Crossing the thresholds: Human ecology and historical patterns of landscape degradation

Ian A. Simpson*, Andrew J. Dugmore, Amanda Thomson, Orri Vésteinsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)


In discussions of landscape sensitivity, human activities have generally been regarded as external forces contributing to landscape change, with a focus on the impacts of cultivation methods, fertiliser practices, grazing pressures and atmospheric pollution. However, there has been comparatively little study undertaken that integrates physical and social systems in a historic context to explain the basis of human activity in sensitive landscapes. Where such attempts have been made, the manner of common land management has figured prominently, with 'tragedy of the commons' concepts used to explain land degradation and to provide a foundation for policy response. This has also been the case in Southern Iceland and in this paper we assess the extent to which common land domestic grazing pressures were the primary external force causing soil erosion and land degradation during the period of occupation from ca. 874 AD. We first provide field observation of soil erosion, temporally defined by tephrochronology, to highlight the extent of land degradation during this period. The 'tragedy of the commons' explanation of degradation is then assessed by evaluating historic documentary sources, and by environmental reconstruction and modeling of historic grazing pressures. These analyses indicate that regulatory mechanisms were in place to prevent overgrazing from at least the 1200s AD and suggest that there was sufficient biomass to support the numbers of domestic livestock indicated from historic sources. We suggest that failure to remove domestic livestock before the end of the growing season and an absence of shepherding were more likely to contribute to land degradation than absolute numbers. Lack of appropriate regulation of domestic livestock on common grazing areas can be attributed to limited cultural knowledge of changing and rapidly fluctuating environmental conditions.

Original languageEnglish
Pages (from-to)175-192
Number of pages18
Issue number2-4
Publication statusPublished - 2001

Bibliographical note

Funding Information:
Aspects of this work have been supported by a National Science Foundation Grant (via the North Atlantic Biocultural Organisation), by the National Geographic Society and by the Leverhulme Trust. We are grateful to Tracy Grieve and Bill Jamieson (both from the University of Stirling) for their assistance in developing the GIS data base.

Other keywords

  • Andisols
  • Common land
  • Cultural knowledge
  • Grazing
  • Historical ecology
  • Soil erosion
  • Tephrochronology


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