Climate 'key driver' in European forest disturbances

Forest fires in countries like Spain and Portugal are a common concern such as this one near Vigo last year

Europe's forests have experienced increased disturbances throughout the 20th Century from wind, bark beetles and wildfires, a study has shown.

A team of European-based scientists identified climatic changes as a "key driver behind this increase".

However, they added, how the expected continuation of climate change would affect Europe's forests in the future remained unresolved.

The findings have been published online by the journal Nature Climate Change.

The researchers wrote: "Natural disturbances, that is, large pulses of tree mortality from agents such as wildfire, insect outbreaks or strong winds, are integral drivers of forest dynamics and contribute to the diversity and adaptive capacity of ecosystems."

But co-author Rupert Seidl from the University of Natural Resources and Life Sciences in Vienna observed: "These disturbances have intensified considerably in recent decades, which increasingly challenges the sustainable management of forest ecosystems."

The authors said the frequency and severity of large wildfires had increased around the globe over the past decade.

They added: "In addition, recent bark beetle outbreaks, for example, in North America and Central Europe, have reached unprecedented levels."

'Severe impacts'

They suggested that an intensification of the disturbances were "thus expected to be among the most severe impacts of climate change on forest ecosystems".

Tree cover forms one of the main planks of the terrestrial carbon sink and is one of the main mitigation measures (planting trees) in the effort to reduce the impact of emissions from human activities.

"A further increase in disturbance damage in the future might thus pose a major risk for Europe's climate change mitigation efforts, as it could counteract the efforts to offset anthropogenic climate change through enhanced [carbon] storage in forest ecosystems," the team warned.

Locals attempt to fight a forest fire in central Portugal in 2013

"Yet, consistent continental-scale assessments of potential changes in the forest disturbance regime under climate change are still missing so far."

The researchers also added that the potential impact would be felt more widely by society as other important ecosystem services came under threat.

For example, timber prices could fall as the product was damaged as a result of wind or fungal infections. Greater disturbances would result in higher management costs.

"Also, the provisioning of drinking water could be negatively affected... as water filtering and retention strongly rely on the maintenance of a continuous forest canopy."

They concluded: "As intensifying disturbance regimes have the potential to strongly interfere with management objectives, consideration of disturbance risk and resilience will require a more central role in Europe's forest policy and management to sustain ecosystem function and services in the future."