Patterns of long-term regeneration of forest fire slopes in the Northern European Alps – a logistic regression approach

ABSTRACT

We report on vegetation recovery after stand-replacing wildfires on steep slopes on limestone and dolostone bedrock. The sites burnt in the nineteenth and twentieth century and some have remained almost bare of vegetation. We mapped and analysed 26 burned slopes to determine site-specific factors influencing regeneration. We followed a multinomial-logistic regression approach to explain the patterns of grassland, shrub and tree vegetation in 10 × 10 m cells. We considered eight potential controlling parameters (time since fire, elevation, aspect, slope, topographical index, distance to forest edge, land cover of neighbouring pixels and lithology). The pseudo R² values for the multinomial-logistic regression point to a reasonably good model fit, even if some potentially important parameters (e.g. post-fire management) could not be incorporated. Tree regeneration is impeded by higher elevation and by steep slope angles while shrubs are unaffected by inclination. Although the probability of pixels with grasslands is higher in proximity to neighbouring grassland pixels, we found no such effect for trees or shrubs. There is no statistical correlation between the type of vegetation and time elapsed since the fire. This means that under adverse conditions, the time required for forest recovery is longer than the time period captured by our investigation (200–300 yr).

KEYWORDS:

• Forest fire
• logistic regression
• regeneration
• Austrian Alps

Acknowledgements

We thank the student assistants of the ‘Alpine Wildfires’ project (i.e. Florian Weber, Rebecca Juraschek and Florence Stöger) for evaluating the aerial photos of the investigated wildfire sites. The helpful comments of three anonymous reviewers are greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Oliver Sass, Working Group on Alpine Landscape Dynamics (ALADYN), Department of Geography and Regional Science, University of Graz.

Sebastian Sarcletti, Working Group on Alpine Landscape Dynamics (ALADYN), Department of Geography and Regional Science, University of Graz.

Additional information

Funding

The summarizing work was carried out in the context of the FIRIA project funded by the Austrian “Klima- und Energiefonds” in the framework of the Austrian Climate Research Program (ACRP project no. K10AC1K00091).