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2021

Thermometer located on a building at Tarfala Research Station shows 30 deg C on July 3 at 2pm. Photo: Nina Kirchner Thermometer located on a building at Tarfala Research Station shows 30 deg C on July 3 at 2pm. Photo: Nina Kirchner

The summer 2021 is facing a heat wave across the northern hemisphere with temperatures rising to more than 10°C above the long-term average in some regions of Scandinavia.

International media has been covering this topic with focus on the extreme high pressure system over parts of Canada, but Finland, Norway and Sweden are also of special interest for meteorologist as The Guardian reported last week. 

SITES maintains long-term meteorological stations that allow for temperature trends to be monitored across several regions in Sweden. In northern Sweden daily air temperature data from Tarfala Research Station and Abisko Scientific Research Station show that in early June of this year temperatures were higher than the average June temperature of previous years (see graphs below). This data is openly available on the SITES Data Portal for use by the research community and those interested in analysing long-term temperature trends.

Check out the most recent meteorological data updates from SITES stations at Tarfala Research Station and Abisko Scientific Research Station.
 

June daily temperature at Tarfala (left) and Abisko (right) in 2021 compared to the average temperature of previous years. Data is openly available on the SITES Data Portal. June daily temperature at Tarfala (left) and Abisko (right) in 2021 compared to the average temperature of previous years. Data is openly available on the SITES Data Portal.
One of the 150 nest boxes checked for reproductive success of starling. Photo: Gunnar Jansson. One of the 150 nest boxes checked for reproductive success of starling. Photo: Gunnar Jansson.
Reproduction is the focus of much of the wildlife monitoring in spring and early summer at Grimsö Wildlife Research Station. Two of the species monitored are starlings and red fox.

Starling (Sturnus vulgaris) reproduction has been monitored annually at Grimsö since 1981. The survey is part of a national system which was initially started to detect potential effects of pesticides used in agriculture at the time. At Grimsö, 150 nest boxes, distributed in six separate areas, are checked several times during the reproductive season and the dates of egg laying, fledging etc. are noted. A slight but significant decrease in starling numbers, but not nesting success, has been observed over time. The factors behind the decrease is unclear, but it is at least partly thought to be related to a reduced use of grazing cattle.

Red fox (Vulpes vulpes) reproduction has been monitored in Grimsö wildlife research area since 1973. In this survey, ca. 190 dens are checked annually for signs of red fox and badger (Meles meles) reproduction. The local fox abundance, which may vary a lot between years, is an important factor and a classic topic in wildlife ecology since fox densities may strongly influence population fluctuations of many small game species like hares and grouse. The fox reproduction in turn, is strongly related to the seasonal abundance of voles which are an important food resource for foxes.
One of the dens checked for signs of reproduction of fox and badger. A trained dog could be very useful in this work when it comes to separate ongoing versus earlier use of a den. Photo: Gunnar Jansson.


Text: Gunnar Jansson.

SITES Community at the 2017 All Hands Meeting. Photo: Helene Hagerman.
SITES Community at the 2017 All Hands Meeting. Photo: Helene Hagerman.

Mark your calendar for 29 Nov – 1 Dec 2021 as we hope the SITES All Hands Meeting can take place in person at Sigtunahöjden!  

The meeting planning has begun and in the coming months, the SITES Secretariat, along with a meeting committee made up of SITES community members, will develop and plan the meeting agenda and activities.

Detailed information about the meeting will be sent out closer to the meeting date.  
We look forward to bringing the SITES community together for this event and really hope things continue to progress so we can meet in person!    

Sampling GHG chambers at Stortjärn (Svartberget). Photo: Andreas Palmén Sampling GHG chambers at Stortjärn (Svartberget). Photo: Andreas Palmén
As part of the SITES Water monitoring program, floating chambers are used to determine greenhouse gas (GHG) emissions of carbon dioxide (CO2) and methane (CH4) from lakes. The GHG program is conducted at five stations (Abisko, Asa, Erken, Skogaryd and Svartberget) and runs throughout the open water season. The sampling strategy, three transects each with four chambers spread across a depth interval, is based on the lake depth structure and is individual for the different stations. Since the lakes are spread across different climate gradients, the open water season varies, with lakes located in southern Sweden able to start the program earlier in the year.   
Chamber placed on Erssjön (Skogaryd)  Photo: Siva Natchimuthu
Chamber placed on Erssjön (Skogaryd) Photo: Siva Natchimuthu
A drone in action at Lönnstorp. Photo: Lars Eklundh. A drone in action at Lönnstorp. Photo: Lars Eklundh.
As part of SITES Spectral, the SITES stations operate drones in the form of small helicopters, equipped with RGB and multispectral cameras.

RGB cameras are useful for mapping the ground in natural colors in 3-D. Multispectral cameras record images in several wavelengths, including near-infrared, and are useful for monitoring vegetation conditions. Depending on camera type and flying conditions, data need to be calibrated to provide accurate data for quantifying vegetation amount.

Per-Ola Olsson, researcher at Lund University, and collaborators have carried out an analysis of errors related to calibration, and developed a methodology for calibration that minimizes variations related to incoming light fluctuations. The analysis shows that calibration is an important step to be carried out before quantitative analyses of multispectral data from drones.

The results and useful guidelines for how to carry out the calibration were recently published in the open access journal Remote Sensing.

