Baltimore Ecosystem Study: Forest Cover in the Gwynns Falls watershed from 1914 to 2004

Landscape structure in the Eastern US experienced great changes in the
last century with the expansion of forest cover into abandoned
agricultural land and the clearing of secondary forest cover for urban
development. In this paper, the spatial and temporal patterns of
forest cover from 1914 to 2004 in the Gwynns Falls watershed in
Baltimore, Maryland were quantified from historic maps and aerial
photographs. Using a database of forest patches from six times—1914,
1938, 1957, 1971, 1999, and 2004—we found that forest cover changed,
both temporally and spatially. While total forest area remained
essentially constant, turnover in forest cover was very substantial.
Less than 20% of initial forest cover remained unchanged. Forest cover
became increasingly fragmented as the number, size, shape, and spatial
distribution of forest patches within the watershed changed greatly.
Forest patch change was also analyzed within 3-km distance bands
extending from the urban core to the more suburban end of the
watershed. This analysis showed that, over time, the location of high
rates of forest cover change shifted from urban to suburban bands
which coincides with the spatial shift of urbanization. Forest cover
tended to be more stable in and near the urban center, whereas forest
cover changed more in areas where urbanization was still in process.
These results may have critical implications for the ecological
functioning of forest patches and underscore the need to integrate
multi-temporal data layers to investigate the spatial pattern of
forest cover and the temporal variations of that spatial pattern.

Zhou, W., G. Huang, S. T. A. Pickett, and M. L. Cadenasso. 2011. 90
Years of Forest Cover Change in an Urbanizing Watershed: Spatial and
Temporal Dynamics. Landscape Ecology 26:645–659.
https://doi.org/10.1007/s10980-011-9589-z.