90 years of forest cover change in an urbanizing watershed: spatial and temporal dynamics
- 595 Downloads
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.
KeywordsForest fragmentation Patch dynamics Gradient analysis Change detection Transition analysis Baltimore Urban ecology
This research was funded by the National Science Foundation LTER program (DEB 042376). We thank the two anonymous reviewers for their helpful comments and suggestions. We also thank Caitlin Hicks and Elizabeth Cook for their assistance with the initial data processing.
- Cadenasso ML, Pickett STA (2001) Effects of edge structure on the flux of species into forest interiors. Conserv Biol 15:91–97Google Scholar
- Cadenasso ML, Traynor MM, Pickett STA (1997) Functional location of forest edges: gradients of multiple physical factors. Can J For Res 27:774–782Google Scholar
- Forman TT (1995) Land mosaics: the ecology of landscapes and regions. Cambridge University Press, CambridgeGoogle Scholar
- Gerard F, Petit S, Smith G, Thomson A, Brown N, Manchester S, Wadsworth R, Bugar G, Halada L, Bezak P, Boltiziar M, De badts E, Halabuk A, Mojse M, Petrovic F, Gregor M, Hazeu G, Mucher CA, Wachowicz M, Huitu H, Tuominen S, Kohler R, Olschofsky K, Ziese H, Kolar J, Sustera J, Luque S, Pino J, Pons X, Roda F, Roscher M, Feranec J (2010) Land cover change in Europe between 1950 and 2000 determined employing aerial photography. Prog Phys Geogr 34:183–205Google Scholar
- Jahnige P (1999) The Gwynns Falls watershed ecological resource atlas. Revitalizing Baltimore project people and parks foundation. Baltimore, MarylandGoogle Scholar
- Lambin EF, Turner BL, Geista HJ, Agbola SB, Angelsen A, Bruce JW, Coomes OT, Dirzo R, Fischer, G, Folke C, George PS, Homewood K, Imbernon J, Leemans R, Lin X, Moran EF, Mortimore M, Ramakrishnan PS, Richards JF, Skånes H, Steffen W, Stone GD, Svedin U, Veldkamp TA, Vogel C, Xu J (2001) The causes of land-use and land-cover change: moving beyond the myths. Glob Environ Chang 11:261–269Google Scholar
- McGarigal K, Cushman SA, Neel MC, Ene E (2002) FRAGSTATS: spatial pattern analysis program for categorical maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. www.umass.edu/landeco/research/fragstats/fragstats.html
- Mieszkowski P, Mills ES (1993) The causes of metropolitan suburbanization. J Econ Perspect 7(3):35–47Google Scholar
- Whitney GG (1994) From coastal wilderness to fruited plain: a history of environmental change in temperate North America from 1500 to the present. Cambridge University Press, CambridgeGoogle Scholar