In India's Western Ghats, researchers are exploring how tropical forests respond to global warming by climbing tall trees and attaching sensors to their leaves. The study, the first detailed analysis of cumulative heat exposure in tropical trees, shows the trees may be in better shape than scientists thought.
Summer temperatures in the region often exceed 37 degrees Celsius, and are expected to rise by about 4 degrees Celsius over the next 60 years. Leaf temperatures are usually higher than the surrounding air. When the temperature exceeds 46.7 degrees Celsius, the photosynthesis mechanism shuts down, causing the tree to be unable to obtain the energy it needs. Many tropical trees have experienced temperatures exceeding this limit.
The study found that while heat poses a threat to trees, the key is the length of exposure to the heat. The researchers monitored the leaves of 12 different tree species for four months in a 6-hectare plantation. Although the sensors were often blown off by strong winds and even damaged by wild animals, the data showed that the blades exceeded the critical temperature for less than 10 minutes in a single day.
Laboratory analysis shows the critical temperature range for trees in the region is 43.4 to 45.5 degrees Celsius, slightly below the global average. While 30 minutes of sustained exposure to these temperatures can permanently damage leaves, the shorter actual exposure time suggests the trees' photosynthetic efficiency will not decrease significantly.
This study provides important insights into how tropical forests respond to climate change. Although the research process is challenging, scientists hope to further reveal the impact of high temperatures on trees by using temperature sensors in more ecosystems around the world. This research not only helps protect forest ecosystems, but also provides a new perspective on combating global warming.