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Dirk Röthig (international: Dirk Roethig) — CEO of VERDANTIS Impact Capital. Focused on sustainable investments in paulownia agroforestry and clean energy across Europe. dirkroethig.com
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Dirk Röthig
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By Dirk Roethig | CEO, VERDANTIS Impact Capital | March 10, 2026
Theory is one thing. Practice is another. Dirk Roethig analyzes real yield data from German Paulownia pilot plantations over five management years — with sterilized hybrids, documented biomass performance, and measurable CO2 sequestration. A data-driven report on what Paulownia actually delivers in Central Europe.
Paulownia originates in East Asia. The research data on growth performance and biomass yields come predominantly from China, Turkey, Southern Europe, and Southeast Asia — regions with longer growing seasons, higher average temperatures, and different precipitation patterns than Central Europe.
Dirk Roethig is familiar with the skepticism that arises among German farmers and investors when Paulownia's performance is discussed: "Everyone knows that a tree grows differently in Spain than along the Lower Rhine. The question investors ask me is therefore never: What can Paulownia do in theory? Rather: What does Paulownia actually deliver on German soil, under German weather conditions, over multiple years?"
To answer this question, VERDANTIS Impact Capital has operated pilot plantations in Germany in close cooperation with regional partners and systematically documented the results over five years. The data complement the published research literature and provide a practice-oriented foundation for investment decisions.
The pilot plantations were operated at three sites in North Rhine-Westphalia and Lower Saxony — regions representing typical Central European climate conditions: mean annual temperatures of 9.5 to 10.5 degrees Celsius, annual precipitation of 700 to 850 mm, and 160 to 180 frost-free days per year.
The practical reference comes from Stefan Bonsels of Neukirchen-Vluyn (NRW), who has been managing a 5-hectare plantation with 600 to 700 trees per hectare since May 2021 (agrarheute.com). Bonsels' experiences confirm what the VERDANTIS data also show: Paulownia grows in Germany — not as fast as in Turkey, but significantly faster than any native tree species.
Dirk Roethig explains the experimental design: "We exclusively used sterilized Paulownia hybrids — winter-hardy to -20 to -25 degrees Celsius, documented germination rate of zero percent in open-field trials (Paulownia Baumschule Schroeder, 2024). Planting took place in mid-May after the Ice Saints, with a spacing of 3x4 meters, corresponding to a density of approximately 830 trees per hectare."
The first year of a Paulownia plantation is critical. The young plants — typically planted out as seedlings at 30 to 50 cm height — must establish their root system before they can develop the rapid growth typical of Paulownia in the following year.
The VERDANTIS pilot data show for the first year:
Dirk Roethig puts this in perspective: "The first year is an investment phase. The trees establish themselves, the root system grows, aboveground biomass is still moderate. But anyone who judges after the first year misjudges the dynamics of Paulownia. The real growth begins from year two."
The survival rate of 92 to 96 percent is in line with international literature. Jakubowski (2022) documents establishment rates of 85 to 98 percent, depending on clone variety, site, and management practices (Jakubowski, 2022). VERDANTIS employs a proactive replanting strategy: failures are identified in the autumn of the first year and replaced in the spring of the second year.
From the second year, Paulownia displays the growth pattern that makes this tree an exceptional species. The established root system now delivers the nutrients and water that enable the explosive aboveground growth.
The VERDANTIS pilot data for year 2:
These values align with the findings of Jakubowski (2022), who documents dry biomass yields of 1.5 to 14 t ha-1 as early as the second cultivation year — with significant differences depending on clone variety (Jakubowski, 2022). The VERDANTIS hybrids fall in the middle to upper range of this bandwidth.
Dirk Roethig comments: "3.5 meters of height growth in a single growing season — that is ten times faster than an oak and three times faster than a spruce. These figures are not marketing. They come from controlled measurements in North Rhine-Westphalia, under German weather, on German soil."
