500 species

Posted on May 13, 2026 by lembrechtsjonas

Last week, I spent a few days just outside of Barcelona for a PhD defence. Perfect timing, I thought, to finally cross the magical boundary of 500 unique species on iNaturalist. I had been hovering just below it for a while, and to me, that number always felt like the line between a casual observer and a slightly more committed enthusiast.

The magic boundary of 500 species on iNaturalist so easily crossed

Now, oh boy, was that easy.

Just a small walk – about an hour – from the train station to the campus, and the boundary was crossed, and then some: 45 new species added to my list. Of course, finding new species is always easier when visiting a new place. But there was something else going on too. The landscape was just that little bit… messy.

Agriculture, but messy – a landscape with room for a lot of biodiversity hidden in the verges, forest edges, shrubberies and the fields themselves.

A kind of messiness that has become unfortunately rare in the Netherlands, yet is so important for biodiversity.

It was farmland, but farmland filled with corners, slopes, edges, shrubs, trees, and tiny neglected patches where wildflowers could persist. The borders between “field” and “nature” were blurry. And those blurry borders were full of life.

That kind of landscape heterogeneity is harder to find in the Netherlands nowadays. Partly because we simply lack the topographic variation of places like Barcelona, where a gradient from a dry hilltop to a wet valley can create many different habitats within a short distance. But also because our landscapes have become increasingly optimized and tidy over time. Fields are cleaner, straighter, and more intensively managed. The small irregularities that once created space for biodiversity have often disappeared.

In the fields outside of Barcelona, it was often unclear where the field ended and the border begun, and plants loved that vagueness!

And when bits of semi-natural vegetation do remain, they are frequently affected by excess nitrogen deposition. Many of these places become dominated by a few highly competitive species – brambles, nettles, coarse grasses – leaving less room for the wide variety of plants that once characterized them.

Walking there made me realize how much I miss that ecological messiness in the Netherlands. Because these messy landscapes create opportunities for iNaturalist enthusiasts trying to reach arbitrary milestones, of course, but more importantly: because they create opportunity for plants, insects, birds and nature to thrive.

Until then, I suppose I’ll keep boosting my species list elsewhere.

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Mountain road microclimate

Posted on April 28, 2026 by lembrechtsjonas

This is a massively important paper. At least for me.

It brings together the work I’ve been doing in the Mountain Invasion Research Network and the Microclimate Ecology & Biogeography Network. And it finally answers one of the key research questions I was left with at the end of my PhD, back in the good old days of 2018.

During my PhD, I studied plant species distributions along mountain roads. That gradually pulled me into the world of microclimate, which seemed to be one of the core mechanisms shaping where mountain plant species can and cannot occur. One of my hypotheses – supported by experimental data from my PhD – was that roadsides create warmer microclimates, potentially allowing lowland plant species to move higher into the mountains.

A reasonable hypothesis, of course, and one we brought up in many papers since. But we still had to test it.So we started installing sensors along mountain roadsides across the network. But somewhere along the way, I got distracted. I started wondering: why limit ourselves to mountain roadsides? Microclimate is crucial everywhere. That eventually led to building SoilTemp, and later the MEB network.

Mountain roadsides are on average substantially warmer than the adjacent vegetation (here: Norway)

Yet the roadside sensors stayed there, and the data accumulated.

Eventually, we retrieved the data and slowly started making sense of it. I worked on it on the side for quite a while, until others joined in and really helped push it forward (Renee and Eduardo – thank you!). And now, after all those years, the results are finally published.

And boy, are they worth it! We observed on average a 1°C shift in mean annual temperature in roadsides as compared with the adjacent vegetation 50 m away from the road. That – and that’s quite mind-boggling – corresponds to more than 200 m of elevational displacement of the temperature regime (as we found a 0.45 degree Celsius elevational lapse rate). That means that plants could find similar average temperatures 200 m higher on the mountain in these roadsides – likely quite helpful with the observed upward movements of both non-native and native species.

Elevational trends in roadside (red) and adjacent vegetation (turquoise) temperatures across all studied regions.

While we observed significant variation in these trends between regions, we especially found strong evidence for warmer annual maxima and summer mean soil temperatures along roadsides compared to the adjacent vegetation, and lower annual minima and mean winter soil temperatures on roadsides at high elevations. Overall, the results suggest that roadside microclimates are much more tightly coupled to macroclimatic fluctuations than nearby natural vegetation. In contrast, intact vegetation appears to buffer temperature extremes, making those systems less directly exposed to broader climatic variation.