Reference
Olsson, P.-O., A. Vivekar, K. Adler, V. E. Garcia Millan, A. Koc, M. Alamrani & L. Eklundh (2021) Radiometric Correction of Multispectral UAS Images: Evaluating the Accuracy of the Parrot Sequoia Camera and Sunshine Sensor. Remote Sensing, 13, 577.
The SITES AquaNet platform at Svartberget. Photo: Johannes Tiwari. The SITES AquaNet platform at Svartberget. Photo: Johannes Tiwari.
The AquaNet team, led by the programme coordinator Silke Langenheder, are proud and happy to announce that a detailed description of the SITES AquaNet infrastructure has now been published in Limnology & Oceanography Methods!


SITES AquaNet offers:

  1. openness to the scientific community
  2. the possibility to use natural lake communities for experiments
  3. the possibility to conduct and participate in modularized experiments across time and space
  4. high frequency sensor systems
  5. expert support by our technical staff and
  6. access to data from the accompanying monitoring programme SITES Water.

To test the infrastructure we conducted a modularized experiment along the latitudinal gradient offered by the five lakes included in SITES AquaNet. More specifically, we manipulated a press disturbance (light reduction) and a pulse disturbance (temporary presence of fish in the mesocosms). With this we could demonstrate the suitability of the infrastructure and autonomous sensor system to host modularized experiments and provide a good example of the power and advantages of such experiments.


Publication (open access)
Urrutia-Cordero, P., Langvall, O., Blomkvist, P., Angeler, D., Bertilsson, S., Colom Montero, W., Eklöv, P., Aagaard Jakobsen, N., Klemedtsson, L., Laudon, H., Liljebladh, B., Lundgren, M., Parkefelt, L., Kelpsiene, E., Pierson, D., Rankinen, J., Striebel, M., Tranvik, L.J., Weslien, P., Hillebrand, H. and Langenheder, S. (2021), SITES AquaNet: An open infrastructure for mesocosm experiments with high frequency sensor monitoring across lakes. Limnol Oceanogr Methods.

Svartberget field technicians Hassan Ridha and Ellika Hermansson measure the growth and overall condition of spruce trees in a previous trial. Photo: Andreas Palmén. Svartberget field technicians Hassan Ridha and Ellika Hermansson measure the growth and overall condition of spruce trees in a previous trial. Photo: Andreas Palmén.
Cooperation with landowners is vital for SITES research focused on sustainable forest management. For example, in a new silviculture project, researchers from SLU, in cooperation with Skogforsk and forest companies, will take an experimental and novel approach on the establishment of pine stands in northern Sweden. Field technicians from Svartberget Research Station will be responsible for the establishment and future monitoring of the field trials.

In total, 19 silvicultural trials will be established over a period of two years on forestland of varying fertility. For some trials, many years have passed since the actual felling. The aim is to study the long-term effects of tree species, soil preparation, reforestation method and plant-fertilization.

Recent inventories of young stands in the interior of Norrland have revealed low stem and quality stem numbers per hectare. In particular, many young pine stands show trees severely damaged by, among other things, moose grazing and fungal infections. The so called multi-damaged pine forests means a large loss in future production. In some cases, the stands are so damaged that the best option is to start all over again. This is very costly for landowners and there is no guarantee that the same problems won’t arise again.

Thus, it is important to avoid previous mistakes in silviculture. The experiments will compare several potential establishment alternatives to improve the knowledge of producing young stands.

Two main alternatives will be tested. One based on various measures to accelerate the height growth of the pine plants which would reduce the time they are susceptible to moose grazing. Using an excavator to prepare mounds that allow for group planting is one such example.

The other alternative to be tested is the use of other tree species like Norway spruce, Silver birch, Russian larch (a.k.a. Siberian larch) and Lodgepole pine. Species comparisons in production are either rare or unfavourable. Spruce suffer less from grazing and are not sensitive to the fungal damages that affect pine. To avoid the low production of spruce compared to pine seen on many locations in the interior of Norrland, plant fertilization of spruce will be tested. Birch is relatively untested in the area, while stands with Russian larch often have shown good results in growth but comparisons are lacking. Experimental results and experience regarding site selection and silvicultural methods are very limited for both. Lodgepole pine is relatively common in the area and avoided by game for grazing.

There are extensive trials where the higher long-term production of Lodgepole pine compared to Scots pine is evident, but the wood quality and stability of planted Lodgepole pine on fertile soil may be questionable. Mixed sowing of pine and Lodgepole pine can therefore be a way to increase the probability of having a high production stock with a sufficiently high number of undamaged stem.
Location of the deployed pressure gauge south of Bolmsö island.  The pressure gauge was installed at a water depth of approximate 1 m. Photo: Clemens Klante. Location of the deployed pressure gauge south of Bolmsö island. The pressure gauge was installed at a water depth of approximate 1 m. Photo: Clemens Klante.
In a new project, the wave climate at Lake Bolmen will be investigated to gain new insights about the hydrodynamics of the lake and the waves’ effect on water quality. Recent measurements of water pressure will be used to help to calibrate and validate wave models, which will be a helpful asset for analysis of current and future conditions.

