eLTER TA site: Postojna Planina Cave System (PPSC)
Postojna-Planina cave systems’ consists of more than 30 km long passages of Postojnska and Planinska jama caves. Their passages collect and conduct surface and underground waters from Pivka and Cerknica and release them to Planinsko polje. It also represents the most biologically diverse cave in the world with more known species of stygobionts (obligate, permanent resident of aquatic subterranean habitats) than any other subterranean site in the world. Such complex system allows researchers to conduct long-term interdisciplinary karstological research that combines knowledge from chemistry, hydrology, physics, geology, geomorphology, meteorology, ecology, zoology etc. Large amount of different data have been collected through years and decades, often with redundancy, which resulted in multiple data collections for same phenomenon at the same time window and in same space. Intention of this research is to consolidate such data so they can be presented through geographic information system (GIS) within same time-space window, providing all the researchers unified basis for further research. Such basis would consist of spatial, numerical and spatio-temporal data, which all together will allow location analysis in such complex systems such caves are.
Figure 1: Fixed cave survey point – the basis for determination of location
But, first things first! Where do data come from? And when? Usually, researchers focus on space and time frame that is proposed by their research objectives. The phenomenon that they are tracking is located in space. Corridor type spaces that caves are represented by are plotted on survey maps by speleologists using different methods and tools. Postojnska jama cave, for example, has fixed cave survey points that have been used to determine exact location of points where data about different phenomenon are being collected by automatic monitoring stations or by manual collections.
Figure 2: Postojnska jama cave corridors with locations of monitoring stations
Data acquisition is dependent on time frame defined by researcher. Intervals can vary from seconds to days within defined time frame. There is variety of phenomenon that can be monitored: cave meteorological data (temperature, humidity, air flow, gases…), hydrological data (pH, water flow, conductivity …), chemical data (presence of metallic elements or solutions), cave species, rock movements, speleothem formation, limestone dissolution etc. So, it is variety of data that can be changes over time.
Figure 3: One of monitoring stations for cave meteorological data
Figure 4: Stalagmite formation in Postojnska jama cave
When we determine location of monitoring stations we can present such data in spatio-temporal visualization. For example, using space-time cubes we can visualize the space-time frame of collected data, and determine whether they can be used for our own research. By providing such data from one central place, e.g. GIS database, we can ease researchers in process of data acquisition, and enable them to perform spatio-temporal and location analysis within their frame or research.
Figure 5: Space-time cube visualization of conductivity values (left) and species number (right) on locations in time
About the Author:
Vojkan is PhD student of Karstology at University of Nova Gorica, whose research focuses on using GIS and Remote Sensing in Karstology researches.
For a while the ocean existed to me as an abstraction. I grew up in Ohio and I’d never been. I imagined it to be the deepest, darkest, scariest, most enchanting thing on Earth and even so, I couldn’t quite imagine it exactly — it was just too big, too distant, too different.
Lately I’ve been thinking about how we require things to be different in order to define our realties. Minutes, hours, days, months and years of being alive have allowed us to define what is ‘normal’ because we’ve experienced numerous ever-changing extremes. Extreme events, extreme people, and extreme ideas are so named for their departure from our expectations rather than for their absolute value, and in doing so we require them to inform our personal and collective understanding of the world. Most simply said, when it comes to understanding complexity so called ‘opposites’ are needed.
With that in mind I’ve been playing around with how the contrast between the sciences and arts might be used to greater understand ocean cycles. Everywhere on Earth, cycles emerge. These cycles are essentially opposites in motion, creating a contrast between what is now, what was then, and probabilistically what will be. Cycles are in a lot of places but in some of the coolest ways they exist in nature and in music. For instance you could define a song for its durable cadence and ephemeral choruses, for its high and low tempos, for the sounds themselves or for the space they leave in the silence. Similarly we can identify patterns in nature that range in magnitude, shape, rhythm, chaos, and duration. These patterns and processes build on each other, much like instruments in a peaking crescendo that crests into dissolution. Inevitably these systems or songs will reset, retreating back into the stillness that birthed them only to begin again sometime in the future.
