Biodiversity in Focus: Axel Hochkirch on research, conservation, and responsibility

An interview with biodiversity researcher Prof. Dr. Axel Hochkirch on species action plans, disappearing habitats, and his vision of a nature conservation centre.

Axel Hochkirch is a German biologist specializing in nature conservation and biodiversity. Since February 2023, he has served as Curator of Ecology at the Naturmusée and is also an adjunct professor of biodiversity and conservation at Trier University.

Axel, could you tell us about your career path?

Even as a young boy, I knew I wanted to become a biologist. I was particularly fascinated by birds, reptiles, amphibians, and insects. My dream was to work in the wild one day and help protect animals. At the age of twelve, I joined nature conservation organizations, and after finishing school, I completed my civil service with BUND (Bund für Umwelt und Naturschutz Deutschland). It was there that I first developed a deeper interest in grasshoppers.

My studies then took me to Bremen, where I explored a wide range of species groups – from true bugs and butterflies to dragonflies – supporting myself by preparing ecological impact assessments. During a six-month stay in Tanzania, I gathered data for my diploma thesis, which examined potential conservation measures and habitat preferences of grasshoppers in montane rainforests.

For my doctoral research, I investigated the evolution of grasshopper species in Tanzania and studied the phylogenetic relationships among different genera in mountainous regions.

But why Tanzania?

I was sitting in an Antarctic seminar with a fellow student and wanted to see penguins. But Antarctica seemed a bit too cold for us. So my classmate sketched the outline of Africa and asked me to close my eyes and point to the map with my finger. That’s how we ended up traveling to Tanzania.

After completing my degree, I took up a position as a research assistant in the Department of Ecology at the University of Osnabrück. There, I worked on topics such as the evolution of endemic grasshopper species in the Canary Islands and the role of sexual interactions between different grasshopper species. I also analysed the impact of conservation measures on insects and investigated the spread of grasshopper species in response to climate change.

To support this work, I established microsatellite analysis techniques in the department’s laboratory and taught courses in animal ecology, population ecology, and conservation biology. This ultimately led to my habilitation in ecology at the University of Osnabrück.

Later, I headed the genetic laboratory in the Department of Biogeography at Trier University, where I specialized in genetic methods, managed the lab, and taught courses.

Most recently, in 2023, I took up my position at the MNHNL.

What makes Luxembourg so special to you as a researcher?

Luxembourg may be small, but that is precisely what makes it such a great advantage. I came here to further expand my work in nature conservation, both internationally and at the local level. My goal was to initiate projects specifically aimed at protecting insects, and Luxembourg offered ideal conditions for that. The short distances, close networks, and fast communication make it possible to take decisions quickly and move things forward efficiently.

When I started at the museum, this strong network helped me greatly. Just a few months after my arrival, the Ministry of the Environment launched a call for proposals for projects focused on pollinator protection, and I seized the opportunity to submit an application. The aim was to develop so-called species action plans.

What exactly are species action plans?

These strategic plans are designed to protect endangered species in a targeted way. They set out concrete measures: who is responsible for what, when, and how.

A key factor is that the plans must be realistic and implementable. To ensure this, we organized several workshops in Luxembourg, bringing together a range of stakeholders from the conservation sector – such as SICONA, SIAS, the nature parks, natur&ëmwelt, and the Administration de la nature et des forêts (ANF). Local experts are most familiar with on-the-ground conditions and can therefore make valuable contributions.

Earlier action plans, such as those from the 1970s, often ended up in drawers. Today, we take a different approach: modern action plans establish steering committees that monitor progress and ensure that the measures are indeed carried out.

And these plans are implemented in Luxembourg?

Yes – that’s exactly what makes it so rewarding here. Here’s an example: we had an area that was gradually becoming overgrown with shrubs, which posed a problem for a highly endangered species of hoverfly. Together with colleagues from SICONA and the Administration de la nature et des forêts (ANF), we went straight to the site, assessed the situation, and by the very next day the area had been cleared. In Germany, this process would likely have taken much longer.

This ability to act quickly and implement measures directly is one of Luxembourg’s greatest strengths.

Let’s turn to your fieldwork: what does a typical day look like when you’re out recording species?

That always depends on the species I’m focusing on at the time. With grasshoppers, for example, I systematically survey a defined area. I can use their song to identify them – each species has its own distinctive call, much like birdsong.

For nocturnal moths, I set up what’s known as a “light trap”: a bright lamp that attracts insects, surrounded by a net. In a single night, it’s possible to observe as many as 60–70 species this way. Today, we identify most species using photographs, supported by AI-based tools such as iNaturalist or the Dutch platform  observation.org. where the records are then validated by experts. The verified data are subsequently entered into our species databases. 

What do you do in your free time?

Since 2010, I have been actively involved with the International Union for Conservation of Nature (IUCN), the world’s largest conservation organization. Within the IUCN, I serve as Chair of the Invertebrate Conservation Committee (ICC) and of the Grasshopper Specialist Group within the Species Survival Commission (SSC), the IUCN’s largest membership commission.

I co-founded this specialist group together with Dutch colleagues after realizing that only about 70 of the roughly 30,000 grasshopper species were listed on the IUCN Red List.

