Winter in Australia’s high country can be beautiful and brutal, sometimes shifting quickly from one to the other within a remarkably short time. Conditions can range from crisp, bright ‘bluebird’ days to freezing rain to blizzard conditions. There are high ridges buffeted by fierce winds and snow drifts strong enough to contort steel. As ice and snow gather across open fields, sheltered lees and deep ravines, it’s easy to see how they have helped shape the contours of the high country. What might be less obvious is how these same elements also shape the unique ecosystems that live within it.
Snow, for example, has a significant effect on how nutrients, energy and water cycle through a landscape. As it accumulates, it becomes an effective insulator keeping ground-level temperatures relatively stable, often hovering around zero degrees Celsius, even as air temperatures plunge well into the negative double digits. Far from being an inert blanket, the snowpack is a fractured labyrinth of micro-refuges, alive with activity.
Winter conditions shape Australia’s unique high country ecosystems. Clockwise from top: high elevation vegetation near an AMRF site; an arthropod continues about its business in the snow; native vegetation collects snowfall (image credits: Nathan Battey, AMRF); last image: endemic alpine sunrays on Mt Kosciuszko (credit: WaiKee via Adobe iStock)
The subnivium – a hidden microenvironment at the interface of snow and soil – acts as a lifeline for numerous plants and animals. Dusky antechinuses and bush rats forage and nest there, while mountain pygmy possums and echidnas curl into a protected winter torpor. Subnivean arthropods and other small fauna scuttle this way and that. Elsewhere, lizards hibernate in snow gum logs and where weak light penetrates the snow, cold-tolerant plants continue to photosynthesise, while hardy fungi and other microbes trade soil nutrients for carbon. Snow keeps the ground relatively moist, too, and the rate at which it melts, which varies substantially across a landscape, influences soil moisture and plant growth well into spring and summer.
Snow and other winter conditions shape nutrient cycling, soil respiration, and carbon fluxes across the landscape. In fact, the Australian Alps contain a substantial amount of carbon content locked into organic matter. As the extremely cold, wet environment slows decomposition, this organic matter builds up in the soil, allowing the mountains to collect groundwater, which steadily discharges throughout the year.
Why winter data matters
Over the course of a winter, snow falls, shifts, melts, and falls again, all the while contributing to ever-shifting biogeochemical and water processes. With TERN’s support, the Australian Mountain Research Facility collects ecosystem and hydrological data via specialised research programs and automated sensor arrays situated at monitoring plots across alpine and subalpine Australia.
The resulting datasets provide valuable information about high country ecosystems throughout the year, and winter data is a particularly important part of that, says Leah Moore, who heads the Applied Water and Soils Hub (AWASH) at ANU where she works on a number of projects associated with AMRF as well as Save our Snow Gums (SOSG).
“We have to monitor year-round in order to get the full picture of what’s going on,” she says. “If we don’t take the samples in winter, we’ve lost a big chunk of our data.”
Moreover, studying these ecosystems in winter provides insight into biological processes unique to the cold season which are still not fully understood, she says.
It’s crucial to get a better understanding of how ecosystem processes – including nutrient, energy and water dynamics — play out in alpine, subalpine and montane regions. And it’s equally important to figure out how they’re going to be affected in the future by warming or drying conditions or land use change.
Top left: researchers take snow cores (credit: Nathan Battey); Top right: researchers use ground/snow penetrating radar to observe the structure of the snowpack. It shows different layers of ice, snow of varying density, and how that changes spatially (credit Nathan Battey); Bottom image: melting snow in Kosciuszko National Park (image credit totajla via Adobe iStock).
Leah is particularly interested in how water moves through the landscape. Much of her work focuses on understanding high-country water systems and soils, their impact on vegetation and broader ecosystem processes, and how all of this is changing over time. She explains that there are still a lot of unanswered questions about how the water balance — the amount of water entering and leaving a landscape – behaves during winter. Weather predictions are useful but knowing the amount of snowfall in a region won’t tell you its hydrological impact. You need to know its moisture content, how it moves across the landscape, where it accumulates, as well as the depth, density and structure of the snowpack. Even rainfall behaves differently when it falls on snow, so you have to look at that, too, she says.