Lake Bolmen is Skåne’s most important drinking water resource. The lake’s ecology and chemical status has changed during the last decades and some of these changes could negatively affect water quality. One of the most noticeable changes is the effect of brownification, resulting in yellow to brown colored water due to the increase of humic substances and iron leachate from the catchment. One aim of the Bolmen Research station is to create knowledge that helps to sustain Bolmen as reliable water resource, ecosystem and place for recreation. Therefore, further insight into changes to water quality is important.
The pressure gauge (the tube) before deployment. The gauge is strapped to a stone (ca.25kg) that ensures that it does not change in position, neither in height nor place. Photo: Clemens Klante. The pressure gauge (the tube) before deployment. The gauge is strapped to a stone (ca.25kg) that ensures that it does not change in position, neither in height nor place. Photo: Clemens Klante.
One factor influencing water quality is the hydrodynamics and the wave climate (see fact box below) of the lake. This is because waves mainly determine transport and mixing conditions through the whole lake and within the water column. Due to Lake Bolmen's relatively large size (183 km2), waves induced by wind are likely to occur, but specific knowledge about them is limited. With the application of a wave model, that later will be combined with a general hydrodynamic model, a better understanding of Lake Bolmen’s hydrodynamics will be gained.

Recently conducted measurements of water pressure will help to calibrate and validate this model. Even though measurements have only been recorded on a single side of the lake, the contribution is rather large as this is the first real measurement of this kind. In addition to the simulation of the present wave climate at Lake Bolmen, analysis of future conditions due to changes in climate and ice cover will be conducted.

In the future the wave measurements will be extended and additional water quality measurements at different locations within the lake will be conducted. This will allow a more detailed combined analysis of water quality changes and interactions with hydrodynamics and the wave climate present at Lake Bolmen.
 
Text: Clemens Klante, Sweden Water Research and Lund University.

Wave climate
Wave climate is defined as the distribution of wave height, period, and direction averaged over a period of time for a particular location.

Source: Herbich J.B., Walters T. (1987) Wave climate. In: Climatology. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30749-4_195

One of the tree seedling plots that has been established at Lönnstorp. Photo: Tarquin Netherway. One of the tree seedling plots that has been established at Lönnstorp. Photo: Tarquin Netherway.
A new project will investigate the role of plant traits and mycorrhizal on plant-soil feedback as well as on microbial community assembly and functioning during seedling establishment. Experiments will be done at the two SITES agricultural stations and therefore include agricultural land in southern and northern Sweden.

The project at Lönnstorp and Röbäcksdalen research stations aims to answer questions around the relative importance of different woody-plant traits, such as leaf and root habits, together with mycorrhizal associations (symbiotic root associations with fungi) for plant-soil feedback mechanisms (i.e. the growth response of plants when growing in a new soil habitat) and for structuring soil, root and leaf-associated microbial communities and their functioning.
 
To investigate this, seedlings of twelve different woody plant species, ranging from conifers, such as spruce, and yew to broadleaf species, such as birch and maple, will be transplanted. The different species associate with different mycorrhizal fungi. Some seedlings will be inoculated with forest soil and some will not. Seedlings will also be planted in soil from the station where they are not planted (i.e. some seedlings at Lönnstorp will be planted in soil from Röbäcksdalen and vice versa) to account for differences in abiotic and biotic factors between the two sites.
 
The growth of the plants will be measured over two growing seasons, during which leaf associated microbial communities and nutrient concentrations will be analyzed. At the end of the experiment rhizosphere soil will be collected to examine the chemical properties and the microbial communities.
 
The results will hopefully contribute to the knowledge about which traits of the plant-soil system are central in altering the growth habitat (negatively or positively) during afforestation. In addition, these results could give an indication of the implications on ecosystem processes such as carbon and nutrient cycling across different climates over the short term, together with unravelling basic ecological questions around the assembly of plant-associated microbial communities and their functioning.  
 
Text: Tarquin Netherway, Department of Ecology, SLU.
Developing shoot of Norway spruce at Asa. Photo: Martin Ahlström. Developing shoot of Norway spruce at Asa. Photo: Martin Ahlström.
Even though arctic winds have reduced the temperature outside, spring is on its way. And with the spring approaching, so is the seasonal start of the Phenology monitoring programme at Asa research station.  

Phenological observations are made on birch, spruce and pine trees as well as on bilberry and lingonberry bushes. Shoot development, autumn leaf colouring, leaf felling and flowering are followed as part of the phenological observations. The monitoring programme started in 2006.
 

Example data from Asa Phenological Monitoring

Relative number of flowers, unripe and ripe berries of lingon, according to phenology assessments made in Asa between 2006 and 2020. Lines represent the 15-year average (solid) and standard error (dashed) numbers. Left panel show number of flowers, unripe and ripe berries vs. date and right panel vs. temperature sum, calculated from air temperature at standard height from the meteorological station in Asa.
 

Relative number of flowers, unripe and ripe berries of bilberry, according to phenology assessments made in Asa between 2006 and 2020. Lines represent the 15-year average (solid) and standard error (dashed) numbers. Left panel show number of flowers, unripe and ripe berries vs. date and right panel vs. temperature sum, calculated from air temperature at standard height from the meteorological station in Asa.
 

Shoot development of Norway spruce, according to phenology assessments made in Asa between 2006 and 2020. Pink dashed lines indicate single year development, black lines represent the 15-year average (solid) and standard error (dashed) shoot development. Left panel show shoot development vs. date and right panel vs. temperature sum, calculated from air temperature at standard height from the meteorological station in Asa.
 

