Reconstructing Historic Ecotones Using the Public Land Survey: The Lost Prairies of Redwood National Park

Abstract

Restoration of natural systems depends, in part, on reconstructing historic landscapes to serve as reference ecosystems. The most effective historic landscape reconstruction relies on multiple lines of evidence at different temporal and spatial scales. This study analyzes original Public Land Survey (PLS) records and compares the results with previous work that relied on dendroecology and aerial photograph evidence of vegetation change. Notations in the land survey regarding the location of prairie-woody vegetation ecotones in the Bald Hills of Redwood National Park were transcribed into a geographic information system. Sugihara and Reed (1987) measured the degree of coniferous forest encroachment into prairies and oak woodlands, estimating a 29 percent loss in the spatial extent between 1850 and 1983. The location of 1875–1882 land survey records of ecotones provides evidence that transects across the prairies might have narrowed by as much as 44 percent. Furthermore, this study found evidence of both oak woodland and coniferous forest encroachment into prairies, and that the diminishment of prairies further inland might result primarily from the expansion of oak woodland. A reconstruction of the historic landscape that relies on both field and archival evidence is the best approach to defining reference ecosystems.