What are your future projects in Luxembourg?

My goal is to further strengthen nature conservation in the country. There are plans to establish a nature conservation centre (a kind of “conservation hub”) that would serve as an interface between science and practice. The concept is already quite advanced, and we have discussed it with various stakeholders.

The main objective is to make existing knowledge about endangered species more accessible and to facilitate the implementation of conservation measures. Planned initiatives include a regular “Luxembourg Nature Conservation Day,” shared data platforms, a biodiversity database, and official Red Lists. Although Red Lists compiled by experts already exist, Luxembourg does not yet have official, government-recognized Red Lists. 

In countries such as Germany, there are central institutions like the Bundesamt für Naturschutz, which operate dedicated Red List centres. Luxembourg could take a similar approach – for example, by creating a digital platform that links Red List information with additional data such as species occurrences or existing conservation measures. This would significantly simplify our work.

What are the biggest challenges for biodiversity in Luxembourg?

On the one hand, we are observing the encroachment of shrubs on land, especially on areas that are no longer used for agriculture. Many valuable open habitats are becoming overgrown, which leads to the disappearance of species that depend on open landscapes.

On the other hand, there is increasing intensification of land use on the remaining areas – particularly grasslands. Where species-rich, flower-filled meadows once shaped the landscape, we now mostly find forage grass fields. This is dramatic for many insect species.

In addition, climate change is creating further disruption: heat-loving, Mediterranean species are spreading into the region, while others are disappearing.

These processes reinforce one another, making the protection of biodiversity all the more urgent.

How does climate change affect biodiversity?

In the past, we assumed that climate change would only affect insect species in the long term. Today, however, we can already see that many species dependent on cooler, more humid habitats are disappearing.

But it’s not only about species loss – many new species are also moving in. A striking example is the praying mantis: once rare in Luxembourg, it is now found almost everywhere across the country.

Are some habitats in Luxembourg on the verge of disappearing entirely?

Yes. Two habitats are particularly affected: heathlands and alluvial forests.

In the past, much of the Ösling was characterized by heathland. Today, these areas have disappeared completely, and many specialized moth species, that depended on them, are no longer found.

A similar situation exists with alluvial forests (the natural woodlands along rivers, typically dominated by poplars and willows). Due to river regulation and the hybridization of tree species, many of their characteristic structures have been lost. In particular, the black poplar, an important host species for specialized moths, has become extremely rare.

When landscapes change and new habitats emerge, don’t species losses and gains simply balance each other out?

Not necessarily. What we observe is that newly emerging habitats are often very species-poor. Many studies over the past 20 years point to a clear trend: biotic homogenization. This means that different habitats are becoming increasingly similar. Gardens, agricultural land, forestry – everything is becoming more uniform. And that has serious consequences for biodiversity.

In the past, agricultural landscapes were diverse and structured: fields of peas, maize, potatoes, and other crops alternated, interspersed with hedgerows, field margins, and open tracks. Today, vast monocultures (especially maize and rapeseed) dominate, offering little structural diversity. Even field paths are often paved. Many wildflowers that once thrived on open sandy or loamy soils are disappearing because their habitats are being sealed over.

In addition, such disturbed or heavily altered environments are often colonized by invasive species. So rather than creating “natural” habitats, these changes tend to produce simplified, species-poor areas populated by introduced species.

In short: the species that benefit are usually widespread and highly adaptable. Specialists – rare species with very specific habitat requirements – are gradually disappearing.

What simple measures can anyone take to support biodiversity in Luxembourg?

Quite simply, you can start in your own garden. Instead of planting exotic ornamental shrubs like cherry laurel, opt for native species. Mow less: once or twice a year is often enough. Personally, I use a scythe and don’t cut everything at once, so that flowers remain available for insects.

Small habitat features such as dry stone walls, deadwood, or herb spirals are also very beneficial. Native fruit trees are another excellent choice: they provide both food and habitat. Even a half-dead apple tree can still bear fruit and serve as an important habitat for specialized insects. 

Consumption habits also make a difference. Choosing organic products, supporting regional agriculture, and eating less meat all help – not only local biodiversity but also ecosystems like tropical rainforests. Soy used as animal feed, for instance, is often grown in South America on cleared rainforest land. I myself have been vegetarian for nearly 40 years.

Is there a particular field experience that has stayed with you?

Oh, there are many. Once in Tunisia, I was collecting grasshoppers when a local man gave us a sack of almonds. He thought we were so poor that we were gathering the grasshoppers to eat them!

Or just this morning: a common kingfisher landed almost right next to me. Moments like these happen all the time.

And finally: how can people be inspired to care about nature?

Technology can really help with that. There are some excellent apps – for example  ObsIdentify for identifying fauna and flora, or Merlin Bird ID for recognizing bird calls. People can walk through nature, hear a bird, let the app listen, and instantly learn which species it is. This creates a new way of connecting with nature, especially for younger generations.

Digital tools can therefore act as a gateway, not just a source of detachment.

But most importantly, it still comes down to getting outside and experiencing nature firsthand.

Interview: Diane Bertel

Editors : Monique Kirsch, Selma Weber