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Science aims to save historic trees in Sanssouci

Weakened group of trees (19th century European beeches) in Sanssouci-Charlottenhof Park (Photo: Rohde/SPSG)

Weakened group of trees (19th century European beeches) in Sanssouci-Charlottenhof Park (Photo: Rohde/SPSG)

With an innovative approach, a team of scientists from Potsdam aims to save the trees in the historic parks and gardens of the State of Brandenburg that are endangered by climate change. Their idea is to increase the water-binding capacity of damaged trees by injecting strengthening humic substances into the roots, to support the active soil microbiome and thus to improve the trees' nutrient uptake. The Brandenburg Ministry of Science, Research and Culture is providing 250,000 euros in seed funding for research in this area.

Brandenburg residents as well as tourists love the beautiful historical gardens and parks in the region. However, in recent years they also had to witness how much the partly irretrievable tree population suffers from the impacts of climate change. There are many reasons for this: long dry periods with excessive heat in summer, a drop in groundwater levels and the sandy soil lead to an increasing weakening of the trees and their subsequent death, in some cases accelerated by insect infestation. Experts expect this trend to continue, especially since irrigation water is limited.

Scientific institutions in the State of Brandenburg, the Prussian Palaces and Gardens Foundation Berlin-Brandenburg (Stiftung Preußische Schlösser und Gärten Berlin-Brandenburg) and the Free University of Berlin have joined forces in a research project to contribute to a sustainable solution for saving the trees. The focus is on humic substances.

In nature, humic substances are formed as a result of the slow decomposition of plant residues by soil animals, fungi and microorganisms. The adsorption and water-holding capacity of these natural organic compounds clearly exceeds that of clay minerals.

Humic substances play a crucial role in improving soil quality in terms of water-holding capacity, pH and redox buffering, and they also provide valuable nutrients for plants. Thus, humic substances act as a kind of plant biostimulants that help to improve the resilience of plants to abiotic and biotic stressors.

Commercially available humic substances have so far been obtained in a technical process by chemical extraction from peat or brown coal. A more sustainable solution is offered by a process for accelerated composting or humification that was developed at the Max Planck Institute of Colloids and Interfaces (MPIKG). By means of a chemical-thermal process, called hydrothermal humification, humic substances can be obtained from residual biomass efficiently while retaining almost all of the carbon bound in the plant material. These so-called 'artificial' humic substances (AHS) from regenerative biomass correspond in their effects to natural humic acids, as studies from China have shown.

"We were indeed surprised by the first, very positive results. The new process was initially only intended to technically accelerate natural composting and improve the hygienic handling of some biological residues, but the effect of our sustainable products is obviously indistinguishable from the familiar charcoal or peat extracts," says Prof. Dr. Markus Antonietti, Director of the MPIKG. "In the process, we use and fix almost the entire carbon pool of the biological residues and thus can take a big step towards a more CO2-neutral State of Brandenburg."

In the initial phase (Nov 2021 to Dec 2022) financed by funds from the State of Brandenburg, first experiments will be carried out and a research proposal for funding on a supra-regional level is to be prepared. The experimental work in this first phase includes studies on the hydrothermal humification of biomass waste such as grass clippings or fermentation residues from biogas plants up to a first application of the AHS in one of the gardens of the Prussian Palaces and Gardens Foundation Berlin-Brandenburg.

"We are very pleased about the sound expertise and cooperation with the Potsdam Leibniz Institute for Agricultural Engineering and Bioeconomy and its partners," says Prof. Dr Michael Rohde, Head of the Gardens Department of the Prussian Palaces and Gardens Foundation Berlin-Brandenburg (SPSG). He sees advantages: "The use of the biomass cycle contributes to climate protection, and innovative soil amendments serve to preserve valuable trees. With scientific monitoring, our parks will become laboratories incubating model climate adaptation strategies."

The research partners will contribute their manifold expertise to the collaboration: the Max Planck Institute of Colloids and Interfaces (MPIKG) in the field of synthesis and characterisation of artificial humic acids and fulvic acids from biomass side streams, the Free University of Berlin (FUB) in the field of stress physiology of trees, the ATB at the interface of biology and technology in the field of hydrothermal carbonisation and the soil microbiome, among others.

"Our original terrain is agriculture, where our research aims to protect climate by creating adapted management strategies on the one hand, and where we develop technical innovation to prepare agricultural production for the consequences of climate change," explains ATB Director Prof. Dr. Barbara Sturm. "We are all the more pleased that, as a Potsdam research institute, we can contribute to the preservation of Potsdam's parks and gardens - cultural assets that are valued worldwide - with our process engineering expertise from the agricultural sector," emphasises Prof. Sturm.

Seed funding of 250,000 euros will be available for the project "Development of methods for deep injection of artificial humic substances against the consequences of climate change - Save a tree in Sanssouci". The funding is provided by the Ministry of Science, Research and Culture (MWFK) of the State of Brandenburg. The project is coordinated by the Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB). Partners in the project are the Max Planck Institute of Colloids and Interfaces (MPIKG), the Prussian Palaces and Gardens Foundation Berlin-Brandenburg (SPSG) and the Free University of Berlin (FUB). Further partners are to join.

Helene Foltan
- Public relations
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The Leibniz Institute for Agricultural Engineering and Bioeconomy e.V. (ATB) is a pioneer and driver of bioeconomy research. We create scientific foundations for the transformation of agricultural, food, industrial and energy systems into a comprehensive bio-based circular economy. We develop and integrate technology, processes and management strategies in the sense of converging technologies in order to intelligently network highly diverse bioeconomic production systems and to control them in a knowledge-based, adaptive and largely automated manner. We conduct research in dialogue with society - knowledge-motivated and application-inspired.