What if we could take a song and stretch it out so that instead of lasting a few minutes it lasted a year long and (abstractly speaking) occupied all of Earth? What might that look like? What might that sound like?
This intrigues me because 1) it’s fun and weird to think about and 2) because sound signals are much like natural fluctuations that can be taken as the sum of many perturbations that together form what we see/hear/smell/taste/feel.
When we scale up a song we could expect patterns that are congruent to the seasonal cycles observed in phytoplankton around the world’s oceans. Phytoplankton are organisms (similar to plants in some ways) that are diverse, tiny, photosynthetic, numerous, global, and lazy. They can’t control their movement; they float in the ocean’s surface waters and harvest energy from the sun. When conditions are good, phytoplankton bloom, much like a huge garden in the sea. They breathe in CO2 and actually contribute nearly half of the oxygen we breathe. Recently I had some fun trying to visualize this* and here is the result:
Naturally a song is not the same thing as an ocean. Even so, comparing their contrasting scales can be scientifically liberating. What differences might arise when looking at a milliliter of ocean water compared to an entire ocean basin? What if we study it for a day or what about for ten years? As people we tend to work on time scales of hours and at distances of feet to miles — but in contrast— phytoplankton time and spatial scales are much smaller and their life cycles are far more rapid than ours. Because of this it’s really important to consider them at their own tempo (not ours) in order to get insights about the greater roles they play in controlling climate and feeding the world’s oceans.
* More accurately I’m visualizing the export efficiency, or the fraction of export of primary production from the surface ocean to the deep. The higher this is, the more CO2 from our atmosphere is removed where it can be stored in the ocean for centuries to millennia. This has profound implications for climate and is thus of much interest!
Kelsey uses a combination of satellite data, oceanographic data collected from trips at sea, and ecological theory to understand how plankton export carbon into the deep ocean. She is a PhD candidate at the University of California, Santa Barbara.
Approximately one third of global soil carbon is stored in northern peatlands as slowly decomposing organic material. Peat carbon is accumulated due to net imbalance of production and decomposition. This enormous amount of carbon is sequestered from the atmosphere by plants and accumulated under the waterlogged, acidic conditions in peatlands which considerably reduce the rate of decomposition. Decomposition is a complex process involving many different microorganisms, including archaea, bacteria and fungi. Any increases in the availability of nutrients by atmospheric deposition, such as nitrogen compounds produced as pollution, can increase the rate of decomposition by these microorganisms. If decomposition rates increase, the sequestered carbon within peatlands may be released as greenhouse gases, including carbon dioxide and methane, and the peatland ecosystem may fundamentally change to a net source of carbon. Peatlands have taken thousands of years to form. Therefore it is critical to understand the potential risks of pollution to peatland ecosystems or we risk further compounding the rate of global warming. This is why we have chosen to study the ecological changes at the long-term fertilization site at Whim Bog, as it is ideal for quantifying the potential effects of increasing atmospheric nitrogen deposition. Whim Bog is an LTER site managed by the Centre for Ecology and Hydrology near Edinburgh, Scotland.
Key to understanding changes in the peatland ecosystem is determining changes to the vegetation and their interactions with the microbial community. The predominant groundcover plants found in peatlands include members of the family Ericaceae, such as heather and bilberry. These Ericaceous species, or ericoids, rely on a symbiotic relationship with fungi for access to organic forms of nitrogen, which are relatively inaccessible to the plant. The fungi which associate with ericoid roots form what are called mycorrhizae, which is when fungal mycelia form a close connection between their hyphae and plant roots. In exchange for organic nutrients, ericoid plants provide sugars to the fungi.
At Whim Bog we are able to measure changes to vegetation diversity and biomass, root production, nutrient allocation by plant species and mycorrhizal colonization rates of ericoid plants. By carefully measuring these different factors across several treatments of increasing nitrogen fertilization, we aim to clarify the changes to the ecosystem. These data have the potential to increase the accuracy of global carbon cycle models which do not fully account for the carbon stored in peatlands and thus the importance of peatlands to global carbon cycling.