Shoot development of Scots pine, according to phenology assessments made in Asa between 2006 and 2020. Pink dashed lines indicate single year development, black lines represent the 15-year average (solid) and standard error (dashed) shoot development. Left panel show shoot development vs. date and right panel vs. temperature sum, calculated from air temperature at standard height from the meteorological station in Asa.

Photo: Ola Eriksson. Photo: Ola Eriksson.
At the Abisko Scientific Research Station (ANS) the vehicle fleet was recently expanded with an “ark”. Here, Magnus Augner, station manager, tells what an ark is and why it was acquired.

Up here in Norrbotten, an "ark" is a kind of living module, usually with a stove, which you pull out on the lake ice with a snowmobile. In the floor of the ark there is a hatch through which you can do ice angling, while you have a nice time in the warmth inside.
 
A few years ago, Håkan Grudd, deputy station manager, got the idea that arks might be something for our Antarctic expeditions. He contacted several manufacturers and in the end we decided on Järvsöarken. A special feature of their arks is that you can place a snowmobile inside the ark, which is a great advantage for transport and storage for a longer period of time.
 
After some discussions, they built three arks for us, which were then adapted to our needs in Antarctica, with e.g. snow melter, stove that allows cooking and solar cells for charging batteries. In the field season 2017-18, we used them for the first time on an expedition and it was clear that this was a good concept for expeditions into "deep field", i.e. so far away from research stations that one has to be self-sufficient, with the exception of fuel depots. Each "two-people set" consists of two snowmobiles, an ark, and a snowmobile sled (for fuel, research equipment, food, etc.)
Photo: Ola Eriksson. Photo: Ola Eriksson.
Why snowmobile arks? A large cost and a clear environmental impact is the fuel that must be transported down to Antarctica in order to conduct all types of activities. Looking for light-weight solutions that also have a high level of security is always an important part of our development of Antarctic logistics. Being able to live "indoors" in a warm space, which does not take time to set up, makes life on expeditions much more comfortable and safer than living in a tent.
 
In order to primarily be able to show and test living in arks during field courses, we have also purchased an ark for ANS. This also provides possible support for researchers who want to be able to live in the field in winter, away from the station and our field cabins.
 
Version 2 of our ark is 20 cm wider than the first one, which means that the beds are now 60 cm wide instead of 50 cm. The ark is equipped with fire extinguisher, carbon monoxide alarm, fire blanket, lighting, solar cells, 12v battery, USB charging, inverter 230 V, stove etc. In short, a small well-equipped "caravan" for snowmobiles, where two people can live quite comfortably.
Research plot from a previous biodiversity experiment (Biodepth) at Röbäcksdalen. Photo: Cecilia Palmborg. Research plot from a previous biodiversity experiment (Biodepth) at Röbäcksdalen. Photo: Cecilia Palmborg.
A new project with field experiments in both Lönnstorp and Röbäcksdalen will investigate the effects of seed dispersal and plant arrival order on grassland vegetation, plant biomass and insect diversity.

Why do plants grow where they grow? Certainly, it is partly due to the environment of a particular site that will favour some species, while deterring others. However, even with knowledge of the local environmental conditions, it is notoriously difficult to predict vegetation compositions using environmental variables alone. This leads to the suspicion that more must be going on. Could chance or luck play a role in shaping the vegetation?

One way plants could experience luck is by having their seeds arrive early to a place that is open for colonization. The arrival time of seeds will depend on seed dispersal, which is known to be very stochastic and therefore a process where chance is involved. Arriving early typically comes with certain benefits, such as access to nutrients, water and sunlight, causing the early arriving species to be more likely to successfully establish. The arrival order of species at a site could thus be one factor that shapes the vegetation.

But how could this idea be tested? It is not possible to go to a field and figure out which of the species was first on the scene. That’s why experiments are needed. Judith Sarneel (Researcher) and Tamara van Steijn (PhD student) from Umeå University will work together with SITES in both Lönnstorp and Röbäcksdalen to set up large scale grassland experiments, starting this spring/summer. In their plots they will introduce a set of grassland species with varying arrival orders between the plots.

The development of the vegetation, as well as the effects on the insect community, above and below ground biomass and other parameters, will then be followed over the years to come.

The results could potentially be useful in restoration of grasslands. Specifically, when seed sowing is used as a restoration method, it would be possible to manipulate the order of sowing in a way that benefits the species that are deemed most interesting. 

Text: Tamara van Steijn.
Niklas Rakos drilling a hole in the ice for sampling the lake sediment. Photo: Erik Lundin. Niklas Rakos drilling a hole in the ice for sampling the lake sediment. Photo: Erik Lundin.
SITES is mapping lake sediments for the lakes included in the thematic programmes SITES Water and SITES AquaNet, to enable a better understanding of biogeochemical processes within the lakes. Sampling has now started at Lake Almbergasjön at Abisko Scientific Research Station.

Since the lake is still ice-covered, Abisko research engineers Niklas Rakos and Erik Lundin took the opportunity to collect a deep sediment core. Using a Russian corer, nearly 3 meters of sediment from Almbergasjön was collected.

