Storm and fire disturbances in Europe: Distribution and trends

Abstract

Abiotic forest disturbances are an important driver of ecosystem dynamics. In Europe, storms and fires have been identified as the most important abiotic disturbances in the recent past. Yet, how strongly these agents drive local disturbance regimes compared to other agents (e.g., biotic, human) remains unresolved. Furthermore, whether storms and fires are responsible for the observed increase in forest disturbances in Europe is debated. Here, we provide quantitative evidence for the prevalence of storm and fire disturbances in Europe 1986–2016. For 27 million disturbance patches mapped from satellite data, we determined whether they were caused by storm or fire, using a random forest classifier and a large reference dataset of true disturbance occurrences. We subsequently analyzed patterns of disturbance prevalence (i.e., the share of an agent on the overall area disturbed) in space and time. Storm‐ and fire‐related disturbances each accounted for approximately 7% of all disturbances recorded in Europe in the period 1986–2016. Storm‐related disturbances were most prevalent in western and central Europe, where they locally accounted for >50% of all disturbances, but we also identified storm‐related disturbances in south‐eastern and eastern Europe. Fire‐related disturbances were a major disturbance agent in southern and south‐eastern Europe, but fires also occurred in eastern and northern Europe. The prevalence and absolute area of storm‐related disturbances increased over time, whereas no trend was detected for fire‐related disturbances. Overall, we estimate an average of 127,716 (97,680–162,725) ha of storm‐related disturbances per year and an average of 141,436 (107,353–181,022) ha of fire‐related disturbances per year. We conclude that abiotic disturbances caused by storm and fire are important drivers of forest dynamics in Europe, but that their influence varies substantially by region. Our analysis further suggests that increasing storm‐related disturbances are an important driver of Europe's changing forest disturbance regimes.

Post‐disturbance canopy recovery and the resilience of Europe’s forests

“…This result reflects the observation that forest area in Europe has increased over recent decades (Forest Europe, 2020), and that rates of timber extraction (from planned harvesting and salvage harvesting of naturally disturbed areas) remain below annual increment in most of Europe's countries (Levers et al, 2014). We further document that even regions affected by large-scale natural disturbance events since the mid-1980s have generally high resilience (e.g., regions affected by large cyclonal storms; Forzieri et al, 2020;Senf & Seidl, 2021c). This underlines that Europe's forests are well adapted to disturbance, and that infrequent, large pulses of tree mortality do not generally threaten Europe's forest ecosystems.…”

“…Portugal currently has the shortest disturbance intervals in Europe, due to a combination of intensively managed short-rotation plantation forests (mostly Eucalyptus globulus, covering approximately one quarter of Portugal's forest area and approximately 10% of its land area; Fernandes et al, 2019;Forest Europe, 2020) and a high prevalence of fires (Nunes et al, 2019;Senf & Seidl, 2021c). Furthermore, high disturbance rates coincide with long recovery intervals here, which might be related to the Mediterranean climate in general and to increasing fire severity in the region.…”

“…Forest disturbances have increased across Europe in recent decades as a result of both land use and climate change (Senf et al, 2018(Senf et al, , 2021. Furthermore, there has been an increase in large-scale forest diebacks in response to drought (Senf, Buras, et al, 2020;Senf & Seidl 2021b), as well as an increase in wind disturbances (Senf & Seidl, 2021c). A continued change in disturbance regimes along the trajectories of the recent past could thus bring Europe's forests closer to critical resilience thresholds.…”

Integrating GEDI and Landsat: Spaceborne Lidar and Four Decades of Optical Imagery for the Analysis of Forest Disturbances and Biomass Changes in Italy

“…This study aims to assess GEDI AGBD data across Italy and its use to study the rate of biomass increase following forest disturbances, which is crucial considering that forest disturbances are expected to increase due to climate change [2,38]. First, we compared about four million AGBD data from GEDI pulses with ALS data available across Italy.…”

Pine Forest Management and Disturbance in Northern Poland: Combining High-Resolution 100-Year-Old Paleoecological and Remote Sensing Data

“…Forest disturbance by storms, including tornadoes, is a rare but important problem that needs to be considered in the development of forest management strategies (Dobrowolska, 2015;Szmyt and Dobrowolska, 2016). Over the past decades, the frequency of extreme events such as storms and tornadoes has increased across Europe (Seidl et al, 2014) and is forecasted to increase further in the future (Senf and Seidl, 2021). Atmospheric phenomena that can damage forests, such as strong winds and tornadoes, are difficult to predict.…”