Scenarios of future land use and implications for sustainability
Frank Ewert
Plant Production Systems Group, Wageningen University
P.O. Box 430, 6700 AK Wageningen, The Netherlands
Tel. : +31 317 484771
Email: frank.ewert@wur.nl
1
Introduction
Land is one of the most important natural resources. The use of land by humans largely shaped
by the interaction between nature and society (Lambin et al., 2001; Haberl et al., 2004). Land
use and land cover (LULC) has changed considerably in the past (Ramankutty, 1999) and is
likely to do so in the future (Rounsevell et al., 2006). LULC is not only affected by biophysical
and socio-economic changes but it also influences a number of services provided by nature to
human society such as the supply of food and water, biodiversity, landscape quality and
recreation.
The sustainable use of natural resources is of large concern (Brundtland, 1987). Four
dimensions of sustainability, i.e. natural, social, economic and institutional have been identified
(Spangenberg, 2002) and should be considered assessing sustainable resource use and
development. Much emphasis in land use modelling has been on describing relationships
between LULC change and individual ecosystem services. Comprehensive approaches trying to
understand LULC change within the context of sustainability are scarce.
The present paper describes scenarios of LULC change as affected by socio-economic and
biophysical conditions and discusses related implications for sustainable development. An
approach of assessing LULC for Europe for the 21st century is presented and associated
impacts are described for different ecosystem services including potential tradeoffs among
these. Challenges for integrated assessment modelling (IAM) are discussed considering
selected results from ongoing projects.
2
Assessing Land use change
2.1
Scenario concept
In spite of progress in integrating biophysical and socio-economic drivers of land use change
(Veldkamp and Lambin, 2001; Veldkamp and Verburg, 2004), prediction of future land use
remains difficult (Rounsevell et al., 2006). A useful technique for the exploration of uncertain
futures is the application of comprehensive, alternative scenarios. A suitable concept for the
development of alternative scenarios of land use change is provided by the IPCC Special
Report on Emission Scenarios (SRES) (Nakićenović et al., 2000). The unique character of the
SRES framework lies in the integrated representation for alternative scenarios of the biophysical and socio-economic dimensions of future development. The four scenario families
describe future worlds that may be global economic (A1), global environmental (B1), regional
economic (A2) or regional environmental (B2).
A limitation of the SRES framework, however, is the geographical scale. SRES provides
coarse scenarios derived for global scale applications, without guidelines to their application at
the regional scale. Furthermore, the framework is generic and qualitative: it does not provide
further descriptions of likely sectoral changes. Thus, in developing scenarios of future land use
1
change within the SRES framework, it is still necessary to both interpret regional scale and
sector-based change drivers as well as to quantify the effects of these change drivers.
2.2
Drivers of land use change
Common to several studies on developing scenarios of LULC change is a methodology that
follows three basic steps: 1) qualitative description of drivers, 2) quantification of effects of these
drivers on land use change and 3) allocation (or downscaling) of these effects to smaller regions
(Rounsevell et al., 2006). Recently, European cross cutting drivers have been derived from the
storylines of the SRES framework for different LULC classes (Rounsevell et al., 2006). An
example is given in Table 1 for agricultural land use in Europe. Consistent with SRES, these
drivers represent important socio-economic and biophysical factors affecting agricultural land
use and refer to changes within and outside Europe.
A range of models has been developed to better understand, assess and project changes in
LULC (Veldkamp and Lambin, 2001; Veldkamp and Verburg, 2004; Heistermann et al., 2006).
Models are typically scale dependent (local, regional or global) and often differ depending on
the LULC class. For instance, agricultural land use in Europe has been estimated considering
changes in food demand and supply where the latter is estimated considering effects of climate
change and technology development on crop productivity (Ewert et al., 2005; Rounsevell et al.,
2005). Quite different models have been used for estimating urban, forest and protected area
land use changes (Rounsevell et al., 2006).
Table 1: Important drivers of European agricultural land use change (from Ewert et al., 2006a;
Rounsevell et al., 2006)
Policy
Socio-economics and environment
Demand
Supply
Market intervention
Population
Resource competition
Rural development
Consumer preferences
Climate change
Environmental policy
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Market liberalisation
EU enlargement
Projected land use changes
Technology & management
Projections of future LULC largely differ depending on the models used and the specific
scenario assumptions (Verburg et al., 2006). Differences among modelling approaches are
largely related to the input data considered and the specific modelling assumptions. An example
of estimated changes in LULC is given in Figure 1a&b. The scenario changes are most striking
for the agricultural land uses, with large area declines resulting from assumptions about future
crop yield development with respect to changes in the demand for agricultural commodities
(Ewert et al., 2005).