Another interesting pattern emerged in winter. Temperature differences between roadsides and adjacent vegetation likely reflect differences in snow cover and snow depth. Roads are often cleared of snow, while adjacent vegetation can accumulate deeper snowpacks through wind redistribution or ploughing. At higher elevations, where snow persists longer, those differences may become especially important.

So after years of assumptions, hypotheses, and scattered observations, the numbers are finally there: mountain roadsides substantially alter microclimatic conditions, often creating much more extreme thermal environments than the surrounding vegetation. Now comes the next step: testing whether those altered microclimates are indeed driving changes in species distributions.

Reference: Lejeune, R., E.Fuentes-Lillo, & Lembrechts, J.J. (2026). Mountain Roads Across the Globe Significantly Alter Local Soil Thermal Microclimates. Global Ecology and Biogeography 35, no. 4: e70237.

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The living farm

Posted on April 21, 2026 by lembrechtsjonas

Last week, we properly kicked off the fieldwork season. Under a bright April sun, we made our way to ‘De Boeije’ – a cosy, somewhat hidden farm right on our own campus at Utrecht Science Park.

‘De Boeije’ and its golden seas of dandelions on a sunny April day

I’m not sure how many of the thousands of people passing through the campus know about this little gem, but it’s well worth a lunchtime walk to the southwest corner on a sunny day.

This time, though, we were there for more than just a walk. We’re monitoring biodiversity as part of our global Ecological Fractal Network. Across the site, we sample vegetation in 1 × 1 m plots at multiple spatial scales to understand how biodiversity is distributed – and, crucially, how it can be maximized across those scales.

Vegetation monitoring. This field harvested around eight plant species per square meter

This hidden farm is one of the project’s flagship sites. Here, we are not just observing change, we are actively helping to shape it. De Boeije has been made into a Living Lab as part of Utrecht University’s Pathways to Sustainability. Within this Living Lab, we’ll collaborate with a wide range of stakeholders – from farmers and neighbours to schools and scientists – to experiment with more biodiverse and sustainable forms of agriculture.

Funny thing: we were already monitoring biodiversity here, and that monitoring has now neatly turned into the monitoring of baseline conditions, before these changes will take place. As the photos show, the farm is already relatively low-intensity, but we expect (and hope) to see further substantial improvements in the coming years.

And when those changes happen, we’ll be there to quantify them!

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Finding refuge on the Canaries

Posted on April 16, 2026 by lembrechtsjonas

Microrefugia. It’s a tempting concept, and one that has quickly moved from theory to the frontline of conservation. As climates warm, these small, buffered places may allow species to persist where they otherwise couldn’t.

So, that’s simple enough: find the cold spots, and you find the refuges. But it’s not that simple.

Most approaches still start from macroclimate: where is it getting warmer, and where might conditions remain suitable? But species don’t experience climate at the scale of weather stations. They experience it at the scale of meters – shaped by topography, vegetation, and local conditions. Even where macroclimate suggests decline, microhabitats can buffer change, creating pockets where species may still persist.

So how do you actually find those places?

Lanzarote, one of the drier Canary Islands. Are there any microrefugia here?

That’s exactly what we tried to tackle in a new paper coming out of the PhD work of Juan Jose García-Alvarado.

From cold spots to real refuges

In this study, we tried to move beyond simply mapping “cool places” and instead asked ourselves:

Where are species most likely to persist?

Rather than treating refugia as fixed features, we defined a probability of refugial function. This combines climate change with ecological context, shifting from binary maps to gradients — some places are simply more likely to act as refuges than others.

We tested this approach in a landscape that almost feels designed for it: the Canary Islands. Steep gradients, strong contrasts, and a remarkable diversity of climates over short distances. A perfect playground for microrefugia and the better holiday experience.

The climate component of our approach was defined a bit differently than usual. Instead of asking where climate remains suitable, we used climate analogues to track how conditions shift over time. By comparing present and future climates, we identified where climates are projected to disappear, and where future climates already exist today but may become rare. This allowed us to pinpoint locations that retain rare or disappearing climate conditions – key candidates for refugia.

We then added fine-scale environmental predictors (terrain, moisture, exposure, and vegetation) to capture how landscapes can buffer these changes. Because ultimately, refugia don’t emerge from climate alone, but from how climate interacts with the landscape.

After doing all that, what I find most fascinating is how strongly these microrefugia vary across space.

Across the Canary Islands, we see a clear east–west gradient. On the drier, older eastern islands, microrefugia are mostly driven by topography: rugged terrain creating local pockets of buffering. These islands were also more homogeneous climatically, and overall have a lower capacity to host refugia. Not surprisingly, perhaps, if you look at the desert-like landscape above.

