Semiarid Environments

by

Sharon E. Nicholson

• LAST REVIEWED: 15 January 2015
• LAST MODIFIED: 15 January 2015
• DOI: 10.1093/obo/9780199363445-0015

Introduction

The world’s semi-arid regions are expected to be among those most sensitive to future climate change and increasing intensity of land use. Thus, the future may not bode well for the two billion people who inhabit these environments. The universal characteristic of semi-arid regions is that water, the essential resource, is discontinuously available in time and space. Environmental processes are extremely sensitive to its availability. Our understanding of these processes has increased exponentially in the late 20th and early 21st centuries. New disciplines such as ecohydrology and new concepts such as critical transitions and abrupt change have emerged at the heart of this new understanding. These emphasize the systems approach to understanding these regions: the interactions of climate, soils, vegetation, and people. Controversial issues still exist, examples being the response to global climate change and the extent of human impact on the environment. Many diverse aspects of this environment are reviewed here. The focus, however, is on the newest concepts and controversies.

General Overviews

A number of authors have provided excellent overviews of various aspects of semi-arid environments, especially the hydrological aspects. Bull and Kirby 2002 focuses on river systems, Wheater, et al. 2007 considers hydrologic modeling, and d’Odorico and Porporato 2006 and Wang, et al. 2012 cover the relatively new area of ecohydrology. Nicholson 2011 provides a detailed look at dryland climates and their links to environmental and hydrologic issues. Bourliere 1986 is an excellent reference on savanna environments, and it is extremely useful despite its age. Reynolds and Stafford Smith 2002 presents a broad-based assessment of issues related to desertification.

• Bourliere, M., ed. 1986. Tropical savannas. Ecosystems of the World, 13. London: Academic.

  This text is a compilation of individually authored chapters that cover a broad range of topics, such as environment, soils, nutrients, energy flow, inhabitants, vegetation, and even Quaternary history. Specific savanna systems on several continents are also discussed in detail.

• Bull, L. B., and M. J. Kirby, eds. 2002. Dryland rivers: Hydrology and geomorphology of semi-arid channels. Chichester, UK: Wiley.

  Contains four sections (twelve individual contributions) covering processes in dryland catchments, channel network expansion, and flooding in ephemeral channels, in addition to an overview on dryland rivers.

• D’Odorico, P., and A. Porporato. 2006. Dryland ecohydrology. Berlin: Springer.

  DOI: 10.1007/1-4020-4260-4

  This excellent overview of dryland ecohydrology contains eighteen chapters by ecologists and hydrologists.

• Nicholson, S. E. 2011. Dryland climatology. Cambridge, UK: Cambridge Univ. Press.

  DOI: 10.1017/CBO9780511973840

  Focuses not only on climate of the drylands but also on a number of environmental aspects such as vegetation, geomorphology, hydrology, and adaptation to drylands. Includes twenty-five chapters and an extensive literature review based on over two thousand references.

• Reynolds, J. F., and D. M. Stafford Smith. 2002. Global Desertification: Do Humans Cause Deserts? Dahlem, Germany: Dahlem Univ. Press.

  Presents the results of a workshop that included researchers from a wide variety of disciplines and with diverse perspectives regarding desertification. The book contains twenty-one individual chapters. It is one of the most extensive resources on desertification.

• Wang, L., P. D’Odorico, and J. P. Evans, et al. 2012. Dryland ecohydrology and climate change: Critical issues and technical advances. Hydrology and Earth System Sciences 16.8: 2585–2603.

  DOI: 10.5194/hess-16-2585-2012

  These authors identify some current critical issues related to dryland systems and their response to changes in climate and land use. They focus on agriculture and food security, population growth, desertification, shrub encroachment, and development.

• Wheater, H., S. Sorooshian, and K. D. Sharma. 2007. Hydrological modelling in arid and semi-arid areas. Cambridge, UK: Cambridge Univ. Press.

  DOI: 10.1017/CBO9780511535734

  This is a collection of eleven chapters by eminent hydrologists. Numerous diverse aspects of hydrologic modeling and forecasting are covered.