2
a)
b)
% of European land surface
% of European land surface
15%
15%
10%
A1FI
10%
5%
5%
0%
0%
others
surplus
biofuels
-15%
forest
-10%
grassland
arable
-5%
Urban
others
surplus
biofuels
forest
-10%
grassland
arable
Urban
-5%
B1
-15%
c)
d)
A1FI
B1
Percentage of
surplus land per
ATEAM cell
Figure 1: Aggregated LULC changes (a & b) and estimated surplus land (c & d) for Europe in
2080 for A1FI (a & c) and B1 (b & d) scenarios (HadCM3). Surplus land refers to abandoned
land from crop land and grassland (from Rounsevell et al, 2006).
The scenarios demonstrate the importance of assumptions about technological development for
future agricultural land use in Europe. If technology continues to progress at current rates then
the area of agricultural land would need to decline substantially and large parts of Europe would
become surplus to the requirement of food and fibre production (Fig. 1c&d). Such declines will
not occur if there is a correspondingly large increase in the demand for agricultural goods, or if
political decisions are taken either to reduce crop productivity through policies that encourage
extensification or to accept widespread overproduction. For the set of parameters assumed
here, cropland and grassland areas decline by as much as 50% of current areas for some
scenarios. Other studies using different models also project a decline in agricultural land which,
however, is less pronounced (van Meijl et al., 2006), mainly due to different assumptions about
technology development.
4
Impacts of land use change
Projected changes in LULC have considerable effects on ecosystem service supply. Impacts
can be positive (for example, increases in forest area) or offer opportunities (for example,
‘‘surplus land’’ for agricultural extensification and bioenergy production), (Schroter et al., 2005).
However, LULC changes (in combination with climate change) may increase vulnerability of
ecosystems especially in the Mediterranean and mountain regions. Specific studies have
quantified the impacts of declining agricultural land use on farmers livelihood (Metzger et al.,
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2006), biodiversity (Berry et al., 2006; Reidsma et al., 2006) and soil carbon (Smith, 2005), and
have stressed the importance for mountain biosphere reserves (Bugmann et al., 2007).
While most studies have focused on a selected number of ecosystem services only few
attempts are available that synthesize impacts on different services (Metzger et al., 2006) or
explicitly analyse tradeoffs between services such as food production and biodiversity (e.g.
Berry et al., 2006).
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Sustainability assessment
It is well recognised that the complexity of sustainability problems demand a holistic perspective
that unifies across sectors, problems, methods, disciplines, spatial and temporal scales (Swart
et al., 2004). Addressing LULC within the context of sustainability will require such holistic
perspective to manage trade-offs between immediate human needs and maintaining the
capacity of the biosphere to provide goods and services in the long term (Foley et al., 2005).
Integrated assessment and modelling (IAM) has been suggested as a solution to the
management of complex environmental systems. In IAM the process of understanding and
management of environmental systems is seen as a joint activity between scientist and decision
makers and consideration of stakeholder needs or demands is essential (Parker et al., 2002).
Impacts on sustainability and sustainable development are commonly assessed and
communicated on the basis of indicators jointly identified with stakeholders (Ewert et al., 2006b).
An integrated approach is also advocated by LULC change modelling community (Kok et al.,
2007). However, the complexity of the systems to be addressed require adequate modelling
tools. Linking models that represent the different parts of the system has been proposed to
allow multi-scale and -sectoral assessment of natural resource management options (Ewert et
al., 2006b; Ittersum et al., 2007). Much emphasis has been on the development of IA
frameworks to support the sustainable use of natural resources including land (SEAMLESS,
2007; SENSOR, 2007).
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Concluding remarks
Considerable LULC changes have been projected for Europe for the 21st century with impacts
on ecosystem service supply that can be positive or negative. Integrated approaches to assess
LULC change as part of sustainability assessment are available but require further elaboration.
Particularly challenging is the integration of models from different disciplines and scales. This
poses emphasis on the development of technical solutions to support the (re-)use of model
components in complex but problem-specific model chains. Interaction with stakeholders should
be an integrated part of the assessment process.
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