metsad on mükoriissemad, kuid suhteliselt vähem arbuskulaar-mükoriissemad võrreldes rohumaadega ning see on põhjustatud erinevustest mullaviljakuses, -happesuses ja -niiskuses. Kontinentaalsel skaalal nähtus, et erinevate mükoriissete tunnustega taimedel on erinev levikumuster piki laiuskraadi: arbuskulaar-mükoriissed taimed domineerivad kogu Euroopas, kuid nende osakaal kahaneb põhjapoolsetel aladel. Seevastu ekto- ja erikoidset mükoriisat moodustavate taimede osakaal on madal laiuskraadist sõltumata. Euroopa põhjapoolsemaid alasid iseloomustab mükoriisse sümbioosi osatähtsuse vähenemine. Lisaks ilmnes, et kontinentaalsel skaalal mängivad mükoriisse sümbioosi levikul olulist rolli nii mulla- kui ka kliimatingimused. Ühtlasi osutasid tulemused ka mükoriissuse tähtsusele taimekoosluste mitmekesisuse kujunemisel: arbuskulaar-mükoriissus soosis taimede liigirikkust uuritud metsades. Üheks võimalikuks viisiks, kuidas mükoriisa moodustamine taimede kooseksisteerimist mõjutada võib, on taimede ressursi- ja elupaiganõudluste ehk niššide muutmine. Oma tulemustega näitasime esimest korda, et erinevate mükoriissete tunnustega taimedel on tõepoolest erinevad nišid, võides seega muuta taimedevahelisi suhteid. Oluliseks probleemiks looduslikes kooslustes on süvenev inimtegevus. Hollandi taimkatte põhjal tehtud uuringus selgus, et inimtegevus muudab taimekoosluste mükoriissust, kuid selle mõju sõltub inimtegevuse tüübist ja koosluse valdavast mükoriisatüübist. Üldiselt selgus siiski, et inimtegevus mõjutab mükoriissust enim metsades ja nõmmekooslustes, võides muuta ka aineringete toimimist.Mycorrhizal symbiosis between vascular plants and soil fungi is considered ubiquitous in terrestrial ecosystems and plays a key role in ecosystem processes. This doctoral thesis advances our understanding about the distribution of mycorrhizal symbiosis in vegetation at larger scales, its drivers and how it relates to plant coexistence and diversity. At regional scale, we show quantitatively that the forests in Estonia are more mycorrhizal but less arbuscular mycorrhizal than grasslands and vice versa. These distribution patterns were driven by edaphic factors, such as soil fertility, pH and moisture. At the continental scale, we revealed the latitudinal distribution patterns of plants with different mycorrhizal traits: arbuscular mycorrhizal plants prevailed across Europe, although their share decreased in the north, while minor but opposite trends were observed for ecto- and ericoid mycorrhizal plants. Northern areas in Europe were characterized by increased share of non-mycorrhizal and facultatively mycorrhizal plants. The mycorrhizal distribution at the continental scale was driven both by soil and climatic factors. Our results also suggest that arbuscular mycorrhization in Estonian forests is associated with higher plant richness. Mycorrhizal symbiosis could potentially affect plant diversity by reducing resource competition between plant species, i.e., by promoting plant niche partitioning. For the first time, we show that plants with different mycorrhizal characteristics indeed show evidence of niche differentiation. Also, mycorrhizal associations could be influenced by increasing human pressure on ecosystems. The analysis of the Dutch vegetation showed that mycorrhization of plant communities is affected by anthropogenic influence, but the effect depends on the type of human impact and the dominant mycorrhizal type. However, the mycorrhization of forests and heathlands were most affected, potentially also having subsequent effects on nutrient cycling.https://www.ester.ee/record=b552954

Taimekoosluste mükoriissus ja selle seosed abiootiliste keskkonnatingimustega

2018-06-0

Anthropogenic measurements for the plots

All three anthropogenic measurements, for all the plots considere

Responses of plant community mycorrhization to anthropogenic influence depend on the habitat and mycorrhizal type

Anthropogenic impact represents a major pressure on ecosystems, yet little is known about how it affects symbiotic relationships, such as mycorrhizal symbiosis, which plays a crucial role in ecosystem functioning. We analyzed the effects of three human impact types – increasing urbanity, introduction of alien plant species (alienness) and modifications in plant species distribution ranges (as a proxy for naturalness) – on plant community overall mycorrhization (including arbuscular, ecto-, ericoid and orchid mycorrhizal plants) and arbuscular mycorrhization (indicating the degree of forming mycorrhizal symbiosis at plant community level using the relative abundance of mycorrhizal and arbuscular mycorrhizal plants, respectively). The study was carried out in three habitat types, each dominated by a distinct mycorrhizal type – ectomycorrhizal woodlands, ericoid mycorrhizal heathlands and arbuscular mycorrhizal grasslands – at the regional scale in the Netherlands. The response of community mycorrhization and arbuscular mycorrhization to anthropogenic influence showed contrasting patterns, depending on the specific aspect of human impact. Community mycorrhization responded negatively to urbanity and positively to increasing alienness, while arbuscular mycorrhization showed the reverse trend. More natural heathlands were found to be more mycorrhizal and less arbuscular mycorrhizal. The strongest responses were detected in woodlands and heathlands, while mycorrhization in grasslands was relatively insensitive to human impact. Our study highlights the importance of considering mycorrhizal symbiosis in understanding and quantifying the effects of anthropogenic influence on plant communities, especially in woodlands and heathlands.</p

