Remote Sensing Reveals Post‐Fire Forest Composition Shifts in Boreal Eastern Siberia
Oleg Zheleznyy, Cornelius Senf, Julia Boike, Dirk PflugmacherABSTRACT
Aim
Wildfires are the primary agents of disturbance in boreal forests. Under climate change, their frequency and size are expected to increase, raising concerns about the long‐term boreal forest resilience. Despite the importance and complexity of post‐fire recovery, large‐scale assessments of post‐fire vegetation composition remain limited for much of the boreal forest biome. Here, we characterised post‐fire vegetation across the forests of Eastern Siberia, one of the major wildfire hotspots.
Location
Eastern Siberia.
Time Period
1990s to current time.
Major Taxa Studied
Boreal forests.
Methods
Based on historical Landsat satellite imagery, we identified 1863 wildfires in 1990–1994. We then mapped the current fractional cover of five key boreal vegetation types using regression‐based spectral unmixing of Sentinel‐2 satellite imagery. We quantified vegetation differences between burned and adjacent unburned areas, assessing the effects of burn severity, proximity to the fire edge and average annual air temperatures on post‐fire compositional changes.
Results
Thirty years following the fire, vegetation on more than 95% of burned area has recovered. Deciduous broadleaf forests maintained their composition even after high‐severity fires, while coniferous trees were commonly replaced by early successional broadleaf species, especially further from the fire edge and in warmer annual air temperatures. In colder mountainous areas and sites with high burn severity, shrubby and herbaceous vegetation outcompeted broadleaf trees in the recovery process. The fraction of evergreen coniferous species decreased even after low‐severity fires, whereas larch showed higher resilience; however, its recovery has been poorer in the southern parts of its range.
Main Conclusions
Post‐fire recovery of East Siberian boreal forests is slow and is characterised by compositional shifts. Increasing frequency and severity of wildfires may pave the way for a permanent shift from coniferous to broadleaf forests in the warmer parts of Eastern Siberia.