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Australia: The Land Where Time Began |
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Pleistocene Megafauna Extinctions – Legacy on
Nutrient Availability in Amazonia According to Doughty, Wolf & Malhi 97 genera of
large animals went extinct in the Late Pleistocene, concentrated in the
Americas and Australia (Barnosky et
al., 2004). There were
significant consequences of these extinctions on the structure of
ecosystems (Gill et al.,
2009), seed dispersal (Janzen & Martin, 1982) and albedo of the land
surface (Doughty, Wolf & Field, 2010). However, the impact of these
dramatic extinctions on the nutrient biogeochemistry of ecosystems with
regard to the lateral transport of dung and bodies has never been
explored. In this study Doughty, Wolf & Malhi used a novel mathematical
framework that analyses lateral transport as a process that is
diffusion-like, and they suggest they have demonstrated the
disproportionally large role of large animals in the horizontal
transport of nutrients across landscapes. An example they give is their
estimate that the Amazonian megafauna extinction decreased the lateral
flux of phosphorus, a limiting nutrient, by more than 98 %, with
similar, though less extreme decreases in all continents outside Africa.
The result of this was a strong decrease in the availability of
phosphorus in eastern Amazonia away from the fertile floodplains, and
they suggest this decline may still be continuing. The limitation of
phosphorus in the Amazon Basin of the present is suggested to possibly
be, at least partially, a relic of an ecosystem that lacks the
functional connectivity it had in the past. Doughty, Wolf & Malhi argue
that the megafauna extinctions of the Pleistocene have resulted in large
disruptions in terrestrial biogeochemical cycling on continental scales
and increased nutrient heterogeneity globally, that are ongoing.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |