Climate News Network

Climate helps trees to wax as corals wane

September 29, 2014, by Tim Radford

European spruce are thriving in the warmer climate
Image: Wonderlane via Wikimedia Commons

Some tree species in central Europe are growing faster as the climate changes, while the rising levels of acid it causes are endangering coral in Australia’s Great Barrier Reef. LONDON, 29 September 2014 – Europe’s spruce trees have started to sprint for growth. Beech trees, too, have begun to accelerate. German scientists report that trees in the European forests have increased their growth speeds by up to 77% since 1960. The researchers can say this with confidence because in southern Germany they have access to the oldest network of measured experimental forest plots in the world. Since 1870, foresters and scientists have made 600,000 measurements of individual trees in Bavaria. Hans Pretzsch and colleagues at the Technical University of Munich report in the journal Nature Communications that they selected beech and spruce for their comparisons because these are the dominant species in the forests of Central Europe. The deciduous beech trees were growing 77% faster, and the evergreen spruce by 32% . The best explanation is that the trees are responding to rising average temperatures and a longer growing season: both consequences of climate change. It is also possible that higher atmospheric concentrations of carbon dioxide are contributing to faster growth. The research was carried out in forests that – 40 years ago – were thought to be in danger of dieback from atmospheric pollution: at the time, environmentalists were more worried about acid rain from factory and power station emissions than about global warming, and the German word Waldsterben entered the international vocabulary. “Interestingly we observed that acid rain only had a temporary slowing effect on the growth of our experimental plots. Indeed, the input of pollutants started to fall off from the 1970s,” said Professor Pretzsch.

“Coral reefs are getting hammered and are likely to become a thing of the past unless we start running our economy as if the sea and sky matters to us, very soon”

Although the trees have both grown and aged faster, the forests as a whole have not greatly changed. The expectation is that foresters will be able to take trees for timber significantly faster. But other denizens of the forests may have to learn to adapt. “The plant and animal species that will be most affected are those living in habitats which depend on special phases and structures of forest development. These species may have to become more mobile to survive.” But if global warming is good for tree growth, it still isn’t doing much for the coral reefs. US scientists at work on Australia’s Great Barrier Reef report in the journal Geochimica et Cosmochimica Acta  that coral growth rates have fallen 40% since the mid-1970s. Jacob Silverman of the Carnegie Institution and Ken Caldeira and others studied a stretch of reef where measurements were first recorded 30 years ago, and made comparisons. They found that the rates of calcification, important in shell and skeletal growth, were 40% lower in 2008 and 2009 than during the same season in 1975 and 1976. This time, the change could be put down not to warming, but to the change in water chemistry. As frequently reported by the Climate News Network, as atmospheric carbon dioxide dissolves in the oceans, it changes the pH value of the water, making it gradually more acidic, with sometimes serious consequences for some families of fish and shellfish. “Coral reefs are getting hammered,” says Professor Caldeira. “Ocean acidification, global warming, coastal pollution and overfishing are all damaging coral reefs. “Coral reefs have been around for millions of years but are likely to become a thing of the past unless we start running our economy as if the sea and sky matters to us, very soon.” – Climate News Network

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