The current (second) phase of SITES is soon coming to an end. As we turn the page and face the next chapter for the SITES infrastructure, there are some imminent changes taking place. For a start, my appointment as SITES Director, which began 5 years ago with the launch of SITES-II, is soon ending and a new Director with lots of energy, new ideas and visions will take over. My sincere welcome and best wishes to Kevin Bishop who will guide and steer SITES in the years to come!

The SITES infrastructure is also experiencing some change, as Tarfala Research Station will be leaving the infrastructure consortium. We plan to establish some type of association to facilitate future synergies and exchange, but for now I just want to extend my gratitude and appreciation to the past and present Tarfala staff and Stockholm University for a fruitful and productive collaboration during my time as SITES Director.
The SITES infrastructure has achieved many things over the past few years, but I particularly want to highlight the launch and development of the SITES Data Portal and the tremendous advances we have made in mobilizing data from all SITES stations and Thematic Programs. We have also kept the momentum in the Thematic Programs and consolidated and secured these activities to be a persistent and valuable resource for the stations and for ecosystem science. These programs have also been a great asset for bringing our stations and community of researchers and technical staff closer together. I really am deeply grateful and proud of the creativity, commitment, dedication and supportive atmosphere that I see within the SITES family!
With this I want to send you all my very best wishes for the upcoming holidays and a happy new year!

- Stefan Bertilsson (SITES current Director)

Despite the December darkness, snow conditions, and at times bitterly cold weather (as much as - 28°C a few days ago), outdoor activities in the forest of Svartberget Research Station are ongoing.

Manual harvest of trees in Svartberget Experimental Forest (Photo: Linnea Larsson) Manual harvest of trees in Svartberget Experimental Forest (Photo: Linnea Larsson)

Currently there is an on-going manual harvest of trees in two field trials at Svartberget Experimental Forest. The harvest has two aims; one aim is to transform the forest into what will eventually be a nice forest to stroll around in and the other is to move, as a first step, towards an example of continuous cover forestry (CCF). A common belief is that this would require a J-curve relationship between tree diameters and tree frequencies, characterized by many small trees and a few larger trees. The manual felling in the plots and the machines driving between plots, are conducted in way to leave as much as possible the existing natural regeneration intact. The forest may not look so nice now, but over time that impression will hopefully change.

The history of this particular forest is a bit complicated with three layers of field trials superimposed on top of each other. The first layer being a former scaling experiment established in 1995 at Svartberget with the aim of understanding the effects of nitrogen deposition on the composition of vegetation. The original scaling experiment constituted five plot sizes (1, 10, 100, 1000, 5000 m2) with three fertilization treatments (0, 12.5, 50 kg N/ha/year). The second layer, established in 2014 by using the original plots in the former experiment, includes two field trials, #7104 and #7105. In one of the field trials only the original 1000 m2 plot and the corresponding fertilization treatments were re-used. In the other trial, the original 5000 m2 plot was used to create 100 x 200m plots with 12 pairwise subplots, one recovering plot and one fertilized plot. All trees were measured and also their geographic positions recorded when these trials were established. The third layer is the current transition of the field trails to CCF conditions. All old trees have now been measured and also inventories of re-growth of new trees and shrubs in the plots have been performed.

What do we expect to find over time by studying the plots? For example, that the addition of nitrogen may promote seedling establishment and growth but maybe also results in more competing vegetation hampering successful seedling establishment. Time will tell.

Field trial layers at Svartberget Experimental Forest.
Field trial layers at Svartberget Experimental Forest.

The Erken Laboratory (Uppsala University) has an open position for a research engineer from February to the end of November 2023. The position includes a variety of different working tasks related to the implementation of the coordinated mesocosm experiments conducted within SITES AquaNet and the EU-project AQUACOSM-plus, Erken’s long-term lake monitoring programme and SITES Water.
This position provides a great opportunity for those interested to work in a research infrastructure and collect field measurements, but also offers many possibilities for interactions within collaborative team science projects related to the planned mesocosm experiments. The mesocosm experiments will focus on the functional and compositional consequences of different run-off and salt disturbance regimes. More information about the experiments can be found here.
The advertised position and a link to the application system can be found here:

Application deadline: January 13, 2023

SITES AquaNet Platform on Lake Erken

High use of external inputs, especially agrochemicals, has considerably increased food production since the Green Revolution. This has, however, also led to a decline in biodiversity and contributed to a change in climate, soil, air and water quality. Hence, there is a need to develop cropping systems that are multi-functional, i.e. not only increase food production, but also improves the environment and economy.

Multi-actor visit to strip cropping field on 27 October 2022. Photo: Raj Chongtham Multi-actor visit to strip cropping field on 27 October 2022. Photo: Raj Chongtham

In order to develop new multi-functional cropping systems, a new project at SITES Lönnstorp, funded by Formas, will study the possibility to design diversified cropping systems based on strip cropping, i.e. growing crops on the same field in distinguishable stripes or patches. The strip cropping will consist of winter oilseed rape and winter wheat and will be intercropped with and without winter pea. The project has a participatory approach and the co-designed cropping systems will be established and evaluated both at farming fields and at SITES Lönnstorps research station during three growing seasons. The performance of each diversification approach (strip cropping and intercropping with winter pea) will be evaluated in terms of pest and natural enemy abundance, weeds, diseases, crop nitrogen acquisition and yield. The sustainability (economic, environmental and social dimensions) of the co-designed cropping systems will also be assessed by using a multi-criteria sustainability assessment tool.

You can read more about the project here

Strip cropping of winter oilseed rape, winter wheat and winter pea on 27 October 2022. Photo: Raj Chongtham

Ornithology has a long tradition in biological research, and there are numerous data sets on various subtopics available both via scientific publications and conservation organizations. The phenology of migrating species (e.g. arrival dates to breeding grounds) has drawn attention in the last few decades, as it describes and helps understand effects of increasing temperatures on bird migration.

Since 1985 such corresponding data have been collected at Grimsö Wildlife Research Station. The dataset at Grimsö comprises of date of the first observation within the research area each year for ca. 80 migratory species, and shows several more or less pronounced changes over the 37 years of data collected.

Common cranes (Grus grus) migrating south for winter. Photo: Rick Heeres Common cranes (Grus grus) migrating south for winter. Photo: Rick Heeres

As expected, and seen in many studies, the long-distance migrants, that spend winter in, e.g. Africa, show very little variation in spring arrival dates between years (as seen in the graph below). In a few cases the date differs >1 week for such species, which is due to other factors than a sudden temperature change. Instead more or less the same dates/week are noted for them throughout the period. This behavior is explained in that the best timing of such long flights cannot be based on the daily weather in the wintering area, but is instead initiated mainly by day length, which in turn relates to a suitable arrival time at the breeding ground.  

Date (Julian day) of the first observation per year (since 1985) of the Common Cuckoo (Cuculus canorus) and the Barn Swallow (Hirundo rustica) within Grimsö Wildlife Research Area. Date (Julian day) of the first observation per year (since 1985) of the Common Cuckoo (Cuculus canorus) and the Barn Swallow (Hirundo rustica) within Grimsö Wildlife Research Area.

On the other hand, several of the migratory birds in Sweden that move only short distances, i.e. southward before the winter, move gradually in response to the local weather (temperature, food availability etc) and show significantly earlier spring arrivals in recent decades compared to the first years of the survey. The mean arrival dates of, for example, the Mallard and the Common black bird were 12 and 19 days earlier, respectively, in the period 2005-2022 and 1985-2004. Moreover, some of the short-distance migratory species nowadays stay in southern and middle Sweden throughout the winter.  

Date (Julian day) of the first observation per year (since 1985) of the Mallard (Anas platyrhynchos) and the Common blackbird (Turdus merula) within Grimsö Wildlife Research Area. The seasonal movements of these species are rather related to local weather conditions than actual migrations, with an apparent trend of earlier arrivals to the breeding grounds in later years. Points along the x-axis (i.e. Julian day = 0) indicate the bird species stayed in the area till the next year.

Here once again this dataset highlights the importance of long term monitoring. If this survey had started for example 10 years ago, we would not yet have recognized stark changes of bird arrivals in the region/data.

SITES Röbäcksdalen Field Research Station has recently welcomed researcher Julianne Oliveira! Welcome to the SITES Community, Julianne! 

Field dat being collected by Julianne Oliveira. Field dat being collected by Julianne Oliveira.

Julianne has a background in remote sensing, GIS and data science applied to agricultural and forest systems. She works with remotely sensed information (satellite, aerial and proximal sensors), field data collection and computer-based modelling to assess and monitor vegetation attributes. Her current research focus is to apply these approaches to forage crops in Northern Sweden. At SITES Röbäcksdalen Field Research Station, her role will be to support the team in the collection, management and analysis of the biological data to be published on the SITES Data Portal. She will also assist in the SITES Spectral activities at the station. Julianne is looking forward to collaborating with the team and assisting with the quality check and dissemination of the data. During her free time, she likes to travel and be outside, including activities such as hiking and running.

Asa High-yield Experimental Forest was established in 2009 and covers an area of 1700 hectares, situated in close proximity to Asa Research Station. Spruce and pine dominates the forest and represent 95% of the total area. The aim of the high-yield experiment is to increase the growth of wood by 50 %, and at the same time avoid creating any negative effects on water chemistry, vegetation, recreational values, etc. Every second year stands within the experimental area are fertilized. Due to the fertilization, water samples are collected and analysed regularly from streams that represent the different catchments within the area, to ensure that there isn’t leakage of nutrients.

Apart from producing water chemistry data from the different catchment areas, the water monitoring program gives an opportunity to follow the water level and discharge through the seasons. This year the water level has differed in comparison to earlier years. It is common that the streams in the forest run dry for a period during the summer, but this year, there has hardly been water in the streams during autumn. As the photo below shows, there is at the moment (in early November) hardly any or only very low flow in the streams.

Low water leves in Asa stream. Photo: Erik Kristensen

The graph below shows one of the streams drying up (i.e. very low discharge) by May and remaining that way into the autumn. March was extremely dry with minimal precipitation. Precipitation in the following six months was actually higher than the annual monthly average but it was still not enough to keep the stream flowing and make up for the lack of rain during March. The data is from an inlet stream to Lake Feresjön, where the water table has been low for a prolonged period, yet this year was even lower.