“There’s more percolation and saturation of the ground when we get rain on snow than there is in summertime,” says Leah. “That’s really important, because you need the soil to be saturated in order for the water to pass through into the groundwater system.”
The amount of rain infiltrating the snowpack also influences how long the snow lingers into spring, and shapes when and where it turns into runoff, and how well it recharges groundwater and feeds streams and rivers. To track this, Leah needs to measure snow depth, density, soil moisture, and more.
“We have to sample across winter in order to understand how much of our precipitation is deposited as snow, how much is stored in the catchment, and how that contributes to the whole budget of water coming into and going out of that landscape. If we don’t look at snow, then a whole chunk of that equation is missing.”
High country data collection
AMRF has established monitoring plots in alpine areas in the ACT, NSW, Victoria and Tasmania. Each of the nine 1 ha plots was established using the TERN AusPlots protocol to map out the vegetation and take soils measurements.
In consultation with TERN, each of the AMRF sites also hosts what is called an AMON station – the Australian Mountain Observation Network – which collect a wide range of standard meteorological data such as temperature, wind speed, precipitation and humidity.
There are rainwater catchers, as well as digital soil moisture and soil temperature sensors. There are also piezometers, she explains. “With those, we can measure the ground water depth and take physical data like EC, pH, plus collect ground water samples to take back to the chemistry lab. We can sample those year-round.”
When it snows, automated snow depth sensors at the AMON sites assess how much has fallen. Snow depth is also double-checked when research teams go out to take snow cores, says Leah. “Snow coring allows us to analyse the density and structure of the snowpack, so we can understand how much water the snowpack contains.”
Left: map of AMRF sites (image via AMRF); AMON station at one of the AMRF sites (image via TERN)
The AMON sites generate continuous streams of ecosystem data from weather stations, cameras, hydrology stations and other instruments, says AMRF Network Coordinator, Nathan Battey, adding that most of the sites have telemetry so the data-streams are accessible remotely. He explains that AMRF’s mission is to provide those continuous data streams for researchers to use year-round. Researchers can also augment the AMRF data streams by co-locating their own observations and experiments.
“I’m in charge of taking care of the equipment year-round and maintaining its continuous operation,” he says. “That is probably most difficult in winter for probably every reason.”
Equipment challenges
The equipment installed at the AMON sites is designed to endure tough conditions. Some instruments, such as the piezometers and soil sensors, are necessarily positioned at or below ground level and can get covered in snow but are pretty robust, says Leah. The sealed boxes where the data is logged can transmit data via Bluetooth. “They can transmit through up to five metres of snow,” she explains. “I can download the data just using my phone, provided I keep it warm enough.”
This raises an important point: winter weather and electronics don’t always play well together. “Some of our electrical equipment plays up a little bit in the cold, so that can be a problem.”
Nathan knows this all too well. “I have a winterising set of field trips just in April and May, where I make sure all these things are buttoned up and in ship shape to stand on their own for a few months if need be.”
But problems still happen.
The above ground equipment, from weather stations to phenocams, are positioned high off the ground to avoid getting snowed under, but snow can accumulate on solar panels and if it lingers too long and overcast conditions persist, the batteries won’t recharge. And even though data logger boxes are sturdy, if they get buried in snow, the humidity infiltrates and accumulates over time, rusting wires and connections, he explains. Meanwhile, winter’s freeze-thaw cycles can compromise seals and gaskets across the suite of equipment.
Rime ice is a particular nuisance. It forms when supercooled water droplets in the air encounter cold surfaces and freeze on contact, so it can accumulate even in the absence of snow or rain. When it builds up on the thin membrane of the snow depth sensor or on the lens of a phenocam, it interferes with data collection, says Nathan. Moreover, when rime ice melts in the sun, the water can seep into crevices and degrade things over time, especially on sensors with moving or exposed parts.
