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Geografisk Tidsskrift-Danish Journal of Geography
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Causal relations and land use transformation in the
Sahel: conceptual lenses for processes, temporal
totality and inertia
Anette Reenberg
a b
a
, Laura Vang Rasmussen & Jonas Østergaard Nielsen
b
a
Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10,
DK-1350, Copenhagen K, Denmark
b
Department of Anthropology, Waterworlds Research Centre, University of Copenhagen,
Øster Farimagsgade 5, DK-1353, Copenhagen K, Denmark
Version of record first published: 14 Jan 2013.
To cite this article: Anette Reenberg , Laura Vang Rasmussen & Jonas Østergaard Nielsen (2012): Causal relations and land
use transformation in the Sahel: conceptual lenses for processes, temporal totality and inertia, Geografisk Tidsskrift-Danish
Journal of Geography, 112:2, 159-173
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Geografisk Tidsskrift-Danish Journal of Geography
Vol. 112, No. 2, November 2012, 159–173
Causal relations and land use transformation in the Sahel: conceptual lenses for processes,
temporal totality and inertia
Anette Reenberga,b*, Laura Vang Rasmussena and Jonas Østergaard Nielsenb
a
Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark;
b
Department of Anthropology, Waterworlds Research Centre, University of Copenhagen, Øster Farimagsgade 5, DK-1353
Copenhagen K, Denmark
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(Received 23 February 2012; final version received 10 September 2012)
The paper addresses the challenge of conceptualizing and analyzing complex change processes and causal explanations in
human–environment systems. To illustrate this challenge empirically, the paper takes its point of departure in the apparent
paradox that the agricultural practices in the desert fringe zone of the Sahel seem to remain remarkably unchanged despite
huge and accelerating changes in major driving forces such as climate variations, population pressure, policies and market
access. Such partly unexpected trends suggest that novel insight is needed into the human environment interactions that
shape the use of land for cultivating purposes in this region. As a background for the paper’s conceptual discussion, recent
developments in the Sahelian land use system are briefly described, using documentation from empirical case studies conducted in the northernmost region of Burkina Faso over the past 20 years. Specific attention is given to presenting (a)
main trends in the transformation of the land use and livelihoods, (b) the co-evolution of possible driving forces that
enables and constrains conditions for change and (c) characteristic trajectories of change. Inspired by the notions of process, temporal totality and inertia, the paper suggests employing a portfolio of complementary perspectives to investigate
change processes. More precisely, four different conceptual lenses to analyze human–environment interaction are proposed
and examined (the land change science framework, the double exposure notion, the system dynamics (SD) approach and
coupled human–environmental timelines). Specific attention is given to the potential contribution of these respective
lenses to enhancing our understanding of the land SD and to uncovering important causal relations. It is concluded that
these conceptual lenses, in concert, can help to put process, in the sense of a sequence of successive stages, in the centre
of our understanding of change and causal relationships in human–environmental systems.
Keywords: system dynamics; land change science; human–environment timelines; exposures
1. Introduction: the point of inspiration
In this paper, we employ a heterodox point of entry to
our exploration of the transformation processes of land
use systems in the Sahel. We highlight the apparent paradox that the agricultural/cultivation activities in some
parts of the Sahelian desert fringe have remained remarkably unchanged over the last decades, despite accelerating changes in underlying conditions – economic,
demographic and climate – that are normally expected to
be significant drivers of land use change.
The majority of the scholarly works about the Sahel
rightly describes agriculture as a very important sector
that sustains most people in the area. A large body of
scientific- and policy-oriented literature about agricultural
systems and livelihoods in the Sahel has been published
in the course of the last 40–50 years. Especially the period following the onset of a series of hard drought years
in the early 1970s has been scrutinized, often with
attention to environmental change and recommendations
*Corresponding author. Email: [email protected]
ISSN 0016-7223 print/ISSN 1903-2471 online
Ó 2012 Taylor & Francis
http://dx.doi.org/10.1080/00167223.2012.741888
http://www.tandfonline.com
for sustainable development pathways. Much of the
attention in this literature has been related to the notions
of degradation and desertification, and, more recently, to
climate change (Barbier et al., 2009; Bolwig et al., 2008;
Marcussen & Reenberg, 1999; Raynaut & Delville,
1997). Several narratives appear to have become established truths beyond need of further documentation.
These include, for example, the notion of vicious circles
of land degradation prompted by population pressure and
low rainfall, leading to excessive expansion of fields
onto marginal land, which in turn leads to irreversible
degradation of the natural resource base, lower productivity and the need for even larger cultivated areas to
sustain the population. Some scattered, recent research
papers do, however, also call for a critical examination
of received wisdom in order to avoid misinterpretation
of the change processes and the likely future trajectories’
(Mortimore et al., 2005).
160
A. Reenberg et al.
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Limited empirical evidence from recent assessments
(Nielsen & Reenberg, 2010b; Rasmussen & Reenberg,
2012) suggests, for example, that land use changes in
the agricultural frontline across the drier part of the Sahel
may not conform very well to a simplistic notion of
more people/less rain => more need for land => field
expansion on marginal land => soil degradation => even
more need for land, etc. If this holds true in more general terms, it will have important implications for the
way in which we envisage the future transformation of
land use systems in this region. If a revised understanding of the processes of change is imperative, it will, in
turn, has implications for policy recommendations in
order to ensure that future land use strategies are
anchored in local realities.
2. Exploring change:
totality and inertia
causal
relations,
temporal
The importance of the dynamic interaction between
humans and the environment in the Sahel is glaring. The
pathways of change of the coupled human–environmental systems are formed by continuous, dynamic interaction between numerous changing factors, social as well
as biophysical, which enable and constrain human
choices of resource management strategies.
Process philosophy (Rescher, 2009) may provide an
ontological source of inspiration for human–environmental system research in as much as it brings process
to the fore. Rechser (2009) emphasizes that processes
have an ineliminably temporal dimension and that a
definitive characteristic of process philosophizing is the
insistence on seeing process as an essential aspect of
everything that exists. Many social scientists have used
the term ‘process’ in a rather loose fashion and have
also been criticized for lacking concern about issues of
methodology and explanation (Vayda et al., 1991). Others have, for example, in connection to land systems
analysis (Liverman et al., 1998; Serneels & Lambin,
2001), found it a useful notion to recognize the fact that
information about the processes and dynamics of a system, including its complex and multidirectional relations. It may infer information, which can help
understanding how and why land use changes are taking place. In the present context, our usage of the term
process does not necessarily postulate a universal model
of similar types of repeatedly unfolding events that
occur in different contexts (as rightly criticized by
Vayda et al., 1991). Rather, the notion is used to capture change of the system in the course of time and
explore how it emerges from multiple, simultaneous
causal loops or feedbacks.