We enjoyed our visits to Whim Bog and the weather was remarkably warm for autumn, with sunshine and comfortable temperatures making our work a pleasure. The beautiful countryside provided many observations of wildlife and picturesque farmland, most especially the lovely gnats. Their occasional bites served to keep us on task and focused. Coming from Finland and working in peatlands much further north, we are accustomed to the attention of biting flies, mosquitoes and swarming gnats. Surprisingly, the Scottish gnats were quite ferocious and reminded us that we should have packed our mosquito net hats. Our visit at the end of August was a fortuitous coincidence with the Edinburgh International Festival. It was a great experience to see the city alive with all manner of arts and crafts. Working with the Centre for Ecology & Hydrology has been thoroughly excellent and we look forward to our continued cooperation.
Heikki is a PhD researcher at the Natural Resources Institute Finland (Luke) and studies microbiology at the University of Helsinki, Finland. His research focuses on mycorrhizal fungi associated with Ericaceous plant species in boreal ecosystems and changes to their relationship due to changing environmental conditions and nutrient availability. His visit to the site, with Dr. Tuula Larmola and Prof. Raija Laiho, both from Luke, was supported by eLTER H2020 Transnational Access award and project funding from the Academy of Finland to Dr. Larmola.
In December 2016, funded by an eLTER Transnational Access grant, I made a visit to the Cairngorms Long Term Socio-Ecological Research (LTSER) platform. The Cairngorms LTSER is the only such platform in the UK; its boundaries are the same as those of the Cairngorms National Park, established in 2003. My mission: to spend a week speaking with about twenty researchers, land managers, and institutional and local stakeholders, whose work is related to the Cairngorms LTSER. I sought to understand how research activities are prioritized, how research may inform policymaking and management activities, and how satisfied stakeholders are with research as it is currently conducted. This case study is one of several I will ultimately use to characterize the state of socio-ecological research across the global LTSER network. My trip began with interviews in Dundee, St. Andrews, and Aberdeen, interviewing ecologists, social scientists, GIS specialists and others about their work in the park, and then I ventured west to the Cairngorms National Park itself.
I learned that the Cairngorms National Park Authority is mandated to manage ecological conservation and promote economic development, a surprisingly integrated vision considering that many economic and governance models still pit environmental protection against economic development. The Authority itself does not own land, nor does it employ park rangers. Rather, it acts as a planning agency that coordinates stakeholders like Scottish Natural Heritage, landholders like private estates (which might host sheep farming, whisky, grouse hunting, and ATV rides), municipalities, and businesses, all within the park.
My visit was planned to coincide with a stakeholder meeting co-organized by my host, Dr. Jan Dick of the Center for Ecology and Hydrology, who was tasked with presenting her findings from the EU’s OPENNESS project to the relevant public, and by Dr. Kirsty Blackstock of the James Hutton Institute, who facilitated a discussion with the participants, focusing on stakeholder priorities for future research. This meeting was a highlight of my trip, as I got to participate in a workshop where researchers, land managers, and farmers were able to have an intimate, targeted discussion.
Meetings with stakeholders revealed the tensions of striving for management that captures the multiple priorities of diverse stakeholders – local citizens, recreational users, farmers, and estate managers – who sometimes feel the burden of too many rules.
In a post-referendum¹ and post-Brexit² world, Scottish lawmakers are unsure of their relationship to both Westminster and the European Union, and Scottish researchers are anxious about the continuity of some projects funded by these governments. I heard in interviews that officials relied upon EU-level legislation for the strongest environmental protections, and Scottish Parliament has already enshrined these standards into law; however, some expressed concern about whether Westminster would have the power to undo or modify these protections. These issues were mentioned by multiple interviewees, highlighting feelings of uncertainty about how law, governance and policy-making may change in the near future.
So how feels the pulse of the LTSER overall? I interviewed the advisory committee of the LTSER – three research scientists, one land manager, and one executive of the Cairngorms National Park Authority. The general feeling among these experts was that the LTSER was a framework useful for relationship-building across sectors and coordination of research activities across agencies and programs. Specifically, LTSER creates a forum and a framework for ongoing, periodic stakeholder dialogue, needs assessment with regard to research, and the coordination of research activities, funding, and data management. It was described as one layer in a web of institutions and research frameworks, important for coordination of research, data, and funding.
