Several research studies show that site preparation has a positive impact on the survival and early growth of forest seedlings and reduces weevil damage. This was also the result of Vera Vollbrecht's and Olga Fischer's fieldwork for a high school essay when they investigated growth, survival and damage of planted birch.
Vera Vollbrecht and Olga Fischer investigated the impact of mechanical site preparation, seedling size and plant protection against pine weevil when planting genetically improved silver birch on forest land previously used for producing spruce. 80 seedlings of improved silver birch were planted in Tönnersjöheden experimental park in Halland in the spring of 2024. Spot scarification was applied before planting half of the seedlings, while the other seedlings were planted in unprepared soil. Within each group half of the seedlings were larger than the others. The plants were inventoried seven times over four months.
The students' results showed that plant mortality was 45 % without site preparation, while it was only five percent when site preparation was applied. The larger plants survived to a greater extent than the smaller ones. Weevil damage was more common on the plants with site preparation but the damage was less severe compared to on the plants that had been planted in unprepared soil. On the unprepared spots there were also more seedlings affected by girdling from pine weevils.
Vera Vollbrecht and Olga Fischer share their experiences from the work with the essay and about future plans:
Which results did you find most interesting?
“We found it very interesting how much difference site preparation actually does for the survival of birch seedlings. We thought there would be a difference, but that it wouldn’t be this big.”
Why did you choose to write an essay about planting of birch?
“We were given the opportunity by SLU to write about birch, which was very suitable for us. We didn't really know what to write about, but we couldn't turn down this chance. It ended up being very good as we both found it very interesting but also very fun to learn more, do some fieldwork and gain insights into that type of scientific research."
What will you do during summer and after graduating high school?
“Olga will work in the stables for the summer and then continue working and travelling. Olga took the programme natur sam in high school, so she is thinking of studying for a full natural science qualification. Vera will do summer work as a field assistant at SLU and then start studying the bachelor's programme in Forest and Landscape at SLU.”
Do you want to read the full essay? Please contact Vera Vollbrecht, vollbrechtvera431@gmail.com, or Olga Fischer, olga.anna.fischer@gmail.com
Page manager: stina.johannesson@slu.se
6/23/2025