August 16, 2017, by Paul Brown
Foresters are being urged to
plant tree species resilient to climate change to save the timber industry as
Swiss trees swelter.
LONDON, 16 August, 2017 – The
most important tree for Switzerland’s forestry industry, the Norway spruce, is
in danger of dying out in much of the country because it cannot adapt fast
enough as Swiss trees swelter in the rising temperatures.
Caroline Heiri, the
lead scientist at the Swiss Federal Institute for Forest, Snow and
Landscape Research (WSL), described the findings as “astonishing” and said
urgent action was needed to save Switzerland’s forests by planting saplings
that can survive the conditions which will occur later this century as the
trees grow to maturity.
Switzerland is already acutely
aware of the
dangers of climate change to its economy as its glaciers shrink and the
Alpine snow line rises. This has already forced some lower ski
resorts out of business and shortened the season for others.
In order to see what effect
climate change would have on another key industry, forestry, scientists planted
16,000 seedlings of the three most important timber species in a nursery to see
how they would respond. The seedlings had been brought from nearly 250
different forest locations at different heights, temperatures and water availability.
Long interval
Although all trees can evolve
and adapt to climate change over time, there is a gap of up to a hundred years
between generations, so the rapid temperature change expected this century will
often be too fast for adaptation to happen.
The three species tested were
Norway spruce, silver fir and European beech, and the seedlings came from all
regions of the country. The researchers studied their growth and monitored the
timing of buds breaking in the spring and growth ending in late summer.
Although the seedlings were
all planted together in one vast nursery, they maintained the growth patterns
that corresponded to the climates at their place of origin.
The scientists, who work in
conjunction with the Federal
Office for the Environment, concluded that of the three species the Norway
spruce had over the centuries adapted very closely to the local climates where
it grows. This means that the growing trees and their descendants in these
locations will not thrive in rising temperatures, especially in regions which
are already warming.
Adaptable fir
The European beech also showed
local adaptation, but it was less pronounced than with the spruce. The silver
fir, on the other hand, had apparently made few adjustments and thrived in many
different conditions, making it a far better bet for Switzerland’s future
forests.
The results, published
by WSL, show that the Norway spruce, the tree most favoured by the Swiss
forestry sector, will be at risk throughout the country from advancing climate
change by the end of the 21st century.
Urgent action is required to
adapt the forests, and the scientists advise planting Norway spruce only on
sites with a good water supply and using seeds originating from warmer
habitats.
This will mean they are likely
to be already adapted to regions that are currently cool but have started
warming. The scientists also suggest planting spruce from the valley floors
higher up the mountains, or obtaining specimens from other countries where the
tree is already accustomed to warmer and drier climes.
A similar procedure could be
applied for European beech, taking seeds from growth locations that are already
dry today. “If we use seeds from trees in warmer and drier regions, we will at
least have a chance for these species to thrive for yet another forest
generation. This way, our forests will remain stable and protect us against
natural hazards”, says Caroline Heiri.
The best option, however, is
to opt for trees tolerant of much wider environmental conditions, like the
silver fir. It may prove Swiss foresters’ major hope for the future, the
research concludes.
– Climate News Network
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