Two years post harvest cut block in the South Nadina.
Photo: Deanna Danskin.

Duncan McColl
University of Northern British Columbia
MSc. (NRES ) Candidate

Direct and indirect effects of harvesting on carabid beetle community composition in regenerating sub boreal spruce stands, and carabid ant interactions

Ground beetles (Carabidae) are active ground dwelling invertebrates which inhabit a wide variety of ecological niches. They occupy several feeding guilds, which represent most trophic levels in forest ecosystems (Lindroth 1969; Lövei and Sunderland 1996). Furthermore, carabids likely make up a substantial component of the diet of a variety of insectivorous vertebrates and invertebrates. These qualities, along with a stable and well known taxonomy, and rapid responses to environmental change, make carabids especially well suited to studies focusing on environmental change (Niemelä et al. 1988; 1992).

In much of the boreal forested regions of the world industrial forestry has replaced natural disturbance (i.e. fire, windthrow, insect outbreaks) as the primary stand initiating event. This shift has played a part in the need to be able to assess the effects of industrial resource management on the land base, in this case forests. Since carabids have been shown to respond rapidly to environmental perturbations, including anthropogenic disturbance, and can be monitored by standardized and cost effective means, these beetles have become favorite subjects as potential indicator species in many studies (Rainio and Niemelä 2003).

Calosoma sp. (?)

Modified Nordlander type pitfall trap in a 15 year post harvest stand.

Carabids have been examined extensively as indicators of forest health. Change in distribution, particularly of large-bodied species has been linked to forest fragmentation in Finland (Halme and Niemelä 1993) and loss of structural cover (Brose 2003). In addition to the direct effects of stand harvesting the indirect effect of increased abundance of aggressive ant species likely has a great effect on carabid abundance, activity and species composition. It has been stated that neglecting ants in carabid studies may lead to misleading conclusions (Lövei and Sunderland 1996). This statement is supported by findings by Hawes et al. (2002), Koivula (2002) and Reznikova and Dorosheva (2004).

Synchus impunctatus attacked by Formica neorufibarbis.
Photo: Robert Higgins

The purpose of my research is threefold: (1) To ascertain what the carabid community composition is in the Sub boreal spruce biogeoclimactic zone of central British Columbia and how that community responds to clear cut forestry practices utilizing modified Nordlander pitfall traps (Lemeiux and Lindgren 1999), (2) to examine possible associations between carabids and environmental variables such as coarse woody debris, vegetation, stand age and ants, and (3) to experimentally assess the impact of Formica aserva on the carabid community in regenerating forests.

Reference List

Photos taken by D.McColl unless otherwise stated.