Water leve data from the Lake Feresjön inlet streams can be found on SITES data portal, and soon it will also be possible to download all water level data and water discharge data from the catchment areas in Asa High-yield Experimental Forest.

Lund University has recently installed two new spectral masts overlooking crop fields in Alnarp, near the SITES Lönnstorp Research Station. Each mast holds two down-looking spectral sensors, one on each side of the mast, overlooking one field each. There are also temperature and soil moisture sensors to follow the weather and climate at the locations continuously through time. The installations are part of a research project sponsored by the Swedish National Space Agency that aims to develop and quantify crop growth and yield based on satellite remote sensing. Accurate field measurements of biomass allocation to root, stem, leaves and seeds have been carried out through the season of 2022 and will form the basis of crop-growth modelling as a support to yield estimation. The stations are affiliated to the SITES Spectral infrastructure and will also provide an input to the Nordic NordPlant collaboration project focusing on plant phenotyping. For more information on the research, contact Lars Eklundh (

Installing the two new spectral mast on agricultural fields in Alnarp. Photo: Lars Eklundh.

A new article focusing on one of the main research fields of Bolmen’s Research Station recently got published in Water Practice & Technology. The article focuses on short-term changes of organic matter in Lake Bolmen, which has direct influences on the color of the water as well as the source water quality for drinking water production in south-western Skåne. Analysis of Kafjorden, a southern sub-basin of Lake Bolmen, was analyzed in detail and it was concluded that it can produce changes of organic matter in a time span of days to weeks. These changes are related to local inflow conditions of Murån, a sub-basin of the main tributary, as well as internal processes like sedimentation and wave driven resuspension.

Karfjorden, a southern sub-basin of Lake Bolmen. Photo: Clemens Klante Karfjorden, a southern sub-basin of Lake Bolmen. Photo: Clemens Klante

Information on how and when variations in organic matter happen in the lake does not only help to improve the drinking water treatment process downstream but it also effects the carbon dioxide (CO2) and waste production of such facilities. The article points out that better source water monitoring is a necessity to enable further analysis, which will not only further help to streamline water treatment efforts but also help to better understand water resources and its interactions. Infrastructures like SITES are a cornerstone to facilitate such vastly needed measurements.

Read the full article: Klante C., Hägg K., Larson M. 2022. Understanding short-term organic matter fluctuations to optimize drinking water treatment. Water Practice and Technology: 17: 2141–2159.

A workshop at SITES Svartberget Research Station, within Vindeln Experimental Forests, took place on Sept 6-7, 2022, with a focus on existing and future research infrastructures (RIs) in the area. The main objective of the workshop was to 1) exchange information about the RIs, 2) discuss ways to optimize and maximize the potential synergies between the RIs, and 3) discuss possible research activities and research papers made possible by the RIs establishments. In total, 23 persons participated in the workshop, representing specific RIs in the Vindeln area. A main outcome from the meeting resulted in plans to apply for funding to create and develop environments that support research collaborations around a common theme connecting the RIs.

Discussion during the workshop at SITES Svartberget Research Station. Photo: Johannes Tiwari.
Discussion during the workshop at SITES Svartberget Research Station. Photo: Johannes Tiwari.

Currently SLU Svartberget contributes to three geographically distributed RIs, all supported by the Swedish Research Council (VR); SITES (Swedish Infrastructure for Ecosystem Science), ICOS Sweden (Integrated Carbon Observation System) and ACTRIS Sweden (Aerosol, Clouds and Trace Gases Research Infrastructure). In addition, the tower-based radar at Svartberget, BorealScat-2, is a recently established RI. Overall, the RIs at Svartberget reflect a broad ecosystem research focus; from long-term forest management trials and their effect on forest production and diversity to water and carbon balance of boreal ecosystems, as well as studies of the direct climate effects of short-lived climate forcers such as aerosols.
Since SITES formation in 2012, Svartberget has played an active role in the RI and includes activities related to the terrestrial environment, such as long-term experimental forest trials and the Krycklan catchment, and the three SITES Thematic Programs – Spectral, AquaNet and Water. Svartberget will continue these activities during SITES next funding phase (2023 – 2028) with plans to develop the connection between SITES activities to other RI activities ongoing at the station and the surrounding area as explained below:  

The Mast house at ICOS Svartberget and also the house that will room ACTRIS Svartberget. Photo: Paul Smith. The Mast house at ICOS Svartberget and also the house that will room ACTRIS Svartberget. Photo: Paul Smith.


ICOS is a European research infrastructure, formed in 2008, with the aim to provide accessible, high-quality data to improve the understanding of greenhouse gas sinks and emissions and to contribute to measures aimed at limiting the climate impact.  All stations in the national networks across Europe follow the same standardized protocols for data gathering. The measurement data are sent to central ICOS facilities where they are quality controlled and processed before being forwarded to the ICOS Carbon Portal and made available to users (Link to data here). SLU contributes with three measuring stations within Vindelns Experimental Forests; an Atmosphere station and an Ecosystem station located in the coniferous forest at Svartberget and an Ecosystem station located on the mire at Degerö, Kulbäcksliden experimental forest. The Atmosphere station measures the amount of greenhouse gases in the atmosphere at different levels up to a height of 150 meters. The purpose of the two Ecosystem stations is to understand the uptake and release of greenhouse gases, primarily carbon dioxide (CO2) and methane (CH4), how they are affected by climate change and to understand whether the northern forests and mires causes an increase or counteracts the greenhouse effect. At the Degerö station, continuous measurements of the biosphere-atmosphere exchange of CO2 by eddy covariance already started in 2001, before becoming an ICOS Ecosystem station.


 ACTRIS is a pan-European research infrastructure initiated in 2011 that provides a network of stations that observe short-lived climate forcers (SLCF). The SLCFs have a short residence time in the atmosphere and include airborne particles, aerosols, and reactive trace gases. The Swedish branch of the research infrastructure is run by ACTRIS Sweden with six organizations (Lund University (Coordinating), Stockholm University, Gothenburg University, SLU, SMHI, and Uppsala University) currently taking part in a 5-year implementation phase.  ACTRIS Sweden has chosen to co-locate its measuring stations with the ICOS infrastructure and from 2022 also at Svartberget.

BorealScat-2 is a 50 m radar tower for studying temporal variations in forest radar measurements. Photo: Albert Monteith. BorealScat-2 is a 50 m radar tower for studying temporal variations in forest radar measurements. Photo: Albert Monteith.


BorealScat-2 is a radar tower experiment established in 2022 at Svartberget Experimental Forest for studying temporal variations in forest radar measurements. The tower, previously used in the BorealScat experiment in Southern Sweden, has been relocated and upgraded. The aim is to investigate forest moisture variations in P-/L-/C-/X-band tower-based radar observations and to develop methods for estimating forest evapotranspiration from space borne radar observations. Evapotranspiration plays a central role in the carbon, water and energy cycles and is closely related to drought-induced tree mortality. Radar observations are directly sensitive to the spatial distribution of water. By establishing a relationship between radar observations and variables contributing to evapotranspiration, space-borne radar is expected to contribute to high spatial and temporal resolution of evapotranspiration observations.

There will be a scheduled maintenance on 24.10.22 from 6:00 to 10:00 AM UTC, during which time the SITES Data Portal with all its attached services may not be available. Please plan SITES Data Portal use accordingly.

In Abisko, autumn arrived in vibrant September-colours. But autumn does not equal calm at the research station. Throughout September, the station continued to be at full capacity. 

Autumn colours in Abisko!  Photographer: Emily Pickering Pedersen
Autumn colours in Abisko! Photographer: Emily Pickering Pedersen
Students from Lund University analysing samples with the gas chromatograph. Photographer: Thomas Holst Students from Lund University analysing samples with the gas chromatograph. Photographer: Thomas Holst

Among other activities, two student courses were hosted: a biogeochemistry course from Lund University and an arctic ecosystem ecology course from Umeå University. In the biogeochemistry course, students focused on the carbon cycle and greenhouse gas exchange between the biosphere and atmosphere. As a part of this course, students also built their own eddy covariance tower at SITES Lönnstorp station and spent two days at the ICOS site Hyltemossa. In the arctic ecosystems course, students gained hands-on experience with ecological research, focusing on topics such as nutrient availability, plant-soil-organism interactions and feedbacks between arctic ecosystems and the climate system. This year, the course had more than twice the number of participants as in previous years!

September was also a month of events – both in Abisko and abroad: A preparatory course was hosted for this winter’s polar expedition to the Swedish research station in Antarctica. This year’s expedition will be a logistics expedition, focusing on maintaining and developing the physical infrastructure. The Abisko research station also hosted the annual Climate Impacts Research Centre (CIRC) Symposium, connected to Umeå University, this year attended with nearly 40 participants.
On the international scene, three delegates from the research station participated in the international ICOS conference in Utrecht, Netherlands. This was a great opportunity to network and learn more about environmental monitoring programmes and equipment. Abisko was also represented at the INTERACT meeting in Iceland, comprising the Station Managers Forum and the General Assembly. Abisko Scientific Research Station is part of the INTERACT network, which is an international collaboration between arctic and alpine research stations.

Newly deployed snow depth sensor near Abisko research station. Photographer: Niklas Rakos Newly deployed snow depth sensor near Abisko research station. Photographer: Niklas Rakos

In the field, SITES Water is preparing for winter. In Almergasjön, the winter measurement string has been deployed. The “winter string” consists of three sets of sensors attached to a string, which is held in place with an anchor and a submerged buoy. The buoy is installed more than a meter below the water surface in order to not freeze into the ice during the winter. The sensors measure oxygen (O2) concentration, conductivity and temperature and are installed at depths 1, 2 and 3.5 meters above the bottom.

In preparation for winter, the Almbergasjön summer raft, which hosts sensors and equipment for open-water measurements during the ice-free period, has been taken to shore. This year’s series of lake carbon dioxide (CO2) flux chamber measurements has also been concluded. This week, a snow depth sensor will be deployed as a part of the long-term environmental monitoring programme in Abisko. The automated sensor is another step in the process of converting the station’s long-term manually collected data series to automated data collection.