The sediment core was sliced and sediment subsamples stored for later analysis (e.g. water content, C, N, grain size). The sediment mapping campaign on Lake Almbergasjön will continue later in 2021 with a sub-bottom profile survey and gravity core collection across the lake.
A sediment core from Lake Almbergasjön collected using a Russian Corer. Photo: Erik Lundin.
A sediment core from Lake Almbergasjön collected using a Russian Corer. Photo: Erik Lundin.
SITES sediment mapping
Sediment sub-bottom profiling has already been conducted and long and short sediment cores have been collected at Lake Erssjön (Skogaryd Research Catchment) and at Lake Feresjön (Asa Research Station). Sediment cores have previously been collected for Lake Tarfala and a high-resolution bathymetry map exists (Kirchner et al. 2019). A sediment sub-bottom profiling survey was conducted for Lake Erken in 2017.  
 
Read more about the sediment sampling in news articles on SITES web and in our newsletter:
A snow-covered Lake Tarfala on 15 March 2021. Low-resolution images such as this is automatically transferred via MMS. High resolution images must be manually collected. A snow-covered Lake Tarfala on 15 March 2021. Low-resolution images such as this is automatically transferred via MMS. High resolution images must be manually collected.
Constrained by the pandemic, a smaller than usual crew has arrived at Nikkaluokta for onward travel to Tarfala as soon as weather conditions allow it.

While waiting, the extra time is used to resupply with spares and food. Once at Tarfala, field work will be carried out at Storglaciären and Rabots glaciär (two of the World Glacier Monitoring Service’s so-called reference glaciers), Mårmaglaciären, and Riukojietna.

The time lapse camera, overlooking Lake Tarfala, will also be visited, and high-resolution pictures taken since the fall will be collected. Low-resolution footage is sent occasionally (depending on weather) via MMS. The images collected contribute to a better understanding of lake ice phenology, which impacts lake mixing and other important processes in the lake.

Text: Nina Kirchner.
 
Nikkaluokta, 6 April 2021. Photo: Nina Kirchner.
Nikkaluokta, 6 April 2021. Photo: Nina Kirchner.


Further reading

Installing a camera and audio recorder as part of the Lifeplan plot at Grimsö. Photo: Gunnar Jansson. Installing a camera and audio recorder as part of the Lifeplan plot at Grimsö. Photo: Gunnar Jansson.
At Grimsö, this season’s field work has now begun for several of the time series monitored in SITES. For example, the collection of phenology data on plants and birds is ongoing.

Dates of e.g. emerging buds and blooming are noted weekly for plants (following the national system Svenska fenologinätverket), and for birds the first observation of each migratory species (ca. 60) within the research area has been noted annually since 1982. Thanks to the rapid disappearance of most of the snow, the spring survey of wildlife pellets (six herbivore species) and habitats could also be started this week. Among the external projects on large carnivores, it is now season for marking wolves (Canis lupus) and wolverines (Gulo gulo).

The sampling for the international Lifeplan project (see below) has been initiated, and so far, the wildlife cameras and audio recorders are up and running in the plot at Grimsö. The Malaise trap and Cyclone sampler will be deployed later this spring when conditions are more suitable. 
A territorial wolf pair with GPS-collars, studied in Scandinavian research projects. Photo: Åke Aronsson.
A territorial wolf pair with GPS-collars, studied in Scandinavian research projects. Photo: Åke Aronsson.

Lifeplan
Lifeplan is a global biodiversity project that will map life on Earth through DNA sampling, sound and image data, as well as traditional methods such as Malaise traps. Besides Grimsö, SITES stations in Asa, Erken, Skogaryd, and Svartberget as well as the associated station Bolmen, participate in Lifeplan.

Read more about Lifeplan at the University of Helsinki.

Niklas Rakos from Abisko Scientific Research Station changing gas tubes at Stordalen. The gas tubes will be used for the EMRGE project. Photo: Erik Lundin. Niklas Rakos from Abisko Scientific Research Station changing gas tubes at Stordalen. The gas tubes will be used for the EMRGE project. Photo: Erik Lundin.
Winter is a generally a period of low activity at Abisko Scientific Research Station, but it is also a good time for heavy overland transport, like changing the gas bottles for the EMERGE project in Stordalen.

The aim of the EMERGE (EMergent Ecosystem Responses to ChanGE) project is to improve the understanding of how thawing permafrost systems respond to climate change and subsequently cause change, with a focus on carbon cycling and microbial populations and communities. The EMERGE project is multi-disciplinary, spanning across biochemistry, genetics, molecular biology, physiology, ecology, evolution, and ecosystem science.

The resultant framework will also provide a foundation for assessing microbial change in other ecosystems.

EMERGE is lead by Virginia Rich (Univ. of Ohio), Ruth Varner (Univ. of New Hampshire, presently at Stockholm University), and Scott Saleska (Univ. of Arizona), and is a continuation of and development from the IsoGenie project.
 
Stordalen
The Stordalen mire is located approximately 10 km east of the research station in Abisko, close to Lake Torneträsk. The site has a long history of climate and vegetation research, going back to the 1970s.

Abisko-Stordalen is the location of an ICOS Ecosystem station.

Stordalen and the IsoGenie project was recently featured in a Nature news article: How microbes in permafrost could trigger a massive carbon bomb.
Ninis Rosqvist. Photo: Max Bergström. Ninis Rosqvist. Photo: Max Bergström.
Ninis Rosqvist has stepped down as director of Tarfala Research Station after 16 years. The station leadership has been handed over to Nina Kirchner and Per Holmlund as new director and vice-director, respectively.

