Some very special forest tree seedlings are growing in a patch of forest next to the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. They are sheltered under metal baskets accompanied by yellow signs indicating "Pohorsko, Slovenia", "Pyrenees, France", "Alborz Mountains High, Iran" and other places. Similar experiments are currently running in seven European countries and will be active for the next five years as part of the European project MyGardenOfTrees. "We want to understand what is the survival and growth potential of a particular forest tree population - and its unique set of genes - by testing it under an extremely wide range of environments" says Dr Katalin Csilléry, project leader and head of the Evolutionary Genetics Group at the WSL.
She took the risk of developing a project that rely on foresters to perform experiments with the seeds that are sent to them. "Foresters care about the future of their forests and are enthusiastic about experiments. I am confident that we can make this work," Dr Csilléry continues. Foresters also contribute with their skills, time, and knowledge to this project. "I want to reward them for their participation by developing a prediction tool that will help foresters select optimal seed sources to make their forests fit for the expected future climate."
Participatory science: good communication is key
"Did you know that Europeans speak around 29 different languages? I don't even know how to say the word forest in most of these languages!" laughs Dr Nicole Ponta, project coordinator of MyGardenOfTrees. "This is why we recruited local coordinators all across Europe." Based in France, Germany, Hungary, Poland, Romania, Greece, Croatia, and Spain, they are now looking to recruit participants for the coming up 2022-2027 trials. "We would like to recruit at least 500 participants this year. Forest managers and owners, or even enthusiastic citizens and communities who have permission from a forest owner are all welcome to join!" explains Dr Ponta.
Participants have to agree to set up a small trial, called a micro-garden, and monitor it for at least five years. In the 2021 pilot phase, the project recruited 25 participants whose observations and feedback were used to develop the protocols. Participants submit their observations using their smartphones, which are sent to the project server and visualized on the webpage [link: https://www.mygardenoftrees.eu/about/results] in real time.
The first results turn out to be encouraging. "Some Eastern European origins stand out with an exceptionally high rate of germination, especially from Slovenia. At this stage we can only speculate, but these findings seem to suggest that origins that harbour a lot of genetic diversity have a good field performance," explains Dr Csilléry.
Seeds directly sown into the forest
The method of the project is rather unusual to foresters: they receive seeds that they sow directly in the forest with minimum soil preparation, a method known as direct seeding. "Foresters are not used to putting those expensive seeds out to the forest, they know that seeds would be eaten and transported by animals and that mortality is extremely high during the first years. This is why they use nurseries. However, this is the only way we can learn about natural regeneration," explains Dr Csilléry.
But the researchers still don't leave it entirely to nature: Dr Ponta had the special metal baskets – that the team calls seed protectors – designed by a company. “They don't only protect the seeds and the seedlings, but also the forest around from possible genetic contamination due to the presence of foreign seeds”.
Getting those seeds ready for the new participants!
The project also collects its own seeds for which it hired several tree climbers. Luckily, 2022 promises to be a mast year for both beech and silver fir. In mast years, trees bear an exceptionally large number of flowers and fruits. Therefore, the team will go seed hunting all over Europe in the autumn. "It will be a great joint effort with local foresters, collaborators and the local coordinators of the project. This is our chance to collect all the necessary seeds that represent the full genetic diversity of these two species" explains Dr Csilléry