Assessing driving forces of land use and land cover change by a mixed-method approach in north-eastern Ghana, West Africa

Highlights

• A combined qualitative and quantitative analysis for assessing drivers of LULCC.

• Rural population growth is with very high confidence the main driver of LULCC.

• Technological and political parameters are currently not driving LULCC.

• The confidence table is a useful tool to compare results of a mixed-method approach.

Abstract

Land use and land cover change (LULCC) is the result of complex human-environmental interactions. The high interdependencies in social-ecological systems make it difficult to identify the main drivers. However, knowledge of key drivers of LULCC, including indirect (underlying) drivers which cannot be easily determined by spatial or economic analyses, is essential for land use planning and especially important in developing countries. We used a mixed-method approach in order to detect drivers of LULCC in the Upper East Region of northern Ghana by different qualitative and quantitative methods which were compared in a confidence level analysis. Viewpoints from experts help to answer why the land use is changing, since many triggering effects, especially non-spatial and indirect drivers of LULCC, are not measurable by other methodological approaches. Geo-statistical or economic analyses add to validate the relevance of the expert-based results. First, we conducted in-depth interviews and developed a list of 34 direct and indirect drivers of LULCC. Subsequently, a group of experts was asked in a questionnaire to select the most important drivers by using a Likert scale. This information was complemented by remote sensing analysis. Finally, the driver analysis was compared to information from literature. Based on these analyses there is a very high confidence that population growth, especially in rural areas, is a major driver of LULCC. Further, current farming practice, bush fires, livestock, the road network and climate variability were the main direct drivers while the financial capital of farmers and customary norms regarding land tenure were listed as important indirect drivers with high confidence. Many of these driving forces, such as labour shortage and migration, are furthermore interdependent. Governmental laws, credits, the service by extension officers, conservational agriculture and foreign agricultural medium-scale investments are currently not driving land use changes. We conclude that the mixed-method approach improves the confidence of findings and the selection of most important drivers for modelling LULCC, especially in developing countries.

Introduction

Land use and land cover change (LULCC) is an emerging threat to the resilience of socio-ecological systems, since it is often related to land degradation (Lambin and Meyfroidt, 2010). In the context of this study, land cover refers to the biophysical (e.g. soil, and water) land surface while land use is related to any human management activity affecting land. We define therefore land use change as either a shift into another land use or the intensification of the current land use (Turner and Meyer, 1994).

Today, it is acknowledged that driving forces of LULCC are often a mix between anthropogenic (social, political, economic, demographic, technological, cultural) and biophysical factors with direct or indirect impacts. Direct drivers of land use change exert obvious impact on the land surface, while indirect drivers are the underlying causes of direct drivers and are channelled through direct anthropogenic drivers, for example governance systems (Díaz et al., 2015, Lambin et al., 2003).

Anthropogenic drivers of LULCC, such as population growth and dry season gardening, have mostly a short-term and often more perceivable impact than biophysical drivers. Conversely, climate change as one of the emerging drivers of LULCC is difficult to detect and quantify in the short term. Consequently, long-term studies are necessary to provide evidence of climate change. Biophysical drivers of LULCC, such as increasing inter-annual rainfall variability, have severe consequences especially in rural areas with a low financial and physical capacity and a high dependency on natural resources (Adger et al., 2003, Lambin et al., 2003). Examples for the eminent relevance of such climatic parameters for LULCC in marginalised rural regions can be found world-wide, but are most prominent in the Global South (Ahmed et al., 2009, IPCC, 2014), including countries like Ghana in West Africa.

The role of climate change for environmental and socio-economic changes in West Africa is still critically discussed in the scientific community (Antwi-Agyei et al., 2016, Mertz et al., 2010, Reenberg, 2001, Tschakert, 2007). Mertz et al. (2010) evaluated 1249 household questionnaires and held focus group discussions in 15 sites in Senegal, Mali, Burkina Faso, Niger, and Nigeria on driving forces for decreasing livestock, crop and pasture production. Climate factors were perceived as a driving force by 30–50% of the households, while 50–70% stated that decreasing production is based on other factors not related to climate. Furthermore, it depends on the climate models whether rainfall in West Africa will increase or decrease and, therefore, cannot be predicted (Mertz et al., 2010, Müller, 2009, Thornton et al., 2006).

The complex and diverse interactions among social-ecological systems make it difficult to identify and quantify the main drivers of LULCC (Ostrom, 2009). We conducted this study against the background that driving forces of LULCC are often analysed from a disciplinary perspective, which lends significance either to socially related drivers or driving forces detected by natural science (Rindfuss and Stern, 1998). A holistic approach across disciplines with a focus on direct and indirect influences causing LULCC is needed for a comprehensive driver analysis which is still rarely conducted in land system science (Van Vliet et al., 2015). Further, an assessment of LULCC should include, as much as possible, the impact of the change on natural resources availability or disaster risks (Bulley, 1996). Knowledge of relevant driving forces and their impact on gains or losses in ecosystem services contributes to provide consultations for sustainable development by delivering improved decision criteria and policy advice (Larigauderie and Mooney, 2010).

The objectives of our study are to identify and characterise the most relevant driving forces of LULCC in the Upper East Region located in the Sudanian and Guinean Savannah Zone of northern Ghana. We selected this study site due to the particularly vital role of LULCC in land degradation and its negative impact on agriculturally dominated socio-ecological systems in developing countries.

Specific research questions are:

• How and why are land use and land cover changing in the Upper East Region? What are the land use types that increase or decrease?

• What are the parameters that drive LULCC? Which ones are the most relevant direct and indirect driving forces of LULCC?

• How reliable are our findings? What are the advantages and disadvantages of a mixed-method approach using our study as test case?

Common methods for the identification of driving forces of LULCC in the Sudanian Savannah Zone are remote sensing (Braimoh, 2006, Mortimore et al., 2005), statistical analysis (Fischer et al., 2002, Zaal et al., 2004), local actor interviews (Mertz et al., 2009, Tschakert, 2007; West et al., 2008) or a combination of the above-mentioned methods (Antwi-Agyei et al., 2012, Dietz et al., 2004, Owusu et al., 2013, Wardell et al., 2003, Yiran et al., 2011).

In this paper, we suggest and present a mixed-method approach which allows for the analysis of one key aspect – driving forces of LULCC – from different methodological angles and provides information on reliability by comparing the findings.