This perspective need not distract our attention from moments of ‘stability’ in
the natural system because, even if thresholds of change are abrupt, succession—
whether progressive or regressive, will be much longer (Margalef 1991). According
to Dietl and Flessa (2011) there are three main ways in which species respond to
changes in their environment: “(1) they can move, tracking environmental changes;
(2) they can stay and adapt to the changing environment; and (3) they can fail to
track habitats or to adapt, thus becoming extinct” (Dietl and Flessa 2011: 32). This
leads us to reflect on a typology of time concepts (change, evolution, transformation, process) (Mendizábal 2013), without neglecting another key concept: resilience, a term that is currently used in many fields. Froyd and Willis (2008: 1726)
defined resilience as “the ability of systems to absorb disturbance and still maintain
the same relationships between populations (…). Thus resilience is the magnitude
of disturbance that can be tolerated before a system moves to another stable state.”
At present, the study of resilience is being applied to the effects of climate change
and paleoecological archives that help us understand why some ecosystems are
more resilient to climate change than other and identify different degrees of resilience in different systems. The number of available studies and the contributions of
genetic diversity have been another important factor for the maintenance of resilience in studies on the conservation of genetic diversity (Willis et al. 2010).
The general debate has focused on the study of interactions between climate,
ecological processes, and human activities in the past in order to better understand
the behavior of ecosystems in the present and future (Dearing and Battarbe 2007).
In this context, high-mountain zones have been considered among the most sensitive and vulnerable to the environmental changes predicted for the 21st century
and one of the priority areas for attention to the value of natural attributes (Huber
et al. 2005).
The reason for this is that human activity cannot be decoupled from landscape
because they form part of it: “Over 75% of the Earth’s terrestrial biomes now show
evidence of alteration as a result of human residence and land use” (Willis and
Bhagwat 2009: 807). Most western European forests today “have long and diverse
histories of anthropogenic disturbance and current conservation values incorporate
both natural and cultural features” (Bradshaw et al. 2015: 194). In this sense, pollen
studies with high spatial resolution have shown that simple temporal concepts like
‘natural baselines’ and the continuity of forest cover underestimate the complexity
of the past (Bradshaw et al. 2015). What is the main problem? The complex nature
of the relations between climate change and human activities. Why? For the following reasons:
(a) The same evidence/variable may indicate different things, and these may
change over time.
(b) The same effect may have multiple possible origins that are completely
opposite and therefore can have multiple origins that are completely opposite
and therefore antagonistic. For example, Willis and Birks (2006: 1263) wrote
that it “is not unreasonable to assume that an increase in aridity would result in
more fires; several studies indicate otherwise.” They base their argument on the
5 The Role of Environmental Geohistory …
111
the natural system because, even if thresholds of change are abrupt, succession—
whether progressive or regressive, will be much longer (Margalef 1991). According
to Dietl and Flessa (2011) there are three main ways in which species respond to
changes in their environment: “(1) they can move, tracking environmental changes;
(2) they can stay and adapt to the changing environment; and (3) they can fail to
track habitats or to adapt, thus becoming extinct” (Dietl and Flessa 2011: 32). This
leads us to reflect on a typology of time concepts (change, evolution, transformation, process) (Mendizábal 2013), without neglecting another key concept: resilience, a term that is currently used in many fields. Froyd and Willis (2008: 1726)
defined resilience as “the ability of systems to absorb disturbance and still maintain
the same relationships between populations (…). Thus resilience is the magnitude
of disturbance that can be tolerated before a system moves to another stable state.”
At present, the study of resilience is being applied to the effects of climate change
and paleoecological archives that help us understand why some ecosystems are
more resilient to climate change than other and identify different degrees of resilience in different systems. The number of available studies and the contributions of
genetic diversity have been another important factor for the maintenance of resilience in studies on the conservation of genetic diversity (Willis et al. 2010).
The general debate has focused on the study of interactions between climate,
ecological processes, and human activities in the past in order to better understand
the behavior of ecosystems in the present and future (Dearing and Battarbe 2007).
In this context, high-mountain zones have been considered among the most sensitive and vulnerable to the environmental changes predicted for the 21st century
and one of the priority areas for attention to the value of natural attributes (Huber
et al. 2005).
The reason for this is that human activity cannot be decoupled from landscape
because they form part of it: “Over 75% of the Earth’s terrestrial biomes now show
evidence of alteration as a result of human residence and land use” (Willis and
Bhagwat 2009: 807). Most western European forests today “have long and diverse
histories of anthropogenic disturbance and current conservation values incorporate
both natural and cultural features” (Bradshaw et al. 2015: 194). In this sense, pollen
studies with high spatial resolution have shown that simple temporal concepts like
‘natural baselines’ and the continuity of forest cover underestimate the complexity
of the past (Bradshaw et al. 2015). What is the main problem? The complex nature
of the relations between climate change and human activities. Why? For the following reasons:
(a) The same evidence/variable may indicate different things, and these may
change over time.
(b) The same effect may have multiple possible origins that are completely
opposite and therefore can have multiple origins that are completely opposite
and therefore antagonistic. For example, Willis and Birks (2006: 1263) wrote
that it “is not unreasonable to assume that an increase in aridity would result in
more fires; several studies indicate otherwise.” They base their argument on the
5 The Role of Environmental Geohistory …
111