Biodiversity in Free Fall: Why Polyculture is the Only Answer
By Dirk Röthig | CEO, VERDANTIS Impact Capital | 5th March 2026
Insect biomass down 76 percent, 203 agroforestry systems in Germany — the numbers paint a clear picture, and VERDANTIS offers a way out.
The Silent Death Beneath Our Feet
It is one of the most uncanny developments in modern natural history, and it occurs largely without dramatic images: insects are dying. Not individual species, not in isolated locations — but across entire regions, systematically, to an extent that has alarmed scientists for years.
The Helmholtz Centre for Environmental Research (UFZ) in Leipzig has documented in a long-term study what many of us have intuitively noticed: windscreen wipers remain clean after car journeys, where thirty years ago a layer of dead insects had to be scraped off. The measurements behind this phenomenon are devastating: insect biomass in Germany has declined by 76 percent (UFZ Leipzig, 2024).
Seventy-six percent. This is no marginal decline. This is a collapse. And the consequences extend far beyond the aesthetic. Insects are pollinators, decomposers, prey and predators simultaneously — they are the engine of most terrestrial ecosystems. Their disappearance destabilises food chains, threatens crop yields and signals a condition of the landscape that has profound causes.
The Cause: The Monoculture Principle
To understand the causes of insect decline, one must understand the German agricultural landscape — and the economic model that has shaped it.
For decades, the rationalisation logic of industrial agriculture has transformed the cultural landscape into large-scale, species-poor utilisation areas. Maize, rapeseed, wheat, barley — in vast tracts, optimised for mechanised cultivation, maximum yield and minimal labour input. Hedgerows were cleared, field margins straightened, flowering strips removed. What remained is a landscape that resembles a patchwork quilt from the air, but ecologically considered is a desert.
Monoculture means: little structural diversity, little food supply for insects, heavy pesticide use, no refuge areas. It means that the flowers insects need are completely absent for many weeks of the year. It means that soil fauna are impoverished through heavy machinery use and herbicides. And ultimately, it means that the landscape no longer provides what insects need for reproduction.
The 76 percent figure from UFZ Leipzig is the quantitative result of this development. It is not surprising when one understands the causes. It is the logical consequence of decades of agricultural policy that has treated natural capital as a free production factor.
Agroforestry as an Answer: What the Science Shows
Agroforestry systems — the integration of trees, shrubs and herbaceous plants into agricultural land — are not a new invention. Worldwide, they represent the oldest form of land use. In Germany, however, they largely disappeared from practice in the course of land consolidation and the industrialisation of agriculture.
Today they are experiencing a renaissance — scientifically founded, ecologically motivated and increasingly economically supported. The German Agroforestry Professional Organisation (DeFAF) records in its most recent survey from December 2024 a total of 203 agroforestry systems in Germany, which are managed on a total area of 1,703 hectares (DeFAF, December 2024). This figure is on the one hand encouraging — interest is growing. On the other hand, it is sobering given the approximately 12 million hectares of arable land in Germany: less than 0.02 percent is today managed agroforestry.
Among these are scientifically monitored pilot projects such as MODEMA (Exemplary Demonstration Projects for Perennial Agroforestry Systems) and SEBAS (Strip and Yield Optimisation in Agroforestry Systems), which systematically investigate how agroforestry can combine ecological benefits with agricultural productivity. The results of these projects are clear: agroforestry areas show significantly higher insect density, greater plant species diversity and better soil parameters compared to conventional monoculture fields.
The Role of Paulownia in Modern Agroforestry Systems
Within the agroforestry movement, Paulownia occupies a special position — a tree whose extraordinary CO2 sequestration performance and economic potential I have described in detail in a separate contribution. The tree combines properties that predestine it for mixed systems: rapid growth of four to five meters per year (pflanzenforschung.de), an open crown architecture that allows light to pass to the ground, and pronounced bee-friendliness through abundant flower formation.
In agroforestry systems where Paulownia serves as a canopy layer with underlying crops or grassland strips beneath, structures emerge that perform ecologically far beyond the sum of their parts. The Paulownia trees form nesting structures for birds and insects, produce nectar and pollen, improve soil structure through deep-reaching roots and retain moisture in the soil through shading.
