Inside Biodiversity

Is biodiversity always declining? Or is the story more complicated? In this special review episode, host Volker Hahn revisits highlights from previous episodes to explore biodiversity change and the biodiversity conservation paradox. Featuring insights from leading researchers, the episode explains why biodiversity trends depend on scale, the metrics we use, and the species we study. It revisits scientific debates, challenges common assumptions, and shows why understanding biodiversity change requires nuance rather than simple narratives.

In this episode, plant ecologists Ute Jandt and Helge Bruelheide explain why a greener planet isn’t necessarily a more diverse one. They discuss global greening, the rise of generalist species, the homogenisation of ecosystems, and how rewilding, forestry, and agriculture can help conserve plant biodiversity in a changing world with podcast host Volker Hahn.

In this episode, Volker Hahn talks to Carlo Rondinini, Professor of Zoology at Sapienza University of Rome, about wolves, beavers, otters, hedgehogs, jackals, and the global fate of mammals. They explore why some species are making remarkable comebacks in Europe, while one quarter of mammals worldwide are at risk of extinction. And although the threats are complex — from habitat loss and overexploitation to climate change — Rondinini says one solution matters more than almost anything else.

Why are insects declining — and what can social media teach us about biodiversity? Entomologist Dr Shawan Chowdhury talks with host Volker Hahn about his research on insect conservation and protected areas, the striking lack of data from tropical regions, and how Facebook, iNaturalist and other platforms can help fill these gaps. Shawan also shares how he uses social media not only as a scientific tool, but as a bridge between research and the public — and why communicating science across cultures matters as much as doing it.

Are insect numbers really declining — and if so, why? In this episode, entomologist Roel van Klink explains what long-term data reveal about global and local insect trends and why the causes behind these changes remain surprisingly uncertain. We also discuss why it is difficult to distinguish between natural fluctuations and human-driven impacts, such as land-use change or climate change. We explore what scientists currently know, what they still don’t know, and why understanding these drivers is crucial for biodiversity conservation.

How can conservation succeed in a polarised society? This episode features Taylor Dotson, a Science and Technology Studies scholar and an associate professor at New Mexico Tech. Together with podcast host Volker Hahn, Dotson discusses his new book, “Conservation by the people – The Future of Biodiversity in a Divided World”. In it, Dotson describes “fanatical confrontations over nature”, and he explores ways of resolving environmental disputes productively and democratically. How can we better understand those who oppose conservation policies? How do we prevent biodiversity policy from becoming as polarising as climate change? How can incremental change through trial and error help us achieve what Dotson calls “biodiversity democracy”?

In this episode, Professor Katrin Böhning-Gaese, scientific director of the Helmholtz Centre for Environmental Research – UFZ, and podcast host Dr. Volker Hahn discuss the Planetary Boundaries framework, focusing not only on the science but also considering the value of this framework for communication. Other questions at the heart of this episode are: Where has communication on climate and biodiversity gone wrong? Is there a tendency to exaggerate risks and understate progress? What are the consequences of catastrophizing rhetoric for mental health and people’s readiness to act? What can biodiversity communication learn from climate communication, and vice versa? Most importantly, how can researchers and the media do better?

In this episode of Inside Biodiversity, Volker Hahn speaks with iDiv's sabbatical guest Miguel Bastos Araújo (Spanish Research Council at the National Museum of Natural Sciences, Madrid), one of the leading experts on species distributions and climate change. Araújo explains how species are shifting their ranges due to climate change, why some traditional protected areas are reaching their limits, and how conservation policy should adapt to a changing climate. The conversation explores how scientific evidence can inform policy and why effective conservation requires navigating multiple, often competing, rationalities. A thought-provoking episode on climate change, biodiversity, and the science-policy interface.

In this episode, Prof. Marten Scheffer from Wageningen University & Research explains critical transitions and tipping points, from shallow lakes and coral reefs to tropical rainforests. Together with host Dr. Volker Hahn, he explores whether local tipping points can be scaled up to a biospheric planetary boundary, and how uncertainty shapes our understanding and communication. Scheffer explains why he believes the concept of tipping points remains relevant for policy and management—even when we do not know where they lie.

Are there tipping points in ecosystems — and if so, can we detect them before the system tips? In this episode of Inside Biodiversity, host Volker Hahn talks with Helmut Hillebrand, professor at the University of Oldenburg and the Helmholtz Institute for Functional Marine Biodiversity, about the science and the politics behind thresholds, regime shifts, and planetary boundaries. Hillebrand says, “Thinking about biodiversity in binary ways, about below and above a threshold, is the wrong way of thinking about how biodiversity works and how we rely on biodiversity.”

Not every species introduced by humans becomes a problem – but some do, especially on islands. In this episode of Inside Biodiversity, invasion biologist Marten Winter (iDiv and Leipzig University) explains how we define alien vs. invasive alien species, why the raccoon is a management challenge for Europe, and why management is particularly tricky in places like Australia. We also discuss the ethical dilemmas of controlling species such as the red fox – and whether it is possible to identify non-native species without knowing their origin.

What should we really aim for in nature conservation—and who gets to decide? In this episode of Inside Biodiversity, science writer Emma Marris challenges long-held ideas about wilderness, ecosystem integrity, and invasive species. She argues that conservation is driven by human values—not objective science—and calls for a more democratic, transparent approach to setting goals for nature. If you’ve ever wondered whether “naturalness” is an illusion or why change in ecosystems isn’t always a loss, this thought-provoking conversation will make you see biodiversity in a whole new light.

Why has biodiversity decreased over the past 20 million years? Why did large mammals, such as giant sloths, tapirs, and mammoths, go extinct at the end of the last ice age, some 50,000 to 10,000 years ago? Why are there many fewer mammal species today than there “should be”? In this episode, we speak with Prof. Susanne Fritz, research group head at iDiv and the Friedrich Schiller University Jena, about biodiversity change over very long time scales. She shares insights into how past extinction events shaped today’s ecosystems — and what that might mean for the future.

While some biodiversity change trends are deeply worrying, such as the decline of common bird species in North America, others offer hope, such as the recovery of rare birds: “I've seen in my lifetime species that were locally extinct come back, and rivers that were dead come back to life,” says Inside Biodiversity guest Henrique Pereira. “And that's because there's been so much positive development from environmental policy in Europe and in other countries in the world.”

Is biodiversity loss always bad? What if cutting down an old-growth forest actually increases the number of species? According to biodiversity researcher Jonathan Chase, “You can have huge levels of biodiversity in habitats that are strongly degraded by people.”

In this episode of Inside Biodiversity, we talk to Andrew Gonzalez about how biodiversity is changing – and how humans are driving this process. Gonzalez discusses shifts in species composition, critiques conclusions drawn from time-series analyses we covered in episode one, and calls for better data to link changes to human impacts. Drawing on climate science, he proposes a “detection and attribution” approach and urges scientists to focus on solutions. A thought-provoking look at the science and communication of biodiversity change.

In this episode of Inside Biodiversity, we look at one of the most controversial questions in biodiversity research: How ubiquitous is biodiversity loss? Our guest, Maria Dornelas, has challenged overly simplistic narratives of how biodiversity is changing. We discuss the current state of knowledge and how best to communicate it. Whether you are a sceptic or an advocate of biodiversity conservation, this conversation will give you new insights into the fascination and complexity of biodiversity change.

Inside Biodiversity invites you to dive into the big and controversial questions shaping biodiversity research today. Subscribe now and get ready to hear from leading experts who are redefining the way we understand our planet, premiering April 3, 2025.