Both Nina Kirchner and Per Holmlund are researchers at the Department of Physical Geography, Stockholm University. Nina Kirchner is an associate professor of glaciology, and Director of the Bolin Centre for Climate Research. Her research focuses on prediction and reconstruction of future and past ice sheet and glacier dynamics in the Arctic and the Antarctic, where she has also conducted fieldwork. Per Holmlund is a professor in glaciology with an emphasis on climate and a long record of work in high alpine areas and in polar regions. He was the station director of Tarfala from 1996 to 2004.

SITES would like to thank Ninis for all her contributions as director of Tarfala, and looks forward to her continued engagement at Tarfala Research Station and in the SITES network! SITES warmly welcomes Nina and Per and looks forward to working with them both.

An upcoming opportunity to hear more about Tarfala is at the vEGU2021 meeting (April 19-30), where several talks focusing on research conducted at and around Tarfala Research Station will be presented!
Lake Erken and the Erken Laboratory. Lake Erken and the Erken Laboratory.
The Erken Laboratory (Uppsala University) has an open 2-year position for a research engineer connected to Erken’s long-term lake monitoring programme, SITES Water and mesocosm experiments conducted within SITES AquaNet and the EU-project AQUACOSM-plus.

The research engineer will support and conduct field measurements, including maintenance of equipment and installations, such as in situ autonomous sensor systems and experimental facilities and data management (e.g. QA/QC). Another important task is the coordination of a distributed mesocosm experiment within AQUACOSM-plus that is planned for 2022 at several SITES stations.
Administrative tasks such as purchases of equipment, reporting, communication with visiting researchers etc. are also part of the position.

Application is due by 15 April 2021.
 
More information, including a link to the application system can be found here:
The CO2 sensors being prepared at Svartberget are placed in chambers on the lake as part of the SITES Water greenhouse gas program, which starts once the ice is gone. Photo: Blaize Denfeld. The CO2 sensors being prepared at Svartberget are placed in chambers on the lake as part of the SITES Water greenhouse gas program, which starts once the ice is gone. Photo: Blaize Denfeld.
As two of the latest SITES news items have shown, now is the time for calibrations and other preparations for the upcoming field season. At Svartberget, preparation for the SITES Water greenhouse gas program is underway and a technical workshop was hosted to prepare for the upcoming field work.

At Svartberget the summer season has not begun, but various calibration activities are about to start, which can be regarded as an early indication of spring. For example, carbon dioxide sensors will soon be prepared as part of the SITES Water lake greenhouse gas measurement program.
It is not only about getting sensors and equipment in shape. The previous week Svartberget and Asa staff had a virtual technical workshop within the Unit for field-based forest research at SLU, which hosts the SITES stations in Svartberget and Asa. The workshop had several aims. First, to "calibrate" the station’s routines for field work and to share knowledge about them among the technical staff. Second, to share routines and knowledge on collected field data within the unit. Last but not least, it was an opportunity to coordinate all stations managed by the Unit for field-based forest research, i.e. the stations at Tönnersjöheden, Asa, Siljansfors and Svartberget.

During the workshop, there were discussions about new regulations regarding unmanned aerial vehicles (drones), the experiences of the Postex-system (used to determine the geographical position of e.g. trees), the Field-data-system software (used to collected data from instruments) and the Freedata-software for measurement of field trials. The collection of phenology data and the outcome and demand for it was also covered, as well as the databases administered by the Unit for field-based forest research (for example the field-trial database, Silvaboreal and the Safe deposit).

The workshop was much appreciated and will be followed by shorter meetings during the spring, focused on, for example, the outcome of the external environmental audit held in February, water sampling protocols and terrestrial laser scanning.
 
Text: Johan Westin.
Calibration of a Skye Ltd. multispectral sensor (large tripod) using a reflectance panel (small tripod). Photo: Lars Eklundh. Calibration of a Skye Ltd. multispectral sensor (large tripod) using a reflectance panel (small tripod). Photo: Lars Eklundh.

The multispectral sensors used in SITES Spectral are regularly calibrated, to monitor their performance and detect possible misfunctioning. By training the personnel at each station, the time the sensors are not collecting data is reduced and the frequency of calibrations can be increased to once a year. Therefore, SITES recently organized a calibration workshop for personnel at the stations.

The workshop had several aims. First, to share knowledge among the stations and technical stuff and strengthen skills within SITES Spectral. Second, to improve the efficiency of data collection and quality. Last but not least, it is positive for the staff at the stations to have a comprehensive understanding of the entire data generating process.

During the workshop, there were discussions about the necessary equipment, the best time and place to perform the calibration, the calibration process itself, and report of results on a calibration certificate. It was an interactive conversation where all participants shared their knowledge and experience for creating the best conditions for reinforcing the fundamentals needed to perform the calibration at their station.

Text: Virginia Garcia.
 

The Workshop was held on 17 February 2021 and was run by Virginia Garcia, Research Engineer in SITES Spectral (virginia.garcia@nateko.lu.se). Given Covid-19 restrictions, the workshop was held online. Personnel from seven SITES stations participated.
Recently, information about the more intensively studied lakes, in Thematic Programs SITES AquaNet and SITES Water, was added to the SITES website. There are seven lakes, Almbergasjön, Bolmen, Erken, Erssjön, Feresjön, Stortjärn and Tarfalasjön, at seven different stations that are central for SITES AquaNet and SITES Water. Use the link below to read more about each lake.

The lakes in SITES AquaNet and SITES Water
 
View of the phenocameras and NDVI sensors placed in the tower and the calibration equipment. Photo: Ryan Davidson. View of the phenocameras and NDVI sensors placed in the tower and the calibration equipment. Photo: Ryan Davidson.