Clockwise from top left: weather station positioned so that it is usually above the snow (credit Nathan Battey); But they can sometimes be buried by heavy snowfall (image via ARMF); Solar panels vs drifting snow; rime ice building up on a weather station; rime ice closeup (last three image credits: Nathan Battey, AMRF).
“Wear and tear happens much faster in the kind of extreme field conditions you get at higher elevations,” says AMRF Data and Experimental Design Consultant, Dr Pieter Arnold, who curates the data streams from the field sites.
“There have been a lot of challenges over the last few years establishing the sites and making sure that all of the sensors, the cables, the infrastructure to actually power the instruments and allow data communication can work through some of the really tough conditions that the Alps throw at them.”
“For the sites that are online, we can see if there is a sensor malfunctioning or something else that we need to consider would require a site visit,” he says.
It’s important that any impact on the data is addressed, so his task is to go through the data to make sure any gaps or anomalies are noted and explained. It also helps determine whether a site visit is necessary.
You hope it’s just a minor problem, but it might be a lot worse.
Cold snap: snow vs steel
“One of the challenges of winter is that you can actually have your equipment destroyed because of the power of the elements,” says Leah.
A few years ago, she was collecting water samples at the Wrights site, AMRF’s highest-elevation site (1970 m) near Charlotte’s Pass in Kosciuszko National Park. “We had big snow drift problems up there,” she says. Her rainwater collector held up remarkably well in the conditions, but while there she discovered that her colleagues’ equipment hadn’t been so fortunate. The AMRF’s Australian Mountain DroughtNet project uses rainout shelters — steel frames topped with Perspex slats that reduce incident precipitation over patches of vegetation — to study how mountain ecosystems respond to reduced rainfall and climate-change-induced drought.
“They got destroyed by the power of snow drifting through them and just contorting the steel and breaking them,” says Leah. “It was an important lesson to learn.”
Rainout shelters usually handle tough conditions (left) but powerful snow drifts cam contort steel (right) (images via AMRF)
Nathan explains that snow drifts are caused by wind redistributing snow across a landscape. “Drifting snow is almost like a sand dune, these things move over time,” he says. They are a significant challenge in high country and have taken out weather stations at a couple of research sites so far.
“We originally put a flux tower up on top of our site at Cruiser,” Nathan recalls. “That particular site is at the crest of a small hill, so the winds reach pretty high speeds as they get up and over the hill.”
“Drifting snow basically picked up the tower and moved it a few metres over the course of the winter. When the snow melted, it fell over, because it wasn’t braced in the way it was originally set up.”
He also describes a weather station above the tree line in Kosciuszko National Park, situated near a lee, or sheltered area, of a hill. It was braced with guy lines securely anchored to star pickets (steel poles driven into the ground). This time, wind wasn’t the problem.
“A lot more snow came in than anticipated, which accumulated up the hill,” says Nathan. “When snow melts, it moves very slowly, but water is very heavy and in this case, the snow built into a really big, slow-moving slide.”
“It pushed everything over as it slid down the hill in one big mass. It even sheared-off the star pickets – it just cut solid steel.”
Sometimes fixing one problem sometimes creates another, says Nathan, recalling the time they placed tarps around the base of a weather station to keep snow and ice from weighing down the data cables and disconnecting them from the data logger. “Unfortunately, the dark colour of the tarp ended up creating a bit of a heat effect,” he says. It melted the snow for a couple of metres all around the station, skewing the snow depth sensors and other measurements. “The data was no longer representative.”
An anomalous signal could mean a lot of things, says Nathan, so there’s usually a prudent wait-and-see phase to determine if it’s a temporary telecom or energy supply issue due to bad weather or snow-covered solar panels. Those problems tend to resolve themselves when the sun comes out, but if that doesn’t happen, he says “at that point you have to go drive out, strap the skis on and get out to see it yourself.”
While some winter trips are occasionally organised to check on anomalies, site visits are usually scheduled in advance to check equipment. The scientific teams also schedule trips – often simultaneously – to conduct research and collect data.
