My major research interest is the carbon, phosphorus and nitrogen cycling in soils and the role of mycorrhizal fungi in belowground nutrient dynamics. The role of plant diversity on belowground microbial diversity, and C sequestration on agricultural soils are the focus of my current research projects.  In addition, I am interested in how belowground processes are linked to gas fluxes from soil and to atmospheric chemistry.

Running research activities

• Strategic Research Council project ‘Multi-benefit solutions to climate-smart agriculture (MULTA)’ 2019-2022 (-2025). I am WP leader on Work package 'Processes' that studies processes of carbon sequestration and climate impacts focusing on knowledge gaps. We tackle the questions 'Which processes in vegetation and soil need to be promoted to enhance carbon sequestration and the formation of stable carbon forms, and which processes must be hindered to prevent carbon losses and other unfavorable climate impacts?

• Maj and Tor Nessling foundation project ‘How biodiversity impacts the ability of agricultural fields to store carbon, TWINWIN’ 2109-2022. I lead the WP 'Soil' where the aim is to investigate plant-diversity related differences in soil chemistry and microbiology, that induce soil C sequestration'.

• Academy of Finland project ‘Biogeochemical and biophysical feedbacks from forest harvesting to climate change’ 2019-2023. I lead a Task where soil C cycling is investigated after forest thinning.

Other research-related activities:

• I am the vice-chair in Helsinki Institute for Life Sciences (HiLIFE) funded Grand Challenge project CLIMSAGE (Climate-smart Northern Agriculture) that aims to connect agricultural soil researchers for improved research and collaboration for sustainable agriculture.
• I am member of the board in CarbonAction project (www.carbonaction.org) that aims to implement the international 4 permille initiative (https://www.4p1000.org/) in Finland.

Earlier research topics

• The interactions between trees and ground vegetation for organic nitrogen uptake via ericoid and ectomycorrhizal fungi (NITROFUNGI).   The aim of the project (2012-2017) is to investigate how changes in climatic conditions affect carbon (C) storage ability of the boreal forest soils. It has been shown that nitrogen (N) has a key role in the decomposition of soil organic matter (SOM) because the need for N partly controls SOM decomposition. Fungi are important decomposers of SOM and some fungi form symbiosis with forest trees and shrubs. The interaction between SOM decomposition, soil organic N uptake, symbiotic fungi and forest plants will be studied using modern methods from stable isotopes and radiocarbon dating to molecular biology. The results improve our knowledge on the effect of climate change on soil C and N storage pools, and provide data to improve ecosystem-scale models used to predict forest growth in the changing climate.
• The interactions between soil fungal communities and soil organic nitrogen (SON) transformation in boreal forests- the effects of season, geographical location and natural disturbances (PYROFUNGI). The main aim of the project (2013-2015) is to identify for the first time the fungal community structure and some of their functions in three main ecosystem stations in Finland. We will connect NGS sequence data (454 pyrosequencing) to organic nitrogen decomposition from several aspects: spatio-temporal dynamics and disturbances in forest ecosystem (fire and reindeer husbandry).
• Revealing sources of biological methane production in boreal upland forests (METAFOR). The aim of the project (2014-2016) is to quantify the biological sources of CH₄ in an upland boreal forest ecosystem, and to identify the microbes, CH₄ producing methanogens, involved in the CH₄ exchange in each of the compartments: soil, ground vegetation and trees. In order to quantify the contribution of each compartment to the net ecosystem CH₄ exchange, the CH₄ emission rates from the forest-floor, tree-trunks or the canopy (branches), will be integrated to represent the fluxes over a large forest area. The information of the microbial community structure and the presence of methanogens will be used to further understand the biological mechanisms and the players in the CH₄ production. Project leader Doc. Mari Pihlatie.
• Decomposition of different fractions of soil organic matter in boreal forest soil; effect of fast cycling carbon and nitrogen on the decomposition of old soil organic matter (FASTCARBON). In this project (2010-2014) the aim is to study organic matter degradation using stable isotope techniques and to determine what is the age of carbon respired after priming by simple sugars. The adding is done either directly as glucose or by Scots pine plant as a natural mixture of recent photosynthates. Experiments to better understand the priming effect are in progress. Project leader Doc. Jukka Pumpanen.
• The cryopreservation of ectomycorrhizal fungi. The MSc project of Ulla Mikkola started in September 2010. The aim of the project is to study how ectomycorrhizal fungi tolerate cryopreservation (-196°C) and whether the survived strains have the same functional properties before and after cryopreservation. Mycorrhiza formation, enzyme production and growth patterns are used as indirect methods to test the functionality. Cryopreservation would greatly facilitate the storage of strains in large culture collections (like FBCC in University of Helsinki) and would allow infinite storage periods.
• BVOC production by soil fungi. The project is done in collaboration with e.g. dos. Jaana Bäck and MSc. Hermanni Aaltonen (University of Helsinki). Biogenic volatile organic compounds (BVOCs) are shown to be important for atmosphere chemistry and cloud formation. Boreal forest are shown to produce significant amounts of BVOCs that consist of numerous organic compuons. The aim of the project is to experimentally test whether soil fungi produce BVOCs, what compounds are produced and  how mycorrhizal symbiosis affect tree roots BVOC production. The first paper of the project was published in 2010 (Bäck et al. 2010).
• Tree root and mycorrhizal associated archaeal communities. The project is done in collaboration with Dr. Malin Bomberg (VTT, Finland). Archaea are a group of micro-organisms that are not well know but do have a contribution to e.g. global methane cycling. However, the significance of this contribution is largely not quantified. In the project, the archaeal community structure in different tree species and different temperatures was determined. The manuscript is submitted November 2010.
• Evaluating the role of shiro formation of Tricholoma matsutake in natural stand of Pinus sylvestris. The project is lead by Dr. Lu-Min Vaario and other collaborators are Drs. Taina Pennanen, Tytti Sarjala and MSc. Eira-Maija Savonen, all from Finnish Forest Research Institute (METLA). My major contribution to the project is the enzyme analysis that are performed from field soil, ectomycorrhiza and bark samples.
• Bioactive compounds for drug discovery. This project was started in late 2005 as part of my post-doctoral project in collaboration with Viikki Drug Discovery Center (http://www.ddtc.helsinki.fi/index.html) and with professors Pia Vuorela, Annele Hatakka and MSc. Päivi Järvinen. Since then I have grown and extracted fungal strains in controlled axenic conditions before filtration and extraction of the growth media. The extract are analysed in the drug discovery center to find interesting novel bioactive compounds.
• The effects of ectomycorrhizal fungi on carbon balance of Scots pine (Pinus sylvestris) seedlings. The project was started in collaboration with professor Hannu Ilvesniemi (Finnish Forest Research Institute, METLA) and his project ‘Role of older humus and rhizobial exudates in the C-balance of boreal forest soils: Impact of clear-cutting, forest regeneration and tree species' funded by the Academy of Finland. There are experimentation going on related to this topic.
• Quorum sensing inhibition by root associated fungi. This collaborative project was done together with Dr. Stephane Uroz from INRA in Nancy, France. The aim of the project was to see whether root-associated fungi can produce bioactive compounds that may affect bacterial quorum sensing. Quorum sensing is an important function in bacterial communities that partly regulates bacterial community responses. See the publication Uroz and Heinonsalo, 2008.
• The interactions of ectomycorrhizal and litter-decomposing fungi. The project was done in collaboration with PhD Kari Steffen (link http://www.drsteffen.com/) at the University of Helsinki (postdoctoral project of  the Academy of Finland called ‘Comparative evaluation of degradative activities in litter-decomposing and facultative mycorrhiza-forming fungi’), prof. Martin Hofrichter (International Graduate School Zittau, Germany) and doc. Maarit Niemi (Finnish Environment Institute, Helsinki, Finland). A manuscript on a novel enzyme analysis method is in preparation from this project.
• Biodiversity of ectomycorrhizal fungi. I did my PhD thesis under supervision of doc. Robin Sen with a title ‘The effects of Forestry Practices on Ectomycorrhizal Fungal Communities and Seedling Establishment’. The project was part of Academy of Finland’s FIBRE project (http://fibre.utu.fi/). Thesis can be found as pdf in http://ethesis.helsinki.fi/julkaisut/bio/bioja/vk/heinonsalo/
• Bioremediation or hydrocarbon contaminated soil by ectomycorrhizal fungi. I did my MSc. thesis in the bioremediation project. The results were published under title ‘Effects of ectomycorrhizal fungi and associated bacteria on hydrocarbon oxidation in forest and petroleum-contaminated soils’. See Heinonsalo et al. (2000).

