Trees grow faster in warmer conditions, and this should act as a natural brake on global heating, as they take up and store more carbon dioxide from the air as they grow. But the new study casts doubt on this beneficial cycle, finding that the faster trees grow, the sooner they die – and therefore stop storing carbon.
Some fast-growing trees, including conifer species in cold regions, have long been known to show shorter lifespans, but what was not known was the impact of warmer conditions that can spur growth as global heating accelerates. An international team of researchers, publishing their work on Tuesday in the peer-review journal Nature Communications, has found that the relationship between faster growth and shorter lifespan appears to hold good across tree species and latitudes.
Trees growing faster in warmer conditions reach their maximum size sooner, and that appears to increase their chance of dying. Trees that grow more quickly may also be more vulnerable to factors such as drought, disease and pests. When trees die, they give up their stored carbon gradually, in the form of methane, a greenhouse gas. This means that many standard climate change models of how we can use forests as carbon sinks, to absorb the carbon dioxide we produce from fossil fuel burning, are likely to overestimate the benefits. This study suggests that although the forests of the future might grow faster as temperatures increase, they could also store less carbon as the trees die off sooner.
Source: Guardian
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