New paper by Köster et al., 2018 assesses the influence of reindeer on the fluxes of three GHGs (CO₂, CH₄, N₂O) in the field layer of a northern boreal forest.

We compared grazed and non‐grazed areas and linked the GHG fluxes to vegetation biomass, plant functional type, and characteristics of soil (root biomass, soil temperature, and moisture).

Our study showed that grazing significantly reduced lichen coverage and biomass. The biomass and coverage of mosses concurrently increased significantly in grazed areas. Our results indicated that grazing induced changes in vegetation composition both positively and negatively affect GHG fluxes from the forest field layer in a northern boreal forest.

Our results showed clearly higher CO₂ emissions from grazed areas, and these were affected by soil temperature and lichen coverage.

Our results also clearly demonstrated that CH₄ and N₂O fluxes were dependent on shifts in aboveground vegetation communities. Soil temperature and moss coverage together with soil moisture explained most of the CH₄ fluxes, and grazed areas consumed more CH₄. Non-grazed areas with lower moss biomass were concurrently a small N₂O sink.

Overall, our results show for the first time that besides influencing the CO₂ fluxes from the northern boreal forest floor, reindeer grazing has an impact on the fluxes of other GHGs. Thus, reindeer may have a significant role in determining the GHG balance of northern boreal forests.

From 1. December we have a new team member as MSc. Christine Ribeiro Moreira de Assumpção started her PhD studies in AGFOREE doctoral shool in University of Helsinki!

Christines research topic is “Short and long term effects of forest fires on soil organic matter and GHG gas fluxes in boreal forests”, and she will work in close collaboration with the Academy of Finland financed project (Academy Research Fellow project for Dr. Köster) “Short and long term effects of forest fires on the stability of carbon pools in boreal forests” (01.09.2016 – 31.08.2021).

As the summer in Finland was as it was – means it was really wet and rainy summer. We were not able to arrange fire in our study area (burning experiment 2017).

Week ago we got also the information that our study areas were destroyed and we are not able to use them anyhow anymore!

Surprisingly for us, the owner of the land (Finnish Forest administration -Metsähallitus) has been doing heavy soil scarification all over the area . . .

The rest is already just history – we lost the areas with one year work (starting from planning and establishing, and finishing with measurements of one growing season), we lost a lot of equipment, as all our equipment (data loggers, thermocouples, temperature and moisture sensors, collars for gas measurements, etc.) were still on the area and were measuring, when the excavator entered . . .

The greenhouse experiment for project “Biochar as a possible new tool for afforestation practices” has established. More than 600 spruce, pine and birch seedlings growing on different biochar treated mixtures.

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More info from BiocharSeedling

Microcosm experiment was established!

The effect of PyC on microbial biomass, SOM quality and decomposition, and on the age of respired CO2 will be studied in microcosm experiment (priming effect study).

Our team member PhD Egle Köster got a grant “Biochar as a possible new tool for afforestation practices” from Marjatta ja Eino Kollin Säätiö.

The new grant is for 2.5 years and the aim is to study the effects of added biochar on growth of containerized planting stock – whether biochar application to the growing mixture would affect the growth of three main tree species (Norway spruce, Scots pine and silver birch) during the first year of growing in the nursery, and whether biochar amendment would increase the survival of plants after the planting to the field.

Obtained results will allow us to analyze if and how biochar application would affect the need for liming, fertilization and irrigation during the nursery period. We aim to provide for the public (forest practitioner, other stakeholders and general public) practical tools to improve the available afforestation practices and at the same time try to produce a new environmental supportive method.

More info from BiocharSeedling

New paper by Köster et al., (2017) is dealing with carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) fluxes from a fire chronosequence in subarctic boreal forests of Canada. The long-term effects of fire on the fluxes of three main GHGs in boreal coniferous forest areas with underlying permafrost were investigated. Fire chronosequence consists of areas where the last fires occurred in years 2012, 1990, and 1969, and results from these areas were compared with control area that had no fire for at least 100 years.

Our results revealed that the only factor that influenced all measured GHGs was the time passed from last the forest fire. We also found that the impacts of a forest fire on GHGs of our studied areas lasted for a rather long period of time. Soil CO₂ efflux decreased after the fire, but increased thereafter for several decades and appeared to reach its peak about 40–45 years later.

Subarctic boreal forests acted as sinks of CH₄ in our study, but changes in CH₄ fluxes lasted for a shorter period of time as the uptake of CH₄ did not differ between the area burned in 1969 and the control area. Increases in active layer depth, in our areas, did not lead to large increases in CH₄ fluxes.

A slight decrease in N₂O emission was observed in the comparison of different fire age classes, and factors that appeared to influence fluxes of N₂O were C and N contents of the soil, and also the depth of the active layer.

In the second half of June in year 2017 a prescribed burning experiment is planned to take place close to Hyytiälä, Finland. The area is located close to Murojärvi (about 17 km from Hyytiälä, SMEAR-I station) and the size of burned area will be 5.9 ha.

At the end of May we were establishing sample plots inside the planned burning area – marking down the sample plots, relocating the biomass, taking the soil and greenhouse gas (CO2, CH4 and N2O) samples.

The sample plots are divided into different biomass treatment plots (with four replicates in each) to mimic the fire with different intensity. The treatments in experiment consist of: control treatment with no fire (T1); all wooden biomass removed from the area (T2) to mimic low severity surface fire; wooden biomass (mostly branches) left to the area after clear cut (T3) to mimic low severity, non-stand replacing fire; extra biomass (branches, tree trunks, etc.) added to the sample plot (T4) to mimic high severity stand replacing fires.

More info

Our research team dealing with disturbances and biogeochemistry is now the member of Viiki Plant Science Centre (ViPS) (01.05.2017 – 31.04.2022) as the Scientific Advisory Board (SAB) of the ViPS has accepted Kajar Köster as one of the new principal investigators (group leaders) in their organisation.

New paper by Palviainen et al. 2017 is dealing with nitrogen balance along the boreal forest fire chronosequence. The aim of this study was to examine changes in the pools, fluxes and balance of N along a 155-year fire chronosequence in sub-arctic Scots pine (Pinus sylvestris L.) stands, and to investigate how the number of microbial genes associated with N cycling are linked to N dynamics.

The results suggest that non-stand-replacing fires in sub-arctic pine forests decrease considerably the N pools in living vegetation and increase the N pools stored in dead biomass. However, it seems that changes in total ecosystem N pool are minor, because large N pool in the soil does not noticeably change. N-fixation depends on the successional stage after a forest fire. Based on the number and intensity of genes related to N-fixation as well as the measurements of N-fixation, it seems that N-fixation rates can be substantial on the surface of the humus layer after the fire. However, because most of the N fixation takes place in mosses, and moss biomass increases with post-fire succession, total ecosystem N fixation rates increase with time since fire. N-fixation is five times higher in mature forests than in recently burned areas.