Phenology of Ground-Dwelling Beetle Assemblages (Coleoptera: Carabidae, Staphylinidae) from Three Fir Stands of Southern Québec (Canada), with Comparison among Selected Species between 1985 and 2006-2010

A total of 5,303 adult epigaeic beetles (Coleoptera) were collected using pitfall traps across three balsam fir (Abies balsamea (Linnaeus) Miller) stands in southern Québec (Canada). Sampling occurred during May–September 1985 in sites representing three distinct understory vegetation types. Three dominant families (Carabidae, Leiodidae and Staphylinidae) together represented at least 93% of catches at each site. Staphylinidae were less abundant than Carabidae at two sites, whereas Carabidae and Staphylinidae were collected in similar numbers at a third stand. Associated with increased abundance and heterogeneity of the understory vegetation, we observed 1) the decrease of specialist forest carabids, often active in spring, such as Platynus decentis (Say), Pterostichus adstrictus Eschscholtz and Pterostichus tristis (Dejean), and 2) the increase of non-specialist forest carabids and staphylinids, often active in mid- or late summer, such as Agonum gratiosum (Mannerheim), Agonum trigeminum Lindroth, Patrobus longicornis (Say), Pterostichus luctuosus (Dejean), Dinothenarus badipes (LeConte) and Tachinus limbatus Melsheimer. Among the nine abundant species captured both in 1985 and during a subsequent study at a neighboring locality (2006–2010), phenological differences were observed only in the rove beetle Lesteva pallipes LeConte. This cold-season species is characterized by aestival adult diapause.