In order to increase forest diversity, Switzerland created these last decades many forest reserves, where any exploitation is prohibited for 50 years. It is generally considered that biodiversity will increase with time, as a result of ageing trees. However, this is particularly valid for insects and fungi, but the impact of forest reserves on understorey flora was less studied.
In 2022, 4.4 km2 of Forêts du Jorat (Swiss lowland, 8 km from the centre of Lausanne) were protected as a new suburban protected parc (Parc naturel du Jorat). In this area, the public access is restricted and only interventions to ensure the visitor safety will be possible. In addition, 4.9 km2 were classified as transition area, with continued forest exploitation and public information.
In order to evaluate the impact of the forest protection on biodiversity, 129 plots were set in 2022 (72 in the protected area and 57 in the transition area) with measurements of forest structure (Jonas Stillhard, WSL), inventories of wood coleopters and fungi (Thibault Lachat and Nicolas Roh, HAFL) and exhaustive inventories of the flora (Pascal Vittoz, University of Lausanne, and Patrice Descombes, Naturéum botanique).
The plant inventories were realised on circular plots (10 m2 and 200 m2), with exhaustive list of species and a visual cover estimation (200 m2). Photographs from different points complete the description. The original survey was established between 2022 and 2024, and the next one is planed from 2032.
One of the inventoried plots viewed from the four cardinal directions.
Active project members
Patrice Descombes
Pascal Vittoz
Loïc Liberati