Great, ongoing efforts are being made to steward this beautiful, remote place, as fairly and effectively as possible, given competing interests. But it seems no pocket of earth is too far removed from a widespread feeling of change and uncertainty that threaten to interrupt the steady progress of ongoing research nor the inexorable human population growth that continues to put pressure on land management priorities.
²On June 23, 2016, British citizens voted 52% to 48% that the UK should leave the European Union. The act of separating from the EU has not yet occurred, and the implications it will bring are as of yet uncertain.
Jen is a PhD student in the Technion Socio-Ecological Research Group in Haifa, Israel and is affiliated with the Israeli LTSER network, with whom she is currently writing an article about applying transdisciplinary action research at the Negev Highlands platform. Her research evaluates impacts of the transition in ecological research toward transdisciplinary socio-ecological research. Her trip to Scotland was funded by an eLTER Transnational Access research exchange grant. She is happy to receive your comments, questions, and feedback at email@example.com.
This past summer I took advantage of an offer to get an early start on my research project in kelp forests off the coast of Santa Barbara. It’s hard to convey here, but I could not have been more thrilled. To put it in perspective, imagine that you’re working in an office cubicle nestled in among dozens of colleagues staring at a computer screens for 40 hours a week. Although you’ve tasted the much coveted ‘9-to-5 life’ of the real world that so many graduate students dream about, you want nothing more than to propel yourself back into the exciting never-ending challenge that is academia. You’ve been accepted into your dream graduate program at the University of California, Santa Barbara and you’re literally counting down the months and days to get started. Then you get that email from your advisory committee asking you to move early to get a head start. It’s all you have ever wanted – and now you can see the root of my excitement. I leaped at the opportunity to be part of the Santa Barbara Coastal Long Term Ecological Research (SBC-LTER) group.
Fast forward to July and I was in the water, learning how to be a field ecologist all over again. I couldn’t believe how challenging it was working underwater, coordinating surveys with other divers, and avoiding kelp entanglements. I remember trying to record all my data along a transect: counting all the kelp fronds at 1m height, measuring the holdfasts, recording invertebrate sizes, and suddenly realizing that my air was nearly gone! Somewhat of a contrast to the comforts of office where you can, you know, breathe whenever you want. Add in the fact that it took me forever to learn anything it seemed that there was no end to the frustration. The research team was like a well-oiled machine, seemingly perfect at data collection and hyper efficient. While I tried my best to keep up, it took me months to learn how to get anything down. Learning how to drive a boat – and not damage it – was likely the hardest part. I still joke with others that each time I drive back to the pier it really becomes a game like Operation, where you have to strategically place the boat to be hoisted up without allowing it touch the dock pilings – never mind the wind and waves. I think my blood pressure peaked at 3 every day over this summer. And this is why I will always refer to my first field season as: kelp forest boot camp.
While this summer was hardcore, I could not have been happier. Despite any of the frustrations I experienced over the summer, I am truly relieved to be working in the field that I love so much. I’m learning something new each day and building connections with others who have interests in kelp forest ecology, community interactions, and ecosystem functioning. I’m getting better at all of my research skills and with a bit more time and experience I hope to become a seasoned kelp forest ecologist. My favorite part about this summer was reconnecting with the field ecologist inside of me and fostering the internal drive to understand the patterns I see in the world. Each time I swim among the kelps we study in the Santa Barbara Coastal LTER I see something new and intriguing. And this keeps the gears in my head spinning as I ask the how or why questions.
I’m really so grateful for the opportunity to join the SBC LTER as a graduate researcher and to be part of the larger LTER network. I truly believe I found the right group of people to connect with in order to learn more about our earth’s ecosystems. I hope to get to know so many of you as I work more with the LTER groups in the future.
Joey is a PhD student in the Santa Barbara Coastal LTER group at the University of California, Santa Barbara. His research focuses on the role of consumer-mediated nutrient cycling in kelp forests.
