Historical land-cover conversion (1665-1820) in the Choptank watershed, eastern United States

Land-cover changes in the Choptank basin were estimated for 1665-1820 by using historical socioeconomic data and crop-rotation models. Socioeconomic data (human population, output per laborer, and crop yields) were obtained from the literature, whereas crop-rotation models, based on historical records, represented how agriculture was practiced. Model parameters and output were validated with export records, census data, and other historical records, and model errors were estimated to be approximately 5%. This approach indicated a sigmoidal pattern for conversion of primary forest to agricultural land by 1800. The initial time period, 1665-1720, was characterized by low-intensity tobacco and corn cultivation. Due to long fallows, the models indicated that there was little land in crops (approximately 5% of the region), but larger areas of secondary forest occurred on former cropland (approximately 15%). Although primary forest de-creased, the initial result in the first 55 years was a low net rate of deforestation and occupation by low-intensity farms. However, after 1720, cropland expanded rapidly due to the use of wheat as a cash crop. From 1720 to 1775, primary and secondary forest rapidly disappeared, increasing agricultural land to 60% of the region. By 1800, approximately 80% was estimated to be converted to agriculture, and little primary forest remained. After 1800, the land needed for crops decreased due to improved management practices and crop yields, and some secondary forest on formerly cleared agricultural sites may have reappeared. We estimate that less than 150 years of European colonization resulted in virtually complete agriculturalization of a primarily forested landscape.