How a Forest Gets Its Nutrients

The German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) and the Swiss National Science Foundation (Schweizerische Nationalfond, SNF) have jointly pledged roughly €7.5 million in funding for the next three years of "Ecosystem Nutrition: Forest Strategies for Limited Phosphorus Resources," which has been an ongoing Priority Program since 2013. The roughly €2 million that the University of Freiburg will receive from this grant will go toward continuing its research in this program, which focuses on the role of ecosystems in plant nutrition. The coordinator of the research program is Prof. Dr. Friederike Lang, Chair of Soil Ecology at the University of Freiburg. Within this project are also several subprojects that are being researched at the University of Freiburg under the leadership of Prof. Dr. Jürgen Bauhus, Chair of Silviculture, Prof. Dr. Cornelia Herschbach, Chair of Ecosystem Physiology, and Prof. Dr. Markus Weiler, Chair of Hydrology.

The researchers in this program are working to determine what role the phosphorus supply in soil plays for trees and forests, and how this vital nutritional element is distributed within the ecosystem. Plants absorb phosphorus from the ground. Although there is only a limited supply of phosphorus, it is continuously recycled in the ecosystem. When a plant dies, the element enters the soil again, where it is then absorbed by other plants.

In the first phase of the program, researchers discovered in their study of beech forests, for example, that trees in areas with low phosphorus concentration recycle this nutritional element from dead organic material with little loss, thus securing its intake. On the other hand, in areas where the element occurs in large amounts, trees use the phosphorus that is bound in minerals in the soil, and recycling thus plays only a minor role. As a result, scientists believe that the lack of phosphorus that has been recently detected in some forests is the result of a disturbance in the natural cycle. "We also found indications that the nutritional strategies used by beech forests not only secure their phosphorus needs; they also have a significant impact on other functions in the ecosystem, like the distribution of humus in the soil profile," explained Friederike Lang.

In order to better understand the mechanism of phosphorus nutrition, beech forests that grow on calcareous soil will be one of the many subjects the members of the Priority Program will be researching in the second phase. This type of soil often shows a lack of phosphorus, as well as an additional frequent lack of water. This can have a negative impact on microbial cycling as well as the intake of phosphorus in plants. Researchers are also planning joint field tests in which they will study to what extent forest ecosystems react to disturbances caused by nitrogen input and climate change.

Project website

Article in the research magazine uni'wissen

Contact:
Prof. Dr. Friederike Lang
Chair of Soil Ecology
University of Freiburg
Phone: +49 (0)761 / 203 - 3625
E-Mail: fritzi.lang@bodenkunde.uni-freiburg.de