An additional, theoretical source of inspiration is
offered by Chen (2011), who proposes that totality and
inertia matter. He suggests, in his paper addressing the
related theme of climate change, a compelling observation that our frequent misinterpretation of causal relations
is a result of our apparent preference for object-based
ontological assumptions as opposed to an ontology that
properly distinguishes between objects and processes.
The root cause of misinterpretation, he argues, is the limitation of the conceptual model. We frequently use a pattern matching heuristic, seeking correlation among data
and using correlations to predict future values. Such a
heuristic may work for simple systems, where input and
output are closely related in time and space, but it is
inappropriate for complex systems with multiple feedback loops and important time delays. In line with the
reasoning offered by Chen (2011, p. 33)
instead of viewing climate change as a dynamic process,
some people may mistakenly see it as an object (pattern
matching heuristic) … However, climate change belongs
to a different kind of ontological existence. It is a
dynamic process with temporal totality and inertia, two
features essential to understand climate change.
If we translate these theoretical reflections to apply to
land use systems, temporal totality addresses the issue of
how a situation at a given point in time is a result of a
specific development pathway, in that human reactions to
a specific event depend on previous developments, not
only on the current state. Inertia concerns the recognition
of changes as hampered or delayed by state specific conditions. Hence, the two features may caution against the
use of simple correlations between e.g. contemporary
population pressure or soil quality and field size for the
prediction of future values, as in the ‘vicious circle’ narrative mentioned above. The contemporary landscapes
are shaped by human activity interacting with nature, but
decisions made in the past constitute the initial conditions for our present day landscapes. It is therefore
important to get away from static assumptions about
cause and effect (Reenberg, 2011).
This paper will look at the strengths and weaknesses
of four conceptual platforms that have been used by the
global change research community to explore the dynamics of human–environmental systems. Notably their ability to account for the issues of temporal totality and
inertia will be considered. First, the empirical case will
be introduced. Then, we will summarize the key characteristics of the notions of ‘land change science (LCS)’,
‘double exposures’, ‘system dynamics (SD)’ and ‘coupled human–environment timelines’. Finally, we will
suggest how these conceptual platforms or heuristics,
individually or in combination, may enhance our insight
into the way change processes are enabled and
constrained by temporal totality and causal relations.
This will be done by briefly returning to the empirical
example from the Sahel.
Geografisk Tidsskrift-Danish Journal of Geography
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3. The empirical example
A couple of Sahelian cases will serve to support our discussion of causal relations and change processes in land
use systems. They are described in more detail elsewhere
(Nielsen et al., 2012; Nielsen & Reenberg, 2010a;
Rasmussen et al., 2012; Reenberg, 2009; Reenberg & Fog,
1995; Reenberg & Paarup Laursen, 1997); hence, in this
context only the main traits of land use (cropland) changes
and the corresponding change in perceived driving forces
(climate, population pressure and globalization) will be
highlighted. Specific attention will be given to traits of the
human–environment interaction that illustrate the
importance of the notions of temporal totality and inertia.
The cases are located in the northern province of
Burkina Faso, which is part of the Sahelian zone south of
the Sahara desert, extending more than 2000 km from
Senegal through Mali, Burkina Faso, Niger and Chad.
Agricultural and pastoral production are the main sources
of sustenance for the population and the land use system
can briefly be characterized as a combination of cultivated fields and pastures. The livelihood conditions are
traditionally and strongly linked to the ability of the natural resources to support the human population and livestock (Reenberg, 2009). Cropping activities are often
integrated with livestock rearing, the most important links
being income, feed and manure (Petit, 2003). Livestock
mostly depend on grazing the bush and the stubble fields.
Tree cover is relatively scarce in these dry regions, hence
the relative importance of browsing for sustaining the
livestock is considered low. The use of livestock manure
enhances soil fertility, and crop residues provide feed for
livestock during the dry season (Claude et al., 1991;
Powell et al., 1995). Manure may be obtained from farmers’ own herds, from the livestock of other farmers or
through exchange relationships with transhumance pastoralists. The main crops are pearl millet and sorghum,
while cowpeas, groundnuts and cotton are grown to a
lesser extent. Moreover, villagers engage in circular
migration, while working for development projects is
another off-farm strategy of importance (Nielsen et al.,
2012). Abidjan, in Côte d’Ivoire, surpassed Ghana and
Saudi Arabia as the major migration destination in the
1970s and has remained so ever since, despite unrest in
Côte d’Ivorie since 2002 (Nielsen & Reenberg, 2010a).
Since 1984 all land has been considered as state
property by national authorities. Anyone seeking access
to land must in theory apply for use rights from the
state, but it is widely recognized that local communities
tend to regard themselves as the true owners of their
land by virtue of their ancestral rights (Nielsen & Reenberg, 2010b; Ouedraogo, 2005). Thus, villagers born in
the village have in principle free access to establish
fields on uncultivated or unclaimed land in the village
territory.
161
Our two examples are the villages of Biidi-2, which
is located in the southern part of Oudalan Province, and
Yomboli, which is located approximately 30 kilometres
further to the north (Figure 1).
No official meteorological records are available, but
it is safe to presume that there is less rainfall in Yomboli
than in Biidi-2 because of the steep north–south rainfall
gradient in the region. The rainfall records from the
provincial capital, Gorom-Gorom (Figure 2) provide an
indication of the main traits of the rainfall variations in
the region. The abundant rains in the 1960s, followed by
very dry periods in the 1970s and 1980s, are significant
features for both cases. However, a very high spatial and
temporal variability is an important characteristic as well.
The landscape and soil conditions are quite similar in the
two sites.
Parts of the village territories are in both cases
located on more recently developed east–west oriented
dune bands (approximately 16,000–20,000 years old),
superimposed on older dunes (more than 40,000 years
old) and pediplains (Figure 3). The cultivation patterns
in the villages follow similar strategies, yet with some
significant disparities. In Biidi-2, the contemporary cultivation is by and large confined to the old, degraded dune
soils whereas cultivation on the younger dune landscapes
was abandoned after the severe drought of the 1970s.
The amount of land cultivated remains almost constant, but the location has changed a little (Figure 4). As
regards Yomboli, the dune landscape remains important
for cultivation. From 1956 to 1988, the field area
expanded on the dune, while villagers at the same time
abandoned southern fields on the pediplain. Since 1991,
the location of fields has shifted towards the pediplain
again due to different yield potentials with varying rainfall amounts (Rasmussen et al., 2012). The total field
acreage in Yomboli more than doubled from 1956 to
Figure 1. The empirical examples underpinning the discussion
in this paper are located in the Sahelian zone of Burkina Faso.
