Protective forests after a wildfire

This project aims to estimate the potential energy dissipation capacity of burnt trees after a wildfire to quantify the protective effect of the burnt forest against rockfall.

Factsheet

Schools involved School of Architecture, Wood and Civil Engineering
School of Agricultural, Forest and Food Sciences
Institute(s) Multifunctional Forest Management
Research unit(s) Mountain Forests and Natural Hazards
Funding organisation BFH
Duration (planned) 01.07.2024 - 31.12.2025
Head of project Dr. Estelle Noyer
Project staff Dr. Estelle Noyer
Lukas Kramer
Partner Berner Fachhochschule

Situation

The estimation of the potential energy dissipation capacity of tree stems can be achieved by testing trees in forests or stems at the laboratory. Despite the reliability and “close-to-reality” of field measurements, this approach is costly and complex. More accessible and repeatable, laboratory measurements focus on the relevant stem mechanical properties. However, only a few data are available in the literature on burnt stem properties (Ruth, 2015). Thus, a dedicated pipeline from stem samples to computation of the protective effect (PE) against rockfalls is still missing, especially in the case of burnt trees. Our main question is how does burn severity impact the green stem mechanical properties for a given stem dimension and, in extenso, its potential energy dissipation to rock impacts. The second question concerns the appropriate model for evaluating the burnt stem size, shape, and properties changes, which will complement RockyFor3D model for calculating the protective effect of the forest.

Course of action

This project will provide proof-of-concept for evaluating the protective effect from forests after a wildfire. This includes two distinct parts. Firstly, the energy dissipation of burnt stems and green stems for a specific loading scenario will be determined. Therefore, mechanical tests on small to medium scale stems will be performed. These tests are used to examine the possibility of drawing conclusions about the energy dissipation of burnt stems from tests on green wood. Secondly, a workflow to determine the shape, size, and mechanical properties of stems after a wildfire will be proposed. This will include tree location, diameter, and severity of burning. This workflow will then be applied to the site of Bitsch (VS).

Result

in progress

Looking ahead

Further development, in collaboration with ETH Zürich and Universities of Applied Sciences, can be then undertaken in term of modelling, but also for innovative laboratory tests (e.g., upscaling small wood properties to tree scale). Model for integrative traits at tree scale will be developed with international expert in tree biomechanics (INRAE Nancy-Grand Est) in the frame of a follow-up project.