For example, the rate of secretions from the roots more than doubled in trees that were exposed to bacteria, compared to trees that were not, in both the irrigated cypress group and the group growing in droughty conditions. In addition, the scientists identified about 100 compounds in the secretions, including phenolic and organic acids, and the concentration of nearly half of these compounds differed significantly between the irrigated trees and those that suffered from a lack of water. “When we added nine of the compounds to the bacteria, as sources of carbon and nitrogen, eight of them encouraged bacterial growth,” Oppenheimer-Shaanan says. “This is evidence that the secretions are a source of food for the bacteria.”
Overall, the study’s results suggest that the health of trees improved as a result of interactions with the bacteria. Moreover, during a drought, the cooperation between trees and bacteria offset the negative impact of the lack of water. The availability of phosphorus in the soil was maintained only for cypresses that were exposed to the bacteria, and this availability made up for the decrease in the levels of phosphorus and iron measured in the foliage of cypresses grown under drought conditions.
A Complete Forest Dictionary
Klein hopes that these research findings will advance our knowledge of forest ecology and the understanding that trees engage in much more extensive cooperation than was previously believed. On the applied level, the findings may have important implications for improving soil health and learning how to support plants that are under stress owing to a lack of resources. For example, recruiting specific bacteria could help to improve tree and forest health and build greater ecological resilience and stability.