Tracking bears to fathom how plants disperse seeds in forests
TOKYO: Plants can’t move once they take root, but they have a few tricks up their sleeve to spread their seeds far and wide - by hitching a ride on animals or blowing through the skies while others, as a researcher recently discovered, are dispersed through bear poop.
“Bears eat nuts and disperse seeds throughout the forest through their poop,” Tokyo University of Agriculture and Technology Senior Assistant Prof. Shinsuke Koike, 36, said. “Some were even dispersing seeds more than 20 kilometres away from where they ate them.”
According to Koike, bears are “vastly superior seed dispersers” when compared to apes with a dispersal range of around 150 metres and birds about 300 metres.
Back in his days as a student at the Tokyo University of Agriculture and Technology, Koike started studying the ecology of Japanese black bears.
He found many different kinds of seeds in their poop, including those of sakura, giant dogwood and crimson glory vine in various states - some were chewed up and digested while others were left intact. The lecturer realised that “they were new clues for forest ecosystem research.”
Taking his studies a step further, 30 bears were captured and fitted with GPS collars to measure their movement speed. Meanwhile, he made observations at a bear park in Akita Prefecture.
“After eating seeds from trees, bears take around 20 hours on average to excrete them out. The longest record was 44 hours,” Koike said, adding that he calculated their dispersal range based on such data.
He said bears are difficult to observe directly since they’re “notoriously shy,” making the collection of poop scattered around mountains a vital process in understanding the role that bears play in their ecosystem. “I’ve only seen them a few times myself,” Koike said.
The task is all but easy - poop is often hidden among vegetation and they quickly break down during summer. Koike would spend entire days trekking across the mountains only to come home empty-handed, but he never gave up. Now, he has a collection of over 1,000 droppings.
“Other researchers don’t stand a chance now that I have so much,” Koike said, laughing.
“There should be lots of other animals tucked away in the mountains with equally surprising roles,” he said. “One by one, I hope to unlock the mysteries of the forest.”
And so, Koike continues to trek into the mountains. — WPBloomberg/Yomiuri Shimbun