Scientists explained what defines the leaves type and that in 100 years a third of the world's forests will change

Newswise —  An international collaboration of scientists with the participation of an ecologist from RUDN University conducted the first global analysis of leaf type. In addition, the authors described the current state of forests and said what will happen to them by the end of the century due to climate change. The results were published in  Nature Plants.

Leaves are important for carbon and energy metabolism in the forest. Photosynthesis, plant respiration, moisture evaporation, and the formation of leaf litter depend on them. Therefore, it is important to understand how different types of leaves affect the ecosystem as a whole. This is also necessary to predict how ecosystems will behave under climate change. However, scientists still do not have such a comprehensive and global understanding. An international collaboration of scientists with the participation of an ecologist from RUDN University conducted the first global analysis of leaf types. 

“If we understand what influences the type of leaves on trees, we will understand their role in terrestrial ecosystems. However, existing data are incomplete. Therefore, we are not sure of the global proportions of needle-leaved, broad-leaved, evergreen, and deciduous trees. To fill these gaps, we conducted a global assessment of the types of forest leaves,” said Dmitry Kucher, Ph.D., head of the Scientific Center for Research, Integrated Design and Development of Urban and Agricultural Development of the RUDN University said. 

The scientists used forest inventory data and data on leaves by shape (broadleaf or needle-like) and type (evergreen or deciduous). The latter is called habitus in botany. To achieve the most accurate results, scientists divided the data into separate “portions” and processed them with hundreds of independent models.

It turned out that the type of leaves in the region depends primarily on the characteristics of the soil and the constancy of temperatures (isothermality). The shape of the leaves depends on the temperature itself. Taking these patterns into account, scientists have concluded that 38% of all trees in the world are evergreen needles, 29% are broad-leaved evergreens, 27% are broad-leaved deciduous trees, and 5% are needle-deciduous trees. The authors also predicted that 17–34% of forest areas will change types by the end of this century. 

“We found that leaf shape is primarily determined by isothermality and soil. Leaf shape mainly depends on temperature. We project that, depending on future emissions, by the end of the century, 17–34% of forested areas will be subject to other forest climates. This indicates climatic stress on forests. Our results will help improve forecasts of the state of ecosystems and the carbon cycle,” said Dmitry Kucher, Ph.D., head of the Scientific Center for Research, Integrated Design and Development of Urban and Agricultural Development of the RUDN University said.