Nature In Brief -- Research spotlights the long lives of sharks; older trees grow faster

Staff Reports
Nature In Brief -- Research spotlights the long lives of sharks; older trees grow faster
   GOOD NEWS FOR SHARKS:  Summer is just around the corner. But before you buy a bathing suit, consider this: Great white sharks live a nice, long life.

      These legendary predators grow slower and live longer than once thought, according to research led by the Woods Hole Oceanographic Institution in Woods Hole, Mass.
       “In the first successful radiocarbon age validation study for adult white sharks, researchers analyzed vertebrae from four females and four males from the northwestern Atlantic Ocean. Age estimates were up to 73 years old for the largest male and 40 years old for the largest female,” according to a press release from Woods Hole.
       “Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies,” said Li Ling Hamady, MIT/WHOI Joint Program student and lead author of the study published in PLOS ONE. “Understanding longevity of the species, growth rate, age at sexual maturity, and differences in growth between males and females are especially important for sustainable management and conservation efforts.”

     OLDER TREES GROW FASTER: Like many humans, trees put on weight faster as they grow older, but unlike in humans, that’s a healthy change. The accelerated growth may mean that old, large trees remove more carbon from the atmosphere than scientists once believed, according to new research published in the journal Nature.
    “Rather than slowing down or ceasing growth and carbon uptake, as we previously assumed, most of the oldest trees in forests around the world actually grow faster, taking up more carbon,” said Richard Condit, staff scientist at the Smithsonian Tropical Research Institute. “A large tree may put on weight equivalent to an entire small tree in a year.”
     Another researcher, Nate Stephenson, lead author and forest ecologist with the U.S. Geological Survey, put that statistic in context: “If human growth would accelerate at the same rate, we would weigh half a ton by middle age and well over a ton at retirement."
      More study is needed, however, to determine whether faster growth of individual trees translates into greater carbon storage by aging forests. Some emissions reduction programs are based on the idea that forest conservation and reforestation mitigate global warming by reducing carbon dioxide in the atmosphere.