Desertification and land degradation: origins, processes and solutions

Table of Contents

1. Authors and acknowledgements
2. Introduction
   1. Aims
   2. Definitions and key concepts
   3. Synthesis of previous and ongoing projects
   4. Key issues and outline
3. Evolution of desertification in the Mediterranean
   1. Climatic fluctuation
   2. Human influence
4. Primary drivers of desertification
   1. Biophysical and socio-economic causes
   2. Pathways of desertification
   3. Driving forces in the Mediterranean
   4. Synthesis of causes for DESIRE hotspots
   5. Conclusions
5. Processes and consequences of desertification in the Mediterranean
   1. Socio-economic and political factors
   2. Biophysical processes
   3. Conclusions
6. Indicators: monitoring desertification
   1. History of monitoring
   2. Indicators
   3. Monitoring and mapping techniques
   4. Concluding remarks
7. Modelling desertification
   1. Definition of modelling
   2. Model types
   3. Biophysical modelling
   4. Socio-economic and participatory modelling
   5. Gaps and progression in modelling
8. Solutions
   1. Biophysical solutions
   2. Political and socio-economic solutions
9. References

Primary drivers of desertification

The causes of dryland degradation are widely discussed in the literature but remain controversial (Thomas, 1997; Lambin et al., 2001; Reynolds and Stafford Smith, 2002; Geist and Lambin, 2004). Apart from papers trying to reach a consensus on the driving factors and feedbacks leading to desertification, many case studies exist in the literature that investigate the causes and processes of dryland degradation in specific areas (Geist and Lambin, 2004). It is not the scope of this review to enumerate all the primary factors or drivers of desertification that have been defined by scientists, or to define these drivers precisely and try to define a comprehensive list, that includes some but excludes others. Primary factors driving the desertification process in the Mediterranean area specifically are mentioned and discussed in this chapter.

First of all it is important to recognize that dryland ecosystems are inherently non-equilibrium systems and ecosystem dynamics are essentially event-triggered (Puigdefábregas, 1998). Most disturbances, such as rainfall variability and fire, are incorporated in dryland ecosystems during their evolution. However, some disturbances are new or not yet incorporated and may drive the system to qualitatively different new states along irreversible trajectories (Puigdefábregas, 1998).