Increasing forest disturbances in Europe and their impact on carbon storage

Abstract

Disturbances from wind, bark beetles, and wildfires have increased in Europe's forests throughout the 20^th century ¹. Climatic changes were identified as a main driver behind this increase ², yet how the expected continuation of climate change will affect Europe's forest disturbance regime remains unresolved. Increasing disturbances could strongly impact the forest carbon budget ^3,4, and are hypothesized to contribute to the recently observed carbon sink saturation in Europe's forests ⁵. Here we show that forest disturbance damage in Europe has continued to increase in the first decade of the 21^st century. Based on an ensemble of climate change scenarios we find that damage from wind, bark beetles, and forest fires is likely to increase further in coming decades, and estimate the rate of increase to +0.91·10⁶ m³ of timber per year until 2030. We show that this intensification can offset the effect of management strategies aiming to increase the forest carbon sink, and calculate the disturbance-related reduction of the carbon storage potential in Europe's forests to be 503.4 Tg C in 2021-2030. Our results highlight the considerable carbon cycle feedbacks of changing disturbance regimes, and underline that future forest policy and management will require a stronger focus on disturbance risk and resilience.

Figure 1. Forest disturbance damage in Europe 1971 – 2030

Values are disturbance damage in Millions of cubic meters of timber per year – please note the different scales on the individual panels. Predictions (lighter hues) assume a continuation of business-as-usual forest management (reference strategy) and represent the median over an ensemble of scenarios of future climate and forest growth. Missing agents – such as bark beetles in the Northern and Atlantic ecoregions – indicate that they were not modeled in these particular ecoregions due to a lack of historical data and/ or relevance of the agent in these areas (see Supplementary Table 5).

Figure 2. Annual disturbance percentage (relative to growing stock) in Europe’s forest ecosystems

Predictions beyond 2010 assume a continuation of business-as-usual forest management (reference strategy). The median, interquartile range (dark grey), and minimum – maximum range (light grey) over an ensemble of scenarios of future climate and tree growth is indicated. Please note that the y-axis is logarithmically scaled.