Master Thesis

Wildfire effects on vitality of temperate broadleaf forests in Southwestern Romania

Alexander Maurer (01/2024-01/2025)

Support: Carl Beierkuhnlein, Frank Weiser

As a result of climate change, extreme drought events and wildfire activity have been increasing across the temperate zone of Europe in recent years. In early spring of 2022, fire activity reached its highest level since recording in Southwestern Romania. This resulted in burning of broadleaf forests on a scale which has not occurred in the temperate zone of Europe in past decades. These ecosystems are naturally not well adapted to this novel type of disturbance. It is therefore unknown how vitality of broadleaf forests was affected. To investigate these issues, remote sensing data from the Sentinel-2 mission was used as a basis for data analysis. Development of the Normalised Difference Vegetation Index (NDVI) over an average of pre-fire years (2019–2021) and post-fire years (2022, 2023, 2024) was assessed for fire affected areas to identify changes in greenness and vitality over time. The Normalised Burn Ratio (NBR) was considered as an additional indicator for the fire year 2022. Annual NDVI peaks were compared to determine short-term and medium-term fire effects on forest greenness. Directly after fire and before development of foliage in spring, a decline in values of both spectral indices was observed. However, contrary to initial expectations, results showed no post-fire loss in annual peak greenness. It is therefore likely that fire severity was very low, so that canopy forming trees were able to resist fire damage. However, negative long-term effects are still possible. Consequently, no decline in forest vitality could be identified in the context of this study and continued monitoring as well as supporting field data would be necessary to obtain more conclusive results.