Deep in the dense forests of New Zealand, there exists a remarkable kauri tree that can absorb nutrients from neighboring trees, despite having only its stump remaining.
This unique kauri stump should have long been dead due to the loss of all its foliage necessary for photosynthesis. However, it survives thanks to the help of neighboring trees. The nearby trees fuse their root systems with the roots of the dying stump, providing it with water and nutrients like a life support system. In 2019, a team of scientists discovered this kauri stump while walking around the Waitākere Ranges in West Auckland, according to IFL Science.
The stump survives thanks to water and nutrients from surrounding trees. (Photo: Sebastian Leuzinger/iScience)
“That stump is very unusual because, despite having no leaves, it still survives,” said Sebastian Leuzinger, an associate professor at Auckland University of Technology.
Astounded by the discovery, the research team decided to conduct experiments on the living kauri trees. The stump and several neighboring trees were connected to sensors that monitored the water and sap flow, as well as the amount of carbon dioxide released. According to an article in the journal iScience, the experimental results revealed that the roots of the leafless stump and the neighboring trees were interconnected, allowing it to receive the necessary water and nutrients for survival.
Leuzinger explained that this differs from how trees typically operate, where the water flow is influenced by the atmospheric pressure. In this case, the stump relies on the surrounding trees. Due to the lack of leaves to transpire water, it escapes the atmospheric pull. The question is why the surrounding trees are willing to help the dying stump.
This relationship is particularly costly for healthy trees because the connection can facilitate the rapid spread of disease. This is especially true for kauri trees, which are among those most vulnerable to extinction in their native environment due to the spread of disease caused by the Phytophthora agathidicida pathogen.
“For the stump, the benefits are clear; it would die without root grafting since it has no green tissue of its own. But why do the healthy trees help the stump survive in the forest while it seems to provide no benefit to them?” Leuzinger said.
One hypothesis is that kauri trees always graft their roots together in an interconnected network to share water and nutrients during dry periods, creating a mutually beneficial relationship. The leafless stump stops providing carbohydrates, but the other trees are likely unaware, allowing it to continue living off the surrounding trees.
This study focused on a single tree, but it is evident that many forest ecosystems seem to operate as a super-organism, interlinking with one another rather than competing as individual entities.