The 19th Annual Krycklan Symposium took place Sept. 21, 2022, with the focus on “The Next Generation for Water: Buffers, Maps and Peatland Management”. There were about 100 people in attendance for the hybrid Symposium, with about 20 of those participating online. In total there were 40 presentations with 4 different sessions; general Krycklan research (highlighting new projects), riparian buffer management, state-of-the-art mapping, and peatland management.
Research presented at the symposium connects to ongoing SITES Water activities at Svartberget Research Station and has relevance to activities at other SITES stations (e.g. Eddy Covariance, rewetting). Check out the live tweets of the event to find out more!

Following the Symposium an excursion, with 40 participants, took place at Svartberget Research Station in the Krycklan catchment . Photo:  Shokoufeh Salimi
Following the Symposium an excursion, with 40 participants, took place at Svartberget Research Station in the Krycklan catchment . Photo: Shokoufeh Salimi

Faba bean varieties developed for needs in Sweden
SLU Grogrund is a centre for breeding food crops in Sweden. Through collaborations with academics and industry, this centre aims to meet the needs described in the Food strategy from the Swedish government 2017. One need described in the Food strategy is an increased self-sufficiency of raw material for food production, and a prerequisite for this is that the farmers have access to varieties of crops that are adapted to Swedish climate conditions. Faba bean or ‘åkerböna’ in Swedish (Vicia faba) is one of the protein crops that is already grown in Sweden today but only in small volumes. However, there is a high potential for increased cultivation of faba bean for use in food. In a research and breeding project on faba bean, financed by SLU Grogrund 2019-2022, a breeding program has been initiated by Lantmännen, and in parallel new plant breeding tools are being developed through research at SLU to make the breeding program more efficient in the future. Desired traits for faba bean are early maturation, disease and drought resistance, high protein content and low levels of antinutritional compounds.

Drone photo of the field experiment from above at SITES Lönnstorp Research Station 2021. Photographer: Aakash Chawade. Drone photo of the field experiment from above at SITES Lönnstorp Research Station 2021. Photographer: Aakash Chawade.

Faba bean genotype collection characterized at SLU Lönnstorp field station

During 2021 and 2022, 220 different faba bean genotypes from all over the world were characterized in field trials at SITES Lönnstorp Research Station. Different agronomic traits were measured in the field, and the harvested seeds were analyzed for seed quality (starch, protein, oil, and antinutritional compounds). The field design was alpha-lattice in two replicates, and each plot was 0.75 m2 with 50 plants. The 220 different faba bean genotypes includes old and new varieties from Sweden and abroad, landraces, and diverse accessions from gene banks all over the world.  The data from 2021 reveals high genetic diversity in traits such as plant height, time of flowering, flower colour, seed size and colour, and seed yield. The faba bean collection is also genotyped, which will reveal DNA sequence differences called single nucleotide polymorphisms (SNPs). By associating the phenotypic differences to the identified SNPs, genetic markers for specific traits will be determined. Such genetic markers can be used in the breeding program to make a more efficient selection of parents to cross and develop new varieties with desired traits.

Photos showing newly established faba bean plants at SITES Lönnstorp Research Station (left) and field demonstrations 2021 and 2022 (right). Photographers: Åsa Grimberg and Lisa Beste.
Photos showing newly established faba bean plants at SITES Lönnstorp Research Station (left) and field demonstrations 2021 and 2022 (right). Photographers: Åsa Grimberg and Lisa Beste.

Collaboration between SLU and industry

The SLU Grogrund project on faba bean is a collaboration between the Department of Plant Breeding at SLU, Lantmännen, Kalmar Ölands trädgårdsprodukter, and Sveriges stärkelseproducenter. In June 2022 a project meeting was held in Alnarp, in which several other industrial stakeholders also participated to discuss the possibilities and challenges of the faba bean value chain; from plant breeding, cultivation, and use of the raw material for both food and feed products. The SLU Grogrund project on faba bean hopes that this collaboration can continue into the future. 

The first AQUACOSM-plus transnational access (TA) experiment using the SITES AquaNet infrastructure finished in Mid-August. The experiment investigated functional and compositional consequences of run-off variability and was synchronized at Lake Erken and Bolmen during 6 weeks this summer. It brought together a team that involved 10 TA participants from Spain, Turkey, Ireland, Hungary and the Czech Republic, 5 participants from AQUACOSM-plus partners at IBG and Oldenburg University in Germany, and several local participants from Uppsala and Lund University.

Group picture with participants in the AquaNet experiment. Photographer: Matilda Andersson
Group picture with participants in the AquaNet experiment. Photographer: Matilda Andersson
During the experiment clear differences were observed in the abundance of Gloetrichica echinulata colonies, which is a cyanobacterium that blooms in Erken during summer. Photographer: Matilda Andersso During the experiment clear differences were observed in the abundance of Gloetrichica echinulata colonies, which is a cyanobacterium that blooms in Erken during summer. Photographer: Matilda Andersso

In the experiment, different run-off scenarios were investigated, which was done by manipulating the intensity and frequency of dissolved organic carbon (DOC), i.e. peat extract, and inorganic nutrient pulses that were added to the mesocosms while keeping the total added amount constant. There was a treatment with daily additions, an extreme treatment where all DOC and nutrients were added as one big pulse and an intermediate treatment where they were added in stochastic pulses of varying intensity. The project participants and SITES AquaNet will now continue with the sample and data analysis to answer how the different treatments affected among others, plankton composition and biomass/abundance, dissolved organic matter (DOM) composition, greenhouse gas emissions and nutrient stoichiometry. The experiment is unique in that it allows comparison of responses between two lakes that have very similar DOC concentrations but differ in DOC composition and dissolved nutrient concentrations.

Now that the summer 2022 experiment is wrapping up, we have started to make plans for the SITES AquaNet experiments in spring 2023 - more information and participation call will follow soon. Stay tuned! 

Preliminary data collected during the experiment in Erken shows that there were clear differences between run-off treatments in dissolved oxygen concentration, measured by a sensor that each mesocosm was equipped with.
Preliminary data collected during the experiment in Erken shows that there were clear differences between run-off treatments in dissolved oxygen concentration, measured by a sensor that each mesocosm was equipped with.

The summer season at Tarfala Research Station (TRS) has been very wet. Heavy rainfall during a couple of days at the end of August brought along temporary and also more permanent changes: Between Lake Tarfala and TRS, Tarfalajokk became so wide and carried so much water that any idea of crossing needed to be dismissed. Lillsjön (translating to “the little lake”) just south of TRS turned into a rather large lake.

Left: Low waterlevel in Lillsjön. Middle: High waterlevel in Lillsjön. Photographer: Nina Kirchner
Tarfala Valley, where the path to TRS has been washed away by recent heavy rainfall. Photographer: Nina Kirchner Tarfala Valley, where the path to TRS has been washed away by recent heavy rainfall. Photographer: Nina Kirchner

A few kilometers down in the Tarfala Valley, several hundred meters of the path to Tarfala Bridge was swept away by water masses. Erosion was substantial, including a landslide on the western valley flank, and a completely changed riverbed. This has made the 6 km hike down to Tarfala Bridge, where the SITES Water discharge measurements are conducted at least once a week, an evolving challenge for the station’s team. At the beginning of September, water levels in Lillsjön and Tarfalajokk returned back to lows, and the first northern lights could be observed. 

After more than two years of travel restrictions and limited field research activity due to the Covid-19 pandemic, Abisko Scientific Research Station is finally back to full speed. The summer of 2022 has been one of the busiest summers in the history of the research station, with the station constantly at – or beyond – full capacity, June through September.

Undergraduate students hard at work in the Stordalen mire, collecting data for ongoing and new research projects, including methane and carbon flux measurements and vegetation quantification. Photo credit: Hannah Holland-Moritz

Researchers have been eager to get back to the field to follow up on long-term projects or to initiate new ones. Over the past few months, the station has accommodated more than 70 research projects, driven by an eclectic community of junior and senior researchers, students, field assistants, and interns. With researchers affiliated with institutions spanning more than 12 countries and 3 continents, the vibe has been international, interdisciplinary, and energetic. Projects have covered research fields ranging from biogeochemistry, plant ecology and soil ecology, through microbiology, entomology, limnology and hydrology, to modelling and remote sensing – to give a few examples.

SITES Water: new installation for measuring stream O2 and CO2 concentrations. A buoy and constant force spring ensure that the cable stays tensioned and that the sensor always stays at the same water depth relative to the surface regardless of changes in water level and discharge throughout the year. This set-up also protects the sensor from sudden changes in water pressure. Photo credit: Alexander Meire

The long-term environmental monitoring programs within ICOS and SITES have also continued successfully, generating high-quality environmental data for long-term monitoring as well as supporting data for associated research projects. In addition to continuous measurements, this summer’s monitoring work included lake chamber flux measurements (SITES Water), extensive vegetation surveys (ICOS) and the development and installation of an improved system for measuring stream O2 and CO2 concentrations (SITES Water).
As the summer season slows down, the Abisko Scientific Research Station transitions into a slightly less intense mode, but research continues here throughout the year with an exciting winter season coming up!


The Global Soil Biodiversity Observation Network (Soil BON) is working in partnership with the Global Soil Biodiversity Initiative (GSBI) and other global and regional partners to increase the monitoring of soil ecosystems. The goal is to connect multi-national partners and initiatives in a worldwide effort to understand soil biodiversity, document how it is changing, how these changes affect people who rely on soil living resources for their well-being and livelihoods, and to better understand how the sustainable use of ecosystems can protect soil biodiversity. To achieve these goals they plan to monitor 1000 locations across the world including Asa Forest Research Station and Aneboda IM along with six other stations in Sweden. The purpose of the sampling is to have two paired sites, one nature conservation site (Aneboda IM) and one non-conservation site (Asa) and the samples need to be from a single habitat type. All eight sites in Sweden are dominated by Norway Spruce.

