Climate change pushing tropical trees upslope 'exactly as
predicted'  By: Claire Salisbury September 27, 2013     Looking
up at a giant tree in the Costa Rican rainforest Photo credit:
Rhett A. Butler / mongabay.comLooking up at a giant tree in the
Costa Rican rainforest Photo credit: Rhett A. Butler /   These
changes corresponded to a mean thermal migration rate of
0.0065°C per year. However, over the past 60 years regional
warming has been 0.0167°C per year, so the average migration
rate observed across plots is not fast enough to keep up with
the rate of warming. Still, encouragingly, when looked at
individually, migration in 4 of the 10 plots did keep pace with
regional warming.  Changes in species composition can be the
result of different processes: species abundance can change
without shifts in the overall range distribution, ranges can
shift, and ranges can expand or contract. Identifying which of
these underlies changes in species composition is important,
because "depending on which of these process