Communities of arbuscular mycorrhizal fungi in spruce forest ecosystem and their effect on performance of forest understorey plant species
Date
2013-11-12
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Abstract
Arbuskulaar mükoriissete (AM) seente mitmekesisus ja koosluste koosseis varieerub nii ajas kui ruumis. Inimtegevus omakorda võib mõjutada looduslikke seenekooslusi nii taimejuurtes kui ka mullas. Varasemad tööd on näidanud, et erinevad AM seenekooslused mõjutavad taimede kasvu erinevalt, mistõttu võivad avaldada mõju ka taimekooslustele ja ökosüsteemidele laiemalt.
Käesoleva doktoritöö üheks eesmärgiks oli kirjeldada AM seenekooslusi kuusiku alustaimede juurtes ning selgitada nende seente mõju taimede kasvule. Samuti uuriti loodusliku AM seente ohtruse mõju metsa alustaimestiku liikide idanemisele ja idandite kasvule erineva mullaviljakuse tingimustes. Kolmandaks eesmärgiks oli kontrollida konkurentsisuhteid AM seente ja ektomükoriissete seente vahel ja uurida, kuidas see mõjutab taimede kasvu. Töö tulemused näitasid, et erinevad AM seenekooslused (vana metsa, noore metsa ja põllu mullast pärinevad) mõjutavad taimede kasvu erinevalt. Näiteks aas-kurereha, harilik käbihein ja külmamailane kasvasid paremini vana metsa AM seenekooslusega kui noore metsa seenekooslusega. Aasristik ja kandiline naistepuna eelistasid kasvada põllumulla AM seenekooslusega ning harilik kuldvits eelistas kasvada noore metsa mullas. Samas leidus taimeliike, mille kasvu ei mõjutanud AM seenekoosluste päritolu. Näiteks aasristiku, kandilise naistepuna, ojamõõla, metsmaasika, süstlehise teelehe ja hariliku nurmenuku kasv ei erinenud oluliselt vana metsa ja noore metsa mullas kasvanud taimede vahel. Eksperimendis kasvatatud taimeisendite juurtes kirjeldati AM seenekooslusi ja selgus, et kui taimed olid inokuleeritud sama AM seenekooslusega, siis erinevaid taimeliike koloniseerisid erinevad seenekooslused. Samuti erinesid AM seenekooslused töötluste kaupa. Põllumullas kasvanud taimede juurtes oli oluliselt erinev AM seenekooslus võrreldes vana metsa mullas kasvanud taimedega. Loodusliku katse tulemused näitasid, et AM seente ohtrus mõjutab metsa alustaimestiku liikide idanemist ja kasvu, mis võib sõltuda mulla viljakusest. Potikatse erinevate mükoriisaseentega näitas, et AM seente ja ektomükoriissete seente vahel ei esine konkurentsi. Ektomükoriissed seened soodustasid arukase kasvu, ja vaher võib eelistada kasvutingimusi, kus ektomükoriissed seened puuduvad.
Kokkuvõttes näitasid doktoritöö tulemused, et maakasutuse intensiivsusel on väga oluline roll AM seenekoosluste ning seeläbi ka taimekoosluste mõjutajana. Nii nagu varieerub AM seenekoosluste koosseis, nii on ka nende seenekoosluste mõju taimeliikidele väga erinev. Juba taimede idanemisel ja kasvama hakkamisel on AM seentel kandev roll. Kuigi antud töös ei tuvastatud konkurentsi esinemist AM seente ja ektomükoriissete seente vahel, ei välista see pingeliste konkurentsisuhete tekkevõimalust kahe erineva seenegrupi vahel muudes olukordades.