Samplings points for Soil BON project Samplings points for Soil BON project

During the last week of August soil samples were taken at Asa Forest Research Station and the Aneboda IM site.  A standard sampling kit is used worldwide and all samples are sent to the same laboratory in Germany for genetic sequencing analyses. In addition to sequencing, analysis of soil functional characteristics will be performed for ecosystem function studies (soil respiration, substrate-induced respiration, microbial biomass, enzyme activity, and soil aggregate stability).

Litter mass loss over time of Rooibos and Green tea (author: Judith Sarnell) Litter mass loss over time of Rooibos and Green tea (author: Judith Sarnell)

Samples consist of bulk and crust samples, taken at nine points. Additionally, at the central point (point 1 in the figure above) eight tea bags (green tea and Rooibos tea) were buried at 5 cm depth. They will be removed after 12 months and their decomposition stage will be determined. Buried tea bags are actually a well-known, unified, and comparable method for determining the speed of decomposition. Two types of tea are used because there are two phases of decomposition – in the first phase decomposition is high as all the “easy” material is being decomposed and in the second phase decomposition slows down as it is only “hard” material left. Green tea decomposes quickly while Rooibos tea decomposes more slowly. Comparing the decomposition stage of both varieties of tea gives information not only about how much easy material is decomposed but also about initial decomposition rate.

The teams at Asa and Aneboda stations are excited to be able to contribute to increasing knowledge about soil ecosystems worldwide!

The pandemic has slowed down and Röbäcksdalen is able to welcome visitors once again.
In June a delegation from LUKE in Finland came by and got a demonstration of our animal and field facilities. They showed particular interest in SITES spectral and SITES water, since similar activities are done in Finland, and there is a potential for fruitful collaborations between SITES and LUKE in these areas. In July, Länsstyrelsen arranged a field day for farmers at Röbäcksdalen. The visit focused on herbicide and pesticide management practices and attracted farmers and advisors from all over northern Sweden. In August the station will be visited by a large group of around 60 animal and plant breeders, as part of a larger workshop occurring in Umeå. The summer season wraps up in September with planned visits from the VH faculty at SLU and from a small group from the government office, who is working with the national food strategy for the government. 
There have also been more external researchers visiting the station now. Among others are a research group from Bonn University, who are sampling soils in Röbäcksdalen, Asa, and Svartberget as part of a larger European project, and a group from Alnarp who are using the drying and milling facilities at Röbäcksdalen. 

Sara Bauke, Heike Schimmel and Dymphie Burger from Bonn University are taking soil samples at Röbäcksdalen in preparation for their experiment. Photo by Boel Sandström.

Friday was the second big sampling day for the SITES AquaNet and Aquacosm mesocosm experiment. The experiment is examining the impact of changes in run-off on lake plankton communities since rainfall patterns, and thereby run-off, are expected to be impacted by climate change. Becuase of the diversity of size within planktonic communities and the wide range of factors that can impact both zoo- and phytoplankton, there are a wide range of samples being taken throughout the experiment including; DOC, dissolved nutrients, chlorophyll, phytoplankton, zooplankton, and greenhouse gasses.


You can’t always see what is being filtered out of water samples with your naked eye, but Lake Erken has a genus of cyanobacteria called Gloeotrichia which forms large colonies that can be easily spotted. These colonies are only one of the many species found in the mesocosms, but during summer they do make up a large part of the biomass.  


Nutrient and DOC additions follow sampling. Shown below, Stella Berger mixes one of the mesocosms while Silke Langenheder adds nutrients and Jens Nejstgaard tries not to get blown away. Luckily the AquaNet platform is shielded by the dock so it remains relatively stable even in stormy weather. 

Photo by: Matilda Andersson

We look forward to sharing the results of the study in the future!

Surprisingly the extreme snowfall events in early April have not delayed the start of the summer season in the Tarfala valley. A warm May and June caused rapid snow melt and the summer conditions are now quite normal. The discharge in the rivers has been generally high over the last month but has now settled to a normal rate. The ice covering the lake Tarfalasjön is still solid but is expected to break up soon. The Tarfala Research Station opened on June 28th and the SITES sampling program is just now getting started for the year. The station will be run as usual this year after two years of reduced activities.

Tarfala Research Station on April 8, 2022. Photo: Per Holmlund
Tarfala Research Station on July 2, 2022. Photo: Per Holmlund

The wild boar (Sus scrofa) project at Grimsö Wildlife Research Station explores several research topics, including, the effects of supplemental feeding on local boar populations and the surrounding habitat. Supplementary feeding is a management practice where attractive food and nutrients are supplied on daily basis at feeding stations. These feeders are often used in hunting to attract animals to a set location but are also used with the goal of shifting habitat use away from agricultural fields. This project explores whether feeders are an effective way to change wild boar movement within the landscape, protecting agricultural or other sensitive areas but also whether the extra feed over time induces changes in the field layer and plant composition around the stations.

Wild boar inside a baited corral. When the trap is set, the camera screen is monitored and the shutter can be triggered from a distance when a suitable situation is shown.

An effective method to study these questions is to use marked animals. The project uses five different study areas in southern Sweden and has collected movement data from >60 GPS-collared and >300 ear-tagged wild boar. The fieldwork is partly done in collaboration with the landowners, an approach where both parties learn from each other.
GPS-collars and ear tags are fitted on adult animals, but during spring the main focus is on piglets. These animals cannot be equipped with heavy collars, due both to their small size and their fast growth but the advantage of tagging piglets is that, once successfully caught, they can be handled without immobilization. Animals with only ear tags do not contribute as much or as detailed information as animals with a GPS, but the marking procedure is comparatively simple and less costly.

Wild boar piglets caught by a camera trap. A feeding station and a trapping coral are show in the back.

The Swedish wild boar population has shown a remarkable increase in the last 15 years and population management is a frequent topic of debate among various stakeholders. Typical issues within the larger debate are; how to reduce boar damage to agriculture and how to evaluate their total cost, as well questions regarding the long-term effects of supplementary feeding of wildlife. These questions are complex and include aspects that may be difficult to study in general and also often vary between regions.
Several studies have been published on related topics in recent years, including numerous reports by stakeholder organizations, but many aspects are still unclear. Further knowledge obtained in projects like this is thus awaited and needed by authorities, managers, and land owners.

PhenoCams are cameras designed specifically for tracking the timing of when plants grow buds, leaf out, flower, fruit and die back, the science known as plant phenology. In Abisko, SITES is operating a PhenoCam which is programmed to take pictures towards Mount Nuolja several times per day. The concept of repeat photography has been increasingly used to continuously monitor the foliage and canopy changes mainly because of its low cost, high temporal resolution, high-quality imagery, and automatic operation. SITES Spectral has these cameras set up at 8 different locations across Sweden taking pictures of different plants in an ecosystem. 
PhenoCams record the amount of green (G), red (R), and blue (B) being reflected from those plants throughout the season and the seasonal trends of this color information (digital numbers; DN). Using digital repeat photography scientists can track the seasonal changes in plant development stages. For example, as plants turn green in the spring, the amount of brightness of green in the image increases, and when the plant turns red in the fall, the camera will record that too. The relative image brightness for the green channel over the overall image brightness (i.e., a total of RGB DN) is called the Green Chromatic Coordinate (GCC) while the same with the red channel is defined as the Red Chromatic Coordinate (RCC). These two indices have been extensively used to extract information about phenology. Plotting the time series of GCC or RCC over the years can indicate when the trees begin to turn green, when they are at their greenest, when the leaves begin to turn red, when they are the reddest, and when the leaves start to fall or the trees die back for the winter. The continuous recording of such data over time makes it possible to compare the dates of plants turning green in the spring and dying back and losing their leaves in the fall, to see if the dates change significantly from year to year. To demonstrate this, the images collected between 2015-2020 using the PhenoCam located at Abisko Scientific Research Station (68°21'16" N, 18°48'57" E) were used. A region of interest, which represents the subalpine birch forest, was defined (yellow polygon, Figure 1) to extract the change and plot the change in redness over the study period.

Figure 1. Sample images from PhenoCam located at Abisko Scientific Research Station with Mount Nuolja in the background. A single region of interest (yellow polygon) was used for extracting the time series of RCC.

The daily change in RCC values throughout the study period is shown in the plot below (Figure 2). The date when the smoothed RCC reached the maximum in spring is defined as the Start of Season, and the maximum of the RCC curve in fall (dash-dot vertical line) is the end of the season (EOS) respectively. Only EOS is marked in the plots as the focus here is to extract and compare when the leaves on the trees are the reddest and if there are any changes in the EOS date throughout the study period.

Figure 2. Daily averaged red chromatic coordinate (RCC) from the PhenoCam located at Abisko Scientific Research Station, are shown as hollow gray circles. The hollow circles (black) are the dates of snow within the region of interest. The end-of-season (EOS) dates for each year are shown as dotted lines (black).
The date each year when RCC peaked:
Year   Date (mm-dd) Max RCC value
2015   09-15 0.461
2016   09-13 0.449
2017   09-19 0.417
2018   09-10 0.433
2019   09-16 0.451
2020   09-19 0.461

The EOS date across the study period varied between 1 - 6 days in general, except for the year 2018 when the trees turned red a few days earlier than normal. The timing of various plant life cycle events such as the EOS helps us understand how external factors like day length, temperature, and precipitation impact vegetation. We foresee more interesting results as the time series from SITES Spectral grow each year.

Abisko Scientific Research Station was built in 1912 after the research station in Katterjokk burned down. The following year, the meteorological measurements were started, and for several decades data has been collected on behalf of SMHI. The over one-hundred-year long series of measurements has qualified the measuring station as a Centennial Observing Station, an award given by the World Meteorological Organization WMO.

The purpose of WMO's award is to emphasize the importance of long series of measurements for forecasting and climate research.

– The location of the measuring site has been unchanged since 1913. In all weathers, day after day, observers went out to read the meteorological instruments. The very first handwritten observation books still exist today. It is both historically, culturally, and scientifically valuable, says Katarina Gårdfeldt, Director-General of the Swedish Polar Research Secretariat.

