The effects of green tree retention and subsequent prescribed burning on ground beetles (Coleoptera: Carabidae) in boreal pine‐dominated forests

Abstract

We studied how two methods to promote biodiversity in managed forests, i.e. green tree retention and prescribed fire, affect the assemblages of carabid beetles. Our experiment consisted of 24 study sites, each 3–5 ha in size, which had been prepared according to factorial design. Each of the eight treatment combinations determined by the two factors explored – tree retention level (0, 10, 50 m3/ha−1 and uncut controls) and prescribed use of fire (yes/no) – was replicated three times. We sampled carabids using pitfall traps one year after the treatments. Significantly more individuals were caught in most of the burned sites, but this difference was partially reflective of the trap‐catches of Pterostichus adstrictus. The fire did not increase no. of P. adstrictus in the uncut sites as much as in the other sites. Species richness was significantly affected by both factors, being higher in the burned than in the unburned sites and in the harvested than in the unharvested sites. Many species were concentrated in the groups of retention trees in the burned sites, but only a few were in the unburned sites. The species turnover was greater in the burned than in the unburned sites, as indicated by the NMDS ordinations. Greater numbers of smaller sized species and proportion of brachypterous species were present in the burned sites. Fire‐favored species, and also the majority of other species that prefer open habitats were more abundantly caught in the burned sites than in the unburned sites. Dead wood or logging waste around the traps did not correlate with the occurrence of species. We conclude that carabids are well adapted to disturbances, and that frequent use of prescribed fire is essential for the maintenance of natural assemblages of carabid beetles in the boreal forest. Small retention tree groups can not maintain assemblages of uncut forest, but they can be important by providing food, shelter and breeding sites for many species, particularly in the burned sites.

Tree retention as a conservation measure in clear-cut forests of northern Europe: a review of ecological consequences

“…Size of the retention group also seems to be important for soil macrofauna (Siira-Pietikäinen & Haimi, 2009), but short-term effects are weak or not present (Siira-Pietikäinen et al, 2001, 2003. Beetles tend to survive better in group retentions, possibly because of the higher heterogeneity of deadwood substrates in these groups (Hyvärinen et al, 2005(Hyvärinen et al, , 2006Martikainen et al, 2006a). However, even very high retention amounts or large groups cannot maintain the forest interior species that are typical in mature and old-growth forests (Koivula, 2002;Martikainen et al, 2006a;Matveinen-Huju et al, 2009).…”

“…Beetles tend to survive better in group retentions, possibly because of the higher heterogeneity of deadwood substrates in these groups (Hyvärinen et al, 2005(Hyvärinen et al, , 2006Martikainen et al, 2006a). However, even very high retention amounts or large groups cannot maintain the forest interior species that are typical in mature and old-growth forests (Koivula, 2002;Martikainen et al, 2006a;Matveinen-Huju et al, 2009). The type of trees that are included in the retention groups may have a strong effect on species composition.…”

Ecosystem Responses to Partial Harvesting in Eastern Boreal Mixedwood Stands

“…Ground beetles (Coleoptera:Carabidae) are an abundant and diverse group of litter dwelling invertebrates and have been widely used to assess the impacts of a variety of intensities of forest harvesting [12,13], including clear cutting [14][15][16], salvage logging [17] and partial cutting with dispersed variable retention [18][19][20]. The intensity of overstory removal plays an important role mediating the composition of ground beetles.…”

Partial harvesting in the Canadian boreal: Success will depend on stand dynamic responses

“…To date, most research examining responses to partial harvesting in the boreal has focussed on biodiversity, specifically looking at how levels of retention affect taxa of conservation or ecological concern, such as small mammals (Moses and Boutin 2001, Fisher and Bradbury 2006), birds (Lance and Phinney 2001, insects (Gandhi et al 2004, Deans et al 2005, Martikainen et al 2006, ectomycorrhizal fungi (Dahlberg et al 2001, Lazaruk et al 2005, understorey plants Vanha-Majamaa 2001, Bradbury 2004), and coarse woody debris, an important habitat substrate (Deans et al 2003, Lilja et al 2005. Most studies find that partial cuts maintain levels of biodiversity higher than those found in clearcuts but lower than those of uncut stands.…”