162
A. Reenberg et al.
800
750
700
650
600
550
mm/year
500
450
400
350
300
250
200
150
100
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50
0
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
Figure 2. Annual precipitation in northern Burkina Faso (Gorom-Gorom). The meteorological station in Gorom-Gorom is the best
available proxy for rainfall in Biidi-2 and Yomboli. Data were derived from the Meteorological Office in Ouagadougou.
Figure 3. The landscape in the case region is dominated by two major elements: large east–west oriented dune formations of a more
recent geological origin, superimposed on a pediplan covered by older, eroded dune formations. The figure gives a rough indication
of a typical land use composition.
1988 (corresponding approximately to population
growth), whereas it was halved from 1988 to 2010
(Figure 5). It should be noted that systematic, rotational
fallow is not important in the region. Occasionally, fields
are abandoned in order to recover their fertility, but most
of the time fields are continuously cultivated (Reenberg
& Paarup Laursen, 1997).
Three major groups of driving forces influence livelihood strategies and changes in the villages: biophysical
conditions, demography and culture, as well as access to
the market economy and income sources beyond agriculture. The biophysical constraints for agriculture are certainly a prominent factor, yet the evolution of the land
use strategies must be understood in a larger context that
includes the historical co-evolution of the driving forces.
The observed persistent prominence of cropping, even in
periods with very limited rainfall, can in part be ascribed
to cultural traditions. The villagers perceive themselves
as farmers and do not want to abandon agriculture
altogether even if the economic rationale for cultivation
disappears when compared with alternative income
sources (such as migration or work for projects). Such a
culturally determined persistence of a specific livelihood
strategy can serve as an illustrative example of the
importance of (cultural) legacy and thus the importance
of understanding the temporal totality of change.
The co-evolution of field patterns and the socio-economic and environmental conditions are, however, very
complex (Reenberg, 2009). Whereas population growth
is a significant ‘slow’ variable, climate, development
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163
Figure 4. The field extent in Biidi-2 in 1995 and 2007. The map from 1995 shows a precise registration of individual fields whereas
the map from 2007 only describes the circumference (from Reenberg, 2009).
intervention, infrastructure and emerging new economic
opportunities (e.g. migration and projects) are equally
important. Climate variation has some impact on field
expansion and contraction, but certainly not in a very
systematic manner as described in the conventional narratives (Reenberg, 2012). The same is true for population
increase. While a tendency towards field expansion in
response to less rain or more people, conforming with
the commonly held notion of pressures on land, is
reported by farmers from the ‘good years’ before our
study period, it is equally important to note that farmers
have actually abandoned fields in recent years. This strategy was explained too as a result of good rains (the reason being that the good rain provides good grazing in
the bush, which enables them to increase their herds;
with more animals to sell they have less incentive to
embark upon hard work in the fields and as a consequence, they diminish cultivation). Hence, two distinct
processes are working simultaneously; both need to be
considered in order to understand current and possible
future directions of change.
A number of income promoting factors are prominent
when farmers list factors of significance for changes in
their livelihood portfolio. In Biidi-2, project intervention
was, for example, perceived as a major factor of change,
as was establishment of infrastructure (road access). The
latter greatly facilitates access to the market as well as
seasonal migration activities, and hence increases the
ability to earn money and provide remittances to sustain
the village. Likewise the role of development projects
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A. Reenberg et al.
Figure 5. Change of field extent in Yomboli from 1956 to 2010. Field limits were mapped from aerial photos (1956), satellite
images (1988) and GPS measurements (2010).
illustrates an interesting causal link between environmental conditions and livelihood components that operate
across time periods. Environmental events are the direct
reason for interventions, which are meant to mitigate
adverse effects, yet the reasons for the villagers joining
the projects are often only remotely related to an ambition to address the problems; the main incentive is that
these activities offer a salary opportunity (Nielsen et al.,
2012).
Other interesting examples can be noted from the
development of Yomboli. In the 1960s, land use decisions were significantly propelled by population growth,
which corresponds to the conventional narrative. Larger
households implied increased food requirements as well
as additional labour. However, after the severe drought
in the 1970s, a cereal bank provided the villagers with
cheap millet and the previous objective of food security
for the family was replaced by a strong focus on food
security for the livestock. Hence, field expansions were
less important.
In recent years, the complexities have increased
further. Due to very dry conditions in 2009, many young
men were forced to go on transhumance towards Mali
and Niger in order to find pasture and water for the
animals and did not return until August–September the
following year. The subsequent lack of labour in
the intensive weeding period and the fact that fields were
not properly supplied with manure meant that it was not
worth the effort to cultivate. In other words, land use
changes were triggered by rainfall events, yet complex
feedback and causal relations created cascading effects
of broader implications for land use decisions across
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Geografisk Tidsskrift-Danish Journal of Geography
time. In the rainy years, the tendency to expand field
acreage was in contrast mainly driven by prestige and
socio-cultural rationality, because a large well-cultivated
field and, more importantly, a big harvest showed
superiority.
Seen in a population pressure perspective, the recent
lack of field expansion is interesting. Accurate figures
for the de facto population present in the village are hard
to establish in societies with circular migration, but
people have been migrating throughout the period of
investigation, so the bias is considered relatively constant. The village surveys revealed that the population in
both villages has increased at a rate of 2–3% per year,
but a suspected close correspondence between population
size and incentive to expand land cannot be observed.
The same lack of support for the notion of an immediate correspondence between low rainfall years and field
encroachment can be noted. In very general terms, the
observed land use dynamic can be characterized as a
result of a number of different feedback loops – all to
some degree triggered by rainfall change, but certainly
adapted through a dynamic process with the nature of
temporal totality as defined by Chen (2011). A few
examples can serve as illustrations: One pathway (more
rain => more fields) conforms to the classical notion. It
certainly holds true that the establishment of millet cultivation in the region was supported by the unusually
favourable rainfall conditions in the 1960s. Field expansions continued to be an important response to food
demand in the dry years that followed for some time,
probably as a result of certain inertia or adjustment time.
A second pathway (more rain => fewer fields), describes
features of the contemporary situation in Biidi-2. Good
rainy seasons in recent years have led to increased pasture productivity, which, as described above, has led to
more emphasis on livestock and less incentive to cultivate all available land. This loop is further strengthened
by the emergence of a range of alternative income
options that enables farmers to rely on other sources of
food and even invest in livestock to build up their herds.