At Abisko Scientific Research Station, meteorological measurements of wind, air, solar time, snow depth, precipitation, ground temperature and radiation are carried out. The earliest information about the seasonal ice status for lake Torneträsk is from the late 19th century, but from 1913 there is a complete data series. In 1917, the leafing began to be recorded, and in 2003 the phenological measurements were expanded, i.e., studies of seasonal changes.

Håkan Wirtén, Director General of SMHI, at the meteorological measuring station at Abisko Scientific Research Station. Photo: Melina Granberg
Håkan Wirtén, Director General of SMHI, at the meteorological measuring station at Abisko Scientific Research Station. Photo: Melina Granberg

Collaboration with SMHI

For a long time, the Swedish Polar Research Secretariat has performed meteorological measurements for the Swedish Meteorological and Hydrological Institute (SMHI).

– The observations are of great importance for SMHI's forecast work and for mapping climate change, and it is very important to have long series of measurements without interruption. The Arctic climate is particularly affected by climate change. In Abisko, for example, the temperature increase is just over 50 percent greater than the global average, says Håkan Wirtén, Director General of SMHI.

Continued measurements are important for the future

The very first books with meteorological observations are well preserved. Photo: Melina Granberg The very first books with meteorological observations are well preserved. Photo: Melina Granberg

The thermometers and instruments used over 100 years ago were of a different standard then today, but of sufficient quality to provide valuable information about historical condi-tions. Today, the measurement methods have been modernized and most data are collected automatically through the weather station in Abisko. The manual observations still include the icing and ice discharge on Torneträsk as well as controls of the water levels in Abiskojokken and Torneträsk.

– Abisko Scientific Research Station is located in the zone with patchy permafrost, i.e., constantly frozen ground and an annual average temperature close to zero degrees. This allows us to study what happens to northern areas in times of climate change. The meteorological measurements at Abisko Science Station are part of the global climate puzzle, so it is important to continue the observations for another 100 years, Katarina Gårdfeldt concludes.

150 m ICOS mast located at Svartberget. Humans for scale. Photo by: Matilda Andersson 150 m ICOS mast located at Svartberget. Humans for scale. Photo by: Matilda Andersson

ACTRIS (Aerosol, Clouds, Trace gases Research Infrastructure) is a pan-European research infrastructure that provides a network of stations for observations of short-lived climate forcers (SLCF). The SLCFs have a short residence time in the atmosphere and include airborne particles, aerosols, and reactive trace gases. The Swedish branch of the research infrastructure is run by ACTRIS Sweden with six organizations (Lund University (Coordinating), Stockholm University, Gothenburg University, SLU, SMHI, and Uppsala University) taking part in a 5-year implementation phase starting in January 2022.  ACTRIS Sweden has chosen to co-locate its measuring stations with the ICOS (The Integrated Carbon Observation System) infrastructure. ACTRIS Sweden is currently considering various options for a measuring station near the ICOS mast at Svartberget.

The ACTRIS measuring stations, of which some are already up and running, will extend along both a latitudinal and air pollution gradient stretching from Hyltemossa in Skåne at the southern end of the gradient to Zeppelin on Svalbard (Norway) at the northernmost extreme. Between these extremes are the stations in Östergarnsholm on Gotland, Norunda in Uppland, and soon Svartberget in Västerbotten.

The location of current and future ACTRIS monitoring stations are shown in red.

Short-lived climate forcers are important to study for several reasons. They have an impact on human health directly, increasing the risk of heart disease, lung cancer, and asthma in people living in areas with high levels of air pollution. In Sweden alone, air pollution causes an estimated 7,000 premature deaths per year. Air pollution also has an impact on global temperatures as aerosols have a direct impact on the amount of sunlight reaching the ground and have an indirect impact on cloud formation and duration. SLCFs, like sulphate particles, typically have a cooling effect.

The complexity of these interactions makes it difficult to evaluate the effects of various short-lived climate-affecting air pollutants on the climate, human health, and ecosystems. It is, therefore, necessary to observe the composition, concentrations, and chemical and physical properties of air pollutants in such a way that useful models can be developed, tested, and verified. As of 2016, ACTRIS was a strategically important research infrastructure for Europe and was given so-called ESFRI status. In 2018, ACTRIS was included in the Swedish Research Council's compilation of nationally important research infrastructures.

ACTRIS will provide benefits to:
Scientists by providing quality-assured and open-access ACTRIS data, and offering access to our stations,
Policymakers by providing novel tools for validating the impact of regulation strategies and emission abatement policies through direct evaluation of atmospheric trends and by the provision of data for predicting climate scenarios.
Civil Society through improved weather, climate, and air quality predictions.  

Service work up in the ACTRIS 30-meter tower at Hyltemossa, a combined ACTRIS-ICOS site in southern Sweden

Natural biological surfactants are ubiquitous at the air-water interface, or the surface microlayer (SML), the uppermost ~1000 µm of surface water. Consequently, surfactants cover ~71% of Earth’s surface and are a principal control of all mass transfer between air and water phases. The accumulation of surfactants in the SML has been found to reduce the air-sea exchange rate of CO2 at the ocean basin scale, but this conclusion cannot be generalised to freshwater systems because relevant studies are absent and given the major contribution of the freshwater system to the global carbon cycle, this is a major omission. This multidisciplinary collaborative study (Newcastle University, UK and Uppsala University, Sweden) aims to address this deficiency by coupling total surfactant measurements in the SML and subsurface water (SSW; ~20 cm depth) with direct gas transfer velocity estimates for CO2 by eddy covariance (EC) at the freshwater Lake Erken.

Lake Erken, June 2021: Surfactants are ubiquitous at the air-water interface, but when they accumulate in high concentrations (> 1 mg L-1) they can be seen with the naked eye, as they form natural surface slicks (areas of flat water). Photo by: Philippa Rickard

To investigate surfactant variability at Lake Erken, seasonal field campaigns have been carried out in summer (June 2021), autumn (October 2021) and spring (May 2022); lake ice-cover prevented sampling during the winter. The SML and SSW have been sampled during seasonal lake-wide surveys, and during approximately daily transects within the footprint of the EC tower (located on Malma Island) throughout each campaign. The resulting data set will enable the first-ever assessment of gas exchange across the surface of a freshwater body, as impacted by varying amounts of total surfactant and indices of the organic composition of the total surfactant pool.

The eddy covariance tower (right) located on Malma Island in Lake Erken. Photo by Kurt Pettersson

Text by Antonia Liess (Halmstad University)

Lake Bolmen, the drinking water reservoir for southern Sweden, as well as a source of local fish production and a popular tourist destination, is becoming increasingly browner. Since this trend is expected to continue, it is important to understand the ecosystem consequences of increased brownification as well as potential concurrent nutrient loading. In summer 2021 a mesocosm experiment was conducted in Lake Bolmen using Aquanet mesocosms and the SITES platform and infrastructure at Sydvatten’s Research Station Bolmen in Tiraholm. The aim of this five-week mesocosm experiment was to untangle the effects of increasing brownification and nutrient runoff for the pelagic food web (microbes to zooplankton) of Lake Bolmen. This experiment was a collaboration between Lund University (Johanna Sjöstedt with PhD students) and Halmstad University (Antonia Liess and Lars Gunnar Franzén).

The Lake Bolmen mesocosm platform on a calm day. Photo by Juha Rankinen

At the beginning of June 2021, twenty mesocosms were filled with lake water containing a natural pelagic communality without fish. Five treatments with four replicates each were applied to the mesocosms and comprised of (1) control without any addition, (2) nutrient addition at high N:P ratio, (3) a nutrient addition with low N:P ratio, (4) a brown treatment where soil extract was added and (5) a brown high N:P treatment where soil extract was added as well as nitrogen. Soil extract was produced using dried and homogenized Lake Bolmen shore soils. Soil extract was added as a “pulse” once in the beginning of the experiment to the appropriate mesocosms to produce the state of brownification expected in 50 years. Soil extract also adds phosphorous (P) but very little nitrogen (N) to the mesocosms. Therefore N:P availability was adjusted in the brown high N:P treatment by adding dissolved inorganic nitrogen (DIN) and in the high N:P and low N:P treatment by adding appropriate amounts of soluble reactive phosphorous (SRP) and (DIN).

During the experiment, absorbance, pH, dissolved oxygen, dissolved and total nutrients, dissolved and total organic carbon, bacteria biomass, phytoplankton pigment concentration and composition, zooplankton abundance and species composition were recorded. Brown and brown high N:P treatments had lower pH, and dissolved oxygen, and higher DOC and absorbance than the control, high N:P and low N:P treatments. Phytoplankton pigment composition showed soil addition caused a succession of blooms. Chlorophyll a peaked during the first (week 1) in the brown and the brown high N:P treatment and later (week 4) in high N:P treatment. Early blooms in week 1 were likely driven by mixotrophs such as chrysophytes, cryptophytes, and dinoflagellates as indicated by patterns in chlorophyll c and carotin concentrations. Later blooms in weeks 2 and 4 were driven by green algae, as indicated by patterns in chlorophyll b concentrations. In the control and low N:P treatment, no pigment peaks were observed. Zooplankton composition and abundance showed similar time x treatment interactions, where copepods increase in dominance during week 2 in the brown and brown high N:P treatments and cladocerans dominate in week 4, but only in the brown high N:P treatment. 

Overall, results from this experiment indicate that increased brownification will lead to shifts in phytoplankton community composition from autotrophic to mixotrophic phytoplankton groups, but that these shifts will be easily reversed once the pulse addition of terrestrial subsidies is over. The effects of brownification and nutrient subsidies propagate to the zooplankton levels and influence the relationship between copepods and cladocerans. Cladocerans, which are better food for fish, are disadvantaged shortly after a terrestrial subsidy pulse, a high frequency of these pulses is likely to have consequences for the fish production and fish community composition in Lake Bolmen.

Close up photo of the mesocosms used in Lake Bolmen. Photo by Tatyana Barnes

The bathymetry of a lake is a crucial cornerstone to be able to conduct hydrological and ecological research in lakes. Existing bathymetric data for Lake Bolmen is now more than 30 years old and very limited in detail. A recently purchased echo sounder, which is able to measure the water depth with the help of acoustic waves, will be used in 2022 and 2023 to update current maps. Other than improved resolution for the bathymetric map, the new echo sounder will provide information on submerged aquatic vegetation cover as well as sediment composition in the lake.
The creation of a new bathymetric map for Bolmen will be very time demanding since it is necessary to measure within each little bay. Moreover, driving speed is limited to prevent measurement failures. Currently, the possibility to involve local citizens is discussed, which would significantly reduce the time of completion as well as increase local commitment to ongoing research projects.

