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News Article

Study finds tree species diversity under pressure

New research shows that many tree species are under significant human pressures and are located in areas with poor protection

A new international study of over 46,000 trees has shown that many species of tree are under significant pressure and have poor protective measures in place.  The research team, led by Aarhus University also investigated how ambitious and smart protected areas could help towards conservation efforts.

Natural capital refers to the value of the world’s stock of natural assets, including soil, air, water and trees that provide ecosystem services that benefit the environment as well as humankind. For example, trees play a vital role in ecosystems, providing habitats that support millions of species of plants and animals.  They also improve air quality, provide energy, shelter, medicine and raw materials and help mitigate against the effects of climate change.  Therefore, protecting these natural assets is important.

Key findings of the study included:

- For the 46,752 tree species analysed, around half of these were located in landscapes that had no protected areas. 

- For 13.6%, there was no protection at all.

- An average of 14.8% of the species were exposed to high/very high human pressures, while 68.5% were under moderate pressure.

- Only 17% of the species studied were not under pressure from human activities.

The research team integrated five large databases with registrations of the occurrence of tree species. They then used this data to calculate the geographical distribution of each tree species.  These distributions were then combined with a global map of how intensely human activities affect nature, as well as the World Database on Protected Areas, which includes information on over 200,000 areas.  By doing so, they were able to identify locations important for preserving and restoring in order to effectively protect the biodiversity there.

"We did this by calculating the most suitable locations of potential protection areas if we are to safeguard tree species diversity, not only with regard to the coverage of species, but also with regard to their evolutionary and functional differences," explained study co-author Dr. Wen-Yong Guo.

In 2021, the Secretariat of the Convention of Biological Diversity (CBD) published a draft post-2020 framework for protecting the worlds biodiversity, which highlights a vision that “by 2050, biodiversity is valued, conserved, restored and wisely used, maintaining ecosystem services, sustaining a healthy planet and delivering benefits essential for all people.”  A number of interest groups are calling for the vision to be brought in line with the Half-Earth Project proposed by Harvard biologist, E.O. Wilson. The Half-Earth Project advocates protecting half the earth's surface by no later than in 2050.

The study shows that implementing this framework will make a substantial difference. However, study lead author Jens-Christian Svenning says that "taking a broad-brush approach or just designating the most convenient areas, for example uninhabited tundra and desert areas, will not have the desired effect. Based on our calculations in this study, we've identified the areas in which nature conservation makes most sense to safeguard global tree diversity. If we're smart, protecting 17 per cent of land areas would mean that, on average, a tree species will have protected areas in 66 per cent of the landscapes in which it is found, as opposed to the current 50 per cent. With the Half-Earth vision, the proportion would be 83 per cent. Two-thirds of the tree species that are currently fully unprotected will have protected areas in the landscapes in which they're found if we reach the 17 per cent target.”

"But in order to achieve this, we have to look at the distribution of all species across the world, and establish protected areas so that they cover the species and their biological functions and evolutionary differences in the best possible way."

Journal reference

Wen-Yong Guo, Josep M. Serra-Diaz, Franziska Schrodt, Wolf L. Eiserhardt, Brian S. Maitner, Cory Merow, Cyrille Violle, Madhur Anand, Michaël Belluau, Hans Henrik Bruun, Chaeho Byun, Jane A. Catford, Bruno E. L. Cerabolini, Eduardo Chacón-Madrigal, Daniela Ciccarelli, J. Hans C. Cornelissen, Anh Tuan Dang-Le, Angel de Frutos, Arildo S. Dias, Aelton B. Giroldo, Kun Guo, Alvaro G. Gutiérrez, Wesley Hattingh, Tianhua He, Peter Hietz, Nate Hough-Snee, Steven Jansen, Jens Kattge, Tamir Klein, Benjamin Komac, Nathan J. B. Kraft, Koen Kramer, Sandra Lavorel, Christopher H. Lusk, Adam R. Martin, Maurizio Mencuccini, Sean T. Michaletz, Vanessa Minden, Akira S. Mori, Ülo Niinemets, Yusuke Onoda, Josep Peñuelas, Valério D. Pillar, Jan Pisek, Bjorn J. M. Robroek, Brandon Schamp, Martijn Slot, Ênio Egon Sosinski, Nadejda A. Soudzilovskaia, Nelson Thiffault, Peter van Bodegom, Fons van der Plas, Ian J. Wright, Wu-Bing Xu, Jingming Zheng, Brian J. Enquist, Jens-Christian Svenning. High exposure of global tree diversity to human pressureProceedings of the National Academy of Sciences, 2022; 119 (25) DOI: 10.1073/pnas.2026733119

Further research on this topic is available to subscribers of the database by using the search string ("species diversity" OR biodiversity) AND trees AND "protected areas" which returns over 1,100 results.  A selection of these records is provided in the further reading section below.

Article details

  • Author(s)
  • Stephanie Cole
  • Date
  • 02 August 2022
  • Source
  • Aarhus University