Balancing Trees and CO2
Tree planting used to be regarded as an effective means of reducing climate change. Perhaps it’s time for us to rethink this practice. Trees pull CO2 from the air. This effectively removes CO2 from the atmosphere. But trees only hold onto CO2 as long as they’re alive. Once they die, trees decay (腐烂) and release that CO2 back into the atmosphere.
Recent studies have found that trees around the world are growing faster than ever. The rise of CO2, mainly due to burning fossil fuels, is probably driving that rapid growth, said Roel Brienen, a forest ecologist at the University of Leeds, UK. High levels of CO2 are increasing temperatures, which in turn speeds tree growth in those areas, he added.
The faster trees grow, the faster they store carbon. It seems like good news. However, it is known that fast-growing tree species, in general, live shorter lives than their slow-growing relatives.
In order to see whether the growth-lifespan trade-off (生长与寿命之间的权衡) is a universal phenomenon, Brienen and his colleagues analyzed over 210,000 individual tree ring records of 110 tree species from more than 79,000 sites worldwide. They found that, in almost all habitats and all sites, faster-growing tree species died younger than slow-growing species, and even within a species, the trade-off between growth and life span held strong.
The team also created a computer program that modeled a forest and tweaked (微量调整) the growth of the trees in this model. Early on, it showed that “the forest could hold more carbon as the trees grew faster”, Brienen reported. But after 20 years, these trees started dying and losing this extra carbon again. “We must understand that the only solution to bringing down CO2 levels is to stop emitting (排放) it into the atmosphere,” said Brienen.
1. What does “this practice” in Para.1 refer to?2. Why are trees around the world growing faster than ever?
3. Read the following statement, underline the false part of it and explain the reason. The team has found that the faster trees grow, the faster they store CO2, and the longer lives they live.
4. Please briefly present what you can do in daily life to reduce the emission of CO2.(about 40 words)
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