Trees get overheated in a warmer rainforest

The ability of rainforests to store carbon can decrease in pace with climate change. This is due to photosynthesis rates in the leaves of rainforest species falling at higher temperatures and the trees’ natural cooling systems failing during droughts. Increased heat threatens especially the species that store most carbon. This has been shown in a studie of PhD student Maria Witteman, so the University of Gothenburg in a press release.

Some species of trees are able to handle rising heat in the tropics by sucking up large quantities of water to their leaves and transpiring through wide-opened pores in their leaves. These are mainly fast-growing trees that establish themselves early as a rainforest grows up. The same cannot be said for the trees that make up the canopy of rainforests in old growth forests. They grow slower, but get bigger and taller, and their leaves do not have the same ability to cool themselves via transpiration.

Forests don’t absorb carbon consistently new study finds – Innovation Origins

Forests and woodlands do not sequester carbon as reliably as previously assumed, say reasearchers from the Ludwig-Maximilians-Universität München (LMU) in a press release.

More sensitive to drought

“We found large temperature differences in the leaves in our measurements. There could be a difference of 10 degrees Celsius between late successional species and early successional species growing in the same location. The late successional species had more difficulty coping with abnormally high temperatures. These trees had a higher mortality rate,” says Maria Wittemann.

“Our results show that photosynthesis rates in rainforest trees falls when the temperature rises in their leaves, which occurs mainly in late-successional species. The proteins and membranes in their leaves, which are essential for photosynthesis, fail, and eventually, the trees die due to carbon starvation because they cannot convert enough carbon dioxide from the air. This affects the entire ecosystem. We know, for example, that some animals eat the fruits of the late-successional species,” says Maria Wittemann.