Asian black bear

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How bears help trees climb mountains

If you’re a plant, there are only two places you can go to escape a warming world: toward the poles, or up a mountain. But because you can’t move, you need to rely on animals to get you—or more accurately, your seeds—there. And what if they aren’t going your way? In a new study, scientists looked at a specific example: a species of Japanese cherry tree (Prunus verecunda) that needs mammals to spread its seeds. Asian black bears (Ursus thibetanus, pictured) eat most of the cherries, and the researchers could determine where the bears—um—deposited the seeds by measuring the seeds’ levels of a variety of types of oxygen, which change with altitude. The bears moved the seeds an average of about 300 meters up in altitude, the team reports today in Current Biology, likely because the timing of cherry fruiting coincides with the bears’ springtime trek up the mountains to follow fruiting plants. That’s a 2°C temperature drop, meaning cherry trees will likely be able to keep up with climate change thanks to the behaviors of their seed-spreaders. Other plants may not be so lucky.