Spring this year has been very odd so far - nights have been really cold, days have been warm and sunny, and there has been very little precipitation. One outcome of this strange spring is that staff at Lönnstorp had to start irrigating their apple trees and hedges in the SAFE (SITES Agroecological Field Experiment) agroforestry system a couple of weeks ago, much earlier than usual. The odd spring has also negatively affected the sugar beet trials at Lönnstorp, with low and variable emergence as a result, which has forced them to reestablish trials. Irrigation measures and reestablishments are very time-consuming activities so everyone is hoping for a more “normal” late spring, summer, and autumn.
There are many activities ongoing at the station at the moment. Aside from the preparation and establishment of trials, there have been many visitors. Last week more than 20 students and researchers from Kiel University visited the station. They were, among other things, looking at a new long-term experiment that investigates what effects a combination of different plant protection measures have on the development of grey mold on strawberries. They also had the chance to see experiments that are searching for agricultural traits in several hundred pea and faba bean varieties that could be suitable for Swedish breeding programs, and a trial that focuses on the effect that catch crops have on nutrient leakage. People connected to the NAPERDIV project have also spent a lot of time at the station during the spring, performing several assessments and measurements in the SAFE infrastructure. Students from SLU have had several lectures and exercises at the station, and this week there were visitors from Väderstad AB, a company developing agricultural machines.

Students from Kiel University are studying the soil profile from a field at SITES Lönnstorp research station. Photo: Johannes Albertsson

People using the infrastructures at SITES Lönnstorp have recently published several scientific papers. Three of the papers are about the perennial grain crop (Thinopyrum intermedium) predominantly commercialized as Kernza® and two are about emissions of nitrous oxide from cover crops and crop residues (see below).

The Perennial Grain Crop Thinopyrum intermedium (Host) Barkworth & D.R. Dewey (Kernza™) as an Element in Crop Rotations: A Pilot Study on Termination Strategies and Pre-Crop Effects on a Subsequent Root Vegetable

Agronomic performance, nitrogen acquisition and water-use efficiency of the perennial grain crop Thinopyrum intermedium in a monoculture and intercropped with alfalfa in Scandinavia

Perennial cereal grain cultivation: Implication on soil organic matter and related soil microbial parameters

N2O emissions from decomposing crop residues are strongly linked to their initial soluble fraction and early C mineralization

Frost killed cover crops induced high emissions of nitrous oxide

Is there life on Jupiter's moon Europa? An ocean suspected to be under miles of ice gives science hope. But how could it be reached and explored?

In March, a six-person research group from the Robotics Innovation Center of the German Research Center of Artificial Intelligence (DFKI) spent two weeks at Abisko Scientific Research Station. 
Their goal was to test an autonomous underwater vehicle (AUV) beneath the ice of lake Torneträsk. The researchers are working on developing a robot that can independently explore the water and stay below the surface for an extended period of time. The technology will be used to explore the subsurface ocean on Jupiter's moon, Europa.

The AUV outside Abisko Scientific Research Station. Photo: DFKI-EurEx-Team

A primary objective of the field trials was to test the AUVs docking behaviour with different levels of autonomy, and the AUV spent about 50 hours actively in the water. The docking station will serve as a "home base" for the AUV during long-term missions, and this is where it can recharge and transmit data. The team looks forward to returning to Abisko in a few years to expand their tests on autonomous under-ice navigation.

You can read more about the project and find cool underwater photos and videos from the AVU on the German Research Center for Artificial Intelligence website

The AUV was deployed through a hole in the ice. Photo: DFKI-EurEx-Team

This spring Asa Research Station has installed new water pressure sensors at the SITES water monitoring locations and the streams in the surrounding catchment areas. By measuring the pressure in the water it is possible to calculate the water level and the discharge. This type of data has already been collected for many years in Asa, but these new sensors are capable of sending the data directly to an online server which gives researchers immediate access to data from the office. This makes it easy to track the effect of sudden events such as heavy rainfalls and periods where changes in water level are expected, for example in early spring when the snow melts or during drought periods.

Measuring location at one of the inlets to Lake Feresjön. Photo by Niels Jakobsen

In March, the Skogaryd Research Catchment (SRC) welcomed about 50 high school students and their teachers from the Erasmus project “Global heat”. This project is an international exchange between Birger Sjöberggymnasiet Vänersborg (Sweden), Heilig Hartinstituut Heverlee (Belgium), Liceo Scientifico Cannizzaro Palermo (Italy) and the Bundesrealgymnasium Schwaz (Austria).

Erasmus student from across europe gather at Skogaryd Research Catchment to learn about Swedish forests and forest soil. Photo by: Leif Klemedtsson

During their visit, the students tested several methods for studying ecosystem processes and focused on three topics:

1) How much forest is there?
Students measured the diameter and height of trees to estimate the total forest biomass by using tree biomass via allometric functions. Knowing the tree biomass in a forest is of interest for forest management planning, but also for reporting greenhouse gas emissions since the tree biomass accounts for a large amount of carbon storage.
2) How much do soils respire?
Soils emit large quantities of carbon dioxide (CO2) to the atmosphere, which is known as soil respiration. The most common way to measure soil respiration in the field is via manual chambers. The students could test the system used at SRC, which measures the concentration of CO2 directly in the field, via an ultraportable greenhouse gas analyser. The change in CO2 concentrations in the chambers during deployment represents the CO2 flux.

3)    What does the soil in a Swedish forest look like?
The students dug a soil profile to study a typical Swedish forest soil. To start with, students described the structure, or soil layers, focusing on the questions: what colour are the soil layers, and how thick are they? This leads to discussions about which processes are important for the formation and development of the soil. Students also measured the soil pH and learned that most Swedish forest soils are acidic. The soil studied was a Podzol, which is the most common forest soil in Sweden.

Researchers demonstrate how chambers are used to measure soil respiration. Photo by: Leif Klemedtsson

On April 11th, the vice chancellor of SLU and her leading council visited the field station at Röbäcksdalen. The purpose of the visit was to learn more about the infrastructure, but also to sign a collaboration agreement between SLU and Umeå municipality. Röbäcksdalen SITES manager Johanna Wallsten talked about the SITES activities in the region, and Charlotta Erefur from Svartberget presented some of their activities, and talked about collaborations between the two SITES stations.  In addition, researchers at SLU in Umeå demonstrated some of the spectral equipment at the station.

Johanna Wallsten and Charlotta Erefur present the SITES activities at Röbäcksdalen and Svartberget. Photo: Olof Bergvall.

The collaboration agreement states the intention by the two parties to collaborate more within certain development areas. The research station at Röbäcksdalen is specifically highlighted in the section about Umeå as a sustainable city. The station is located within the city and is already a green oasis for local residents. The research performed, the association to SITES, and the location makes Röbäcksdalen research station a good focal point for the city’s work around ecosystem services and biodiversity.

SLU vice chancellor Maria Knutson Wedel and Chair of Umeå municipality board Hans Lindberg sign the collaboration agreement at SITES Röbäcksdalen. Photo: Fredrik Larsson

The central data coordination team has scheduled several data-focused meetings with individual stations to facilitate uploads to the SITES Data Portal during the off-season when field sampling is less time demanding for the station staff. 

Currently, the SITES secretariat and staff from Erken Laboratory are processing data from complex lake profile measurements collected using YSI sonde technology which will be uploaded soon. Follow-up data meetings are scheduled with Svartberget and Skogaryd, so more data will be available for download in the coming weeks. 

Open access to data produced within the long-term monitoring programs can be found on the SITES Data Portal

Keep yourself updated! 

Malma Island located in Lake Erken during the early spring. The island is equiped with high frequency sensors which measure meteorological and micrometeorological paramaters as well as lake water balance and thermal stratification. Photo by: Roberto Lo Monaco

The snow cover around Tarfala Research Station has changed dramatically as a result of a period with a high rate of cyclonic activity. About a meter of snow has accumulated in the area around the station recently, and while this accumulation is good news for the glaciers it makes travel and measurements more difficult. After a storm, it takes several days for the snow to settle, making ground transportation possible and reducing the threat of avalanches. Late snowstorms also make mass balance studies difficult to perform properly. If a snowstorm in April adds 10% to the snow cover after a snow accumulation survey it may add errors in the measurements. The staff at Tarfala Research Station are now preparing for the planned mass balance surveys and hopes that the low-pressure systems will avoid them for the rest of the spring. Tarfala Research Station opened Monday, March 28th, and will close the 2022 spring season on May 2nd.

Tarfala Research Station on April 7th, 2022. Photo by Per Holmlund.
Tarfala Research Station on April 7th, 2022. Photo by Per Holmlund.

In fall 2021 a temporary technical workshop was established at Grimsö Wildlife Research Station to develop technology for decreasing the number of traffic accidents involving wildlife. Research and development projects are conducted with project leaders from Grimsö in collaboration with several national and international stakeholders, including, the Swedish Transport Administration, Interreg Sweden-Norway, the Norwegian Institute of Bioeconomy Research (NIMBO), and the Norwegian railway infrastructure BaneNOR. This work is part of a broad range of activities concerning wildlife and traffic, a complex topic with growing importance in recent decades. More information about the project and innovative solutions to reduce wildlife collisions in traffic can be found at Om projektet – Vilt och Trafik.   

Four MASS units, plus energy source, rigged and ready to be put out for tests. Photo: Gunnar Jansson

To find effective measures to prevent wildlife – traffic accidents these projects evaluate the best design for various types of wildlife passages (bridges, tunnels, etc). The current sub-project “Viltvarning vid järnväg” focuses on developing techniques to scare animals away from railroad areas using sounds. This is being explored as an alternative to exclusion fences and wildlife passages, as it has the potential to be a more flexible and less expensive solution, and allows for animals to move more freely through the environment. The new design being tested is called a MASS unit (Movement Activated Scaring System) and uses IR sensors to detect movements, which in turn activate loudspeakers that send out various sounds (horns, voices, etc) at high volume (>70 dB). The units are powered by car batteries and solar panels. This year the equipment is tested along railroads and cameras monitor how animals respond to the sounds.  
The collaborative work among authorities, consultants, and researchers in this project producing the MASS units and the scientific evaluation of their effectiveness is a good example of how SITES stations can be utilized.

