Browsing by Author "Palomäki, Anne"

In nutrient poor boreal peatlands, a significant proportion of photosynthesis-derived carbon of mycorrhizal plants is allocated to their fungal symbionts in exchange for nutrients. The soil carbon cycle is intertwined and affected by inputs of e.g. nitrogen and sulfur, whose amounts both in the soil and atmosphere have increased since the Industrial Revolution. In addition, as stated in the recent Global Warming of 1.5 °C -report (IPCC 2018) global warming is likely to reach 1.5 °C above pre-industrial levels before 2052. In this study, data from ericoid mycorrhizal fungi (ErMF) abundance, enzyme activities and the fungal taxa associated with them under increased warming and nutrient depositions were connected. This thesis is part of the Nitro-Erica -project of Natural Resources Institute Finland (LUKE) and it has been funded by the Academy of Finland (SA286731). Root fragments of Vaccinium oxycoccos L. and Andromeda polifolia L. were observed under a light microscope to determine the abundance of all root associated fungi, ErMF and dark septate endophytes (DSE). Fluorometric and photometric assays were used to study the ability of the fungi to degrade organic material and scavenge nutrients. Finally, direct PCR and Sanger sequencing were used to learn the dominant fungal taxa in the roots. A decrease in the abundance of ErMF and DSE was observed, indicating the possibility of a reduction in the carbon sink potential of peatlands through a decrease in the number of fungi. An increase in acid phosphatase activity under nitrogen deposition was observed in the two plants, which was expected as boreal peatlands are often nitrogen limited. In contrast, sulfur deposition suppressed the activity of all carbon acquiring enzymes which we concluded was likely to be the result of the sulfur inhibiting the growth of two parasitic fungi that greatly contributed to the overall high activity of carbon acquiring enzymes. More research is needed to gain a comprehensive understanding of the fungal abundance, communities and their functioning in peatlands under the changing environmental conditions.