Dynamics of root-associated fungal communities in relation to disturbance in boreal and subarctic forests

• Main Author: Huusko, K. (Karoliina)
• Other Authors: Markkola, A. (Annamari), Ruotsalainen, A. (Anna Liisa), Saravesi, K. (Karita)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Oulun yliopisto 2018
• Subjects: 454-pyrosequencing; Deschampsia flexuosa; Ion Torrent sequencing; diversity; succession; 454-pyrosekvensointi; Ion Torrent -sekvensointi; diversiteetti; sukkessio; Betula pubescens ssp. czerepanovii; Picea abies; Subarctic
• Online Access: http://urn.fi/urn:isbn:9789526218038

Abstract Disturbance may shift microbial communities from one state to another. However, species differ in their ecological characteristics and their abilities to withstand disturbance. No single species or individuals of a species exist alone, but they are parts of complex interaction networks including species above- and belowground. In boreal and subarctic forests, almost all plants and a high number of fungi form mycorrhizas at the plant roots. In mycorrhiza, the fungal partner harvests nutrients for the host plant and, in return, gains carbon from the plant. In general, these common associations benefit both partners, but as heterotrophs, fungi are dependent on carbon photosynthesized by plants, whereas plants can survive alone as autotrophs. In addition to mycorrhizal fungi, also other fungi, such as endophytes, saprotrophs and pathogens, live in and on plant roots. This thesis concerns the impacts of disturbance on fungi living in plant roots and in soil near the roots. I hypothesized that i) root-associated fungal (RAF) and soil fungal communities and colonization types change after disturbance, that ii) the observed shifts relate to disturbance intensity and that iii) they co-occur with changes in soil conditions and vegetation. Changes in RAF were studied as changes in root fungal colonization, or in fungal community composition. The latter were detected with next-generation sequencing methods. The responses of RAF to disturbance seemed to be context dependent and related to sources of fungal communities (e.g. soil, RAF networks), environmental conditions (e.g. soil pH and nutrients) and host performance. It seems that abundances of those RAF species, which are present in the roots first (priority effect), may be increased by disturbance. Research produced new information related to ecological roles of the genera Phialocephala and Meliniomyces. Altogether, the results indicate connections between both abiotic and biotic environments and RAF, and host species viability and RAF. Tiivistelmä Häiriöt ...