Storms, fires and bark beetles have caused increasing damage to Europe’s forests over the past 70 years. In particular, the share of bark beetles has grown strongly over the last 20 years. It is partly a result of increasing droughts, which in turn are caused by climate change. That appears from an analysis published this Monday in the scientific journal Global Change Biology.
The researchers warn that the mounting damage could pose a threat to political goals. Last year, the European Commission made proposals for a new ‘forest strategy’. The pressure on European forests is expected to increase as more and more requirements are set. It should help in the fight against climate change – for example by planting three billion extra trees. More forests also need to be protected to maintain and improve biodiversity. In addition, more wood is expected to be needed for energy supply and for sustainable construction (as a replacement for concrete and cement).
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European forests have increased in area since the Second World War, and now cover about one third of the territory. But the damage is also increasing, as the analysis shows. Measured as a percentage of the total forest, this is a relatively small share, less than one percent. “Nevertheless, this involves large volumes of damaged wood,” says Marco Patacca, first author of the article and affiliated with Wageningen University & Research. That amount, measured in cubic meters of wood, has risen slightly to 16 percent of the annually harvested (good) wood.
monotony
According to Patacca, the increase in damage is partly due to the monotony of the forests. Reforestation has mainly been done with species that the timber industry is geared to, conifers and conifers. From the report published two years ago State of Europe’s Forests 2020 shows that one species dominates in 33 percent of the total forest area. This monotony makes trees more vulnerable to disease.
In recent years, more studies have been published about damage to European forests, but these were based on satellite images, which show the crown of forests. “It is difficult to see the difference between, for example, a felled and a flattened piece of forest.”
The analysis now performed is based on observations on the ground. Those data already existed for the period 1950-2000, but not yet for the following twenty years. The researchers managed to retrieve this data from national inventories and various local archives.
This method also has a drawback. Not all pieces of damaged forest are visited and inventoried, for example because the manpower is not there. The researchers advocate large-scale, structural monitoring of European forests.
Causes
In addition, says Patacca, more research is needed into the causes of damage and their interaction. “If a tree is attacked by bark beetles, it will blow over more easily. And after a storm there is a lot of dead wood that attracts all kinds of organisms. This often creates hotspots for pest outbreaks.”