While providing benefits to the environment, some trees also emit gases to the atmosphere that worsen air pollution and alter climate.
While providing benefits to the environment, some trees also emit gases to the atmosphere that worsen air pollution and alter climate. Field trials in Oregon and Arizona show that poplar trees, which emit trace amounts of the gas isoprene, can be genetically modified not to harm air quality while leaving their growth potential unchanged.
The findings, published today in the journal Proceedings of the National Academy of Sciences, are important because poplar plantations cover 9.4 million hectares (36,294 square miles) globally – more than double the land used 15 years ago. Poplars are fast-growing trees that are a source of biofuel and other products including paper, pallets, plywood and furniture frames.
Poplars and other trees used in plantation agroforestry, including palms and eucalyptus, produce isoprene in their leaves in response to climate stress such as high temperature and drought. The isoprene alleviates those stresses by signaling cellular processes to produce protective molecules; however, isoprene is so volatile that millions of metric tons leak into the atmosphere each year.
The emitted isoprene reacts with gases produced by tailpipe pollution to produce ozone, which is a respiratory irritant. Isoprene also causes higher levels of atmospheric aerosol production, which reduces the amount of direct sunlight reaching the earth (a cooling effect), and it causes the global warming potential of methane in the atmosphere to increase (a warming effect). The warming effect is most likely greater than the cooling effect. The net effect of emitted isoprene is to worsen respiratory health and, most likely, warm the atmosphere.
Read more at University of Arizona
Photo credit: Hans via Pixabay
