On the measurement of microclimate

Ecologists nowadays are trying to get closer to measurements of the microclimate that organisms are actually experiencing. Weather stations are great, standardized sources of temperature data at 2 m in the air, yet organisms often relate more strongly to what happens much closer to the ground. This rapidly increasing interest in microclimate ecology is great and much needed, but sometimes it is important to take a step back and ask that one important question: how good are we actually now at measuring the temperatures that we care about?

Indeed, microclimate measurements are done with a wide range of temperature sensors and radiation shields, professionally-built or home-made creations, and we lacked a good insight in how different the results could be. The big question is: are the temperatures as these sensors measure them close to the temperature as a beetle would experience it at the same location? This is exactly what we set out to answer in a recently published paper in the journal Methods in Ecology and Evolution.

Let’s start with some good news: for measurements of soil temperatures, we don’t expect too many issues. What you measure should match fairly well with what’s actually happening. However, it is above-ground that the trouble starts. More precisely: when the sun is shining and especially when and where wind speeds are low. Indeed, most commonly used sensors yield large errors under direct sunlight, reaching up to a whopping 25°C.

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Temperatures on a sunny day as measured with different iButton sensors are often up to 20°C different during the day from those given by a minuscule thermocouple.

Unfortunately this problem cannot be wholly overcome by shielding the thermometer from sunlight, as the shield itself will influence both the temperatures being measured and the accuracy of measurement. Importantly, however, when there is no direct sunlight, for example at night or in shaded environments like forests, errors turned out to be much smaller (see graph).

What’s the impact of shade on air temperature measurements? You see TMS4s with and without hats, and in the background a ‘shading table’. Differences are – as could be expected – substantial. Picture by Koenraad Van Meerbeek

So, what to do if one wants to measure air temperature close to the ground? In our paper, we provide two clear suggestions:

  1. Whenever possible, use the smallest temperature sensors you can find, as these will be affected much less by heat absorption. Low‐cost and unshielded ultrafine‐wire thermocouples were clearly ‘best of the test’, as they will affect the surrounding temperatures the least due to their small size.
  2. In shaded environments, there are more options available, and in some circumstances the use of other logger types, particularly TMS4 dataloggers, is appropriate. The latter are an especially good choice when trade-offs for costs and practical use have to be made. These might also be your go-to solution when the measured effect sizes (i.e., the difference between your location and weather station data) are large compared to the expected errors, such as may occur when regional or elevational variation in temperature is the primary concern, or in locations where weather stations are sparsely distributed.
The best of the test of the ‘traditional’ microclimate sensors: the TOMST TMS4. However, on such an open area as this carrot field, air temperatures can still be several degrees different from the truth when sun is shining. In this set-up, soil and surface sensors are below the surface and thus spared from the issues.

In short: there is no perfect way to measure microclimate temperatures, but there are definitely better or worse ways to do it. When working with such data, one should thus be *very* careful that no conclusions are made that should not be made.

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Good family man or sulking teenager: an update on our data network

May be an image of outdoors

The data from the lawn network of our citizen science project (CNidT) is transmitted via the Internet of Things. With its 5,000 connected sensors, CNidT is also the largest Internet of Things network in Belgium. Pioneering work, therefore, and that gives as many interesting surprises as challenges.

The name, Internet of Things, or IoT, refers to a set of devices that are connected to the Internet. In this way, the devices can send data to the cloud, communicate with databases or exchange data among themselves.

Many devices on the IoT are equipped with a sensor to collect data. In the case of CNidT, the soil sensor has several sensors that measure air temperature, soil temperature or soil moisture every 15 minutes. Via a SIM card, the sensors are connected to Orange’s IoT network and once a day the collected data is transmitted to our database and the participants’ dashboards (you can check out the dashboard of the sensor at the University of Antwerp here!).

After over a month of data collection, we now have a great view of how faithfully the lawn daggers transmit their data to the CuriousNoses database at UAntwerpen. What is surprising is that part of the network reacts like a “good family man”, while another part acts more like a “sulking teenager”.

Schermafbeelding 2021-05-11 om 11.24.41

About 50% of all sensors send their data every 24 hours (these are the good family men). The other 50% still like to hold the data for one or more days, only to send it all in one burst at a later time (these are the stubborn teenagers).

Is your garden dagger by any chance a sulking teenager? No need to panick yet. You won’t indeed see new data appearing on your dashboard every 24 hours. But this data is not lost: the data is stored in the internal memory of the soil sensor and transmitted when there is connection again. Either way, this data gets ultimately included in our analyses.

From an Internet of Things perspective, these good and bad lawn daggers are highly fascinating: why is the network reacting the way it is? Is there reduced coverage in certain locations? Are there large trees or buildings nearby? Or does the weather play a role in connection reliability? And what can we learn from this for the future rollout of large IoT networks? We are currently investigating these interesting questions with partner Orange, sensor builder TOMST and the Internet of Things wizards at ID lab at UAntwerpen.