A third pathway (less rain => fewer fields) describes the
recent situation in Yomboli, where lack of rain triggered
an increase in transhumance and a corresponding
absence of labour for field work in the subsequent period
of good rainfall conditions for cultivation.
4. Conceptual lenses for analyzing transformation of
human–environment/interaction
Much of the recent research aimed at understanding the
dynamics of coupled human–environmental systems
relies on conceptual models or notions that include
environmental factors, social factors and feedbacks at
different spatial and temporal scales and identify the
driving forces of change (Fox & Vogler, 2005; GLP,
165
2005; Lambin & Geist, 2006; Scoones, 1998; Stafford
Smith, 2008; Walker & Salt, 2006; Zimmerer & Bassett,
2004).
In various ways, they build on the legacy of a range
of classical theoretical works on rural populations’ adaptability to exogenous and endogenous stressors such as
changes in the availability of natural resources, population pressure or available technologies (Bennett, 1976;
Boserup, 1965; Diamond, 2005; Netting et al., 1993).
The recent development of the global society and environment has increased the need to broaden the conceptualization to account for additional perspectives related to
rapidly increasing global market integration, globalization and climatic changes (Lambin & Meyfroidt, 2010).
In the present context, we will look at a few of these
conceptual perspectives proposed in the literature to
guide the analysis of causal relations and interactions in
human–environmental systems – with a special view to
their ability to consider the temporal totality of Sahelian
livelihood systems (Table 1). We have found these four
perspectives specifically complementary and useful in
our own work, but acknowledge that they share important traits with a number of other interdisciplinary
approaches within the field of human–environment interaction, e.g. political ecology (Blaikie & Brookfield,
1987; Zimmerer & Bassett, 2004), human ecology
(Haber, 2004), landscape ecology (Bastian, 2001),
cultural ecology (Zimmerer, 2004), event ecology
(Walters & Vayda, 2009), sustainability science (Clark &
Dickson, 2003) and ecological economics (Daly &
Farley, 2004). The four approaches that will be discussed
are:
A: LCS (Lambin & Geist, 2006; Turner et al., 2007;
Turner & Robbins, 2008).
B: Double exposure notion (Liechenko & O’Brien,
2010; O’Brien & Leichenko, 2000).
C: SD approach (Picardi, 1976; Rasmussen et al.,
2012; Sendzimir et al., 2011).
D:
Coupled
human–environmental
timelines
(Reenberg et al., 2008; Reid et al., 2000).
These four approaches have been employed to investigate the array of forcing functions affecting human–
environment interaction (including social, economic and
biophysical factors). They do, however, vary with respect
to (a) how research questions are framed and (b) how
much emphasis is given to different system characteristics, functional characteristics, temporal dimensions,
spatial dimensions, etc.
4.1. Land change science
The mindset proposed by LCS is depicted in Figure 6.
LCS (Foley et al., 2005; Lambin & Geist, 2006) has
emerged as a discipline that first and foremost recognizes
the pivotal role of land change in the Earth system but
Pathways
Legacies
Co-evolution
d
d
d
Local scale
Scale interaction
Embedded scale
Spatial configuration and
dimension
d
d
d
Temporal dimensions
Events
Functional characteristics of
specific concern, e.g.
d Events
d Feedback
Local-to-global interaction
Aims at extrapolation from
local to global
Using the notion of
(sustainable) pathways
Human–environment
interaction
Feedback (as a general notion)
1. How do globalization,
institutiona, and demographic
processes affect local-toregional land use decisions
and practices?
2. How do changes in land
management practices affect
the ecosystems?
3. How do changes in the
Earth system affect ecosystems
and what are the feedbacks of
ecosystem changes on the
Earth system?
Questions addressed-examples
Land change science
Recognizes that human–
environmental systems can be
found at all scales
Considering impact of change
Not specifically scale oriented
(implicit)
Simulation of systems
behaviour
Feedbacks
Endogenous system properties
(cause-effect)
How does a complex social,
managerial, economic or
ecological system develop in
time, as a result of internal
interdependence, mutual
interaction, information
feedback and circular
causality?
How do political and
economic changes interact
simultaneously with
environmental or climatic risks
(at different scales) to impact
the livelihoods and
vulnerability of people?
Impact of climate and
globalization – and especially
the connection between the
two
System dynamics
Double exposure notion
Not specifically scale oriented
(implicit)
Describing co-evolution
Events
Co-evolution
What is the temporal sequence
of important factors
(environment conditions,
resource management,
population parameters and
livelihood strategies)?
Human–environmental
timelines
Table 1. Key characteristics of the conceptual lenses proposed by land change science, the double exposure notion, systems dynamics and human-environmental timelines,
respectively.
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167
Figure 6. The Land Change Science conceptual framework (GLP, 2005).
in more general terms is also important for multidisciplinary approaches to human–environment issues
(Rindfuss et al., 2003, 2004).
The conceptual framework specifically stresses that
(1) land use decisions play a pivotal role in land change;
(2) land use management impacts ecosystem variables;
(3) ecosystem services influence land use decision making; and (4) socio-economic-cultural–institutional variables influence land use decision-making. It emphasizes
the complex patterns of interactions and feedback mechanisms between the socio-economic-cultural and the biophysical components of the land system and across
multiple spatial scales. Although the multi-level nature
of both societal and ecological structures does not explicitly appear in the conceptual diagram, it is understood to
be an important part of any analysis of the nature of
change in coupled socio-environmental land systems.
The framework inspires the adoption of a dynamic
approach that can accommodate non-linear dynamics,
thresholds and feedback loops and possibly also consider
how past couplings enable or constrain present and
future possibilities.
The framework is focused on three main issues. The
first is to identify and quantify the agents, structures and
nature of change in coupled socio-environmental land
systems. The second is to assess how the provision of
ecosystem services is affected by such changes. The
third is to identify the nature and dynamics of vulnerable, resilient and sustainable coupled socio-environmental
land systems in relation to interacting perturbations,
including climate change.
One partial perspective is the environmental and agricultural land use history of specific places. The development of contextualized histories that explicitly recognize
layered scales of analysis in both time and space can
highlight the complexity of specific local geographical
and historical settings and identify, for example, the
importance of disturbance regimes. This will require longitudinal studies at the national, regional or local levels
using composite methodologies (for example, remotely
sensed data, archival records and oral histories) as well
as studies of the changing values, ideologies and interests of decision-makers in economic and political structures (Batterbury & Bebbington, 1999; Klein Goldewijk
& Ramankutty, 2004).
