Agroforestry at TUM

How can we achieve more sustainable agriculture that feeds humanity and also creates ecological added value? One approach is agroforestry systems, which combine arable farming with forestry and animal husbandry. For example, crops and shrubs or trees are grown alternately in strips. This not only makes more efficient use of the land, but also enhances its ecological value: biodiversity, soil health, and climate protection all benefit equally.

Agroforestry systems are now considered one of the most promising land use concepts for creating sustainable, multifunctional, and resilient agricultural landscapes.

Test areas at TUM

Since 2023, TUM has been setting up its own agroforestry landscape experiments. At the Roggenstein experimental farm, around 20 kilometers west of Munich, 31 hectares of test areas have been created for this purpose. There are a total of 80 subplots where various agroforestry plots can be compared with arable and forest plots (see overview in the fourth image in the slider).

There is also a test site on the campus of the TUM School of Life Sciences in Freising: the agroforestry showcase in Dürnast. The demonstration area covers 1.5 hectares and showcases four agroforestry designs.

Research questions

The research focuses on the following questions, among others:

• How do newly established agroforestry systems develop over time?
• What role do trees and shrubs play in the productivity of agricultural land?
• How quickly can the ecosystem services of agroforestry systems—such as pollination, pest control, and climate regulation—be utilized?
• How do tree strips contribute to sustainable, resource-efficient, resilient, and competitive agriculture?

“To answer these questions, we need a systemic and interdisciplinary approach,” explains Margit von Lützow, science manager at the Hans Eisenmann Forum (HEF) at TUM. She is responsible for promoting young talent and the focus area of agroforestry systems and biodiversity, and has been involved in the design of the agroforestry trial areas since 2020.

Interdisciplinary research

Researchers from various disciplines—including agricultural, forestry, and engineering sciences—are working on the agroforestry systems at TUM. This diversity reflects the numerous potentials of agroforestry:

• Strengthening ecological and economic resilience
• Improving the microclimate
• Closing nutrient and water cycles
• Carbon fixation by trees
• Promoting biodiversity

Results to date: Growth, growth sleeves, and modeling

Initial results from Dürnast show varying growth rates among trees in the establishment phase. A total of 15% of the planted trees died, mainly in the first few years after planting. The studies conducted by the Chair of Forest and Agroforestry Systems under Professor Annighöfer also found no effect of structural arrangement or slope gradient on tree growth.

In Roggenstein, the Chair of Ecoclimatology, headed by Professor Menzel, was able to determine initial results: young trees protected by growth sleeves sprout earlier and grow stronger than unprotected young trees. The main reason for this is the warmer microclimate inside the growth sleeves.

The Chair of Geodesy (Professor Kolbe, Dr. Donaubauer) is also working with data from agroforestry systems. The chair's staff modeled solar radiation in the micro-landscape of the agroforestry system. Over 40 years, the growing trees reduce radiation by 20%. To do this, they used the digital terrain model (DGM1) of the Bavarian Surveying Administration, 3D tree models, and a semantic 3D model developed by the Chair of Geoinformatics.

The findings of the Chair of Soil Physics and Environmental Systems show that agroforestry systems offer significant advantages for soil water balance. In the areas studied, arable crops consumed around six times more water than young tree rows, meaning that soils in agroforestry systems remain richer in water overall and provide better conditions for plant growth. In addition, trees change the soil structure: more clay accumulates under the rows of trees, indicating a higher water storage capacity compared to soils under neighboring arable crops. Overall, the results suggest that agroforestry systems are both more efficient in their water consumption and have improved water storage capacity.

The research results of Prof. Schloter and Dr. Steffi Schulz (Chair of Environmental Microbiology) show that agroforestry systems have positive effects on soil life shortly after establishment. Just one year after planting the trees, the activity of soil microorganisms is promoted, especially those that mobilize phosphorus bound in the soil and thus make it available to plants. In addition, microorganisms involved in the conversion of nitrogen and phosphorus are more closely interconnected in agroforestry systems. This stronger interconnection promotes more efficient nutrient cycles and improves the nutrient supply to plants.

The consortium is currently working on further research projects. We will provide further information on the results on the HEF website.