It is estimated that currently only 30% of the world’s forests are primary forests, that is, without human intervention. These forests are known to be very important for biodiversity and as regulators of global carbon and water cycles, and their three-dimensional structure plays a very important role in this. Complex structures are known to influence gas and energy exchange processes with the atmosphere, while providing a great diversity of habitats to support numerous species (a forest in which all trees have the same size or age, one with trees of different heights, they are species in the understory, alternation of clearings with areas of shrub, different intensities of light, etc.)
Now, an international team of scientists has published an article in the journal Nature Communications in which they investigate the variety of complex structures found in the world’s forests, as well as the factors that explain this diversity.
Two years touring the forests of the world
Since the idea was to investigate the structure of different primary forests at different latitudes and climate zones, the team spent two years traveling to remote areas around the world to record the structure of forests with the help of 3D laser scanners. The 3D representations of the forest allow you to calculate very important metrics that define the structure.
The scientists found that the global variability of forest structures can be largely explained by the amount of precipitation and thus the availability of water in different ecosystems. Based on these findings and with the help of climate data, they were able to create maps of the world’s forests that show the global variability of structural complexity.
“One of the long-term goals of our research is to better understand how human influence and climate change affect the forest, its structure and the processes linked to it. The structure of primary forests is an important reference point for this.” says Martin Ehbrecht, a researcher at the University of Göttingen and first author of the work.
How do changes in rainfall patterns due to climate change affect the structure of forests? “The importance of water for the formation of complex forest structures can be explained by various interaction mechanisms,” explains Ehbrecht. “Water availability is an important driver of tree species diversity. The more tree species a forest contains, the more pronounced the coexistence of different tree canopy shapes and sizes. This means that the space available for canopies of trees can often be used more efficiently in species-rich forests, which makes the structure of the forest more complex . “
Which forests have the most complex structures?
The results revealed that rainforests have a more complex structure than deciduous and coniferous forests found in temperate zones, which in turn are generally more complex in structure than boreal coniferous forests such as those of Scandinavia or the savannas. of subtropical forests in Africa. “However, forests with high structural complexity can also be found in temperate zones, such as in areas with high rainfall such as the Pacific Northwest of the United States or in coastal forests of Chile,” says Professor Ammer, lead author of the study and director of Forestry and Forest Ecology of Temperate Zones at the University of Göttingen.
The results of this study are an important starting point for future work. “With the help of the satellite recording of the forest structure in 3D, in the future it will be possible to accurately record the real complexity of the forests,” says Ehbrecht. “This will allow us to better understand the effects of forest management and climate change on the world’s forests. Our world maps can serve as an important reference for this.”
Referencia: Martin Ehbrecht et al. Global patterns and climatic controls of forest structural complexity. Nature Communications (2021). Doi: https://doi.org/10.1038/s41467-020-20767-z
