A beech stump felled 400 years ago was still green inside
Peter Wohlleben found it in his forest near the German village of Hümmel and had to scrape the bark to believe what he was seeing.
A stump can't photosynthesize. Without leaves, it has no mechanism for making its own food. By every normal expectation, a tree stump felled four or five centuries ago should be inert wood — cold, gray, desiccated.
But when German forester Peter Wohlleben scraped the surface of a wide beech stump in his managed nature reserve near Hümmel, he found the tissue still green with chlorophyll. The only explanation available was that the surrounding beeches were feeding it: pumping sugar through the mycorrhizal fungal networks connecting their roots to the old stump's root system.
Scientist Suzanne Simard at the University of British Columbia had by then documented the mechanism in quantitative detail. What Wohlleben found in his forest, she had demonstrated in controlled experiments: carbon flows between trees through mycorrhizal connections, and it flows preferentially toward those in greatest need. Related trees receive more than strangers.
In The Hidden Life of Trees, Wohlleben describes this as something that unsettles a tidy competitive model of nature. Trees in an undisturbed forest are not racing each other to the light in pure rivalry — the largest, oldest ones are also feeding the weakest. The stump near Hümmel had been receiving this support across centuries, kept biologically active by a community that had apparently not written it off.
Whether trees experience anything like intention in doing this remains deeply contested. The carbon transfer, however, is not.