Land cover and its spatial patterns are key ingredients in ecological studies that consider large regions and the impacts of human activities. Because humanity is a principal driver of land-cover change over large regions (Turner et al. 1990), land-cover data provide direct measures of human activity, and both direct and indirect measures of ecological conditions within human-dominated landscapes (O'Neill et al. 1997). Thus, incorporating land-cover information is a way to place humans directly into regional ecological models and assessments.
Riitters, Kurt H.; Wickham, James D.; Vogelmann, James E.; Jones, K. Bruce. 2000. National land-cover pattern data. Ecology 81: 604