The Amazon is kind of like Pokemon Go for biologists. A new study suggests that, to date, we’ve found more than 11,000 tree species in the region’s rainforests and savannas, but there are at least another 4000 out there, waiting to be discovered. If we keep spotting them at our current pace, researchers say, catching them all could take us another three centuries. They discussed their findings in the journal Scientific Reports.
Before the researchers could speculate on those known unknowns, they had to tally up the, well, known knowns. The team knew that the Amazon—the largest rainforest in the world, spanning nine countries—is home to around 1300 species of birds, 427 species of mammals, and 50,000 species of seed plants. And thanks to an earlier study, they had a pretty good guess of the number of tree species: 16,000. But that was just an estimate. To date, nobody had counted.
So the team, which included botanists from six countries, dug into museum collections around the world and started counting. They reviewed more than half a million specimens from the last 308 years. The final tally was 11,676 different tree species, each one a unique thread in the Amazon’s vivid and varied tapestry. Think about that for a moment. How many different trees can you name off the top of your head? Got a number? Good. Now multiply it by a lot.
The team’s sum total doesn’t invalidate the earlier estimate of 16,000 species. Quite the opposite, in fact. Based on the number we’ve found so far, and the rate at which we’ve been collecting and discovering them, the authors believe we’ve got at least another 4000 to track down.
Doing that could take a while, says study co-author Nigel Pitman, senior conservation ecologist at The Field Museum in Chicago. “Since 1900, between 50 and 200 new trees have been discovered in the Amazon every year,” he said in a press statement. “Our analysis suggests that we won’t be done discovering new tree species there for three more centuries.”
Will there even be an Amazon in 300 years? That remains to be seen. Deforestation levels have decreased in the last few years, but hardly stopped. “If deforestation were to increase to levels of the early 2000s,” the authors write, “most of the rare—and possibly unknown—species in eastern and southern Amazonia would face threat of extinction.”
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