Tulip trees have been around for millions of years, but a new analysis of their structure has revealed a previously unknown species of tree. The findings could explain why trees are so good at sequestering carbon, and aid our efforts to do the same.
Trees are powerful allies in the fight to reduce the amount of carbon in the atmosphere and, as a result, mitigate the effects of greenhouse gases that are rapidly warming our planet. According to the Arbor Day Foundation, a single mature tree can absorb more than 48 pounds of carbon dioxide from the air each year, and one acre of mature trees can absorb the same amount of CO2 as a car traveling 26,000 miles (~42,000 km).
One tree that is particularly good at removing carbon from the air is the tulip tree, which consists of two species: Liriodendron tulipiferaWidespread in North America and Liriodendron chinenseNative to central and southern China, these trees are ancient relatives of the magnolia and can quickly grow to over 100 feet.
Recently, researchers from the Jagiellonian University (JU) in Poland and the University of Cambridge in England took samples from 33 different tree species from the botanical gardens of the University of Cambridge. They then froze these samples using a nitrogen bath and examined them under a low-temperature scanning electron microscope. When they got to the tulip tree sample and examined its secondary cell wall, they were astonished to find that they had come across a completely different tree species.
“The basic building blocks of wood are secondary cell walls, and the architecture of these cell walls is what gives wood its density and strength and what we rely on in construction,” says lead study author Jan Łyczakowski from JU. “Secondary cell walls are also the largest carbon store in the biosphere, making their diversity even more important to understand in order to advance our carbon capture programs to help mitigate climate change.”
All tree species have long tube-like fibers in the secondary cell wall called macrofibrils that hold the wood cells together. These fibers are made up of cellulose chains and give the trees their stability.
During this research, the team found that angiosperms, which are generally hardwoods like oak and cherry, have macrofibrils with an average diameter of 17 nanometers. In gymnosperms, which are generally softwoods like pine or cedar, microfibrils average 29 nanometers. But in the case of the tulip tree, microfibril diameters were around 20 nanometers, placing it right between the two well-known tree species. The researchers called this wood that is neither hard nor soft “intermediate wood.”
Not only do researchers believe the unique structure of the tulip tree’s secondary cell wall is responsible for its rapid growth rate, but they also think it may have evolved in response to the rapidly decreasing availability of carbon in the atmosphere around 30 to 50 million years ago. When less carbon dioxide was available for use in photosynthesis, the thinking goes, trees evolved these unique cellular structures to hold as much of it as possible. This makes them great at helping to reduce the overabundance of the gas in our atmosphere today, and could help scientists learn how to use trees to an even greater extent to combat climate warming.
“Both Tulip Tree species are known to be extraordinarily effective at locking up carbon, and their expanded macrofibrillar structure may be an adaptation to help them more easily capture and store larger amounts of carbon when atmospheric carbon availability decreases,” said Łyczakowski. “Tulip Trees could be useful for carbon capture plantations. Some East Asian countries use Liriodendron plantations to effectively lock up carbon, and we now think this may be related to the new wood structure.”
The research findings were published in the journal New Phytologist.
Source: University of Cambridge, via EurekAlert