After a mild autumn, the real winter has arrived at Lönnstorp Research Station. Over the last two weeks, temperatures have been below zero, with a minimum of -12ºC, according to the automatic weather station. These low temperatures have caused ice to form on the sea surface, which is just 3 km away from the station, and the fields around the station are covered in snow.

Despite the winter conditions, the station staff are already thinking about the spring season, as there is less than two months until the first crops should be sown and therefore time to check and calibrate the spectral equipment.

Solar panels that supply energy to the tower equipment. Photo: Ryan Davidson.
The spectral equipment consists of three phenocameras and two NDVI sensors (see fact box), powered by a solar panel and placed on a 10 meter high tower. The station staff implement regular revisions of all equipment and currently they are calibrating the NDVI sensors.

Text: Ana Barreiro.
 

Normalized difference vegetation index
Normalized difference vegetation index (NDVI) is an index that describes the greenness of the vegetation. Through SITES Spectral, SITES monitors NDVI at Lönnstorp Research Station and six other stations.

The data from SITES Spectral is available through SITES Data Portal.

Climbing to reach the soil sampling site 17 June 2014. Photo: Therese Zetterberg, SLU. Climbing to reach the soil sampling site 17 June 2014. Photo: Therese Zetterberg, SLU.
Studying natural or semi-natural forests gives us a better understanding of the effects of forestry. However, since disturbances such as storms are a part of natural ecosystem, field work is sometimes challenging.

The monitoring program IM - Integrated monitoring - follows both physical and chemical processes and their impact on the biological system in four small catchments dominated by coniferous forest, located in different parts of Sweden’s climate and air pollution gradients. One of the areas, Aneboda IM, is through SITES associated with Asa Research Station. A severe storm hit Aneboda sixteen years ago, and the effects are still impacting the biogeochemical status and field work in the area.
During 8–9 January 2005, southern Sweden was hit by Cyclone Gudrun. At Aneboda IM, maximum wind speeds exceeding 20 meters per second were recorded over nine hours. About 15–20 percent of the trees were knocked down by the storm.

After the storm, the fallen Norway spruce trees (Picea abies) attracted bark beetles (Ips typographus), which caused a massive insect outbreak. The beetles infested a large proportion of the Norway spruce trees that survived the storm. In the 2011 survey, almost half of all Norway spruce trees with diameters larger than 20 cm were dead.
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The slideshow above shows how the forest in one of the plots where the vegetation is monitored changed from a closed old growth Norway spruce stand to an open area with primarily birch saplings and large amounts of coarse woody debris, during the years 2004–2019.
These change benefits the biological diversity in the area, but it makes part of the monitoring more difficult. As the pictures above and to the left show, both vegetation and soil sampling surveys have become a challenge for the field staff.

Text: Stefan Löfgren and Ulf Grandin, SLU.
Facts about Aneboda IM
The Aneboda IM site and the nearby forest and bog are part of a nature reserve. Long-term monitoring in Aneboda IM was initiated in the mid-1990s in semi-natural coniferous forests, where atmospheric deposition of pollutants and anthropogenically induced climate change are the main human disturbances.
Aneboda IM is one of four Swedish IM catchments within the program Long-Term Ecosystem Research in Europe (eLTER). These programs provide infrastructure, data and management for research at reference conditions on hydrological and biogeochemical processes, including interactions with the biota.
 
Issues of special interest are soil and surface water acidification, weathering, carbon sequestration, leaching of nutrients, DOC and trace metals, including Hg, as well as the biological effects on organic matter decomposition, bioelement uptake by vegetation and changes in the microbial and vegetation communities down to species level. The semi-natural state at these sites defines the limits for what could be expected without forest management, e.g. defining background conditions and elemental dynamics at reference conditions.
Röbäcksdalen’s 75 cm record snow depth, with the field station building in the background. Photo: Malin Barrlund. Röbäcksdalen’s 75 cm record snow depth, with the field station building in the background. Photo: Malin Barrlund.
The weather this winter around Umeå in northern Sweden has so far been erratic. Both November and December were unusually warm with little snow, but in January the temperature fell, it started to snow, and multiple snowstorms occurred during a period of just a few days.

Snow situation at Röbäcksdalen
Röbäcksdalen Field Research Station is measuring snow depth since 2010. So far this season, 75 cm of snow have accumulated at the station, which is the deepest snow cover since the recording started. Usually, the highest snow depths are measured later in the season which shows the magnitude of the current situation and that there is a possibility for more snow to come before this winter is over.
Almost a meter of snow at Svartberget – a record for January
At Svartberget research station, about an hour drive inland from Umeå, the snow depth increased with over 60 cm during the period with several snowstorms in January, which added onto the already existing snow cover.
Digging out field equipment (this one is measuring ozone) is a big challenge this year at Svartberget. Photo: Pernilla Löfvenius.
Svartberget has measured snow depth since 1980 and the record so far is from 1988 when 113 cm was recorded. A lot of the snow that year fell in February and March. The accumulated 97 cm of snow this January is the deepest ever recorded so early in the season, but the most astonishing is in how short time the snow assembled.