A red fox fox (Vulpes vulpes) detected by a MASS at one of the test sites, before and after hearing the sound.

We are excited to welcome Emily Pickering Pedersen, to the Swedish Polar Research Secretariat at Abisko Scientific Research Station.

Emily is a plant and ecosystem ecologist with a strong focus on arctic ecosystems. Her research addresses how arctic plants respond to climate-induced environmental change, specifically focusing on plant-nutrient dynamics, carbon and nitrogen cycling, plant-microbe interactions, and vegetation change in response to permafrost thaw and a warmer climate. Her work has comprised a variety of field-based methods including field manipulation experiments and isotopic labeling, with field sites in western Greenland (Qeqertarsuaq) and northern Sweden (Abisko). She has a background in ecology and environmental science with a B.Sc. from McGill University (CA) and M.Sc. and PhD from the University of Copenhagen (DK).

At Abisko Scientific Research Station, Emily will be taking on the position of administrator and laboratory coordinator. She is looking forward to welcoming and assisting researchers at the station, developing the laboratory and common garden facilities at the research station, and working with outreach and communication. We are excited to have her as part of the SITES team and can't wait to see the interesting research that she facilitates in Abisko!

The staff of Tarfala Research Station are busy preparing for the forthcoming spring season, with station-based operations from March 28 to May 1

The short spring season at TRS is of extreme contrast to the extended summer season. Instead of hiking the 24 km from Nikkaluokta one must use a snow scooter, instead of worrying about mosquitos one must be aware of avalanches and one must be even more prepared for the unpredictable infamous Tarfala weather. Yet spring is an essential time in the Tarfala calendar, representing the beginning of the station’s glacier mass balance programme.
Staff at Tarfala station are aiming to continue the mass balance data series of the four Swedish reference glaciers this year. These are Mårmaglaciären, Riukojietna, Rabots Glaciär and Storglaciären, with the latter representing the longest mass balance record of its type in the world. During the spring season the station staff plan to record the winter mass balance at each, by measuring the amount and distribution of snow fall across all four glaciers, as well as drilling a series of ablation stakes that will form the basis for the coming summer mass balance measures later in the year.
At Tarfala station, the staff are in a key location to contribute to the development of understanding of how glaciers are responding to climate change, especially in an amplified Arctic environment. The strong negative trend in mass balance recorded at the glaciers surrounding the station and other Arctic glaciers greatly impact other research programmes at Tarfala, therefore producing accurate and extensive datasets from the upcoming spring season is of vital importance.

Storglaciären beneath Kebnekaise. Photographer: Karuna Sah
Storglaciären beneath Kebnekaise. Photographer: Karuna Sah

A case study in Krycklan (Svartberget)

A restoration case study called “Beaver re-introduction” is the Swedish contribution to the new EU Green Deal project MERLIN*. The case study will have a before-after design, which means experimental construction as well as removal of 60 beaver dams in Sweden, of which 10 will be located in the Vindeln Catchment including Krycklan (Svartberget Research Station). It is a four-year project and aims to sample two years before the measures (dam construction/removal) and two years of sampling after the measures.

The beaver (Castor fiber), considered a keystone species, recreating new habitats impacting entire landscapes. Photographer: Jörgen Wiklund
The beaver (Castor fiber), considered a keystone species, recreating new habitats impacting entire landscapes. Photographer: Jörgen Wiklund
Wetland area created by beaver dams - changing landscape characteristics. Photographer: Fraucke Ecke Wetland area created by beaver dams - changing landscape characteristics. Photographer: Fraucke Ecke

The studied parameters will be similar in all case studies within the MERLIN project; the focus on beavers as a case study will only be conducted in Sweden. A variety of biota are planned to be sampled as the focus is on biodiversity aspects with elements of potential ecosystem services. Likely parameters to be studied are e.g. fish migration, mitigation of climate change effects (flood and drought resilience, formation of greenhouse gases), methylation of mercury and pathogens (especially Francisella tularensis causing tularemia [Swedish harpest] and Sindbis virus causing Sindbis fever [Swedish Ockelbosjukan] in humans) in beaver systems.

A beaver dam built of logs, branches and sediment. The beaver aims to impound flowing water to create a wetland for it to live in. Photographer: Fraucke Ecke A beaver dam built of logs, branches and sediment. The beaver aims to impound flowing water to create a wetland for it to live in. Photographer: Fraucke Ecke

The MERLIN project as a whole is a ‘research and innovation action’ funded under the European Commission’s H2020 programme that involves 44 partners from across Europe, including universities, research institutes, nature conservation organizations, and stakeholders from businesses, governments and municipalities. The involved partners from Sweden are the Swedish Forest Agency (SFA) and SLU, where SFA is responsible for the construction related work and SLU is the scientific partner of the beaver-reintroduction case study. 
Specific questions on the Swedish case study can be directed to Frauke Ecke - contact mail:

MERLIN is an abbreviation for Mainstreaming Ecological Restoration of freshwater-related ecosystems in a Landscape context: INnovation, upscaling and transformation. MERLIN learns from 17 restoration case studies as best-practice demonstrators in terms of innovative restoration measure types, governance and financing frameworks. With investing more than 10 million € in further hands-on upscaling measures.
Find more information on the project´s webpage:

Ongoing work by SITES spectral uses satellites to give researchers a broad spatial view of vegetation conditions at SITES stations. This work generates data layers describing vegetation productivity and phenology for 20 x 20 km areas. Layer data ready for inclusion in GIS databases will be distributed in analysis-ready format, in the Swedish reference system. The data show the seasonal development of green vegetation and can be useful for monitoring vegetation’s response to variations in weather, human influence, and other factors. Below is an example of an agricultural area at Lönnstorp station, showing annual variations in vegetation productivity between 2017 and 2020. Note the strong decrease in productivity in 2018 in response to the drought.

The data source is the Copernicus HR-VPP, which stems from research at Lund University. You can find more information about the data on the Copernicus website

By 2022, SITES Spectral will generate vegetation productivity and phenology from satellite observations for all SITES stations!

In 2018 researchers from Sweden and Germany used the SITES AquaNET mesocosm infrastructure to participate in a global mesocosm experiment on salinization led by scientists from the University of Toledo in the US and Queen's University in Canada. The overall aim of the project was to study how the increasing salt concentration in lakes observed in many parts of the world resulting from human activities (e.g. road deicing, mining, agriculture) and increasing droughts and water scarcity affect life in freshwater ecosystems. In the project, mesocosm experiments were implemented in 16 locations in North America and Europe, including 3 SITES AquaNet lakes (Erken, Feresjön, and Stortjärn) where a salinity gradient was manipulated and the effects on plankton communities studied.

Sampling was conducted in mesocosms set-ups in three lakes that are a part of the SITES research infrastructure Photo: Andreas Palmén.

This week results of the global experiment were published in PNAS showing that zooplankton communities are in many cases sensitive to salinity concentrations below the thresholds set by current water quality guidelines used in North America and the EU. These guidelines are meant to protect freshwater organisms, but the thresholds appear to be too high to keep all trophic levels safe from salinization. The loss of zooplankton triggered a cascading effect causing an increase in phytoplankton biomass at almost half of the study sites. Higher phytoplankton biomass has the potential to alter lake ecosystems services, namely providing high-quality drinking water, recreational opportunities, and productive fisheries. The experimental results demonstrate that new thresholds need to be considered at local and regional scales to protect freshwater organisms from the harmful impacts of salinization.

You can find the publication here: Current water quality guidelines across North America and Europe do not protect lakes from salinization

and a second paper from the Global Salt Initiative here: Lake salinization drives consistent losses of zooplankton abundance and diversity across coordinated mesocosm experiments

and the swedish press release here:
Salta eller inte salta mot halka - en fråga om miljöpåverkan

New organic experimental field

SITES Lönnstorp will start the process of converting 10 ha of farmland to an organic experimental field this year. SITES Lönnstorp will manage this field and we hope that it will be available for organic experiments as soon as next year. The field will be visible from the road leading to Campus Alnarp (see map below) and we think that the location close to campus will help to attract interesting experiments. We expect that this visible location will also help to promote the facilities and infrastructure to students, researchers, companies, and the wider public.   

The new organic experimental field is shown in red. Map: Lantmäteriet orthophoto 2020

New irrigation facilities
The Landscape Architecture, Horticulture and Crop Production Science (LTV) faculty, together with SITES Lönnstorp, will invest in two new irrigation facilities for agricultural and horticultural research. One of the irrigation facilities will be located at SITES Lönnstorp research station and the other one will be located near the new organic field described above. These irrigation facilities will enhance the conditions for conducting relevant and interesting sustainable agricultural research at SITES Lönnstorp. We hope that these facilities will be ready to use for the 2023 growing season.
New experimental infrastructure
The DiverIMPACTS project at SITES Lönnstorp will end this spring. Within this project, two organic crop rotations have been established. SITES Lönnstorp has decided to continue the crop rotations through 2022 and add them to the SITES infrastructure since their continuation will generate interesting and important agricultural data. The infrastructure will be open to anyone as long as SITES continues to finance it. We also plan to upload data from the infrastructure to the SITES data portal.

Are you interested in leading and further developing Sweden’s national infrastructure for ecosystem research?

The Swedish Infrastructure for Ecosystem Science (SITES) consists of nine research stations distributed across Sweden and is focused on promoting long-term field-based terrestrial and limnological ecosystem research. The infrastructure capabilities include access to field stations and local expertise for Swedish and international researchers and making data openly available. The director is the front figure of the infrastructure and will lead the development into the new funding phase from 2023 onwards, helping it to further develop and maintain its excellence. Candidates should have experience in ecosystem science and as a leader of large-scale collaborative projects, preferably involving field stations or other research infrastructures. In addition, the ability to use larger perspectives and to build connections within SITES and with outside collaborators is highly valued. The position can be combined well with your individual research pursuits. For more information about the infrastructure, you are welcome to visit the SITES website:

The application and a detailed description of the position and required qualifications are provided on SLU´s website and can be found under the following link: SITES director.