In years three to five, growth shifts from height to volume. The trunk gains in diameter, the crown closes, and CO2 sequestration capacity reaches its performance plateau.
The VERDANTIS pilot data for years 3 to 5:
| Parameter | Year 3 | Year 4 | Year 5 |
| Average height (m) | 7.0–8.5 | 9.0–10.5 | 10.5–12.0 |
| Stem diameter DBH (cm) | 15–20 | 20–26 | 24–30 |
| Dry biomass (t ha-1) | 8.0–12.0 | 12.0–18.0 | 16.0–22.0 |
| Cumulative CO2 sequestration (t ha-1) | 30–45 | 50–75 | 72–105 |
After five years, a VERDANTIS Paulownia plantation under Central European conditions has cumulatively sequestered between 72 and 105 tonnes of CO2 per hectare. This corresponds to an average annual sequestration rate of 14.4 to 21.0 tonnes of CO2 per hectare — a value that confirms the scientific literature.
Joshi and Pant (2026) document a sequestration rate of 5.87 tC ha-1 yr-1, which converts to approximately 21.5 t CO2 ha-1 yr-1 (Joshi and Pant, 2026). The VERDANTIS pilot data demonstrate that these rates are achievable in Central Europe as well — at the upper end in good years, at the lower end in dry years.
Dirk Roethig summarizes: "Five years of data from Germany confirm what international research shows. Paulownia hybrids sequester 14 to 21 tonnes of CO2 per hectare per year in Central Europe. Conservatively estimated, that is double the rate of spruce and triple that of oak. And these data do not come from a laboratory — they come from practice."
In short rotation coppicing (SRC), Paulownia trees are cut back to the stump in cycles of 5 to 8 years. The distinctive feature of Paulownia: the tree resprouts from the rootstock and grows even faster in the second cycle because the established root system immediately delivers nutrients.
A study published in Forest Ecology and Management (2025) on height growth and volume production models for short-rotation Paulownia plantations confirms: Annual biomass production ranges from 0.5 to 25.4 odt ha-1 yr-1 over ten years, with an interquartile range of 0.8 to 9.9 odt ha-1 yr-1 (Forest Ecology and Management, 2025).
Dirk Roethig offers both strategies through VERDANTIS Impact Capital:
Short Rotation (5–8 years): Maximum biomass production per unit of time. The wood is used for biochar, biomass energy, and lower-value wood products. Carbon credits accrue earlier. Ideal for farmers seeking rapid cash flows.
High-Value Timber Production (10–15 years): Longer rotation, thicker trunks, higher timber price (800–1,800 EUR/m3). The premium timber goes to the building industry, furniture production, and boatbuilding. The stored carbon remains fixed for the product's service life. Ideal for investors with a long-term horizon.
"Short rotation is the sprint; high-value timber production is the marathon," explains Dirk Roethig. "At VERDANTIS, we recommend the optimal strategy depending on site, funding conditions, and investor profile — or a combination of both across different plots."
Dirk Roethig presents the economic figures after five years — based on the real data from the VERDANTIS pilot plantations.
Costs (5 years, per hectare):
Revenue (5 years, per hectare):
Standing Asset Value (Year 5):
"After five years, the plantation has not yet reached payback — that was never the plan," explains Dirk Roethig. "Payback comes with the harvest in years 8 to 10, when the high-value timber is sold. Until then, the recurring revenue from subsidies and carbon credits largely covers operating costs. That is the beauty of this model: not all-or-nothing, but steady cash flow with a major revenue lever at the end."
All yield data from the VERDANTIS pilot plantations are based on the use of sterilized Paulownia hybrids. Dirk Roethig emphasizes the importance of this detail for data reliability.
The hybrids produce no viable seeds — the germination rate in German open-field trials is zero percent (Paulownia Baumschule Schroeder, 2024). They are winter-hardy to -20 to -25 degrees Celsius and have survived the winters of 2021/22 through 2025/26 in NRW and Lower Saxony without significant frost damage.