It’s 4:00AM. Between prepping equipment and anxiety about today’s experiments, I only got a couple hours of sleep last night, but I’m full of adrenaline and ready to go. My undergraduate student and I drive to our first sampling site in beautiful northern Wisconsin, USA. The sun isn’t up yet, but the loons are laughing as we disturb Sparkling Lake’s calm waters, paddling our way to the buoy at its center. We drop our instruments into the water and wait a few minutes until exactly 5:00AM. In a flurry of motion, we begin to collect our samples – lake water concentrated through filters that must be collected in under 5 minutes and immediately frozen in liquid nitrogen. It’s over as quickly as it began, and the sun finally makes its way over the horizon. One timepoint down, thirty-five more to go.
I’m an LTER grad student, but this past summer, I ran an experiment on short-term changes in bacterial metabolism. Bacteria are crucial and beneficial members of lake ecosystems, where they recycle nutrients, harvest energy from sunlight, and decompose organic matter. My lab has studied freshwater bacteria in Wisconsin lakes for over a decade. I’m interested in carbon cycling specifically, and to find out what carbon sources are being used by the bacterial community at any given moment, you can collect a molecule called RNA. RNA is a messenger molecule in cells, and deciding what RNA to make and how much is a major way that bacteria regulate their metabolisms. Essentially, it’s the middle step between “I have the enzymes I need to eat this” and “I have the instructions to make those enzymes.” But because it would not be helpful for a cell to have all these old messages hanging around, RNA degrades fast. To collect it, we need to filter our samples quickly and immediately freeze them in the field. On top of that, our bodies make enzymes that degrade RNA as a defense against viruses, so while sampling, you are constantly spewing enzymes with the potential to destroy your experiment. RNA work is not something to embark on lightly.
We initially considered adding RNA sampling to our long-term time series, but there was one major problem: we didn’t know if there were short-term dynamics of RNA in freshwater. I’d just read a study in the ocean where huge changes in RNA were observed at different times of the day, as the bacteria adapted their metabolisms to take advantage of changing light conditions. I was concerned that if we tried to add RNA to our long-term sampling, we’d get different results depending on what time of day we sampled throughout the year. My professor’s response? “You should write a grant to study that!”
Fast-forward a year and a half. I did write a grant, and that grant got funded (!), and here I was at the crack of dawn attempting to sample three lakes every 4 hours for 48 hours each, all within two weeks. See, that ocean study that inspired me used a sampling torpedo. They dropped it off in their current of choice and picked it up a week later, all samples safely stowed on board. I, on the other hand, convinced/begged/harassed everyone I could to help me with the fieldwork. With my amazing volunteers, all the equipment I could haul in a university vehicle, and much trepidation, we began sampling.
I was keenly aware of everything that could go wrong. But after that first timepoint, I felt like I had done everything I could, like I had pushed a start button and now just had to sit back and let events unfold. And amazingly, the field work went quite smoothly! Well, we had to reschedule one timepoint due to thunderstorms, and once the boat flooded and nearly sank in high winds, and there was the time I got stopped by law enforcement on suspicion of illegal night fishing – but I was ready for these things. Call me a pessimist, but that’s how field work is supposed to happen. You react and revise your plans, and you come back with your samples and some crazy stories.
By this point, the samples I collected last summer are nearly all processed and I’m just waiting on the RNA data. I’m excited to learn if bacteria in lakes show the same changes during the day as they do in oceans, and to see how their short term trends compare to the long-term trends we’ve been studying at LTER for years. And then maybe the next LTER grad student can take what I’ve learned and plan a super awesome multi-year RNA experiment!
Alexandra Linz is a PhD student in the Microbiology Doctoral Training Program at the University of Wisconsin – Madison. She works with Prof. Katherine McMahon studying bacterial carbon cycling in Wisconsin lakes. Alex is passionate about science outreach and also writes for her lab’s blog, uwmcmahonlab.wordpress.com. When not doing crazy experiments, Alex enjoys photography, playing guitar and piano, and reading science fiction.
I want to tell you about my visit to the LTER site at Whim Bog, Edinburgh, Scotland. The Centre for Ecology & Hydrology, based on the Natural Environment Research Council, manages a LTER site with facilities to study the effects of dry and wet nitrogen deposition. Nitrogen is an essential element for plant growth, however, like everything in life, too much is just too much. Wet deposition occurs when nitrogen enters the system in the form of precipitation, and dry deposition refers to forms of nitrogen dissolved in the atmosphere. Excess of nitrogen can lead to severe changes in ecosystems, especially if they are oligotrophic – meaning that they are adapted to low nutrient conditions. Studying these changes is exactly what this LTER site is about. The site is a peatland ecosystem, dominated by the shrub Calluna vulgaris and the sedge Eriophorum vaginatum.
