Where on Mars could the first tree grow?

We previously wrote about the work of the team led by Prof. Robert Olszewski from the Faculty of Geodesy and Cartography while the scientists were still running simulations. Now, their results have been published in the journal PLOS ONE.
In the study, the Siberian pine—a coniferous tree that tolerates low temperatures well—was selected as a model species. Based on observations of forests growing in harsh terrestrial conditions, scientists determined the temperatures required for the first pine tree to grow on the Red Planet. The growing season for such a tree has been established as lasting at least 110 Martian days (called sols). During this period, the daily minimum temperature could not fall below minus 6 degrees Celsius, the average temperature should exceed 6 degrees, and the maximum temperature should not exceed 40 degrees for extended periods.

To perform these calculations, the surface of Mars was divided into 4,002 areas. Temperature changes were analysed separately for each area, taking into account factors such as terrain topography, solar irradiation at different times of the Martian year, heat exchange with the ground, and energy flux between different parts of the planet. The researchers also examined how conditions would change under varying atmospheric pressures and different intensities of the added greenhouse effect.

"In 1969, Neil Armstrong said during the Moon landing that it was 'one small step for man, one giant leap for mankind.' Buzz Aldrin, the Lunar Module pilot accompanying him on the Apollo 11 mission, declared a few years later that it was time for the next step – 'Mars is there, waiting to be reached.' However, realizing his vision of establishing a permanent presence on the Red Planet requires that, before the grandchildren of our grandchildren can live on Mars, the first tree must grow there. The research team from Warsaw University of Technology wants to play its part in modelling this process. By collaborating with NASA, we are creating solutions that could contribute to the terraforming of the Red Planet," said Prof. Robert Olszewski.

It might seem that we need to seek suitable conditions for the first tree near the equator, where the most solar energy arrives. However, simulations showed that the appropriate temperature range appeared earliest in the Hellas Basin—a vast depression in Mars's southern hemisphere. This result is influenced by both the planet's surface topography and its position relative to the Sun. The Hellas Basin, a massive impact crater, lies several kilometres below the average Martian surface level, which makes the atmospheric pressure there higher than in surrounding areas. Furthermore, summer in the southern hemisphere coincides with the period when the planet is closer to the Sun, making it warmer. The combination of these factors makes this location the earliest place where thermal conditions for a tree could arise.

The authors of the publication "Conceptual thermal constraints on the growth of the first tree on a terraformed Mars" are Prof. Robert Olszewski (Faculty of Geodesy and Cartography, WUT), Agnieszka Wendland, PhD, Eng. (Faculty of Geodesy and Cartography, WUT), Piotr Pałka, PhD, Eng. (Faculty of Electronics and Information Technology, WUT), along with Alison F.C. Bridger (San Jose State University), Melinda A. Kahre and Christopher P. McKay (NASA Ames Research Centre), and Christian Körner (University of Basel).