RESEARCH ARTICLE Effects of surrounding urbanization on non-native flora in small forest patches Ste ´ phanie Duguay Æ Felix Eigenbrod Æ Lenore Fahrig Received: 19 May 2005 / Accepted: 9 October 2006 / Published online: 12 December 2006 Ó Springer Science+Business Media B.V. 2006 Abstract The purpose of our study was to compare the number, proportion, and species composition of introduced plant species in forest patches situated within predominantly forested, agricultural, and urban landscapes. A previous study suggested that agricultural landscape con- text does not have a large effect on the proportion of introduced species in forest patches. Therefore, our main goal was to test the hypothesis that forest patches in an urban landscape context contain larger numbers and proportions of non- native plant species. We surveyed the vegetation in 44 small remnant forest fragments (3–7.5 ha) in the Ottawa region; 15 were situated within forested landscapes, 18 within agricultural land- scapes, and 11 within urban landscapes. Forest fragments in urban landscapes had about 40% more introduced plant species and a 50% greater proportion of introduced plant species than frag- ments found in the other two types of landscape. There was no significant difference in the number or proportion of introduced species in forest fragments within forested vs. agricultural land- scapes. However, the species composition of introduced species differed among the forest patches in the three landscape types. Our results support the hypothesis that urban and suburban areas are important foci for spread of introduced plant species. Keywords Forest plants Á Forest flora Á Forest vegetation Á Introduced species Á Non-native species Á Landscape context Á Urbanization Á Species richness Á Forest patch Á Forest fragmentation Introduction Most introduced plants are open-habitat species (Fensham and Cowie 1998; Cadotte and Lovett- Doust 2001; Weaver et al. 2001; Rubino et al. 2002; Charbonneau and Fahrig 2004; Gray 2005). Landscapes containing more open habitats should therefore contain more introduced plant species and higher abundances of introduced plant spe- cies than landscapes containing mainly forest. High abundances of introduced plants in open landscapes should produce a large influx of seeds of alien plant species into remnant forest patches within these landscapes (Boutin and Jobin 1998; Cullen et al. 2001). This should, in turn, result in S. Duguay Á F. Eigenbrod Á L. Fahrig (&) Geomatics and Landscape Ecology Research Laboratory, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada e-mail: lenore_fahrig@carleton.ca S. Duguay e-mail: stephausoleil@hotmail.com F. Eigenbrod e-mail: felix.eigenbrod@gmail.com 123 Landscape Ecol (2007) 22:589–599 DOI 10.1007/s10980-006-9050-x