Moving west, vegetation becomes increasingly important, adding a much stronger layer of buffering on top of topography. Same concept, very different mechanisms, and thus very different context for the organisms living there!

Once you have these maps, the next question asks itself: what can we do with them?

We explored this for La Palma, for example. Are these refugia already protected? Where should conservation efforts focus? The answer is… interesting, and helps open up a debate for future conservation of the region: some key refugial areas fall outside the current protected network, particularly in fragmented laurel forests and regions under strong human pressure. At the same time, there are clear opportunities to improve connectivity and strengthen the existing network – if we know where to look.

Our maps are a step forward, but of course not the final answer. Identifying refugia is only part of the story – linking them to species, management, and real-world decisions remains a major challenge.

But it’s an important step already: from mapping cold places to the multidimensionality of what defines where landscapes can actually hold on to life.


Reference: García‐Alvarado, J. J., Bello‐Rodríguez, V., Lembrechts, J. J., & González‐Mancebo, J. M. (2026). Designing a Spatial Framework to Create Refugia‐Probability Maps for Conservation Planning: Applications in the Canary Islands. Diversity and Distributions, 32(2), e70146.

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INNATURE: Building biodiversity and belonging in urban spaces

Posted on March 12, 2026 by lembrechtsjonas

By Olivia van der Weiden

Over the past months, we’ve been working hard on the preparations for INNATURE, an EU-funded project on nature based solutions in urban areas. The mission of this project is straightforward: co-create nature-based solutions to promote both biodiversity and social inclusion in Europe’s urban living spaces.

What makes INNATURE unique is how many people with different backgrounds are included.

Local communities, researchers, artists, designers, policy-makers, and ecologists all share their knowledge and perspectives. Combining all these strengths, we aim to provide sustainable, beautiful, and inclusive solutions in order to help cities respond to climate change and strengthen people’s connection to nature close to home. A complex web of voices and opinions to navigate, but – we hypothesize – resulting in more robust and beneficial solutions at the end.

Five locations, five stories

We’re trying out this co-creation experiment through five demonstration cases across Europe: Belgium, the UK, Denmark, Finland, and Romania. Each case faces its own ecological challenges.

The demo case of Borgerhout, a city investing a lot in urban greening

Some of the cases focus on climate change-induced effects, such as stormwater floods or droughts, while others tackle biodiversity loss, for example, supporting endangered species whose habitats are disappearing. But ecological challenges rarely come alone. In several of the cases, people feel disconnected from nature. We see things like landscape blindness (not noticing the nature that is there) and the loss of local knowledge, such as how rainwater can be captured and used wisely. Tackling the biodiversity loss thus needs to come as much from ecological decisions as from social action.

Each different case requires widely different nature-based solutions, reflecting the complexity and uniqueness of our urban areas. Across the demonstration cases, interventions range from greenifying streets, to planting zigzag clover to support an endangered moth, to vertical storm management, storing floodwater in aboveground measures. While some cases already have a clear plan and focus, others are still brainstorming options and are defining what they want to achieve.

Preparations: more than choosing solutions

Greening the city needs to start small, but can create a beautiful ripple effect if implemented well

But planning nature-based solutions is not only about deciding what you want to implement. It is also about agreeing on:

  • When to implement
  • Where exactly implementations will take place
  • How we will measure whether they work

That’s also where monitoring enters the picture, and that’s exactly where we take the wheel.

Monitoring

In most of the cases, there are two phases you go through when monitoring:

  • Baseline monitoring before implementation (what is the situation right now?)
  • Follow-up monitoring after implementation (what has changed?)

To know if these changes were indeed the effect of the interventions, you also need comparison areas:

  • A negative control site: a similar area where nothing changes, and/or
  • A positive control site: an area that already has the conditions we want to achieve

Part of the preparation work has been to map these control sites, but it’s also about deciding what we measure there. Across all cases, monitoring microclimate (both local temperature and humidity) is the main focus of interest, together with monitoring biodiversity (plants, insects), and sometimes soil health. While microclimate can be measured using sensors and soil health with soil samples, for biodiversity monitoring we need people, and that’s when social engagement becomes important.

Social engagement: turning monitoring into participation

INNATURE is not only about the ecological side: it’s also about making the local community feel involved and engaged with the nature in their surroundings. That’s why we have been carefully thinking about how monitoring can become a moment of connection.

In these cases, residents will be involved in measuring microclimate in these implementation and control sites, and in several cases also in backyards, with results visible on a digital platform. By seeing data change over time, such as seeing their own street getting cooler after greening, the impact becomes more tangible.