The local newspaper refers to old farmer’s traditions, which says that half of winter’s snow should have arrived by now. However, data from previous years at Svartberget show that half the amount of snow usually has arrived by Christmas time and that the maximum snow depth is in the beginning of March. The same data supports the likelihood that another 10-20 cm of snow will fall before the winter is over. However, the variation between years is large and climate change makes it difficult to predict the weather, especially in the past years.
Snow depth (cm) over a season at Svartberget. The red line shows this season. The dashed line is the the minimum, the black line is the average and the dotted line the maximum for the period 1980-2010.
Two master students, Fredrik Andersson and Tobias Möhl, participated in the sampling. Here they are pulling the geo-radar (Malå Geoscience Ramac) equipment over the ice. Photo: Leif Klemedtsson. Two master students, Fredrik Andersson and Tobias Möhl, participated in the sampling. Here they are pulling the geo-radar (Malå Geoscience Ramac) equipment over the ice. Photo: Leif Klemedtsson.
Sediment investigations that enable a better understanding of biogeochemical processes are ongoing in the thematic program SITES Water.

During the autumn 2020, an initial sediment investigation was conducted at Lake Erssjön and Lake Feresjön (see SITES December Newsletter for more information). To determine the sediment depth a sub-bottom profiler (Innomar SES-2000) was used. The profiler uses acoustic signals of different wavelengths to produce images showing bottom surface, sediment layers and underlying bedrock. However, gas bubbles in the sediment layers can make it difficult to interpret the bottom profile images and the bubbles can mask the bedrock transition zone. To counteract these issues, during the initial campaign, surface sediment was collected from many locations and deep sediment sampling was carried out at the deepest point of the lake.
Two master students, Fredrik Andersson and Tobias Möhl, participated in the sampling. Here they are pulling the geo- radar (Malå Geoscience Ramac) equipment over the ice. Photo: Leif Klemedtsson.
Two master students, Fredrik Andersson and Tobias Möhl, participated in the sampling. Here they are pulling the geo- radar (Malå Geoscience Ramac) equipment over the ice. Photo: Leif Klemedtsson.
Data from the initial sediment sampling of Feresjön identified the depth of the soft sediment layer, however some areas were shadowed by bubbles. For Erssjön the data was more difficult to interpret, which, in part, was due to data shadowed by bubbles.

Thus, additional data from Erssjön is needed to interpret the data. Fortunately, the ice-cover that formed in January 2021 on Erssjön made further investigations possible, as a stable platform is required for working with deep sediment cores.
Some of the sediment sampling was done close to the platform used for measurements in SITES Water. Photo: Leif Klemedtsson. Some of the sediment sampling was done close to the platform used for measurements in SITES Water. Photo: Leif Klemedtsson.
Deep sediment sampling at the deepest point of the lake, using a “Livingstone” corer, was conducted. Five locations were also sampled for sediment to assist the interpretation of data from the sub-bottom profiler. Furthermore, a geo-radar was tested. Sediment depth mapping using a geo-radar could potentially compliment and improve future campaigns.
A wolf with a GPS-collar just awakening after immobilization. Photo: Barbara Zimmermann. A wolf with a GPS-collar just awakening after immobilization. Photo: Barbara Zimmermann.
The most intense field survey work at Grimsö Wildlife Research Station is in spring and summer, although important work is also being done during the winter months. A number of surveys at Grimsö run throughout the year, some of which peak in winter. Some fieldwork and data collection are facilitated by snow, and for some methods snow is required.
Typical winter activities at Grimsö are, for example, to catch and mark roe deer (Capreolus capreolus) and wolves (Canis lupus). Due to limited food availability in winter, especially if there is lots of snow, roe deer are more easily trapped. Roe deer monitoring has been ongoing for more than 40 years and over 1,000 roe deer have been captured during this time. The data collected includes life history traits, kinship and body measurements.
A photo from one of the wildlife cameras at Grimsö, showing two roe deer, one collared and one inside the trap (not trigged at the time). The data series on marked roe deer started in 1976 and is one of the longest time-series in the Grimsö base program.
One of the wildlife cameras in the camera trap system covered by snow and in need of some “cleaning”. Photo: Gunnar Jansson. One of the wildlife cameras in the camera trap system covered by snow and in need of some “cleaning”. Photo: Gunnar Jansson.
The dominating method to catch wolves is via darting (immobilization) from a helicopter, which is easier during winter as the wolves are easier to spot when the ground is covered by snow. The same goes for obtaining reliable results from aerial surveys of moose (Alces alces). However, too much snow can create some problems or delays in sampling, such as difficulty in reaching the study area due to road closures. Therefore, snowmobiles are sometimes used during winter. Another problem that may occur is that wildlife camera becomes covered by snow, resulting in blacked out pictures until they are cleaned.

Winter is also the time for planning for upcoming field work. At Grimsö, plans to start the sampling for the LIFEPLAN project, along with other SITES stations, is already underway.

The SITES Secretariat, SITES Station Directors and a selected core writing group of Swedish researchers in ecosystem science, are currently busy preparing an application for the 3rd phase of SITES funding (starting in 2023). The Swedish Research Council has opened a call for grants to research infrastructures of national interest.

Research infrastructures, like SITES and its research stations, are crucial to support the national and international research community with long-term, high quality monitoring data, especially in a warming climate. Advanced user support and mobilization of SITES data are therefore central components in the application. Exciting ideas and new plans to increase our engagement with a broad user community are part of the potential new funding period.

Keep your fingers crossed that it will be a successful application!

Photographer Gunnar Jansson

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