4.2. The notion of double exposures
The accelerating complexity of changing environmental
and societal conditions that local people are confronted
with has been coined ‘double exposure’ by Liechenko
and O’Brien (2010), pointing to the fact that societal
transformations alter the context for environmental
impact and adaptation to climate change. The notion of
double exposure stresses that human–environmental systems can be found at all scales, from the local household
and its surroundings to the regional or planetary scale.
This is important to recognize in a number of situations,
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e.g. when assessing local impacts of events such as alterations in climate conditions or global connectedness. The
impact of perturbations often affects not only humans
but also the environmental system with which they interact and creates feedbacks of a positive as well as a negative nature. Such feedbacks, in turn, may impinge on
human coping strategies under different external conditions. Furthermore, the accelerating global connectedness
under the current wave of globalization (Young et al.,
2006) has many implications for local and regional livelihoods. It leads, for example, to the faster spread of
information, people and commodities.
The notion of double exposure suggests that because
the processes of climate change and economic globalization include implicit winners and losers, both processes
must be considered simultaneously. Hence, it recognizes
that climate impacts are influenced not only by current
socio-economic trends, but also by structural economic
changes that are re-organizing economic activities at the
global scale. When dealing with human adaptation to
environmental changes and climatic risk in marginal
regions (Eakin & Luers, 2006; Evans & Geerken, 2004),
it is widely acknowledged that economic, cultural and
political processes have a major influence on vulnerability and risks. The ‘double exposure’ lens is helpful in
focusing on how political and economic changes interact
simultaneously with environmental or climatic risks to
impact the livelihoods and vulnerability of people. These
changes are of interest because understanding their nature and timing can lead to a greater understanding of the
processes connecting the two.
The notion has helped alert people to the fact that
there are multiple causes of vulnerability, which are also
likely to increase the impacts of climate stress; double
exposure has been demonstrated to alter vulnerability
patterns of farmers in the Sahel (Tschakert, 2007).
4.3. SD approach
SD is a computer-aided approach to policy analysis and
design. The field developed initially from the work of
Jay W. Forrester, which was and still is considered a
significant statement of philosophy and methodology in
the field. The system approach defines problems dynamically, in terms of graphs over time. It implies thinking
of all concepts in the real system as continuous
quantities, interconnected in loops of information feedback and circular causality (http://www.systemdynamics.
org/what_is_system_dynamics.html).
A SD approach applies to dynamic problems arising
in complex social, managerial, economic or ecological
systems, i.e. to any dynamic system characterized by
interdependence,
mutual
interaction,
information
feedback and circular causality. The concept of endogenous change is fundamental to the SD approach, whereas
exogenous disturbances are seen at most as triggers of
system behaviour; the causes are contained within the
structure of the system itself. Corrective responses are
not modelled as functions of time, but are dependent on
conditions within the system. Importantly, practitioners
strive for an endogenous point of view, looking for the
sources of system behaviour that exist within the structure of the system itself. Hence, integrative and quantitative approaches that take a system-oriented stance are
suggested as a means of untangling the complexities of
the biophysical and socio-economic systems (Dougill
et al., 2010; Forrester, 2007; Guneralp & Seto, 2008).
System dynamic models have to a limited extent been
applied to simulating changes in the Sahel (Bah et al.,
2006; Picardi, 1976; Stephenne & Lambin, 2001). The
models range in scale from the Sudano-Sahelian region
(Picardi, 1976; Stephenne & Lambin, 2001) to local
scale (Bah et al., 2006). One recent application of the
systems dynamics notion (Sendzimir et al., 2011)
employs the causal loop diagrams to present the patterns
of interaction, yet without proceeding to a quantitative
modelling of the system. These models join the dominant causal narrative of a vicious circle of land degradation and land expansion prompted by population
pressure and low rainfall. Recently, Rasmussen et al.
(2012) have used a system dynamic model as a tool to
investigate the understanding of dynamics in Sahelian
agro-pastoral systems by exploring the behaviour of the
system under a variety of conditions (Figure 7).
It appears to be a valuable approach to explore how
the systems will react if external conditions are altered.
Notably, the generation of ‘what if’ scenarios is useful to
capture realistic alterations that may be expected to affect
human–environmental interactions in the Sahel such as
changes in agricultural commodity prices, migration or
rainfall variability. For example, the model findings lend
credence to the argument that non-climatic factors may
play a more crucial role than annual rainfall and warn
that simple causal explanations of links between climate
variability and land use change may be misleading.
4.4. Human–environmental timelines
As stressed earlier, environmental factors, social factors
and feedbacks in human–environmental systems operate
at different spatial and temporal scales. Hence, trajectories of change may best be understood by looking at the
co-evolution of different driving forces playing out at
different spatial scales. In this vein, Reid et al. (2000)
proposed a simple heuristic method (called ‘ecological
timelines’) as a means to capture different causes and
consequences of land use changes over time. Simple
timelines of events, main drivers of change and resource
management strategies appear to contribute significantly
to clarifying the temporal dynamic interactions between
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Figure 7. Causal loop diagram for a system dynamics model of the land use system in Yomboli (from Rasmussen et al., 2012).
Figure 8. A human–environmental timeline for Biidi-2, which depicts the co-evolution of a number of important factors (from
Reenberg, 2009).
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A. Reenberg et al.
humans and the environment; the approach has been
developed further by Reenberg et al. (2008) to demonstrate temporal perspectives of human–environment interaction in a Pacific Island community and unveil
correspondence and co-evolution between environmental
conditions and socio-economic actions. Although in principle, a simple heuristic, these coupled human–environmental timelines have proven to be a useful tool to
illustrate the co-evolution of environmental conditions
and events, resource management options and livelihoods
in various other contexts, e.g. the Sahel (Nielsen &
Reenberg, 2010b; Reenberg, 2009) (Figure 8). While
they neither address issues of temporal totality nor
directly document causal relations or provide quantitative
analysis of the observed factors, they may nonetheless
help to create a holistic view that guards against flawed
cause-effect conclusions. The compelling visualization of
the temporal development pattern of key factors in the
human–environmental interaction can also help to identify the structured sequence of successive stages or
phases to which process philosophy draws attention.
4.5. The composite lenses put into practice
Without going into detail and providing a full review of
the practical use of the four approaches to guide the
empirical analyses of the Sahelian cases, we will suggest
a number of contributions of each of them to the
research process.
