Host‐use patterns of saproxylic phloeophagous and xylophagous Coleoptera adults and larvae along the decay gradient in standing dead black spruce and aspen

Abstract

Wood‐feeding insects play important functional roles in forest ecosystems, contributing significantly to wood decay processes. However, sampling these species in a direct and quantitative way is difficult because they live most of their lives as larvae deep into the wood; knowledge of species‐specific host‐use patterns along the decay gradient is thus lacking in this group. To cope with these difficulties, we used a novel approach, snag dissection, to investigate occurrence patterns of such Coleoptera adults and larvae. We selected 80 snags of both black spruce and aspen along four classes of decay in five different stands distributed over the tree species’ ranges within the province of Quebec, Canada, and dissected a one‐meter section of each. All adults and larvae of Buprestidae, Cerambycidae and Scolytinae (Coleoptera: Curculionidae) were collected and identified to the lowest taxonomical level possible. Wood density and snag age were also calculated for each sampled snag. In black spruce, host‐use was mostly concentrated at the beginning of the decay gradient. Patterns observed in aspen were opposite, as few insects were found in fresh snags, while most snags in middle to late stages of decay contained insects, often in large numbers, in some reaching densities of over 1000 cerambycid larvae m−3. For both tree species, patterns observed were similar across regions sampled. Differences in host‐use patterns between the coniferous and deciduous host species may be due to differences in secondary chemistry, mechanical defence mechanisms or the stand dynamics typically associated with each tree species.

Experimental studies of dead-wood biodiversity — A review identifying global gaps in knowledge

“…2, upper inset). In contrast to saproxylic beetles (Saint-Germain et al, 2007), the diversity of fungal fruiting bodies has its maximum at later decay stages, for example, after ten years in temperate forests (Heilmann-Clausen, 2001;Stokland et al, 2012). Thus, an essential part of the fungal succession on experimentally manipulated dead wood cannot be studied within the time span of most funding schemes by traditional surveys of fruiting bodies.…”

A decade of change in the saproxylic beetle fauna of eucalypt logs in the Warra long-term log-decay experiment, Tasmania. 1. Description of the fauna and seasonality patterns

“…Between the first and second decay-classes, the average rank-abundance of predatory and woodfeeding families decreased significantly, while fungus-feeders increased (although not significantly so). In another Canadian study of saproxylic beetles from spruce and aspen snags across the full spectrum of four decay-classes (Saint-Germain et al 2007), many individual species demonstrated strong preferences for wood of a particular density-range, with density itself being inversely related to decay-class.…”

Écologie de nidification du pic à dos noir (Picoides arcticus) en forêt boréale non brulée /

“…Individuals preferentially selected recently decayed snags (decay class 4), and avoided mid-(decay class 6) and advanced-decay snags (decay class 8). Saproxylic insect density in black spruce is higher in recently decayed snags (Saint-Germain et al 2007) and recently dwd (Vanderwel et al 2006). In the study area, these substrates were mainly located in post-mature coniferous stands, which Black-backed Woodpeckers have recently been shown to preferentially select for foraging (Tremblay et al 2009).…”