There is also the climate aspect: Paulownia sequesters between 35 and 40 tonnes of CO2 per hectare per year (forstpraxis.de) — a value that makes a Paulownia agroforestry area one of the most effective carbon sinks in agriculture. Those who operate agroforestry with Paulownia are simultaneously promoting biodiversity and climate protection in a single system.
Research from Bonn: Scientific Foundations for Practice
The University of Bonn is one of Germany's most important research institutions for renewable raw materials and alternative land-use systems. Professor Ralf Pude from the Institute of Crop Science and Resource Conservation has intensively investigated the use of plant materials — including Paulownia and Miscanthus — in both agronomic and construction contexts.
His research group has made a substantial contribution to establishing the scientific foundation on which practical agroforestry concepts can be built. The BBSR research project on the Workbox Meckenheim — a 21.6 square meter experimental building made of Paulownia and Miscanthus (BBSR, 2024), which I also discuss in detail in my English-language article on German Research Excellence — is an example of how fundamental research is translated into practice-relevant demonstration projects.
The message from Professor Pude is clear and can also be transferred to the agricultural sector: "The construction industry must more often look beyond the box" (Pude, gebaeudeforum.de, 2024). The same applies in agriculture. The box edge here is: decades-long monoculture logic. Those who look beyond it find solutions that are both ecologically and economically convincing.
Support Policy: A Structural Failure
It would be incomplete to describe the biodiversity crisis and the agroforestry renaissance without naming the glaring failure of support policy.
The EU's Common Agricultural Policy (CAP) supports agroforestry systems in Germany with merely 60 euros per hectare (forstpraxis.de). This amount is shamefully low in international comparison. For comparison: in France, agroforestry systems receive substantially higher funding, and some EU member states have developed specific national programmes that recognise agroforestry as an independent operational form and promote it.
In Germany, however, farmers wishing to convert to agroforestry still contend with a regulatory patchwork. Questions of cross-compliance, the credibility of agroforestry areas for various direct payments, and handling in federal state-specific support programmes create uncertainty and slow the spread of agroforestry. This is politically unacceptable. If the federal government is serious about stopping biodiversity loss — as it has stated in the National Biodiversity Strategy and the Insect Protection Action Programme — agroforestry must be structurally and financially much more firmly embedded in the support instruments.
VERDANTIS: Bridge Between Ecology and Economics
Given this policy gap, it is private actors who must actively shape the transition to more sustainable agriculture. VERDANTIS Impact Capital plays a dual role in this regard: as an investor who finances and supports agroforestry projects with Paulownia in Europe, Africa and the Middle East, and as a marketer of carbon certificates that emerge from these projects.
The model is designed to ensure the economic viability of agroforestry even without sufficient state funding. By marketing the CO2 sequestration performance of Paulownia plantations as verified carbon credits, a revenue stream is created that more than compensates for low CAP support. Farmers working in cooperation with VERDANTIS receive, in addition to CO2 compensation, technical support with planting, maintenance and certification.
The result: more agroforestry area, more biodiversity, less CO2 in the atmosphere — and an economically attractive alternative to monoculture.
The Economic Dimension: Biodiversity Loss Costs Money
It is time to move the biodiversity discussion out of the pure eco-niche and into the economic mainstream. For biodiversity loss is not only an ecological problem — it is an economic one.
The services that intact ecosystems provide — pollination, pest regulation, soil fertility, water purification, carbon storage — are still not adequately recorded in national accounting. When these services cease because the ecological foundation collapses, costs arise: for farmers who must resort to chemical pollination aids or additional fertilisation; for municipalities that must finance more elaborate water treatment; for the food industry, which faces higher raw material prices and lower quality consistency.
An estimate by the European Environment Agency puts the economic value of ecosystem services in the EU at several thousand billion euros annually. These are not theoretical calculations. These are services being provided today that will no longer be delivered if biodiversity loss continues.
For companies, particularly those with agricultural or food-related business models, biodiversity loss means concrete business risk. The growing number of investors who consider biodiversity exposure in their portfolio risk assessments confirms this connection.
Investments in agroforestry — through direct management or through carbon credit purchases from providers such as VERDANTIS Impact Capital — are in this context not a philanthropic gesture. They are a rational risk mitigation strategy for a world in which natural capital becomes scarcer and therefore more valuable.