During my visit I studied the effects of dry deposition of nitrogen in the plant community – I assessed plant diversity and structure, using a set of transects along a gradient of ammonia (NH3). This gradient is imposed to the plant community by an automated free air release facility that releases gaseous ammonia. The system fumigates only when wind speed and direction are within determined values, creating an ammonia gradient covering about 60 m in extend, with ammonia values ranging between ambient (c. 0.5 NH3 µg m-3) and 100 µg NH3 m-3 (annual averages).
One last thing about the Scottish experience. You ever heard about midges? Before my trip to Edinburgh I never heard about them. And, until my last day of my field work, when I was starting to think the midges were little more than a myth, they appeared in full force. It seems that until then there were never the perfect conditions. But, on that last afternoon, the sun shone brightly after a light rain, the wind had stopped blowing, and from one second to another, millions of little flying dots appeared from under the shrubs to land on our hands, faces, ears… everywhere. So I learned what midges are.
Melanie is a fellowship researcher at the Centre for Ecology, Evolution and Environmental Changes, Universidade de Lisboa. She studies plant functional diversity, mainly of the Mediterranean vegetation in Portugal, in response to different environmental changes, such as desertification and grazing.
The BRACE project (Background Reflectance ACross Europe) is one of 23 small projects supported by the eLTER H2020 project’s Transnational Access scheme (which is funded by the European Union). The objective of the project is to collect in situ measured background/understory reflectance data across diverse ecosystem research sites in Europe. The results should be particularly useful for validating remotely sensed data and for producing Northern hemisphere maps of seasonal forest dynamics, enabling analysis of understory variability, one of main contributors to uncertainty in present estimates of spring leaf emergence and fall senescence. Our data can also be used as an input for improved retrieval of biophysical parameters and for modelling local carbon and energy fluxes.
First stop was the Kindla Integrated Monitoring site in Sweden, which my colleague, Krista Alikas, and I visited in July 2016. Kindla is one of the most inaccessible and wild areas in Örebro county, and it is also a large nature reserve (over 900 hectares). To get good quality data, we have to collect our measurements in overcast, diffuse light conditions. You cannot do much when the sky is blue and the sun is shining, and during such moments we explored our surroundings and gorged on huge quantities of ever-present blueberries.
There are 15 km of paths in the nature reserve area, allowing individual walks of 7-10 km – just perfect to fit within the windows of our (in)activity when there was no hope of sudden increased cloudiness. Kindla’s summit, 425 meters above sea level, is also one of the county’s highest points. There is an additional 11-meter viewing tower, which allows you to rise over the treetops to get a fantastic view over the green sea of surrounding forests.
We were told that you can find traces of bear, wolf, lynx and wolverine in Kindla, but the animals are clearly very shy and maybe unsurprisingly we failed to make a closer encounter with any of these animals. On the other hand, we were apparently sharing our accommodation with another typical local representative. We were staying in a nice and cosy barn-turned-into-hostel (we were the only guests all week) in the nearby tiny village of Nyberget. During nights we could often hear a strange, not entirely unpleaseant murmur coming from the base or underneath the building. Upon our departure we were told that it was most likely a badger.
With support from the eLTER H2020 project, we are looking forward to making similar measurements from two other European LTER sites this year: Montado in Portugal and Zöbelboden, Austria.
Author: Jan Pisek
Jan got his PhD. degree from University of Toronto, Canada. He is currently a senior research fellow at Tartu Observatory, Estonia. Jan is primarily interested in field- and space-based multi-spectral and multi-angle optical remote sensing, biophysical parameter and vegetation structure mapping. Jan would like to thank Lars Lundin and Stefan Löfgren of Swedish University of Agricultural Sciences (SLU) for providing excellent supplementary materials and introduction to the Kindla Integrated Monitoring Site.