A birdseye view of the walkway over the lake-wetland transition area at Skogaryd Research Station.

Lifeplan is a global research effort aimed at mapping biodiversity around the planet in a systematic way. It will run for six years and involves more than 100 locations around the globe. Five different kinds of data are collected; soil, spores, insects, audio for bird and bat recognition, and camera images. Here at Asa Research Station we have had equipment up and running for nearly a year now and it is working well. The research area is a one-hectare square plot with natural vegetation (forest). Wildlife cameras and audio recorders are placed in each corner as well as in the middle of the plot, where a cyclone sampler for collecting spores and a malaise trap for collecting insects are also located. Sampling is done weekly and depending on the type of sample collected, continues throughout the year. Some of the samples will be analyzed using DNA-sequencing and Big Data analysis.

Red fox. Vulpes vulpes. (Photo by Erik Kristensen.)

The cameras are set to respond to passive infrared motion up to a distance of about 20 meters. We have collected quite a few images of animals so far. Mainly mammals but also a few birds. In some images, there are no visible animals, but these images will be analyzed using computerized recognition technology, hopefully revealing critters not detected by human eyes. Below are some examples of images we collected from last summer.

Fallow deer. Dama dama. (Photo by Erik Kristensen.)
Elk. Alces alces. (Photo by Erik Kristensen.)

Röbäcksdalen research station is a bit different from the other SITES stations. It is a managed ecosystem that produces biomass, which feeds the animals on the station’s farm. The farm has a crop rotation that is typical for northern Sweden, with leys of grass and clover, barley, pasture, and some additional pea/oat mixtures and fallow fields. The annual output from this ecosystem varies with many things including; winter survival of perennial crops, temperature and rainfall during the vegetation season, and much more.

The seasonal output from the fields in 2021 was reflective of a cold spring, a moderate summer, and a rainy fall. The cold spring should have resulted in a harvest of high-quality forage for the cows. The grass grows well at quite low temperatures, but will not mature until the temperature increases, hence a cool spring is preferable from a forage quality point of view. The result turned out to be quite moderate, though. At the end of May, the average temperature was below 10 °C. However, during the last week before harvest, the temperature increased significantly to an average of around 16 °C. Consequently, the quality of the grass decreased quite significantly in a very short time.

Grass harvest at Röbäcksdalen 2021. Photo by Reija Danielsson

Unlike other field stations that can only offer small-plot fields for studies, the size of the fields at Röbäcksdalen makes them suitable for satellite use. Everything done in the fields is documented and the plan is to publish all data, ranging from management activities to resulting forage quality in the SITES database. These activities are all a part of the station’s SMURF project which is an important tool for researchers working to develop management tools for the farming community. Growth models and remote sensing tools are considered the way forward in developing decision support tools for a sustainable farming community, but these studies need on-site information, like the data collected in SMURF, to be useful.

Barley harvest at Röbäcksdalen 2021. Photo by Reija Danielsson

Many of the research questions related to forage production are also relevant for grain production, and at Röbäcksdalen this research is focused on barley. Using annual crops in the crop rotation is important for decreasing the number of weeds in the system, and grain is also an important feed component for highly productive dairy cows. Collaboration with the local entrepreneurs offers interesting data collection from our fields. One example is how the harvester can measure grain production from the fields. This is an important tool to manage the fields and to detect issues e.g. with drainage. 

The grain harvester measures how the yield varies in the fields. Red is low, blue is high yield. The grain harvester measures how the yield varies in the fields. Red is low, blue is high yield.

The total amount of grass silage from the different harvests in 2021 was almost 2 400 tons of dry matter. In comparison, the 2020 harvest only resulted in 1 800 tons, since a lot of the leys were killed during winter that year. The barley harvest averaged 3 700 kg dry matter/hectare, yielding around 320 000 kg in total. In addition to the productivity of the fields, researchers at Röbäcksdalen are also measuring other ecosystem services provided by the farm. In summer 2021 staff at the station started measuring insects and spores in and around fields as part of the biodiversity project LifePlan. The farm is also part of a bird feeding initiative, where the aim is to establish special fields where cranes and other migrating birds can eat their fill without destroying the output of the farms. Stay tuned for more news about these initiatives in the future.

On a global scale, forests currently act as a sink for atmospheric CO2. Forest management plays a large role in determining the CO2 uptake and long-term carbon storage in forests. Managed forests usually have lower ecosystem carbon stocks compared to pristine or old-growth forests, hence there is great potential to increase active terrestrial carbon sequestration if forests are managed appropriately. There is an ongoing debate over which forest management system provides the greatest long-term climate benefits. Reliable, long-term scientific data on carbon stocks, uptake, and sequestration, as well as data on emissions of other greenhouse gases, are needed to resolve the question of which management system is most beneficial.

PhD student Ulrika Ervander is measuring tree heights in the spruce forest at Skogaryd Research Catchment. Individual trees are marked to allow identification for later remeasuring the trees to follow PhD student Ulrika Ervander is measuring tree heights in the spruce forest at Skogaryd Research Catchment. Individual trees are marked to allow identification for later remeasuring the trees to follow

At the SITES research station Skogaryd Research Catchment (SRC), a new long-term experiment is getting underway. A 60-year-old Norway spruce (Picea abies) forest has been the subject of extensive research over the past decade, including measurements of greenhouse gas exchange using eddy covariance and chamber techniques, lateral transport of dissolved organic matter (by SITES Water), in addition to studies on sap flow and tree rings. The forest is mature and ready for harvest, which opens up the opportunity to study different approaches to forest management with the aim of evaluating the climate benefits of different management practices. Three different forest management systems will be established during harvest 2022/23, (i) continuous cover forestry with selection harvest based on target diameter cutting, (ii) clearcutting with subsequent replanting of saplings (rotation forestry), and (iii) extended rotation period, where the current 60-year-old forest will be allowed to continue growing undisturbed.

Map of the planned long-term forest management experiment at Skogaryd. Shown are the exact position of the 344 trees (in 10 plots) where tree diameter and height (selected trees) measurements were measured. (Map by Ulrika Ervander)
Map of the planned long-term forest management experiment at Skogaryd. Shown are the exact position of the 344 trees (in 10 plots) where tree diameter and height (selected trees) measurements were measured. (Map by Ulrika Ervander)

During summer and winter 2021/22 the diameter and exact positions of 344 trees in 10 plots with a 15 m radius were measured (see Map). In addition, the height of a select number of spruce trees has been measured. This allows for the determination of the total aboveground biomass, and hence carbon stock, of the trees in the forest stand. This coming spring, a student thesis project will investigate the soil carbon stocks by systematically taking soil samples of different horizons and measuring the soil carbon content as well as bulk density. Those measurements combined will provide a baseline estimate of the total ecosystem carbon stock.

Field assistant Andreas Arleborg (right) and station manager Tobias Rütting (left) set up the Postex system (Haglöf Sweden AB) for measuring tree diameter (using a digital caliper) and exact tree position in the spruce forest at Skogaryd Research Catchment. In total, 10 plots with a radius of 15 m have been measured. (Photo by Leif Klemedtsson)
Field assistant Andreas Arleborg (right) and station manager Tobias Rütting (left) set up the Postex system (Haglöf Sweden AB) for measuring tree diameter (using a digital caliper) and exact tree position in the spruce forest at Skogaryd Research Catchment. In total, 10 plots with a radius of 15 m have been measured. (Photo by Leif Klemedtsson)

Measurements of the ecosystem carbon stock will be repeated in a couple of years to estimate any changes due to forest management, providing information on the climate benefits of different management systems. The project will use the ongoing eddy covariance flux studies, part of the SRC base program, and dissolved organic carbon (DOC) data from the SRC SITES Water program. The ecosystem carbon fluxes will be followed in detail by using eddy covariance measurements of the net ecosystem exchange of CO2 (selection harvest plot), estimating gross primary production via sap flow measurements, quantifying DOC in the groundwater, and by measuring soil respiration and nitrous oxide emissions using automatic chambers. The ultimate goal of the project is to provide quantitative knowledge on the climate benefits of different forest management systems for spruce forests in southwestern Sweden.

A microscope, forceps, and sometimes a thin probe, are needed when classifying the ticks. (Photo: Gunnar Jansson) A microscope, forceps, and sometimes a thin probe, are needed when classifying the ticks. (Photo: Gunnar Jansson)

In midwinter, when fewer field surveys are running, SITES´ data collection continues indoors. One project is to go through tick (Ixodes) material from last summer and the physical samples from marked animals.

After collection in the field, samples are stored in Cryo freezers (-80°C), until they can be analyzed. Tick occurrence and frequency in different habitats are estimated using a specific survey method (“flagging”), but ticks are also collected from wild animals that are handled, e.g. voles (Microtus spp.) and roe deer (Capreolus capreolus). 

Every season hundreds of ticks are collected and good organization is needed to keep track of all these tiny samples. (Photo: Gunnar Jansson ) Every season hundreds of ticks are collected and good organization is needed to keep track of all these tiny samples. (Photo: Gunnar Jansson )

The ticks are later sent to project partners (e.g. National Veterinary Institute) for analyses of potential pathogens since the risk of zoonoses related to climate change has received more attention in recent years.

Tissue- and blood samples from marked animals are also checked and digitalized over the winter. For roe deer, these data are used to construct a scheme of relatedness (pedigree) among individuals in the local population, with samples from >500 animals collected in recent decades.

The SITES Secretariat wishes our community, friends and associates a good start in the New Year. We hope that despite the ongoing pandemic a way back to a normal life with regular activities like in-person meetings, workshops and travel will be possible this year. There are many exciting things to look forward to in 2022, not least the transition into a new funding phase.
We wish you endurance for the probably still tough weeks ahead and stay healthy!

Photo: Holger Villwock
Photo: Holger Villwock

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