The LCS framework has been important to guide the
formulation of a research proposal towards consideration
of local-to-global scale interaction. Specifically, it helps
focus attention on human decision-making, and it invites
to anchor research questions in the wider notions of vulnerability and sustainable pathways as well as to pay
attention to dynamic feedback between social and ecological factors. In these respects, the LCS framework (and
earlier versions of it) has proven very useful as a platform
for interdisciplinary research on sustainable resource management in the Sahel (e.g. research projects like LaSyRe
and SEREIN). It captures the interdisciplinary nature of
the environmental problems in the Sahel, where land use
management decisions are enabled and constrained by
environmental as well as socio-economic conditions, and
hence assist in overcoming the well-known divides in
mindset between the social and natural sciences (Reenberg, 1998). The double exposure notion conveys, first of
all, the importance of having a multiple dimension perspective on contemporary challenges arising from climate
threats. Again, the value of presenting research proposals
that are based on acknowledged terminology must be
appreciated. On the one hand, it is a plea in support of
bringing climate research into a broader, interdisciplinary
framework. On the other hand, the notion also assists in
the research question formulation phase by rightly
insisting on addressing socio-economic changes, which
interact simultaneously with environmental risks to
impact local peoples’ livelihoods and vulnerability. The
Sahelian example hints that land use development can be
caused by intertwined relations between climate
conditions and opportunities created by globalization
(migration), e.g. the abovementioned cascading implications of drought-related migrations that lead to lack of
labour and consequent bottlenecks to the improvement of
agricultural production in the subsequent season.
The SD approach offers a tool that in a rigorous
fashion enables simple analysis of the temporal dimensions of causal relations, once a certain insight into the
hypothetical relationship between a number of key
parameters has been supported by empirical evidence. In
spite of the necessary caveat against simplistic perceptions, it can be a helpful instrument to investigate the
sensitivity of the processes of change to alterations of
important conditions.
Finally, the human–environmental timelines approach
has proven to be of great value, not least in the data collection process. This simple tool constructively supports
interactive group interviews, in which participants indicate the temporal evolution of societal and environmental
factors and events of importance for local natural
resource management and livelihood strategies. In this
respect, it is a strong instrument for participatory
approaches to the study of human–environment interactions. It enables local people to point to events of specific importance for their choices of livelihood and
resource management strategies. The timeline in Figure 8,
for example, draws attention to the causal relation
between project interventions (and related salaries) and
livestock pressure. A similar exercise in Nielsen and
Reenberg (2010b) helped identify a causal relationship
between the events of the end of slavery and the introduction of gardening in Biidi-2.
5. Discussion and conclusion
One of the challenges in dealing with complex human–
environmental systems such as Sahelian land use systems
stems from the fact that typically, the cause and effects
may be separated across different spatial and temporal
scales (Guneralp & Seto, 2008). This issue has been
acknowledged for decades; attention was fuelled in
particular by the major drought and environmental degradation in the Sahel starting in the 1970s. Recently, the
climate change debate has brought new momentum to
research into the dynamics of human–environmental
interaction. However, experience shows that the complexities of the systems are often beyond the grasp of
our mental models, notably because causal relations are
far from obvious and because the temporal totality of the
change processes is hard to explore.
May lead to the misinterpretation of co-occurrences as causal relations
Offers only a simple overview
Explicit quantification of feedback
Provides a simple heuristic device that enhances the temporal
development perspective
Builds on system pre-defined causal links – dominated by an
‘endogenous variable’ view
Coupled human–
environment timelines
Notion of double exposure
System dynamics approach
Offers only a very general notion
Not very specific guidance of cause-effect relationships across different
times or scales
Must be combined with more specific tools
171
Helpful as an organizing principle for the narrative of dynamic
processes
Implicit acknowledgement of feedback
Implicit dynamic multi-spatial scale
Takes feedbacks into account
Considers duality between climate and globalization causes
Compelling narrative/label
Strong tool for ‘what if’ analysis
Land change science
framework
Main shortcomings for exploring causal relations – taking into account
temporal totality and inertia
Main strengths for exploring causal relations – taking into account
temporal totality and inertia
Theoretical perspective
Yet, in order to guide sustainable development strategies and interventions, it is crucial to understand the
functioning and causal relations of the coupled human–
environmental systems on which local livelihoods
depend – i.e. to get the mental models of these dynamics
systems right. Only with a full understanding of the evolution and feedback mechanisms of social and productive
systems will it be possible to assess the potential and
vulnerability of food production vis-à-vis perturbations
related to climate changes or other changes in external
conditions.
Currently it seems plausible to suggest that no single
analytical tool will suffice. A portfolio approach that
uses a number of different lenses to scrutinize the empirical reality in an explorative and iterative fashion may be
the best solution at our current point of conceptual and
theoretical insight.
The four different lenses discussed in this article
seem to complement each other for the purpose of providing a platform for describing, understanding and conveying information about some of the dynamic
properties and causal linkages in the Sahel, e.g. in relation to climate variations – as summarized in Table 2.
As briefly discussed in the previous section, the
approaches have each in their way proven to be useful
in various parts of the research process. The respective
qualities mentioned are not exclusive and are obviously
inspired by the concrete experience from our Sahelian
research. The different lenses are continuously being
developed and improved to account for and include some
of the emerging, acknowledged grand challenges in
human–environmental research (ICSU, 2010). Grand
challenges are, by definition, big and difficult problems,
and will require a focused, multidisciplinary and integrated research commitment to have a reasonable prospect of success (ICSU, 2010). Hence, we propose that a
diversity of topics is taken into account but are united as
elements of a broad system approach that examines how
the coupled social–environmental system is changing
and what actions and interventions that may alter the
environmental and social outcomes.
To summarize, there is a need for knowledge about
the pathways of change, the driving forces and the processes of change, including how they work at different
temporal and spatial scales. Such issues are, in part,
within the concern of each of the approaches discussed.
A thorough discussion of the shortcomings of each
approach may be provocative and hard to provide,
because the approaches are subject to continuous development and improvement by their users. By way of
example, SD have been portrayed as being endogenous
and fixed scalar in nature, yet, recent improvements
have included functioning within scales, e.g. how
endogenous variables interact, and functioning across
scales.
Table 2. Potential contributions to insight: strengths and weaknesses of the conceptual lenses.
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A. Reenberg et al.
The discussed portfolio of approaches certainly does
not provide the full and final answer to how we can fully
internalize the notion of temporal totality and bring processes of change to the forefront of ontological concern
for land systems analysis. Yet, they may, in concert, help
us to appreciate the crucial importance of including the
temporal dimensions of multiple feedbacks in our understanding of change and causal relationships in human–
environment systems.