If it wasn’t for this geological bump (the highest peak 549m), the northern part of Serbia would remain devoid of many ecosystem services, much of its biodiversity, life forms, oxygen, historical values and research opportunities. In simple terms, it would be quite boring area. Fruška gora is the first Serbian National park, founded and proclaimed in 1960. Once an island in the Pannonian sea, after the sea went dry it became an isolated mountain chain about 80 km long and completely surrounded by flat land. Due to its origin, the mountain treasures rich deposits of fossils in its rocks allowing us to peek into the past whenever we are feeling curious. It’s a soulful place with many stories and historical events carved in its forests and stones.
Its deciduous broadleaved forest is comprised of beech, oak, lime and hornbeam, the main edificator species. Out of 110 species of birds recorded on Fruška gora, it is certainly worth to mention the Imperial eagle, one of the most endangered species on The IUCN Red List of Threatened Species. Around 1500 of plant species grow on Fruška gora and that’s a lot of species for such a pimple. Among them more than 700 have medicinal value and many are of relict and endemic character.
Besides potential excitement after running from a wild boar there is not much adrenalin rushing nature phenomena on Fruška gora. Fruška gora lies in the temperate zone thus you will not find a hand size isopods in the area however the research we conduct can be quite alluring to scientifically inclined, not to say odd, individuals.
In addition to standard and not so charming monitoring of common soil and air parameters, we are conducting some fancy research studies here. One of them is studying syrphid flies. Syrphids are flies from the insect family Syrphidae which pretty much look like bees and wasps, though unlike these insects they hover like little helicopters and can stay motionless in the air which is why they were nicknamed hoverflies.
Why would anyone study this group of flies? Well besides they are really cute, they are also quite important pollinators enabling the existence of the myriad plant species. In fact, after the bees, hoverflies are the second most important group of pollinators. They are also very sensitive to habitat and climate change thus great environmental change indicators, meaning that their presence and abundance specifies the degree and the rate of environmental change. We are studying the influence of external environmental traits including climate change on the occurrence of selected hoverfly taxa.
How do we study hoverflies?
Using sweep netting at chosen sites along transect lines followed by species identification, either by observing morphological characters or using DNA barcodes.
Climbing 30 m high trees to get the data
Besides practicing tree climbing, a fascinating and a hell of a fun activity, we are collecting leaves from the highest branches which we later analyze for leaf traits such as N and P concentrations, leaf dry matter content, specific leaf area and leaf size.
Plant species react to the environment they live in, their physiological processes such as photosynthesis and transpiration are heavily dependent on their surrounding.
By collecting the leaves in the areas differently affected by human activities (mainly by logging) and measuring chosen set of leave functional traits, we are tracking plant responses to these disturbances. Different species may respond differently to habitat change i.e. different disturbance level.
To us it is interesting to investigate whether lime (Tilia argentea Desf. ex DC), which became heavily dominant after years of logging suppressing the oak and beech, has the same level of physiological excellence as the species which were formerly much more abundant.
Using satellite images to observe forest cover change
By using satellite images we are detecting changes in forest cover such as deforestation and fragmentation in order to quantify change patterns, ascertain the nature, extent and rate of forest cover change over time and space. We are using these results to analyze changes in spatio-temporal framework, upgrade the management of timber resources and update forest cover maps.
Dušanka Krašić is a researcher at the Biosense Institute in Serbia, Novi Sad and a fourth year PhD candidate at University of Novi Sad, Department of Biology and Ecology.
My second time in Germany starts on a hot and sunny summer day. After a short meeting with researchers and technicians from the Helmholtz-Centre for Environmental Research in Leipzig, and some instrumentation checking, me and the other group member are ready to reach the TERENO field site near the Selke River, in Saxony-Anhalt. But why are we here? Let’s take a step back!
A layer of water-bearing permeable rock or soil from which water can be extracted is called “aquifer” and its characterization is important for many reasons, especially for human use. From a wider point of view, aquifers belong to the so called Earth’s Critical Zone, the thin outer layer of our planet where interactions between soil, water, rock, air, and living organisms take place. Each aquifer has its own characteristics (some are shallow and some are deep, some are confined and some are unconfined…) but all of them can be characterized using the same methods, which are actually a lot. So that’s why we are here: to study a shallow fresh water unconfined aquifer!