Site visits entail logistics at any time of year, but going out to the wilderness in wintertime is even more complicated, says Nathan, explaining that it takes time to put a trip together, get approvals, work with national park authorities and other partners, like ski resorts.
On occasion they get permission from a nearby ski resort to use the chair lifts.
“We have a good relationship with them and they, you know, they often know who we are. We’re the ones with the big, weird-shaped backpacks and snowshoes or something and not just goggles and skis.”
AMRF also has a purposely designed vehicle for fieldwork, with high clearance for travelling over snow and other rough terrain. It helps transport gear in and out. But sometimes, even that’s not enough.
“We have some sites that have an access road that is fully open and accessible to us in summertime – you can almost drive up to the site, maybe a couple 100 metres up a hill,” says Nathan. “But in wintertime, it ends up being a 10K snowshoe or ski along a trail to get there the long way.”
Field safety in winter
Leah explains that there’s always someone on the site visit who knows the terrain and all members are equipped with good personal gear and personal locator beacons (PLBs) which, if triggered, sets a helicopter search in motion. Thankfully it hasn’t been necessary yet, she says, but it’s an important safety precaution. After all, conditions can change suddenly in the mountains and whiteouts can move in fast, severely limiting visibility.
“Usually, you monitor the weather so that doesn’t happen, but I have had to navigate in and out of the site at Cruiser in zero visibility,” she says. Mercifully, phone coverage in the alpine areas is pretty good, so it was possible for the team to track their location on a digital map. “We managed to find the site, do the work and get out without ever being able to see where we were,” she recalls. “We found all the piezometers and the rainwater sampler and then sampled another creek that’s sort of across the other side of the valley and still got ourselves out again safely.”
These days, Leah and her team are focusing more on subalpine sites, where they’re studying snow gum dieback, work that involves snowshoeing out to multiple subalpine sites every month through winter to collect rainwater samples.
“We walk for extended periods in snowshoes or ski into sites with big packs on our backs,” she says. “One of our sites is eight kilometres in, so you have a sixteen-kilometre round trip skiing or walking in snowshoes, which is strenuous.”
Left: Researchers keeping warm in harsh winter conditions. Working with delicate equipment, isn’t easy with thick gloves or cold fingers; Right: researchers need good gear to stay warm and safe, especially in whiteout conditions where visibility is reduced (image credits: Nathan Battey, AMRF)
Strict cold-weather health and safety protocols apply whenever teams venture out in winter. Communication equipment is kept on hand and scheduled check-ins are mandatory. Everyone holds up-to-date CPR certification, and at least one person per team has additional remote area first aid training. Hypothermia is an ever-present risk, says Leah. “We’re really monitoring it all the time.”
There’s also a research station cottage where gear can be dried out: clothes, boots, and so on. When people come in from the cold, the team makes sure they warm up and aren’t becoming hypothermic.
Ground truthing
It’s hard work going out in the field in winter, and risky. But all that cold weather work ensures data flows reliably over time and helps reveal how these unique ecosystems function and the risks they face.
Being there in person is also like a gut check, says Nathan. “It’s the sweat and the equity you put into getting out there, making sure that you’re measuring what you want to be measuring.”
That human element of science is vital, he explains. “Even if things aren’t going wrong or need maintenance, it’s important to just go out there and get a sense of what the conditions are like, and this helps you set everything up better. It’s being part of a living piece of infrastructure.”
“It’s also really nice to get out there and see some things a lot of people don’t get to see,” he says.
“I’ve seen days where you look out over the mountain range and it looks like all of Kosciuszko is shining because it’s just covered in like an icy layer of snow and the sun’s hitting it just right…it’s a privilege to be out there.”
Leah agrees that there’s nothing quite like it.
“It’s part of the joy as well,” she says. “Just being out there and having some wilderness time is actually really good for the soul.”
Feature image at top of story: researchers hike out to a field site in winter (credit: Nathan Battey, AMRF)