Amazonian trees

Today a non-malacological topic, but still relevant in my opinion. Trees in Amazonia may host a largely unknown (at least a highly under-collected) malacofauna. Personally I’m convinced that if malacologists would explore canopies better, it would yield very interesting results.

Anyway, this post is provoked by a review on the Amazonian tree flora by ter Steege et al., (2016). Their abstract reads as follows “Amazonia is the most biodiverse rainforest on Earth, and the debate over how many tree species grow there remains contentious. Here we provide a checklist of all tree species collected to date, and describe spatial and temporal trends in data accumulation. 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. These figures support recent estimates of 16,000 total Amazonian tree species based on ecological plot data from the Amazonian Tree Diversity Network. Botanical collection in Amazonia is characterized by three major peaks, centred around 1840, 1920, and 1980, which are associated with flora projects and the establishment of inventory plots. Most collections were made in the 20th century. The number of collections has increased exponentially, but shows a slowdown in the last two decades. We find that a species’ range size is a better predictor of the number of times it has been collected than the species’ estimated basin-wide population size. Finding, describing, and documenting the distribution of the remaining species will require coordinated efforts at under-collected sites”.

terSteege2016

The article gives a historical overview of the collections made in Amazonia, i.e. French Guiana, Suriname, Guyana, Ecuador, Colombia, Brazil, Peru, Venezuela, and Bolivia, together with data of diversity and collection density, taxonomic patters, collection frequency, population size and range size. The discussion offers valuable suggestions for further research and concludes with a citation from Hubbell (2015) that is mutatis mutandis applicable also to malacology: ‘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’.

References:
Hubbell, S. P., 2015. Estimating the global number of tropical tree species, and Fischer’s paradox. – Proceedings of the National Academy of Science USA 112, 7343–7344.
ter Steege, H., Vaessen, R.W., Cárdenas-López, D., Sabatier, D., Antonelli, A., Mota de Oliveira, S., Pitman, N.C.A., Møller Jørgensen, P. & Salomão, R.P., 2016. The discovery of the Amazonian tree folra with an updated checklist of all known tree taxa. – Scientific Reports 6: 29549. Available at http://www.nature.com/articles/srep29549

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