Abstract
Exposed riverine sediments are unique riparian environments that exhibit high biodiversity and harbor many specialist species. Ground beetles are the most well studied inhabitants within these environments where they are often sampled using pitfall traps. In order to develop conservation measures for species occupying these habitats a logical first step is to refine sampling methods so that proper biodiversity assessments can be carried out. To that end, the effectiveness of two pitfall trap designs (standard trap vs. barrier trap) was evaluated. Over three sampling periods we collected 5,186 individuals represented by 43 species. Barrier traps proved to be superior, yielding significantly greater numbers of individuals (n = 3,456 vs. 1,730) than standard traps. Additionally, we collected more ground beetle species (37 vs. 30) in barrier traps than in standard pitfall traps. This study supports the rationale for deployment of more than one trap design to avoid deficiencies exhibited by a single type.
Highlights
Exposed riverine sediments (ERS) are sparsely vegetated areas consisting of gravel, sand, or silt that occur between the stream bank and the water’s edge
The barrier traps caught almost twice as many individual ground beetles as the standard traps (n = 3,456 vs. 1,730) where they accounted for 66% of the total
A paired ttest revealed significant differences in the mean number of ground beetles collected from barrier pitfall traps (M = 864, SD = 473.33) and standard traps (M = 432.5, SD = 245.49); t(3) = 3.23, P = 0.048. (Fig. 4)
Summary
Exposed riverine sediments (ERS) are sparsely vegetated areas consisting of gravel, sand, or silt that occur between the stream bank and the water’s edge. This ecotone generally has a high level of habitat heterogeneity associated with high beetle diversity (Bates et al, 2007a). Many of the beetles residing on ERS exploit aquatic food sources (Hering & Plachter, 1997; Paetzold et al, 2005) whereas others predominantly known to occur in forested habitats have been caught on ERS suggesting that they are opportunistically taking advantage of resources stranded near the water’s edge (Horn & Ulyshen, 2009). In order to maximize monitoring programs aimed at pinpointing causal agents of ERS degradation and subsequent acts of restoration, it is imperative to develop sampling methods that are both easy to deploy and highly effective for targeted organisms
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