Can a small park preserve its flora? A historical study of Bic National Park, Quebec

摘要: We reconstructed the 100 year history of the botanical composition of a small (19 km2) park (Bic National Park, Bic/St. Fabien, Quebec) located within an agricultural landscape. Using 64 historical sources and a botanical field survey, we documented changes in the native and exotic vascular flora that occurred before and after the creation of the park in 1984. We evaluated how many native species were lost from 1984 to 2005, and the number of exotic species that became established during the same period. A total of 585 plant taxa were found in Bic National Park before its creation, of which 488 (83%) were native. The park harbours more taxa today (710) than in the past, but the proportion of exotic taxa has increased significantly (from 16% to 25%) since 1984. Despite its small area, Bic National Park has very successfully preserved its flora during its 21 year history. Thirteen species have likely been extirpated from the area occupied by the park. However, 12 of these 13 species have not been seen since at least 1957, so they were probably extirpated before the creation of the park. On the other hand, the creation of the park did not stop the introduction of exotic species. Land-use changes, an increase in the number of visitors, and horticultural plantings are probably the main causes explaining the rise in the number of exotic taxa observed during the last 21 years. A small park located far from urban centres may preserve its flora, but is not necessarily a bastion against exotic species.