Team members

Dos. Mari Pihlatie, University of Helsinki, Finland

Dr. Hui Sun, (post doctoral scientist), University of Helsinki, Finland

Antti-Jussi Kieloaho (PhD student together with dos. Mari Pihlatie), University of Helsinki, Finland

Minna Santalahti (PhD student), University of Helsinki, Finland

Past team members

Aki Linden (PhD student together with dos. Jukka Pumpanen), University of Helsinki, Finland

Maëlle Durant, trainee, Université Claire Pascale, Clermont-Ferrand, France (2013)

Cecile Pimbert, trainee, Université Claire Pascale, Clermont-Ferrand, France (2012)

Kirsi Bäcklund (MSc. student),  University of Helsinki (2011)

Ulla Mikkola (MSc. student), University of Helsinki

Julie Villemot, MSc student, Université d’Angers, France (2008)

Edith Patissier, trainee, Université Claire Pascale, Clermont-Ferrand, France (2010)

Melanié Jonniaux, trainee, Université Claire Pascale, Clermont-Ferrand, France (2010)

Collaborators:

Dos. Jukka Pumpanen, University of Helsinki

Maria Dominguez, MSc., University of Helsinki

Prof. Marja-Liisa Riekkola, University of Helsinki

Dr. Jevgeni Parshitsev, University of Helsinki

Prof. Andreas Richter, University of Vienna, Austria

Dr. Vesa Palonen, University of Helsinki

Dr. Eloni Sonninen, Natural History Museum, University of Helsinki

Prof Hannu Ilvesniemi, Finnish Forest Research Institute

Dos. Taina Pennanen (FM Sannakajsa Nylund), Finnish Forest Research Institute

Dr. Lu-Min Vaario, Finnish Forest Research Institute

Dos. Hannu Fritze, Finnish Forest Research Institute

Dos. Maarit Niemi, Finnish Environment Institute

Dos. Kari Steffen, University of Helsinki

Dos. Sari Timonen, University of Helsinki

MSc. Pekka Oivanen, University of Helsinki

Dr. Marc Buée, INRA-Nancy, France

Dr. Jean Garbaye, INRA-Nancy, France

Prof. Jaana Bäck, University of Helsinki

Dr. Hermanni Aaltonen, University of Helsinki

Dr. Malin Bomberg, VTT, Finland