A new study found that tropical trees grow less in years when the dry seasons are drier than usual. The study was published by Nature Geoscience.
Scientists believed that tropical tree rings were absent because of low temperatures and high rainfall fluctuations. Recent decades have shown that growth rings can be formed in hundreds of species of tropical trees, which are sensitive and susceptible to drought. They also experience at least one month of slightly reduced precipitation every year. Scientists can better predict how climate change will affect tropical trees if they have a better understanding of how they respond to unusually dry or warm conditions.
The study defined the tropics so that it also included the subtropics, which are any area between 30° north latitude (30° south latitude). Researchers also found that warmer and drier years have a greater impact on tropics located in more arid areas. This suggests that tropical trees may be more sensitive to climate fluctuations due to climate change. The temperature at the study sites is expected to rise by half a degree Celsius every decade in the future.
The study’s results have helped to explain large fluctuations in carbon uptake worldwide. Model simulations have shown that tropical vegetation is less likely to grow in hotter or drier seasons and so absorbs less carbon dioxide. Unfortunately, there have never been any measurements of actual vegetation growth. Research has shown that slower growth increases the likelihood of topical tree deaths. This means that tropical vegetation may become more of a source of carbon dioxide than it absorbs, which could lead to climate change.
Pieter Zuidema, a lead researcher at Wageningen University & Research in The Netherlands, said that these (tropical tree rings) contain a wealth information about the growth history and development of trees. This study aims to exploit this potential. He said that this is the first time that we have a pantropical view of how tropical tree growth responds to climate fluctuations.
We know that photosynthesis and wood-production of tropical trees peak during the dry season,” Valerie Trouet (a professor in the Laboratory of Tree-Ring Research) and Flurin Babst (an assistant research professor at the UArizona School of Natural Resources and the Environment). “So why does the dry season affect the year-to-year variation in trunk growth? This puzzled and surprised us. Our explanation is that water is more available in years with wetter and cooler dry seasons. The growing season is therefore longer. This leads to greater trunk growth,” he said.
The study also filled a crucial gap in tree ring data. Zuidema explained that the world maps showing locations of tree-ring research often have a hole at the middle, in tropics.
He said, “Our network fills the tropical data gap.” The International Tree-ring Databank, a global database of tree-ring information, has uploaded tree-ring data for more than 100 locations.
Zuidema concluded that “In this manner, the tree-ring information we’ve assembled will be freely accessible for everyone.” (ANI)
(This story was not edited by Devdiscourse staff. It is generated automatically from a syndicated feed.
