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Tropical mountain forests
With warmer temperatures, ecosystems often respond
by moving upslope to colder climates (Feeley and
Silman, 2010). This trend has been observed for
Adaptation policies must be designed to
acknowledge the local variation in both hazards
from climate change, and the vulnerabilities of
local people and ecosystems. Lake Titicaca is the
largest lake in South America in terms of volume.
Due to its size and depth, it has a substantial
effect on the local climate. The immediate areas
around the lake today are about 4-5°C warmer
and are also wetter than comparable areas at the
same altitude. Palaeological records have shown
that as water levels of the lake lowered during
warm, dry, interglacial periods, a regional cooling
effect took place and even reversed the trend
towards warming. In a warming world, species are
generally expected to migrate upward in order to
stay within their optimal temperature range. This
has already been observed on tropical mountains
(Feeley et al., 2011). However, Lake Titicaca may
be an example where such general assumptions
do not apply and where the upward migration
of forests will be halted abruptly (Bush et al.,
2010). However, a reduced Lake Titicaca would
have a huge impact on irrigation and agriculture
downstream and Lake Titicaca has an impact on
the whole endorreic (closed drainage system)
Titicaca-Desaguadero-Poopó-Salares watershed.
Lake Titicaca – Cooler as it becomes drier?
decades as some species of trees are attempting to out-
climb the heat (Feeley et al., 2011).The aforementioned
biome-based model predicts that areas currently
covered by páramos will become suited to tropical
mountain forests (Tovar et al., 2013). The model also
predicts a reduction of evergreen forests, in favour of
more seasonally dry forests. However, the predicted
rate of warming requires forests to migrate by more
than 9m in altitude per year (Feeley and Silman, 2010).
This is much lower than observed migration rates
and it is likely that most species will lose substantial
proportions of their population.
Variance in ability to migrate partly determines
the implications of climate change on species and
ecosystems. Cloud forests, for example, have been
unable to migrate into the high grasslands while
being diminished in lower elevations (Rehm and
Feeley, 2015). Features of both species themselves
and their environment can limit migration. For
instance, insurmountable peaks and steep valleys
represent migration borders. Land use can also
reduce the ability for tropical mountain forests to
migrate. Studies show faster upward migration in
protected than in non-protected areas (Lutz et al.,
2013). However, the rate of migration is still too slow
to match the predicted changes in climate.
Lakes and rivers
The aquatic ecosystems of the Tropical Andes include
a great number of lakes, rivers and wetlands occupied
by fish, microinvertebrates, plankton, algae and plants.
The diversity of fish species declines with altitude,
while algae and aquatic plants show the greatest
diversity above 3,000 m (Maldonado et al., 2011). Lake
Titicaca, with its numerous endemic species of fish,
plants and algae, is an exception.The highly vulnerable
aquatic ecosystems could be an early indicator of
climate change in the region. However, few studies
exist on the topic. Studies from Europe suggest a
substantial decrease of cold-water species in favour of
more warm-water species. Rivers and lakes depending
on water from vulnerable areas such as páramos and
glaciers could experience the largest impact.
Lake Titicaca