New Delhi: Climate change has slowly been altering the composition of forests, found a new study by Japanese researchers at the Osaka Metropolitan University. Forest ecosystems are adapting to include more trees that are adapted to warmer climates.
The study, a part of the December issue of Forest Ecosystems, analyses the long-term effects of climate change on the Japanese forest biome. Researchers studied the changes by compiling data from 191 forest plots across Japan between the 1950s to 2020.
“Japan spans a wide range of climatic zones and contains diverse forest biomes, making it an ideal setting for investigating forest change,” lead author associate professor Tetsuro Yoshikawa said in a statement.
Yoshikawa and his team measured what ecologists call the ‘Total Basal Area’ (TBA) — a measurement taken at about 1.3 to 1.4 metres from the ground, which calculated the surface area of all the tree trunks in the region. This measurement allows researchers to understand the size of trees, the density of a forest, and the dominance of the major tree families – the boreal conifers, deciduous broadleaved trees, and the evergreen conifers.
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Changing forests
The data revealed that a rise in mean temperatures led to an increase in TBA, and a rise in rainfall led to a decrease in TBA. The team found that over time, the boreal conifers that did well in the winters, declined, and the deciduous broadleaved trees, adapted to warmer climates, increased in several regions.
“These changes suggest that warming is affecting not just the growth of individual trees but also the composition of Japan’s forests. Over time, such changes could contribute to shifts in the distribution of forest biomes,” co-author professor Yayoi Takeuchi said in a statement.
This phenomenon has been observed across species and ecosystems, and is called ‘thermophilization’ — an increase in the dominance of species adapted to warmer temperatures.
“Although our findings capture changes that occurred in Japanese forests up to 2020, the impacts of climate change are expected to become even more pronounced in the future. Continued long-term monitoring of forest ecosystems will be increasingly important for detecting ecological changes and improving our ability to predict their consequences for forest environments and people’s lives,” Yoshikawa added.