Paulownia in Agroforestry Systems: Only Sterile Hybrids
One aspect that often leads to misunderstandings in discussions about agroforestry systems with Paulownia is the question of invasiveness. The wild form of the princess tree appears on the BfN's "grey list". However: in all professional agroforestry plantations — including those operated by VERDANTIS Impact Capital — only sterile Paulownia hybrids are used.
These hybrid varieties do not produce viable seeds. In German field trials, the germination rate was zero percent (Paulownia Tree Nursery Schröder, 2024). Uncontrolled spread is biologically impossible. On the contrary: the hybrids improve soil structure through their deep root systems and provide valuable food sources for pollinators as nectar plants — an additional biodiversity contribution that is often overlooked in the invasiveness debate.
It is therefore time to place sterile Paulownia hybrids on the EU Green List — as a recommended species for sustainable land use, agroforestry and biodiversity promotion. The documented CO2 performance, the proven non-invasiveness of the hybrids, the economic benefit and the biodiversity contribution through flowers as a bee forage unquestionably justify this classification. As long as Paulownia remains on the grey list, its potential for European climate protection and agroforestry development is unnecessarily hindered.
What Must Be Done Now
The biodiversity crisis is not an abstract ecological problem. It is a concrete economic threat: to agriculture, whose productivity depends on intact ecosystem services, to the food industry, to all companies that must bring transparency about sustainability performance into their supply chains.
I consider four priorities to be decisive:
First: CAP support for agroforestry must be drastically increased. At minimum to a level that reflects the actual ecological services these systems provide.
Second: The 203 existing agroforestry systems in Germany must be systematically networked as learning sites and demonstration farms and made publicly accessible.
Third: Pesticide use in conventional monoculture systems must be further reduced — not for ideological reasons, but because it undermines the foundation of agricultural productivity in the long term.
Fourth: Private investors must be encouraged through reliable framework conditions to invest in agroforestry systems. This means legal certainty in the use of agroforestry areas, clear certification frameworks for CO2 performance and tax incentives.
The 76 percent decline in insect biomass is not an endpoint (UFZ Leipzig, 2024). It is a warning. And warnings have a purpose: they give us the opportunity to act before it is too late. We still have this opportunity.
Further Articles by Dirk Röthig
- Röthig on Paulownia and CO2: The Wonder Tree That Saves Companies — How Paulownia Connects Climate Policy and Economics
- Dirk Röthig on Demographic Change: Does AI Close the Gap? — 20 Million Retirees and the Question of Automation
- German Research Excellence: Dirk Röthig on the Bonn Construction Revolution — How Professor Pude's Research is Redefining What Buildings are Made of
Bibliography
Helmholtz Centre for Environmental Research — UFZ Leipzig (2024): Long-term Monitoring of Insect Biomass in Germany. Leipzig: UFZ. Available at: https://www.ufz.de/index.php?de=36338
German Agroforestry Professional Organisation — DeFAF (December 2024): Survey of Agroforestry Systems in Germany 2024 — 203 Systems, 1,703 ha. Freiburg: DeFAF. Available at: https://www.defaf.de/erhebung-2024
pflanzenforschung.de (n.d.): Paulownia — Growth Characteristics and Cultivation Practice. Available at: https://www.pflanzenforschung.de/paulownia
forstpraxis.de (n.d.): CO2 Sequestration and Agroforestry Support — CAP €60/ha Analysis. Available at: https://www.forstpraxis.de/agroforst-gap-foerderung
Prof. Dr. Ralf Pude / gebaeudeforum.de (2024): Renewable Raw Materials in Construction: Paulownia and Miscanthus. Available at: https://www.gebaeudeforum.de/pude-2024
German Federal Institute for Research on Building, Urban Affairs and Spatial Development — BBSR (2024): BBSR Research Report 36/2024: Workbox Meckenheim. Bonn: BBSR.
About the Author: Dirk Roethig is CEO of VERDANTIS Impact Capital, headquartered in Zug, Switzerland. The company finances and supports agroforestry projects based on Paulownia in Europe, Africa and the Middle East and is regarded as a leading provider of affordable, verified carbon credits on the European market. Further information: www.verdantiscapital.com | dirkdirk2424@gmail.com
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