Text by Sanne de Rooij, translated by Jonas Lembrechts

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Cold fieldwork news

I received some pictures from the snowy colds of the Norwegian mountains this week, where The3DLab-member Ronja went on a cross-country ski tour to her seed addition experiment to measure snow depth.

Snow is a crucial component of microclimate as it serves as a blanket: a thick snow pack can keep soil- and near-surface temperatures close to 0°C all winter.

Ronja in a black-and-white world, on the road to her fieldwork plots. Picture by Eivind Bering

In Ronja’s experiment, we are especially interested in local variation in these snow covers, as we are comparing exposed with sheltered locations. In the exposed location, wind prevents the accumulation of a thick snow pack, with potentially much more intense freezing around our seedlings, yet also an earlier onset of spring. In the sheltered locations, snow can accumulate, providing this important blanket against heavy freezing, yet also delaying the start of spring for the plants underneath the blanket.

Locating your fieldwork plots under a blanket of snow needs good GPS-coordinates. Picture by Eivind Bering
A sheltered location, where no plots can be seen. Picture by Ronja

Often these winter measurements of the snow depth are lacking – few are brave enough for winter fieldwork. But Ronja fears no cold (and has equally brave friends to provide fun fieldwork company) and got us the precious data we need.

Very much looking forward to see how the seedlings look when snow is gone!

An exposed plot, with very little snow cover. Picture by Eivind Bering
The precious winter data! Picture by Ronja
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Saving the world isn’t rocket science

The3DLab member Ronja got interviewed for a podcast at her university in Trondheim! A very nice summary of her research. You can find the podcast here, or on Spotify!

The podcast investigates the environmental impacts of hiking trails in the Trondheim area. Norwegians are active practitioners of “friluftsliv” and hiking is one of the most popular activities. Ronja Wedegärtner, Ph.D. candidate at NTNU, discusses the influences of hiking trails on vegetation shifts in mountains in the Northern Scandes, giving away some cool insights about her PhD-research!

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Ronja in the Swedish mountains in search for impacts of trails on vegetation

Want the scoop of some of the most fascinating results from her work, then this podcast is a must-listen!

Saving the world isn’t rocket science

The rapid growth and challenges related to agriculture, urbanization, tourism and human-wildlife conflicts require knowledge to take action. Listening to this podcast, you will be updated on state-of-the-art science related to issues in Trondheim. “Saving the World isn’t Rocket Science” shares knowledge from the science community by interviewing local researchers about sustainability problems in Trondheim and possible solutions.

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Aliens in the Arctic

In a recent study co-authored by The3DLab-member Ronja Wedegärtner, a team of researchers have mapped invasive plants on Svalbard, and the results leave no doubt; alien plants grow where humans have been.

Two of the researchers on fieldwork in Svalbard. Photo: Lawrence Hislop / Norwegian Polar Institute 

The research team found 36 alien plant species, which grew exclusively in areas with human activity. Both around tourist attractions in settlements, and where there has previously been farming.

All of this might sound minor – finding 36 alien plant species should not be that much work, right? – yet the remoteness and challenging working conditions on Svalbard make organized alien species inventories far from straightforward. With this new study, the researchers finally provided a benchmark for continuous monitoring, that will greatly facilitate keeping track of changing biodiversity in the Arctic in the future.

More details on the study can be found in this nice blogpost.

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And we are live!

Distribution of sensor locations across Flanders. Yellow dots represent private gardens, purple are schools, red is for participating municipalities. The green ones in Antwerp represent a separate project in nature reserves.

There we go, today marks the official launch of CurieuzeNeuzen in de Tuin, the day on which 4500 microclimate sensors pop up across Flanders!

1906 sensors connected at noon on ‘D-day’. These will only start sending data on Sunday night, so only 300 are currently actively transmitting data (bottom)

You can take a look at their distribution on this map here.

These are scary and exciting moments, where we can follow in real-time if the connection of the sensors to the Orange Internet of Things-network are successful. As you can see on the right here, things are starting to look good, with already almost half of the sensors successfully installed.

Don’t underestimate that achievement: this is by far the largest IoT-sensor network that the country has ever seen, and we are thus truly technological pioneers.

But all is working relatively smoothly, while microclimate sensors are popping up in gardens across the whole region. Here at home, there was a little scientist helping out in any case (one that especially loves the little blinking lights that comes when sensors fail to connect to the network and, believe me, we have seen plenty of those during development!)

Location selection was done using our recently published selection algorithm that maximizes environmental heterogeneity. Hence the higher density of points in the more complex southern half of the region, and in urban centers.

Finally, below a sneak peek of the dashboard where participants will be able to follow the patterns in their own data, and how those compare with the rest of the region (available for participants from April 6th).

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