Satellite images display changes in the condition of European forests


Date:
September 15, 2020
Source:
Technical University of Munich (TUM)
Summary:
The forest canopy, the closed vegetation cover consisting of
treetops, is rapidly declining according to new research. The team
used satellite images, to create the first high-resolution map
of canopy openings in Europe's forests and reached the conclusion
that the canopy of more than 36 million forest areas has been lost
over the past 30 years.



FULL STORY ========================================================================== Rupert Seidl (Professor of Ecosystem Dynamics and Forest Management in
Mountain Landscapes at TUM) and his colleague Cornelius Senf (lead author
of the study) for the first time produced a high-resolution map of all
openings in the canopy of European forests. They have analyzed more than
30,000 satellite images and identified more than 36 million areas where
large trees have given way to open spaces of young trees. This corresponds
to a loss of the canopy in 17 percent of the European forests in 30 years.


==========================================================================
The reasons for the canopy openings range from regulated wood use to
wind storms and forest fires. The team also found that the size of the
canopy openings varied widely from area to area.

For example, Sweden has the largest canopy openings (averaging
almost two hectares) while Portugal has the highest number of canopy
openings. Switzerland has the smallest openings with just 0.6 hectares
on average (which is smaller than a soccer field) while the average
size opening in Germany is 0.7 hectares and in Italy 0.75 hectares. The
largest opening documented by the researchers is in Spain, where a single
fire in 2012 burned 17,000 hectares.

Chance for tree generation adapted to climate change The novel map the
team has created also makes it possible to describe changes in forest conditions. The researchers have found, for example, that throughout
Europe forests have become more open and the frequency of forests being interrupted by open spaces has increased. In addition, the openings
themselves on average have increased in size primarily due to wind storms
and forest fires in recent years.

In such areas, however, the tendency is that more trees are surviving
due to the availability of seed material. This, in turn, promotes the
recovery of forests after a disturbance and can be seen as an indication
of the increase in low-intensity forestry in Europe, where only single
trees or crops of trees are taken rather than clear cutting large areas.

Therefore, despite the major changes in Europe's forests, the researchers
see positive developments. As Cornelius Senf has said, "In most cases,
new, young trees grow up after a loss of the old stand." However,
he goes on to say: "To understand where forests may be at risk of
irreversible damage, we need a baseline as a reference. This is provided
by the newly created map." Professor Rupert Seidl adds: "The new maps
help us to understand how Europe's forests are changing. After all,
increasing opening in the canopy pose a risk to the forest, but also other opportunities for new generations of trees that are better adapted to
climate change to establish themselves. Among other things, the maps can
help to identify areas where regeneration needs to be promoted through
targeted planting or where the forests can rejuvenate themselves. In
this way, the forest can be made fit for climate change -- a task that, especially in the last two years, has gained in urgency."

========================================================================== Story Source: Materials provided by
Technical_University_of_Munich_(TUM). Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Cornelius Senf, Rupert Seidl. Mapping the forest disturbance
regimes of
Europe. Nature Sustainability, 2020; DOI: 10.1038/s41893-020-00609-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200915105951.htm

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