primary productivity in the oligotrophic waters of mountain lakes of Sierra Nevada
(Villar-Argaiz et al. 2001).
Elevation range extension
The consequences of climate and land-use changes are typically most evident in
mountain habitats, where expansions or contractions in species’ distribution ranges
along elevation gradients may occur via the migration of species to new areas
(Jump and Peñuelas 2005; Lenoir et al. 2008). Species may expand upwards into
new areas that become favourable, and retract from those that turn unfavourable.
For instance, a comparative study on macroinvertebrate communities in the rivers
of Sierra Nevada in the 1980s and today reveals substantial changes (Sáinz-Bariáin
et al. 2015). Some species in the 1980s that were associated with the middle
elevation stretch of the rivers are today found in the higher reaches. As a result, the
diversity of species in the upper reaches of rivers is far greater than 30 years ago. In
places where the water temperature has increased more, there has also been a major
increase in the diversity of caddisflies. In the case of Plecoptera, it has been found
that the lower limits of the distribution of some species have contracted, while the
distribution at the upper limits has remain unchanged.
In terrestrial ecosystems a similar pattern has been found. Faunistic inventories
conducted 20–40 years ago have been repeated in recent years. Significant changes
in the spatial distribution and/or abundance of several groups of species were found.
For insects, an elevational migration has been confirmed for dung beetles
(Menéndez et al. 2014). The results show that within 25 years, 89% of the species
increased their average elevation and upper distribution limits while more than 84%
increased their lower distribution limits. The average elevational ascent of dung
beetles in Sierra Nevada over 25 years was 400 m, coinciding with a rise of the
same magnitude in the butterfly Apollo (Barea-Azcón 2016). Meanwhile, ants
(Formicidae, Hymenoptera) have also risen in elevation, at least in the case of two
species (Proformica longiseta and Formica fusca/lemani), which have expanded
their upper distribution limits by about 200 m on the southern slopes of Sierra
Nevada (González-Megías et al. 2016).
Among vertebrates, equivalent responses have also been found. For instance,
passerines have shown marked temporal dynamics over the last 30 years which
have been strongly influenced by global change (Zamora and Barea-Azcón 2015).
Some generalist mountain species are now more abundant than before in
high-mountain areas, while the most typical alpine species have become progressively scarcer. Overall, there has been a decline in montane species, which have
been replaced by more thermophilic Mediterranean lowland species. We conclude
that, within the global change context, protected mountain areas play a vital role in
maintaining biodiversity, as populations can adapt to shifting conditions, moving
along elevation gradients, according to their ecological requirements.
Ongoing changes in climate are altering ecological conditions for many plant
species, and are most evident at the edge of the geographical distribution of a
species, where range expansions or contractions may occur. For example, the
demographic structure of both Pinus sylvestris and Juniperus communis
402
R. Zamora et al.
(Villar-Argaiz et al. 2001).
Elevation range extension
The consequences of climate and land-use changes are typically most evident in
mountain habitats, where expansions or contractions in species’ distribution ranges
along elevation gradients may occur via the migration of species to new areas
(Jump and Peñuelas 2005; Lenoir et al. 2008). Species may expand upwards into
new areas that become favourable, and retract from those that turn unfavourable.
For instance, a comparative study on macroinvertebrate communities in the rivers
of Sierra Nevada in the 1980s and today reveals substantial changes (Sáinz-Bariáin
et al. 2015). Some species in the 1980s that were associated with the middle
elevation stretch of the rivers are today found in the higher reaches. As a result, the
diversity of species in the upper reaches of rivers is far greater than 30 years ago. In
places where the water temperature has increased more, there has also been a major
increase in the diversity of caddisflies. In the case of Plecoptera, it has been found
that the lower limits of the distribution of some species have contracted, while the
distribution at the upper limits has remain unchanged.
In terrestrial ecosystems a similar pattern has been found. Faunistic inventories
conducted 20–40 years ago have been repeated in recent years. Significant changes
in the spatial distribution and/or abundance of several groups of species were found.
For insects, an elevational migration has been confirmed for dung beetles
(Menéndez et al. 2014). The results show that within 25 years, 89% of the species
increased their average elevation and upper distribution limits while more than 84%
increased their lower distribution limits. The average elevational ascent of dung
beetles in Sierra Nevada over 25 years was 400 m, coinciding with a rise of the
same magnitude in the butterfly Apollo (Barea-Azcón 2016). Meanwhile, ants
(Formicidae, Hymenoptera) have also risen in elevation, at least in the case of two
species (Proformica longiseta and Formica fusca/lemani), which have expanded
their upper distribution limits by about 200 m on the southern slopes of Sierra
Nevada (González-Megías et al. 2016).
Among vertebrates, equivalent responses have also been found. For instance,
passerines have shown marked temporal dynamics over the last 30 years which
have been strongly influenced by global change (Zamora and Barea-Azcón 2015).
Some generalist mountain species are now more abundant than before in
high-mountain areas, while the most typical alpine species have become progressively scarcer. Overall, there has been a decline in montane species, which have
been replaced by more thermophilic Mediterranean lowland species. We conclude
that, within the global change context, protected mountain areas play a vital role in
maintaining biodiversity, as populations can adapt to shifting conditions, moving
along elevation gradients, according to their ecological requirements.
Ongoing changes in climate are altering ecological conditions for many plant
species, and are most evident at the edge of the geographical distribution of a
species, where range expansions or contractions may occur. For example, the
demographic structure of both Pinus sylvestris and Juniperus communis
402
R. Zamora et al.