Acknowledgement
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The research is funded by two major projects: a grant from
Danida-FFU (09-001-KU) (A region wide assessment of land
systems resilience and climate robustness in the agricultural
frontline of the Sahel) and the ERC project Waterworlds. The
authors appreciate the constructive comments of two reviewers.
References
Bah, A., Toure, I., Le Page, C., Ickowicz, A., & Diop, A.T.
(2006). An agent-based model to understand the multiple
uses of land and resources around drillings in Sahel.
Mathematical and Computer Modelling, 44, 513–534.
Barbier, B., Yacouba, H., Karambiri, H., & Zoromé, M. (2009).
Human vulnerability to climate variability in the Sahel:
Farmers’ adaptation strategies in northern Burkina Faso.
Environmental Management, 43, 790–803.
Bastian, O. (2001). Landscape ecology
towards a unified
discipline? Landscape Ecology, 16, 757–766.
Batterbury, S., & Bebbington, A. (1999). Environmental histories, access to resources and landscape change: An introduction. Land Degradation & Development, 10, 279–289.
Bennett, J.W. (1976). The ecological transition. Cultural
anthropology and human adaptation. New York, NY:
Pergamon Press.
Blaikie, P., & Brookfield, H. (1987). Land degradation and
society. London: Methuen.
Bolwig, S., Rasmussen, K., & Hansen, M.K. (2008). New perspectives on natural resource management in the Sahel.
Second Draft. Copenhagen: Department of Geography and
Geology, University of Copenhagen.
Boserup, E. (1965). The conditions of agricultural growth.
London: Earthscan.
Chen, X. (2011). Why do people misunderstand climate
change? Heuristics, mental models and ontological assumptions Climatic Change, 108, 31–46.
Clark, W.C., & Dickson, N.M. (2003). Sustainability science:
The emerging research program. Proceedings of the
National Academy of Sciences of the United States of
America, 100, 8059–8061.
Claude, J., Grouzis, M., Milleville, P., Fauck, R., Chevallier, P.,
Langlois, M., …, & Collinet, J. (1991). Un espace sahelien: la mare d’Oursi, Burkina Faso Please provide translated English title for reference ‘Claude et al. (1991)’.
Paris: ORSTOM.
Daly, H., & Farley, J. (2004). Ecological economics. Principles
and applications. London: Islands Press.
Diamond, J. (2005). Collapse: How societies choose to fail or
succeed. New York, NY: Penguin Group.
Dougill, A.J., Fraser, E.D., & Reed, M.S. (2010). Anticipating
vulnerability to climate change in dryland pastoral systems:
Using dynamic systems models for the Kalahari. Ecology
and Society, 15.
Eakin, H., & Luers, A.L. (2006). Assessing the vulnerability of
social–environmental
systems. Annual Review of
Environment and Resources, 31, 365–394.
Evans, J., & Geerken, R. (2004). Discrimination between climate and human-induced dryland degradation. Journal of
Arid Environments, 57, 535–554.
Foley, J.A., DeFries, R., Asner, G.P., Barford, C., Bonan, G.,
Carpenter, S.R., … Snyder, P.K. (2005). Global consequences of land use. Science, 309, 570–574.
Forrester, J.W. (2007). System dynamics – a personal view of
the first fifty years. System Dynamics Review, 23, 345–358.
Fox, J., & Vogler, J.B. (2005). Land-use and land-cover change
in Montane Mainland Southeast Asia. Environmental
Management, 35, 1–10.
GLP. (2005). Science plan and implementation strategy. IGBP
Report No.53/IHDP Report No.19. Stockholm: IGBP secretariat.
Guneralp, B., & Seto, K.C. (2008). Environmental impacts of
urban growth from an integrated dynamic perspective: A
case study of Shenzhen, South China. Global Environmental Change – Human and Policy Dimensions, 18, 720–735.
Haber, W. (2004). Landscape ecology as a bridge from ecosystems to human ecology. Ecological Research, 19, 99–106.
ICSU. (2010). Earth System Science for global sustainability. The
grand challenges. Paris: International council for Science.
Klein Goldewijk, K., & Ramankutty, N. (2004). Land cover
change over the last three centuries due to human activities:
The availability of new global data sets. GeoJournal, 61,
335–344.
Lambin, E.F., & Geist, H.J. (2006). Land-use and land-cover
change. Local processes and global impacts. Berlin:
Springer.
Lambin, E.F., & Meyfroidt, P. (2010). Land use transitions:
Socio-ecological feedback versus socio-economic change.
Land Use Policy, 27, 108–118.
Liechenko, R., & O’Brien, K.L. (2010). Environmental change
and globalization: Double exposures. Oxford: University
Press.
Liverman, D., Rindfuss, R.R., & Stern, P.C. (1998). People
and pixels: Linking remote sensing and social science.
Washington, DC: National Academy Press.
Marcussen, H.S., & Reenberg, A. (1999). On scale and
disciplinarity in the study of natural resource use in the
Sahel – lessons from the SEREIN research program.
Geografisk Tidsskrift, Danish Journal of Geography Special
issue, 2, 1–13.
Mortimore, M., Ba, M., Mahamane, A., Rostom, R.S., Serra
del Pozo, P., & Turner, B. (2005). Changing systems and
changing landscapes: Measuring and interpreting land use
transformations in African drylands. Geografisk Tidsskrift,
Danish Journal of Geography, 105, 101–120.
Netting, R.M., Stone, G.D., & Stone, M.P. (1993). Agricultural
expansion, intesnification, and market participation among
the Kofyar, Jos Plateau, Nigeria. In B.L. Turner II, G.
Hyden, & R.W. Kates (Eds.), Population growth and
agricultural change in Africa (pp. 206–249). Gainesville:
University Press of Florida.
Nielsen, J.O., & Reenberg, A. (2010a). Cultural barriers to
climate change adaptation: A case study from Northern
Burkina Faso. Global Environmental Change-Human and
Policy Dimensions, 20, 142–152.
Nielsen, J.O., & Reenberg, A. (2010b). Temporality and the
problem with singling out climate as a current driver of
change in a small West African village. Journal of Arid
Environments, 74, 464–474.
Downloaded by [193.111.162.2] at 05:42 28 February 2013
Geografisk Tidsskrift-Danish Journal of Geography
Nielsen, J.O., D’haen, S., & Reenberg, A. (2012). Adaptation
to climate change as a development project: A case study
from Northern Burkina Faso. Climate and Development, 4
(1), 16–25.
O’Brien, K.L., & Leichenko, R.M. (2000). Double exposure:
Assessing the impacts of climate change within the context
of economic globalization. Global Environmental Change,
10, 221–232.