Arbuscular mycorrhizal (AM) fungal communities in plant roots vary in space and time. Anthropogenic activities can affect the local AM fungal communities in plant roots and in soil. Differences in the diversity and community composition of AM fungi may result different growth responses in host plants and changes in the structure of plant communities and ecosystem functioning. The aims of this doctoral thesis were to study the effect of natural mycorrhizal fungal community variation on plant establishment and growth. Also, to describe the communities of AM fungi in the roots of forest understorey plants and is it related to the forest management intensity. As different types of mycorrhiza coexist in temperate ecosystems, interactions between AM and ECM plants were addressed. Results of this study demonstrated that the AM fungal communities from differently managed ecosystems can have different effect on the growth of forest understorey plant species. For instance, Geranium pratense, Prunella vulgaris and Veronica chamaedrys showed better growth with AM fungal community from old forest than young forest stand. Trifolium pratense and Hypericum maculatum responded more positively to the arable field inoculum, and Solidago virgaurea had higher growth rate with AM fungi from young forest compared to old forest inoculum. Moreover, there were also plant species (T. pratense, H. maculatum, Geum rivale, Fragaria vesca, Plantago lanceolata and Primula veris) which showed no difference in response to old and young forest inoculum. AM fungal communities in roots showed different composition in treatments. Plants grown with arable field inoculum hosted a different AM fungal community from those grown with old forest inocula. The distinctive mycorrhizal communities emerged in the roots of experimental plant species growing with the same inocula. Study results showed also that AM fungi influence the success of seedling recruitment in forest ecosystem, and it is more pronounced under low nutrient availability for plants. However, no competition between AM and ectomycorrhizal (ECM) fungi emerged in this study. ECM fungi had strong positive effect on Betula pendula growth, and Acer platanoides plants seemed to prefer growth conditions without the presence of ECM fungi. In conclusion, the results of this study add new evidence about the influence of land use intensity on AM fungal communities and hence its effect on plant growth. AM fungi are important already in seedling stage for plants. Further experimental studies are needed to explore the competition between different types of mycorrhizal fungi and to understand its effect on plant performance in more detail.
Arbuscular mycorrhizal (AM) fungal communities in plant roots vary in space and time. Anthropogenic activities can affect the local AM fungal communities in plant roots and in soil. Differences in the diversity and community composition of AM fungi may result different growth responses in host plants and changes in the structure of plant communities and ecosystem functioning. The aims of this doctoral thesis were to study the effect of natural mycorrhizal fungal community variation on plant establishment and growth. Also, to describe the communities of AM fungi in the roots of forest understorey plants and is it related to the forest management intensity. As different types of mycorrhiza coexist in temperate ecosystems, interactions between AM and ECM plants were addressed. Results of this study demonstrated that the AM fungal communities from differently managed ecosystems can have different effect on the growth of forest understorey plant species. For instance, Geranium pratense, Prunella vulgaris and Veronica chamaedrys showed better growth with AM fungal community from old forest than young forest stand. Trifolium pratense and Hypericum maculatum responded more positively to the arable field inoculum, and Solidago virgaurea had higher growth rate with AM fungi from young forest compared to old forest inoculum. Moreover, there were also plant species (T. pratense, H. maculatum, Geum rivale, Fragaria vesca, Plantago lanceolata and Primula veris) which showed no difference in response to old and young forest inoculum. AM fungal communities in roots showed different composition in treatments. Plants grown with arable field inoculum hosted a different AM fungal community from those grown with old forest inocula. The distinctive mycorrhizal communities emerged in the roots of experimental plant species growing with the same inocula. Study results showed also that AM fungi influence the success of seedling recruitment in forest ecosystem, and it is more pronounced under low nutrient availability for plants. However, no competition between AM and ectomycorrhizal (ECM) fungi emerged in this study. ECM fungi had strong positive effect on Betula pendula growth, and Acer platanoides plants seemed to prefer growth conditions without the presence of ECM fungi. In conclusion, the results of this study add new evidence about the influence of land use intensity on AM fungal communities and hence its effect on plant growth. AM fungi are important already in seedling stage for plants. Further experimental studies are needed to explore the competition between different types of mycorrhizal fungi and to understand its effect on plant performance in more detail.
Description
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Keywords
kuusikud, mükoriisa, seened, fungi, koosluste dünaamika, kasv, taimekooslused, maakasutus, spruce forests, mycorrhiza, fungi, community dynamics, growth, plant communities, land use