Simultaneously, this platform also supports biodiversity registration, not only during events like a bioblitz (where people try to document as many species as possible in a certain area), but also over the longer term. One idea we’re exploring is gamification: using gaming elements, such as receiving points when you register five species, to make participation fun and motivating. In this way, residents can become aware of the actual biodiversity that their neighbourhood harbours. They get curious about it, learn what species are called, and see it as something they care for.

Beyond microclimate and biodiversity, this platform could also become a space where people share experiences and observations about their neighbourhood, such as highlighting beautiful locations or reporting fly-tipping. In this way, the project can support nature stewardship and strengthen the feeling that urban nature is something shared and protected together.

So, what’s next?

Preparations: there’s more to it than you first see. We have our hands full with ordering sensors, meetings with each case to co-create and fine-tune our plans, and preparing upcoming site visits where sensors will be placed and monitoring will begin.

With five demonstration cases running in parallel, coordination is a project in itself, but it’s also one of the fun parts. With each case being unique and contributing its own insights, together they build a broader understanding of how nature-based solutions can support both biodiversity and belonging in the spaces where we live.

– To be continued! –

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Where the soundscape is pleasant

Posted on March 11, 2026 by lembrechtsjonas

So, where in Flanders does it still sound nice?

A simple question, perhaps. But one for which the data has long remained elusive. Sound is a complex, multi-dimensional beast, and capturing how people actually experience it is not straightforward.

In a new paper stemming from De Oorzaak and led by Ablenya Barros, we now take a stab at answering that question. We asked close to 4000 citizens across Flanders to take a short walk outside, listen closely, and report how they perceived the soundscape around them, including which sound sources they heard.

Pretty simple, right?

Set-up of the paper, from soundwalks over machine learning models to key findings about the role of roads and green spaces.

For participants it took only a few minutes, but the resulting dataset is a gift that keeps on giving. In this newest paper, we threw a machine-learning model at the data to disentangle the spatiotemporal context behind people’s perception: why do some places and moments sound pleasant, while others do not?

Spatial distribution of our soundwalks across Flanders, with each observation coloured by the perceived ‘pleasantness’ as reported by the participant. The map itself is coloured by population density.

In essence, we ran two analyses.

The first focused on the role of sound sources in defining two key soundscape metrics: pleasantness and eventfulness (the official descriptors used in soundscape research). As expected – and consistent with earlier work – these models performed quite well. Pleasantness correlated strongly and negatively with traffic, industry, construction noise, alarms, and priority vehicles. On the positive side, natural sounds and silence clearly improved perceived pleasantness. Human sounds and music were more divisive: a little can be enjoyable, but a lot of either was often perceived as unpleasant.

The relationship between reported sound sources and perceived pleasantness, coloured by the relationship.

The second analysis looked at the geospatial context of these soundscape experiences. This is where the real novelty lies, because it helps us identify where problems occur and which spatial factors might help solve them.

These models were less predictive than the first ones, which makes sense. It has shown to be much easier to link people’s subjective soundscape experience to the sound sources they report themselves than to the messy complexity of the real world. Still, similar patterns emerged. Proxies of traffic, such as road network density and distance to highways, explained a large portion of the variation in soundscape experience. Meanwhile, a higher percentage of green space in the surrounding area increased perceived pleasantness.

Interestingly, road density and nearby green space also influenced eventfulness. More nature and fewer roads generally resulted in a less eventful environment – and those quieter environments were typically perceived as more pleasant. One could think that eventfulness would be appreciated as well, but in general, we’re all really looking for the sound of ‘boring, quite nature’.

Where the sound is pleasant

Putting all this together allows us to do something pretty cool: predict where in Flanders soundscapes are likely to be most pleasant.

The role of nature is clearly crucial. More green space within a 500-metre radius around you significantly improves the soundscape experience. But there is an important catch: if that same 500-metre buffer is filled with roads, the positive effect of green space essentially disappears, as shown in the figure below.

Pleasantness (colours) as a function of the ratio not green and the length of the road network within a 500 m area. Green was beneficial (yellow), but only in areas with few roads.

So yes – green helps. But only when it is sufficiently far from road traffic.

Again and again we thus see the disruptive effect of traffic on our soundscapes. But we also repeatedly see the positive role of greenery – even if it often struggles to compete with the dominance of traffic noise.

Clearly, there is still work to be done to improve our soundscapes. Luckily, we have not only identified the problems but also proposed solutions. Recently, we published the 200-page final report of De Oorzaak (in Dutch, unfortunately). It contains an extensive section with policy advice and recommendations on how to create healthier and more pleasant soundscapes across Flanders.

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