Predicting the post-fire responses of animal assemblages: testing a trait-based approach using spiders

Abstract

Summary1. Developing a predictive understanding of how species assemblages respond to fire is a key conservation goal. In moving from solely describing patterns following fire to predicting changes, plant ecologists have successfully elucidated generalizations based on functional traits. Using species traits might also allow better predictions for fauna, but there are few empirical tests of this approach. 2. We examined whether species traits changed with post-fire age for spiders in 27 sites, representing a chronosequence of 0-20 years post-fire. We predicted a priori whether spiders with ten traits associated with survival, dispersal, reproduction, resource-utilization and microhabitat occupation would increase or decrease with post-fire age. We then tested these predictions using a direct (fourth-corner on individual traits and composite traits) and an indirect (emergent groups) approach, comparing the benefits of each and also examining the degree to which traits were intercorrelated. 3. For the seven individual traits that were significant, three followed predictions (body size, abundance of burrow ambushers and burrowers was greater in recently burnt sites); two were opposite (species with heavy sclerotisation of the cephalothorax and longer time to maturity were in greater abundance in long unburnt and recently burnt sites respectively); and two displayed response patterns more complex than predicted (abdominal scutes displayed a U-shaped response and dispersal ability a hump shaped curve). However, within a given trait, there were few significant differences among post-fire ages. 4. Several traits were intercorrelated and scores based on composite traits used in a fourth-corner analysis found significant patterns, but slightly different to those using individual traits. Changes in abundance with post-fire age were significant for three of the five emergent groups. The fourthcorner analysis yielded more detailed results, but overall we consider the two approaches complementary. 5. While we found significant differences in traits with post-fire age, our results suggest that a traitbased approach may not increase predictive power, at least for the assemblages of spiders we studied. That said, there are many refinements to faunal traits that could increase predictive power.

Successional specialization in a reptile community cautions against widespread planned burning and complete fire suppression

“…), invertebrate (Langlands et al . ) and bird (Barlow & Peres ) communities following disturbance. This approach has had variable success in describing the response of reptiles to disturbance (Caughley ; Letnic et al .…”

The impact of management strategies in apple orchards on the structural and functional diversity of epigeal spiders

“…The development of a trait-based ecology provides insight into assemblage-wide functional responses in environmentally variable environments (LeViol et al 2008;Violle et al 2007). Until now, in spiders, this approach by traits has been rarely used (Lambeets et al 2009;Langlands et al 2011). For environments that are strongly affected by natural or anthropogenic disturbance, species assemblages are expected to be structured by their ability (traits) to react to these disturbances (Ribera et al 2001;Bonte et al 2006).…”

Dry sandpits and gravel–sandpits serve as key refuges for endangered epigeic spiders (Araneae) and harvestmen (Opiliones) of Central European steppes aeolian sands

“…When a particular habitat was overgrown by trees (e.g., Populus nigra), most of the red-listed spider species disappeared (Appendix S4). The importance of the habitat age for spider assemblages diversity is consistent with their limited ability to colonize newly emerging habitats (Langlands et al, 2011;Bråten et al, 2012), particularly those distant from any well-preserved steppe habitats from which the species radiate into the newly emerging post-industrial sites. This trend differs from that previously observed for aculeate Hymenoptera, which responded much quicker to the emergence of new habitat and were tightly bound to extensive bare sand or bare soil patches .…”