in Sierra Nevada. Multiple pieces of evidence indicate that from about 3,000 years
ago to the present, human activity intensified in Sierra Nevada (Anderson et al.
2011; Jiménez-Moreno and Anderson 2012; Jiménez-Moreno 2016). After 3000 BP
the frequency of fires increased, and there are signs of grazing as well as mining;
more recently, olive cultivation on a large scale at the lowest elevations together
with pine reforestation have become characteristic.
The mountain landscapes of Sierra Nevada have undergone massive land-use
changes from the past century. The sharp decline in agro-pastoral pressure due to
rural depopulation raises major environmental and societal issues. For instance,
there is evidence from paintings, forestry maps, and the land registry of the last
100 years (Jiménez-Olivencia et al. 2016; Moreno-Llorca et al. 2016) of a clear
land-use shift over the last 50–60 years, due to both the abandonment of agricultural and livestock activities, as well as a surge in active reforestation (pine plantations; Fig. 16.6). Land-use change in the last 50 years has affected over half of the
170,000 ha of Sierra Nevada Protected Area.
We hypothesized that the land-use changes in Sierra Nevada should facilitate the
native forest regeneration, and a process of colonization of marginal habitat
(abandoned cropland, pine plantations) will occur. The distribution of the oak
forests in Sierra Nevada and their degree of conservation are determined both
by biophysical variables that are expressed at present (slope, climate, water
availability‚ etc.), and by the dynamics of land-use changes in recent decades
(intensive use and subsequent abandonment). We have quantified the ecological
functions “seed production and dispersal” and “sapling survival and growth” both
at the upper elevational limit as well in marginal habitats (i.e. abandoned croplands
and pine plantations). The preliminary results showed that oak forests regenerated
more readily on the north-eastern than on the southern slopes, whereas the colonization of abandoned crops seems to occur more intensely in the south than in the
north-east (possibly due to the greater incidence of herbivory in the latter slope)
(Pérez-Luque et al. 2015; Bonet et al. 2016).
Moreover, the ecosystem transformation associated with land-use changes
drastically diminishes the biological legacies, including remnant native woody
plants and their propagules. Consequently, the recuperation of community diversity
within human-created habitats (such as abandoned cropland, pine plantations)
depends heavily on both internal, in situ biological legacies, and external,
well-conserved nearby areas, as a source of propagules. The effect of these historical and current ecological factors on current Quercus species regeneration under
pine plantations has been analysed in Sierra Nevada massif (southern Spain). Our
results indicate that native oak forest regeneration ability under pine plantations
depends largely on land-use legacies, although nearby, well-conserved areas also
provide propagules for colonization from outside the plantation (Gómez-Aparicio
et al. 2009; Navarro-González et al. 2013; Pérez-Luque et al. 2016a). The higher the
land-use intensity in the past, the weaker biological legacies are and, therefore, the
weaker the current native forest regeneration ability, and vice versa.
398
R. Zamora et al.
ago to the present, human activity intensified in Sierra Nevada (Anderson et al.
2011; Jiménez-Moreno and Anderson 2012; Jiménez-Moreno 2016). After 3000 BP
the frequency of fires increased, and there are signs of grazing as well as mining;
more recently, olive cultivation on a large scale at the lowest elevations together
with pine reforestation have become characteristic.
The mountain landscapes of Sierra Nevada have undergone massive land-use
changes from the past century. The sharp decline in agro-pastoral pressure due to
rural depopulation raises major environmental and societal issues. For instance,
there is evidence from paintings, forestry maps, and the land registry of the last
100 years (Jiménez-Olivencia et al. 2016; Moreno-Llorca et al. 2016) of a clear
land-use shift over the last 50–60 years, due to both the abandonment of agricultural and livestock activities, as well as a surge in active reforestation (pine plantations; Fig. 16.6). Land-use change in the last 50 years has affected over half of the
170,000 ha of Sierra Nevada Protected Area.
We hypothesized that the land-use changes in Sierra Nevada should facilitate the
native forest regeneration, and a process of colonization of marginal habitat
(abandoned cropland, pine plantations) will occur. The distribution of the oak
forests in Sierra Nevada and their degree of conservation are determined both
by biophysical variables that are expressed at present (slope, climate, water
availability‚ etc.), and by the dynamics of land-use changes in recent decades
(intensive use and subsequent abandonment). We have quantified the ecological
functions “seed production and dispersal” and “sapling survival and growth” both
at the upper elevational limit as well in marginal habitats (i.e. abandoned croplands
and pine plantations). The preliminary results showed that oak forests regenerated
more readily on the north-eastern than on the southern slopes, whereas the colonization of abandoned crops seems to occur more intensely in the south than in the
north-east (possibly due to the greater incidence of herbivory in the latter slope)
(Pérez-Luque et al. 2015; Bonet et al. 2016).
Moreover, the ecosystem transformation associated with land-use changes
drastically diminishes the biological legacies, including remnant native woody
plants and their propagules. Consequently, the recuperation of community diversity
within human-created habitats (such as abandoned cropland, pine plantations)
depends heavily on both internal, in situ biological legacies, and external,
well-conserved nearby areas, as a source of propagules. The effect of these historical and current ecological factors on current Quercus species regeneration under
pine plantations has been analysed in Sierra Nevada massif (southern Spain). Our
results indicate that native oak forest regeneration ability under pine plantations
depends largely on land-use legacies, although nearby, well-conserved areas also
provide propagules for colonization from outside the plantation (Gómez-Aparicio
et al. 2009; Navarro-González et al. 2013; Pérez-Luque et al. 2016a). The higher the
land-use intensity in the past, the weaker biological legacies are and, therefore, the
weaker the current native forest regeneration ability, and vice versa.
398
R. Zamora et al.