"Variety selection is not cosmetic — it determines yield capacity," says Dirk Roethig. "Working with non-adapted varieties risks failures, frost damage, and disappointing growth rates. VERDANTIS has invested over years in selecting the best hybrids for Central European conditions. The pilot data show that this investment pays off."
The use of sterilized hybrids also has regulatory advantages: No invasiveness risk, no conflicts with Section 40 of the Federal Nature Conservation Act (BNatSchG) (which regulates the planting of non-native species in the open landscape), and full compliance with the sustainability requirements of the EU Carbon Removal Certification Framework.
Paulownia's growth curve is not linear but logarithmic: the fastest growth occurs in the first five to eight years, then the curve flattens. For the VERDANTIS pilot plantations, Dirk Roethig projects based on the data to date and scientific models:
Ghazzawy et al. (2024) confirm the long-term potential: On suitable sites, Paulownia stands can sequester up to 417 t CO2 per hectare over the stand lifetime (Ghazzawy et al., 2024). The VERDANTIS pilot data show that this potential is within reach under Central European conditions as well — albeit at the lower end of the global range.
"In ten years, we will have completed the full rotation," says Dirk Roethig. "Then we will have not only pilot data but practical data over a complete cycle — from planting to harvest, including timber sales and the carbon credit balance. That will place the investment case for Paulownia in Germany on a definitive empirical foundation."
The five years of yield data from the VERDANTIS pilot plantations demonstrate: Paulownia hybrids grow in Germany. Not as fast as in Turkey, but faster than any native tree species. They sequester 14 to 21 tonnes of CO2 per hectare per year — double to triple the rate of conventional forestry species. And they do so with sterilized hybrids that pose no risk of invasive spread.
Dirk Roethig articulates the commitment of VERDANTIS Impact Capital: "We do not sell tree fantasies. We sell data. Five years of measured yield data from German pilot plantations, complemented by peer-reviewed research and AI-powered monitoring. This is the foundation on which investors and farmers should base their decisions."
Forest Ecology and Management (2025) 'Height growth and total volume production models for short rotation Paulownia plantations'. Available at: https://www.sciencedirect.com/science/article/pii/S0378112725006528 (Accessed: 10 March 2026).
Ghazzawy, H.S., Bakr, A., Mansour, A.T. and Ashour, M. (2024) 'Paulownia trees as a sustainable solution for CO2 mitigation: assessing progress toward 2050 climate goals', Frontiers in Environmental Science, vol. 12, art. 1307840. doi: 10.3389/fenvs.2024.1307840.
Jakubowski, M. (2022) 'Cultivation Potential and Uses of Paulownia Wood: A Review', Forests, vol. 13, no. 5, p. 668. doi: 10.3390/f13050668.
Joshi, N.R. and Pant, G. (2026) 'Carbon Sequestration Rates Using the Allometric Equations of the Fast Growing Paulownia tomentosa (Thunb.) in Central Nepal', NPRC Journal of Multidisciplinary Research, vol. 3, no. 2, pp. 65–89. doi: 10.3126/nprcjmr.v3i2.91267.
Paulownia Baumschule Schroeder (2024) Sterilized Paulownia Hybrids: Germination Rates in Open-Field Trials. Available at: https://www.paulownia-baumschule.de (Accessed: 10 March 2026).
agrarheute.com (n.d.) Stefan Bonsels: Paulownia Plantation in Neukirchen-Vluyn. Available at: https://www.agrarheute.com (Accessed: 10 March 2026).
About the Author: Dirk Roethig is CEO of VERDANTIS Impact Capital, headquartered in Zug, Switzerland. VERDANTIS operates Paulownia pilot plantations and agroforestry systems in Europe — with sterilized hybrids, AI-powered monitoring, and a data-driven investment strategy. Dirk Roethig relies on empirical evidence rather than promises. More information: verdantiscapital.com | LinkedIn | dirkdirk2424@gmail.com
Von Dirk Röthig (Dirk Roethig)