This aquifer in the Central German Lowland is already well known from the UFZ group in Leipzig, as many data are already available, but when it comes to aquifer characterization (or any other thing in any other science field) data are never enough! Furthermore, this case study is a good example of the combination of the two main types of field information: direct and punctual vs. indirect and extensive. But what does this mean?
The first type of information (direct and punctual) comes from the typical approach to aquifer characterization, based on observation wells. They are drilled from the surface into the aquifer and are equipped with many types of probes, which automatically measure several parameters like electrical conductivity, temperature, and so on. In our field site we took advantage of the direct push-system, which pushes tools and sensors into the ground to create a borehole and, simultaneously, creates a log measuring several parameters at different depths. On the other hand, the second type of information (indirect and extensive) consists in measuring quantities that are related to the ones we are actually interested in, since determining them directly would be too difficult or too expensive. A good example is electrical resistivity, a physical parameter that depends on many factors (e.g. water content, salinity, temperature, etc.)
So the point is: which approach is the best? The choice depends on the characteristics of the area, on the amount of money at our disposal, and, most of all, on the questions that need to be answered. But probably the best solution is to combine the two of them, and this is exactly what we chose for our field site.
The first thing we do is measuring the depth of the water table, i.e. the upper boundary of our unconfined aquifer (or, in other words, the surface separating the water-saturated soil – below – from the unsaturated soil – above). Water table depth varies over time depending on many factors and gives us information regarding the direction of groundwater flow. These direct measurements rely on the number of observation wells available, which are usually a few, as they may be too expensive and/or may modify the actual aquifer properties. Therefore, these punctual values are then properly combined to infer information also on the area between these wells, thus leading to a so-called “isophreatic map” (i.e. a map showing how the water table depth varies in the space, like a topographic map shows altitude variations)
The second thing we do is a tracer test, to gather indirect and extensive information. Tracer tests consist in injecting a substance that can be easily detected (why appropriate tools) into the aquifer, to monitor how it changes the properties of the investigated domain. In our case, this consists in injecting a certain amount of water with a known electrical conductivity (i.e. the inverse of electrical resistivity) and to monitor how electrical resistivity and electric potential difference vary consequently over time.
To measure these physical quantities, we decided to combine two different methodologies, named electrical resistivity tomography (ERT) and mise-à-la-mass (MALM) respectively. Even if their names seem complicated, their application is rather simple. The former consists in injecting electrical current into the subsoil and measuring the generated corresponding voltage, using several metallic elements called “electrodes”. We put these electrodes directly into the aquifer thanks to four new boreholes. The voltage values are then turned into the corresponding electrical resistivity, which is finally represented into images known as resistivity cross-sections. These pictures show the resistivity pattern at the measurement time, as if we were cutting a vertical slice in the soil (perpendicular to the ground surface) among the boreholes. These resistivity values can be related to the direct information obtained from the observation wells, so as to extract only the information we are actually interested in.
The latter methodology is based on the same principle, i.e. injecting electrical current and measuring the corresponding voltage. In this case our electrodes are placed on the ground surface, creating a sort of grid covering the area over which the tracer should move: here, the aim is obtaining a voltage map, which represents how voltage varies in the space of the investigated area. The main idea is that the tracer varies the measured voltage (and therefore also resistivity) over time, according to its movement, which depends on the aquifer properties. Thus, the detection of these variations should provide insights regarding the investigated domain, such as direction and flow velocity.
Even if the data analysis will require some time, as combining all this information together is not so simple, the preliminary results are definitely promising. Our goal is to assess the same direction and flow velocity both from surface (i.e. MALM) and borehole (i.e. ERT) acquisitions. Thus we will be able to say that, yes, sometimes one can judge an aquifer only from the surface!
Laura Busato is a PhD student at the University of Padova (Italy). She combines non-invasive geophysical methods and hydrological models to characterize the movement of water in the Earth’s Critical Zone (i.e. the thin, outer layer of our planet, where the interactions between air, soil, water, rock, and living organisms take place). She really likes listening to rock music and baking cakes.