Amazonian tree diversity - 300 more years of work

...we need far better data on the geographic ranges and abundances of tropical tree species to finally put the “how many species?” question to rest. It seems to me that our priorities are misplaced. We spend many billions of dollars to look for extra-terrestrial life but far less to understand life and its distribution on our own planet. (SP Hubbell)

There are more different tree species in the Amazon rainforest than anywhere else on earth, but the exact number has long been a mystery. In 2013, scientists estimated that the number of species was around 16,000. However, no one had ever counted them all up nor been able to describe them all.

In a new study, the same scientists delved into museum collections from around the world to confirm just how many tree species have been recorded for the Amazon region so far and how many have yet to be discovered. The study relied upon the digitization of museum collections data, photographs and digital records of the specimens housed in museum collections that are shared worldwide through aggregator sites like IDigBio.

We report 530,025 unique collections of trees in Amazonia, dating between 1707 and 2015, for a total of 11,676 species in 1225 genera and 140 families.

The researchers interpret this to mean that their earlier estimate of 16,000 species is valid, and that about 4,000 Amazonian trees remain to be discovered and described. There is a bit of a problem though. The colleagues also state that since 1900, between fifty and two hundred new trees have been discovered in the Amazon every year. Based on the new results this would mean that it will take us more than 300 years to discover the rest. It is likely that some of them will be gone by the time we would be able to find them. According to the authors if deforestation were to increase to levels of the early 2000s, most of the rare - and possibly unknown - species in eastern and southern Amazonia would face threat of extinction.

The colleagues have some suggestion to speed up the process a bit:

• Digitize all Amazonian herbarium specimens as there might be up to 50% of the undiscovered species hiding in some collections.
• Support and develop taxonomic and floristic expertise
• Accelerate and facilitate information exchange on Amazonian trees
• More focus on Amazonian research
• Target geographic areas where collection effort is low and expected diversity is high
• Embrace new technologies (they explicitly include DNA barcoding in this)