Ouedraogo, H.M.G. (2005). The land policy process in Burkina: Experience in building a national consensus on access
to land. ANGOC & ILC: LandNet West Africa.
Petit, S. (2003). Parklands with fodder trees: A Fulbe response
to environmental and social changes. Applied Geography,
23, 205–225.
Picardi, A.C. (1976). Practical and ethical issues of development
in traditional societies – insights from a system dynamics
study in pastoral West-Africa. Simulation, 26, 1–9.
Powell, J.M., Fernández-Rivera, S., Williams, T.O., & Renard,
C. (1995). Livestock and sustainable nutrient cycling in
mixed farming systems of sub-Saharan Africa. Proceedings
of an international conference held in Addis Ababa, Ethiopia, 22–26 November 1993. Addis Ababa, ILCA.
Rasmussen, L.V., Rasmussen, K., Reenberg, A., & Proud, S.
(2012). A system dynamics approach to land use changes
in agro-pastoral systems on the desert margins of Sahel.
Agricultural Systems, 107, 56–64.
Rasmussen, L.V., & Reenberg, A. (2012). Land use rationales in
desert fringe agriculture. Applied Geography, 34, 595–605.
Raynaut, C., & Delville, P.L. (1997): A shared land: Complementary and competing uses. In C. Raynaut (Ed.), Societies
and nature in the Sahel (pp. 109–137). London: Routledge,
Stockholm Environment Institute.
Reenberg, A. (1998). Analytical approaches to agricultural
land use systems in the Sahel. Copenhagen: SEREIN.
Reenberg, A. (2009). Embedded flexibility in coupled human–
environmental systems in the Sahel: Talking about resilience. In K. Hastrup (Ed.), The question of resilience.
Social response to climate change (pp. 132–158). Copenhagen: The Royal Danish Academy of Science and Letters.
Reenberg, A. (2011). Toolbox options for conceptualizing
change in human–environmental systems. Pathways, path
dependency, legacies, syndromes and scenarios. GLP
Report No. 2. Global Land Project.
Reenberg, A. (2012). Insistent dryland narratives: Portraits of
knowledge about human–environmental interactions in Sahelian environment policy documents. West African Journal
of Applied Ecology, 20, 97–111.
Reenberg, A., Birch-Thomsen, T., Mertz, O., Fog, B., & Christiansen, S. (2008). Adaptation of human coping strategies
in a small island society in the SW Pacific – 50 years of
change in the coupled human environment system on Bellona, Solomon Islands. Human Ecology, 36, 807–819.
Reenberg, A., & Fog, B. (1995). The spatial pattern and
dynamics of a Sahelian agro-ecosystem: Land use systems
analysis combining household surveys with georelated
information. GeoJournal, 37, 489–499.
Reenberg, A., & Paarup Laursen, B. (1997). Determinants for
land use strategies in a Sahelian agro-ecosystem – Anthropological and ecological geographical aspects of natural
resource management. Agricultural Systems, 53, 209–229.
Reid, R.S., Kruska, R.L., Muthui, N., Taye, A., Wotton, S.,
Wilson, C.J., & Mulatu, W. (2000). Land-use and landcover dynamics in response to changes in climatic, biological and socio-political forces: The case of southwestern
Ethiopia. Landscape Ecology, 15, 339–355.
173
Rescher, N. (2009). Free will: A philosophical reappraisal.
New Brunswick, NJ: Transaction Publishers.
Rindfuss, R.R., Walsh, S.J., Mishra, V., Fox, J., & Dolcemascolo, G.P. (2003). Linking household and remotely sensed
data – methodological and practical problems. In J. Fox, R.
R. Rindfuss, S.J. Walsh, & V. Mishra (Eds.), People and
the environment – approaches for linking household and
community surveys to remote sensing and Gis (pp. 1–30).
Boston, MA: Kluwer Academic.
Rindfuss, R.R., Walsh, S.J., Turner, B.L., Fox, J., & Mishra, V.
(2004). Developing a science of land change: Challenges
and methodological issues. PNAS, 101, 13976–13981.
Scoones, I. (1998). Sustainable rural livelihoods: A framework
for analysis. IDS Working Paper, 72, 1–22.
Sendzimir, J., Reij, C., & Magnuszewski, P. (2011). Rebuilding
Resilience in the Sahel: Regreening in the Maradi and Zinder Regions of Niger. Ecology and Society, 16.
Serneels, S., & Lambin, E.F. (2001). Proximate causes of landuse change in Narok District, Kenya: A spatial statistical
model. Agriculture, Ecosystems and Environment, 85, 65–
81.
Stafford Smith, M. (2008). The desert syndrome: Causallylinked factors that characterise outback Australia. The
Rangeland Journal, 30, 3–14.
Stephenne, N., & Lambin, E.F. (2001). A dynamic simulation
model of land-use changes in Sudano-sahelian countries of
Africa (SALU). Agriculture Ecosystems & Environment,
85, 145–161.
Tschakert, P. (2007). Views from the vulnerable: Understanding
climatic and other stressors in the Sahel. Global Environmental Change, 17, 381–396.
Turner, B.L., & Robbins, P. (2008). Land-change science and
political ecology: Similarities, differences, and implications
for sustainability science. Annual Review of Environment
and Resources, 33, 295–316.
Turner, B.L., Lambin, E.F., & Reenberg, A. (2007). Land
change science special feature: The emergence of land
change science for global environmental change and sustainability (vol 104, pg 20666, 2007). Proceedings of the
National Academy of Sciences of the United States of
America, 105, 2751–2751.
Vayda, A.P., McCay, B.J., & Eghenter, C. (1991). Concepts of
process in social science explanations. Philosophy of the
Social Sciences, 21, 318–331.
Walker, B., & Salt, D. (2006). Resilience thinking. Sustaining
ecosystems and people in a changing world. Washington,
DC: Island Press.
Walters, B.B., & Vayda, A.P. (2009). Event ecology, causal
historical analysis, and human–environment research.
Annals of the Association of American Geographers, 99,
534–553.
Young, O.R., Berkhout, F., Gallopin, G.C., Janssen, M.A.,
Ostrom, E., & van der Leeuw, S. (2006). The globalization of socio-ecological systems: An agenda for
scientific research. Global Environmental Change, 16,
304–316.
Zimmerer, K.S. (2004). Cultural ecology: Placing households
in human–environment studies – the cases of tropical forest
transitions and agrobiodiversity change. Progress in Human
Geography, 28, 795–806.
Zimmerer, K.S., & Bassett, T.J. (2004). Political ecology – an
integrative approach to geography and environment-development studies. New York: The Guilford Press.