Victorin’s gentian COSEWIC assessment and status report: chapter 7

Population Sizes and Trends

Legault (1986) reported that Victorin’s gentian was known in 20 localities in 1985, including two destroyed localities. The Lotbinière population totaled 15 individuals, the Berthier-sur-Mer population had 10 individuals and the Saint-Vallier population had 300 individuals. The inventory by Brouillet et al. (1996) resulted in the discovery of several new localities, and the inventory of 2002 confirmed the disappearance of several localities and resulted in the discovery of one new population. In 2002, the Centre de données sur le patrimoine naturel du Québec (CDPNQ) had information on 49 populations of Victorin’s gentian, but after verification, it was found that a number of populations appeared twice, with slightly different names (e.g., Pointe à Belleau and Pointe à Alain, which designate the same location). A different problem occurred in Saint-Jean-Port-Joli, where CDPNQ created two occurrences for a single locality, whereas the two sub-populations are within 100 metres of each other. The opposite occurred at Saint-Vallier, where Anse de Saint-Vallier and Pointe de Saint-Vallier were combined, despite the fact that the two sub-populations were 5 km apart. The situation was reported to CDPNQ and will soon be corrected. The four questionable localities will not be included in this report.

Victorin’s gentian is now known in 43 localities and we have demographic data for 32 of the 43 localities. The populations are classified as follows: 7 populations have a quality index A, 2 populations have a quality index B, 4 populations have a quality index C, 12 populations have a quality index D, 7 populations have a quality index X (eradicated population), and 1 population has a quality index E (see Tables 1 and table 22 for explanation of index ratings). There are also 10 historic populations.

The discovery of many new populations has resulted in a significant increase in the number of known individuals of Victorin’s gentian since 1986. Seven of these populations alone (Deschambault, Pointe Platon at Sainte-Croix, Pointe d'Argentenay at Saint-François, Grosse-Île, Pointe de Saint-Vallier at Saint-Vallier, Sainte-Augustine-de-Desmaures and Anse chez Porteous à Sainte-Pétronille) account for over three-quarters of the Victorin’s gentian plants in Canada (between 90% if we use the lower limit and 75% if we use the upper limit). New populations may still be discovered along the St. Lawrence River. The inventories of the summer of 2002 on several localities resulted in the discovery of a new population (Sainte-Pétronille, Anse chez Porteous) and made it possible to update the demographic data for certain populations (Saint-Vallier, Pointe à Labrecque and Saint-Augustin-de-Desmaures). Five of the remaining 10 historic localities, should not be considered eradicated because the habitat is favourable to the growth of Victorin’s gentian.

[Subsequent to the completion of this report, two populations were re-discovered. Despite many previous efforts to locate it, Victorin’s gentian was finally found in July 2003 by André Sabourin at the Saint-Jean-Port-Joli, Pointe à Menin, site. It consisted of 50 -100 flowering plants. Victorin’s gentian was also re-located at a historic site at Saint-Roch-des Aulnaies, Pointe à Chouinard where Sabourin found 70-100 flowering plants in August 2003. These new data have been included in the technical summary.]

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