Arbuscular mycorrhizal fungal community composition determines the competitive response of two grassland forbs

We performed a greenhouse experiment to assess how differences in AM fungal community composition affect competitive response of grassland plant species. We used a full factorial design to determine how inoculation with natural AM fungal communities from different habitats in Western Estonia affects the growth response of two grassland forbs (Leontodon hispidus L., Plantago lanceolata L.) to competition with a dominant grass (Festuca rubra L.). We used AM fungal inocula that were known to differ in AM fungal diversity and composition: more diverse AM fungal communities from open grasslands and less diverse AM fungal communities from former grassland densely overgrown by pines (young pine forest). The presence of AM fungi balanced competition between forb and grass species, by enhancing competitive response of the forbs. The magnitude of this effect was dependent on forb species identity and on the origin of the AM fungal inoculum in the soil. The grassland inoculum enhanced the competitive response of the forb species more effectively than the forest inoculum, but inoculum-specific competitive responses varied according to the habitat preference of the forb species. Our findings provide evidence that composition and diversity of natural AM fungal communities, as well as co-adaptation of plant hosts and AM-fungal communities to local habitat conditions, can determine plant-plant interactions and thus ultimately influence plant community structure in nature

Data from: Niche differentiation and expansion of plant species are associated with mycorrhizal symbiosis

Mycorrhizal symbiosis is a widespread association between plant roots and mycorrhizal fungi, which is thought to contribute to plant niche differentiation and expansion. However, this has so far not been explicitly tested. To address the effect of mycorrhizal symbiosis on plants’ realized niches, we addressed how mycorrhizal status (i.e. the frequency of occurrence of mycorrhizal symbiosis), flexibility (i.e. the ability to grow both with and without mycorrhizal symbiosis) and type of a plant species affect the realized niche optima, widths and volumes. For this, we used co-occurrence data from the flora of the Netherlands along soil fertility, moisture, pH, salinity, light and temperature gradients. Phylogenetic dependency of the species was taken into account using phylogenetic generalized least squares models. We show that facultatively and flexibly mycorrhizal plants have the widest niches compared to non-mycorrhizal and obligately mycorrhizal, and inflexible plants respectively. Among obligate plant symbionts, ecto- and ericoid mycorrhizal plants exhibited the widest niches compared to plants with other mycorrhizal types. Also, plants with different mycorrhizal statuses and types differed in their realized niche optima. Synthesis. Our results indicate that mycorrhizal symbiosis mediates plant niche differentiation and expansion, facilitating the understanding of current distribution patterns of plant species, as well as predicting shifts in plant distribution and dominance due to environmental changes

Data from: Responses of plant community mycorrhization to anthropogenic influence depend on the habitat and mycorrhizal type

Anthropogenic impact represents a major pressure on ecosystems, yet little is known about how it affects symbiotic relationships, such as mycorrhizal symbiosis, which plays a crucial role in ecosystem functioning. We analyzed the effects of three human impact types – increasing urbanity, introduction of alien plant species (alienness) and modifications in plant species distribution ranges (as a proxy for naturalness) – on plant community mycorrhization and arbuscular mycorrhization (indicating the degree of forming mycorrhizal symbiosis at plant community level using the relative abundance of mycorrhizal and arbuscular mycorrhizal plants, respectively). The study was carried out in three habitat types, each dominated by a distinct mycorrhizal type – ectomycorrhizal woodlands, ericoid mycorrhizal heathlands and arbuscular mycorrhizal grasslands - at the regional scale in the Netherlands. The response of community mycorrhization and arbuscular mycorrhization to anthropogenic influence showed contrasting patterns, depending on the specific aspect of human impact. Community mycorrhization responded negatively to urbanity and positively to increasing alienness, while arbuscular mycorrhization showed the reverse trend. More natural heathlands were found to be more mycorrhizal and less arbuscular mycorrhizal. The strongest responses were detected in woodlands and heathlands, while mycorrhization in grasslands was relatively insensitive to human impact. Our study highlights the importance of considering mycorrhizal symbiosis in understanding and quantifying the effects of anthropogenic influence on plant communities, especially in woodlands and heathlands

Mycorrhizal trait data and niche characteristics for vascular plants in the Dutch flora

File includes updated mycorrhizal status, type and flexibility data with new additional references, and realized niche optima, widths and volumes along soil fertility, pH, moisture, salinity, light and temperature axes for the vascular plant species in the Dutch flora. Also, a legend is provided as a separate sheet in the file. More details can be found in the README file

The role of plant mycorrhizal type and status in modulating the relationship between plant and arbuscular mycorrhizal fungal communities

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